A prospective observational study of immediately loaded platform switched 3i implants

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A PROSPECTIVE OBSERVATIONAL STUDY OF

IMMEDIATELY LOADED PLATFORM SWITCHED 3I IMPLANTS

by

Jackie Chi

A Thesis Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
(CRANIOFACIAL BIOLOGY)

May 2009

Copyright 2009 Jackie Chi

ii

TABLE OF CONTENTS

List of Tables iv

List of Figures v

Abstract vi

Preface vii

Chapter 1: Introduction 1
Dental Implants 2
Implant Integration 3
Bone Structure and Formation 7
Loading Protocol 9
Biological Width 21
Platform Switching 24
Implant Complications 26
Microgap 30
Occlusal Overload 32
Micromotion 34
Patient Factors 36
Peri-implantitis 38
Measurement of Implant Stability 45

Chapter 2: Materials and Methods 49
Test Device 51
Study Procedures 52
Surgical Procedures 60
Restorative Procedures 61
Clinical Measurements 63
Visual Analog Scale 64
Microbiological Sampling 65
Evaluation Criteria 67
Statistical Analysis 67

Chapter 3: Results 72

iii

Chapter 4: Discussion 92
Crestal Bone Loss 101
Microbiology 109
Visual Analog Scale 115
Causes of Implant Failure 116
Study Limitations 132

Chapter 5: Conclusion 135

Bibliography 137

iv

LIST OF TABLES
Table 1: Timing of Implant Loading 11
Table 2: Patient Inclusion Criteria 49
Table 3: Patient Exclusion Criteria 50
Table 4: Gingival and Plaque Index 55
Table 5: Descriptive Statistics 73
Table 6: Crestal Bone Loss 79
Table 7: Microbial Results 81
Table 8: Percentages of Cultivable Periodontal 82
Pathogens for Pooled Natural Teeth at
Baseline and Integrated Implant sites at
3 Months

Table 9: Percentages of Cultivable Periodontal 83
Pathogens for Pooled Natural Teeth at
Baseline and Failed Implant Sites at
3 Months

Table 10: Percentages of Cultivable Periodontal 84
Pathogens for Integrated vs. Failed Implants
at 3 Months

Table 11: Comparison of Overall Periodontal 85
Pathogens

Table 12: Patient VAS Correlations 90
Table 13: Comparison of Patients’ VAS Results 91

v

LIST OF FIGURES
Figure 1: 3i Osseotite Certain IOL Implant Device x
Figure 2: Baseline Clinical Conditions Form 56
Figure 3: Implant Placement Form 57
Figure 4: Clinical Evaluation Form 58
Figure 5: Prosthesis Evaluation Form 59
Figure 6: Crestal Bone Analysis 69
Figure 7: VAS Patient Evaluation Form 70
Figure 8: VAS Investigator Evaluation Form 71
Figure 9: Implant Survival Graph 74
Figure 10: Mean Crestal Bone Level 77
Figure 11: Comparison of Overall, Mesial, and 78
Distal Implant Sites

Figure 12: Microbial Count: P. gingivalis, 86
P. intermedia, and T. forsythia

Figure 13: Microbial Count: Campylobacter sps., 87
Eubacterium sps., and Fusobacterium sps.

Figure 14: Microbial Count: P. Micros, Enteric Gram 88
Negative Rods, Yeast, and E. Corrodens

vi

ABSTRACT
The present prospective clinical study investigated immediate occlusal
loading in relation to long-term, clinical outcomes with the 3i Osseotite Certain
IOL implant. Radiographs, bacterial sampling, and clinical measurements were
obtained at baseline and at follow-up (up to 3 years).
The overall survival rate was 70.6% (12/17) and mean crestal bone loss
was 2.04 mm (SD = 1.26). Mesial implant sites had an average greater bone
loss (2.22 ± 1.66 mm) than distal sites (1.85 ± 0.67 mm). Microbiological
sampling of integrated and failed implants revealed similar periodontal pathogens
compared with baseline and pool. VAS indicated patient satisfaction was highly
correlated (r >0.91, p <0.002) with the ability to chew, pain on chewing, and
comfort.
3i IOL implants did not provide a viable and predictable method of
treatment and platform switching did not prevent crestal bone loss. Immediate
loading did not notably influence the composition and quantity of periodontal
pathogens.

vii

PREFACE
The objective of the present study is to investigate immediate occlusal
loading in relation to long-term, clinical outcomes with the 3i Osseotite Certain
IOL (Integrated Osseous Lateralization) implant test device. In addition, the
study aims to determine whether immediately loaded dental implants harbor
greater quantities and/or different species of periodontal pathogens than natural
teeth.
Brånemark (1969) established the original implant protocol recommending
a two-stage postoperative healing period which consisted of countersinking the
implant below the crestal bone, soft –tissue coverage, and minimal implant load
for 3 to 6 months. The rationale for delayed loading is to minimize the risk of
failure.
1,2
Recently, a reevaluation of the traditional Brånemark two-stage
protocol has occurred due to patient demands for shorter healing periods. Some
researchers contested that the required duration of an undisturbed healing was
empirically based and has not been verified experimentally.
3

Immediate occlusal loading of dental implants is a controversial treatment
option consisting of a one-stage surgery (non-submerged implants) and loading
of implants with a provisional or definitive restoration within 24 hours.
4

Immediate loading of implants provides several benefits such as accelerated

1
Albrektsson et al. 1981, 86
2
Brunski et al. 1992
3
Szmukler-Moncler et al. 1998
4
Ostman 2008
viii

overall treatment time, less surgical intervention, psychological benefits,
increased pt acceptance of implant therapy, and enhanced esthetic appearance
during the healing period.
5,6

Several investigators have reported that immediately loaded implants
placed in good quality bone are clinically equivalent to implants placed with a
delayed loading protocol. Schroeder et al.
7
showed that osseointegration with a
one stage procedure is predictable, which was confirmed by animal and
controlled clinical studies using the Brånemark System® (Nobel Biocare AB,
Göteborg, Sweden).
8 ,9,10
Schnitman et al.
11
published the first longitudinal clinical
trial supporting immediate loading in the mandible and found an 85% survival
rate.
A 2007 Cochrane systematic review of immediate, early, and conventional
loading times determined that it is possible to successfully load implants
immediately or early after placement.
12
However, most literature supporting
immediate loading are based on retrospective data or uncontrolled cases and
there is growing concern that immediately loaded implants may result in
increased failure rates. Currently, few randomized prospective longitudinal
studies exist evaluating immediate loading of platform switched implants.

5
Yoo et al. 2006
6
Ostman et al. 2008
7
Schroeder et al.1976
8
Esposito et al. 2007
9
Ericsson et al. 1997
10
Abrahamsson et al. 1996
11
Schnitman et al. 1997
12
Esposito et al. 2007
ix

The 3i Osseotite Certain IOL (3i, Implant Innovations, Inc., Palm Beach
Gardens, FL) prototype implant system consists of an internal connection,
threaded titanium alloy implant, and features three design elements of exisitng 3i
concepts (natural taper (NT), expanded platform (XP), and platform switching) to
enhance immediate occlussal load (Figure 1).
Osseotitie NT implant has shown to be successful in immediate loading
restorations as it achieves a strong primary fixation at time of surgery. The
expanded platform, at the coronal portion, allows a rigid stabilization with
enhanced emergence profile with the larger platform. The implant is lateralized
where the seating surface tapers at a 15 degree angle. In addition, the platform
switching component medializes the implant – abutment junction, to move the
interface away from the surrounding crestal bone. In theory, the inflammatory
connective tissue infiltrate is contained above the platform, and the peri-implant
bone is protected from the inflammatory connective tissue infiltrate and thus
reduces crestal bone resorption.
13

13
Lazzara, Porter 2006
x

Figure 1. 3i Osseotite Certain IOL Implant Device

A. B.

A. 3i Osseotite Certain IOL test device has a combination of three features:
Osseotite NT, Osseotite XP, and Platform switching.
B. The coronal aspect of the implant features the platform switching
component. The implant is lateralized where the seating surface tapers at a
15 degree angle.

xi

The three key design elements of the Osseotite IOL implant is postulated
to enhance immediate loading. Clinical trials are needed to evaluate the device
for successful osseointegration, restoration, and long-term performance. Specific
study objectives include to document the performance and safety characteristics
of the Osseotite IOL implant system when used for immediate restoration with
occlusal loading.
In addition, numerous investigations have shown an association between
periodontal pathogens, peri-implantitis, and dental implant failures.

On the
basis of a MEDLINE search, no studies have specifically addressed the
microbiology related to immediately loaded dental implants.
The purpose of the microbiological investigation was to examine within
and between subject differences with regard to the microflora of immediately
loaded dental implants. To specifically determine if immediately loaded dental
implants show an increased or decreased quantity of putative periodontal
pathogens in peri-implant microbiota when compared to the natural dentition and
whether immediately loaded dental implants exhibit a microbial composition
different from that found in the natural dentition.
1

CHAPTER 1: INTRODUCTION

Dental implants are a reliable alternative to conventional removable
prosthesis and have dramatically improved masticatory function with consistent
long term results. Removable prostheses result in accelerated bone loss,
deteriorating effects on masticatory efficiency and loss of overall lifespan.
14,15

Implants provide patients with a natural and stable long term alternative for the
replacement of edentulous areas. The American Academy of Periodontology
(2000) estimates 300,000 to 428,000 dental implants are placed yearly.
16
The
advantages of implants include preservation of adjacent teeth, improved
esthetics, ability to clean interproximal tooth surfaces, and reduced risk of dental
caries, sensitivity and endodontic problems of adjacent teeth.
17
Numerous
studies have documented success rates of dental implants to be approximately
97% for 10 years.
18,19,20,21

The concept of dental implants was founded 4,000 years ago by the
ancient Chinese. Peg-shaped bamboo sticks were constructed to replace
edentulous areas. Sea shells, gold, and various other metals were used as
possible materials for implants. In 1809, Maggiolo, from France, created a

14
Chen et al. 1984
15
Joshipura et al. 1996
16
AAP 2000
17
Misch et al. 2008
18
Goodacre et al. 2003
19
Schmitt et al. 1993
20
Haas et al. 1995
21
Fugazzotto et al. 2005
2

root form implant from gold. Strock (1938, Boston, Mass) designed a one-
piece implant fabricated from cobalt chromium molybdenum alloy. The Strock
implant lasted 15 years in the maxillary lateral position. Research in dental
implantology was first led by Brånemark from Sweden in the early 1960s.
Brånemark ‘s discovery that titanium could integrate with living bone tissue led
to the breakthroughs in dental implantology.
22

DENTAL IMPLANTS
Implants can be subperiosteal (framework placed above bone) or
endosteal (root-form). Currently, the majority of implants used are endosteal
implants which are placed within bone and consist of either root, blade, or
plate form.
23
Implants are screw or cylindrical-shaped and are made of
titanium or titanium alloy (titanium-aluminum-vanadium). Titanium is non-
corroding, light weight metal

with a high strength-to-weight ratio which allows it
to be alloyed easily with other metals.
24
Aluminum and vanadium are added to
titanium due to their unique properties. Aluminum is light weight and increases
the strength of the alloy. Vanadium acts to scavenge the aluminum and thus
prevent corrosion.
Implant macrostructure and microstructure have been continuously
modified to allow for faster integration and to reduce healing process.

22
Branemark et al. 1969
23
Mefferet 1994
24
Sarment 2004
3

Alterations in implant macrostructure include the design and shape of the
implant. Microstructural modifications include changes in the surface
properties. Implant surfaces, range from smooth to rough and current studies
indicate that bone cells react favorably to roughened titanium surfaces.
25

Commonly used methods to roughen implants are mechanical, chemical, or
combination of both. Mechanical means employ sand-blasting or etching
chemically with various acids (i.e. hydrochloric or sulfuric acid). Also, the
implant surface is covered by a titanium oxide layer. Albrektsson originally
described the formation of an oxide layer on implant surfaces (3 – 5 Å) by the
oxidation of titanium alloy.
26
Exposure of titanium to oxygen creates a
titanium dioxide coating on the surface and thus allows a natural attachment
between bone cells. The oxide layer is hydrophilic, corrosion resistant, and
highly biocompatible.
27

IMPLANT INTEGRATION
Implant stability is defined by the absence of clinical mobility and is
dependent on the form of contact between bone and implant surface or
osseointegration. Brånemark first coined the term osseointegration.
28

Osseointegration is the direct mechanical connection between bone and

25
Palacci et al. 2001
26
Albrektsson 1985
27
Hansson et al. 1983
28
Branemark et al. 1969
4

implant and has led to the success of dental implants.
29,30,31
Several
definitions of osseointegration have incorporated the ideal of a direct bone
deposition on implant surfaces or a functional ankylosis.
32
Studies indicate
that osseointegration is obtained approximately 4 weeks post-implant
placement.
33
Another form of bone to implant contact is biointegration.
Biointegration is the bonding of living bone to implant surface that is
independent of any mechanical interlocking mechanism.
34
The
hydroxyapatite bond to alveolar bone is an example of biointegration. Bone
has been shown to be approximately either in contact or 20 nm away from the
implant surface.
35,36
The stability of the implant is due to the contact between bone and
implant surface; however, various systemic, implant design, and surgical
factors contribute to implant success. Primary implant stability is the
mechanical engagement with cortical bone that occurs at the time of implant
placement.
37
It is governed by the mechanical properties of the bone and
susceptible to surgical technique and implant design. Secondary stability or
biological response is achieved through bone regeneration and remodeling

29
Schenk et al. 1998
30
Brånemark et al. 1977
31
Listgarten et al. 1991
32
Schroeder et al. 1981
33
Ostman 2008
34
Meffert et al. 1987
35
Albrektsson et al. 1985
36
Listgarten et al. 1991
37
Palacci et al. 2001
5

which occurs after the initial healing period.
38
An undisturbed healing period
is essential for proper osseointegration.
Implant success is defined as an osseointegrated dental implant that is
restored fully and allows functional gain of support.
39
The criteria for implant
success includes lack of mobility, lack of pain, absence of persistent infection,
absence of peri-implant radiolucency, and changes in crestal bone level ≤ 1.5
mm in the first year of function and < 0.2 mm annually in subsequent years.
40

The correlation of implant surface and primary stability has been
controversial. Implant surface modifications aim at accelerating the rate and
improving the quality of osseointegration. Critical factors for the establishment of
osseointegration are the implant surface microtopography and the local
mechanical environment. Glauser et al.
41
compared machine and oxidized
implants using an immediate loading protocol and found less stability with
machined implants during the first 3 months post-loading.
However, Hermann et al.
42
found high success rates with machined
(smooth) implants. Also, various other reports
43,44
found similar decrease in
stability with machined implants during early healing periods. Furthermore,

38
Palacci et al. 2001
39
Wood et al. 2004
40
Albrektsson et al. 1986
41
Glauser et al. 2001
42
Hermann et al. 2000
43
Rompen et al. 2000
44
Khang et al. 2001
6

several contradictory studies
45,46,47,48
claim no differences between rough or
smooth implant surfaces with regard to implant stability. Vandamme et al.
49
in
an animal study, evaluated the bone response around a turned and roughened
implant for either an unloaded or loaded (prosthesis placed within 24 hours after
implant placement) environment. The results indicated no microtopographic
dependence of the bone further away from the implant in both unloaded and
loaded conditions. For a load-free implant, rough implant surfaces showed a
higher osseointegration, however, under loaded conditions there was no
significant difference in osseointegration between rough or machined surfaces.
A 2003 ITI Consensus Conference
50
established the insertion torque
(primary stability) of a dental implant to be a minimum of 35-45 Ncm.
However, the main determinants of implant stability are the mechanical
properties of the bone and how the implant is engaged with the bone. Primary
implant stability is dependent on the bone density, implant design, implant
diameter, and the anterior/posterior position of the implant.
51

The greatest
risks of implant failure are during the first week after implantation. Bone is
stronger on the day of implant placement in comparison to 3 months post-
surgery, since there is more mature lamellar bone.
52
However, the cellular

45
Al-Nawas et al. 2007
46
Froberg et al. 2006
47
Shalabi et al. 2006
48
Vandamme et al. 2008
49
Vandamme et al. 2008
50
Third ITI Consensus Conference 2003
51
Smith et al.1989
52
Strid 1985
7

component of the implant surface condition is not formulated at this time.
During implant placement there is residual cortical and trabecular bone around
the implant and upon insertion, the implant contacts the remaining bony
socket. Thus, early cellular repair is triggered by the surgical trauma and an
increased vascularization and repair process begins at the injured bone.
Numerous studies
53,54
have reported the reliability of immediately
placed implants at time of extraction. Lazzara in 1989 was the pioneer of
immediate implant placement in fresh extraction sockets and found high
success rates.
55
Yet, histological studies show woven bone formation by
appositional growth may only begin to form the second week after implant
insertion, at a rate of 30 to 50 microns per day.
56
The bone to implant contact
is weakest and at the highest risk of overload at approximately 3 to 5 weeks
after implant placement.
57

BONE STRUCTURE AND FORMATION
Bone consists of cortical (compact) and cancellous (trabecular, spongy)
bone. Cortical bone is 95% mineralized bone and is arranged into densely
packed sheets of lamella with osteons and a highly organized Harversian
system.
58
In contrast, cancellous bone is only 30% mineralized and 10 to 20

53
Schwartz-Arad et al. 1997
54
Wagenberg et al. 2006
55
Lazzara 1989
56
Strid 1985
57
Strid 1985
58
Palacci et al.2001
8

times softer than cortical bone. Cancellous bone is porous and filled with bone
trabeculae and bone marrow tissue. Woven bone (primary) and lamellar bone
(secondary) are types of mineralized bone. Initial bone healing or
development consists of woven bone. Woven bone is soft, fiberous, irregular,
and filled with loose collagen fibers. Lamellar bone is more organized and
consists of osteocyte lacunae and mineralized fiber bundles. Mechanical
support for implant stability requires the strength of cortical and lamellar bone.
The maxilla contains a thin outer layer of cortical bone and the mandibular jaw
bone is composed of dense cortical bone that is thicker towards the anterior
(lower border) and posteriorly (upper border).
Embryogenesis of bone formation can be divided into three stages:
intramembranous, endochondral, and appositional. All craniofacial bone
(except the condyle) is from intramembranous formation. Intramembranous
ossification begins with mesenchymal stem cells that differentiate into
osteoblasts and form osteoid in a collagen matrix.
59
Next, mineralization of
osteoids occurs and osteoblasts become trapped into mineralized bone and
transform into osteocytes, thus there is no intermediate cartilage phase.
Endochondral origin forms the long bones, vertebral column bones, and base
of skull. Endochondral bone formation requires an intermediate cartilage
phase that will subsequently be replaced by bone. Appositional bone
formation occurs when osteoblasts produce bone on existing bone surfaces.

59
Palacci et al. 2001
9

Examples of appositional bone formation occur in the periosteal enlargement
of bones during growth and remodeling.
Dispute over the embryonic role of intramembranous and endochondral
bone healing still remains. Some authors contest that there is no difference
between intramembranous and endochondral embryogenesis. However,
several investigators in the literature indicate a clear distinction in early bone
formation. Rabie et al.
60
discovered the different cytokines and growth factors
required for healing in intramembranous or endochondral bone. Wong and
Rabie
61
showed that demineralized intramembranous bone matrix induces
bone without an intermediate cartilage stage or mesenchymal stem cells
differentiate directly into bone cells. Furthermore, Zins and Whittaker
62

determined that intramembranous bone shows less resorption due to rapid
revascularization of cancellous bone.

LOADING PROTOCOL
In 1969, the Brånemark group in Goteborg first established the
principles of modern implant treatment. The protocol recommended a two-
stage surgical procedure (two-piece implant) with the fixture submerged or
soft-tissue coverage of the implant for a 3 to 6 months healing period,
countersinking the implant below the crestal bone, and maintaining a minimally

60
Rabie et al. 1996
61
Wong et al. 1999
62
Zins, Whitaker 1983
10

loaded implant environment for 3 to 6 months. The rationale for the
submerged and countersink surgical approach was to reduce and minimize the
risk of bacterial infection, to prevent apical migration of the oral epithelium
along the body of the implant, to minimize the risk of early implant loading
during bone remodeling.
After implant placement, a second-stage surgery was necessary to
uncover the implants and place a prosthetic healing abutment. Predictable
long-term, clinical rigid fixation has been reported after this protocol in both
completely and partially edentulous patients. Premature loading may result in
fibrous tissue encapsulation that may prevent osseointegration. Studies
63,64

indicate that implant micromotion greater than100µm may result in fibrous
tissue encapsulation.
Immediate loading consists of implant placement and restoration within
24 hours and early loading is the delivery of the restoration within one to a few
weeks after implant placement. The prosthetic loading of implant is
considered occlusal loading when the crown/bridge is in contact with the
opposing dentition in centric occlusion. Non-occlusal loading is when the
crown/bridge is not in centric occlusion contact with the opposing dentition in
the natural jaw position. Table 1 illustrates the current terminology of implant
loading protocol.
65,66

63
Brunski 1992
64
Adell et al. 1981
65
Aparicio 2003
66
Ostman 2008
11

Table 1. Timing of Implant Loading

In 1977, Brånemark
67
published a long-term investigation on the
treatment of 235 edentulous jaws (128 maxillas and 107 mandibles) between 9
months to 8 years. The study revealed that 85% of all the supra- constructions
installed were stable thus the study determined that screw-type implants made
from titanium osseointegrated successfully.

In addition, Adell et al.
68
reported
90% survival rates in the anterior mandibular region with the Brånemark 15-
year case series investigation.
Submerged implants were preferable for initial rigid fixation. Other
factors for successful implant integration are the quality and quantity of bone
available at the implant site.
69
Jokstad and Carr’s
70
systematic review on the
effect on treatment of time-to-loading of implants determined that the average

67
Brånemark et al. 1977
68
Adell et al. 1990
69
Wood 2004
70
Jokstad et al. 2007
Immediate
Loading
The prosthesis (provisional or definitive) is attached to the
implant within 24 hours of implant placement.
Early
Loading
The prosthesis (provisional or definitive) is attached at a
second procedure, within days/weeks of the implant
placement.
Earlier than the conventional healing period of 3 to 6
months.
Delayed
Loading
The prosthesis (provisional or definitive) is attached at a
second procedure after a conventional healing period of 3 to
6 months.
12

outcome favored delayed loading. In addition, the authors made no
recommendations against early loading of implants.
Patient concerns and desire for shorten treatment time initiated the
growing research in immediate loading of implants. Problems arose for
patients undergoing the traditional two-stage protocol, which included avoiding
any prosthesis for a minimum of 2 weeks to promote uneventful healing (loose
denture, pain, difficulty with chewing during transitional removable prosthesis
wearing period), and the necessity of additional surgery to expose implant
fixtures.
71,72
These concerns have caused physiological, psychological, and/or
sociological challenges for patients undergoing implant treatment.
73

The Brånemark protocol has been continually challenged to minimize
treatment time, reduce the number of surgical procedures, and maximize
esthetic results.

Early reports of immediate implant loading were often
unpredictable due to findings of fibrous encapsulation around implants,
however, this was often the result of poor implant designs and lack of
understanding the mechanical aspects of implant loading. There are several
biological or mechanical factors that determine implant success. According to
Ostman
74
the requirements for long-term success with immediate-loaded
implants include high primary implant stability, moderately rough implant
surface, prolonged implant stabilization by splinting, controlled occlusion, and

71
Schnitman et al. 1997
72
Gapski et al. 2003
73
Salama et al. 1995
74
Ostman 2008
13

biocompatible prosthetic material. Sennerby and Roos
75
determined that
primary implant stability is determined by bone quality and quantity, implant
design, and surgical technique.
Schnitman et al.
76
in 1990 was the first to report long-term successful
immediate-loaded Brånemark implants with implant supported fixed
prostheses. In a 10 – year follow-up study the authors concluded that 4
(15.3%) of the immediately loaded implants failed, thus the long-term
prognosis was considered guarded for immediate loaded implants.
77
Also, it has been shown that immediate loaded implant failures occurred
primarily between 3 – 5 weeks postoperatively with signs of mobility (without
signs of infection).
78
Horwitz et al.
79
examined the immediate restoration of
dental implants in patients with periodontal disease and determined the ISQ
and survival rate was comparable in immediately restored, non-restored, and
submerged implants. Survival rates were 100% in partial-arch restorations,
94% in the mandible, and 78% in the maxilla. However, there were no
statistically significant differences in ISQ or insertion torque between failed and
successful implants, restored, and non-restored implants. Thus immediate
restoration of dental implants holds a variable success rate.

75
Sennerby et al. 1998
76
Schnitman et al. 1990
77
Schnitman et al. 1997
78
Buchs et al. 2001
79
Horwitz et al. 2007
14

However, several investigators have reported that immediately loaded
dental implants, placed in good quality bone were clinically equivalent to
implants placed with a standard or delayed loading protocol.
80,81,82,83
A 2007
Cochrane systematic review of immediate, early, and conventional loading
times showed that it is possible to successfully load dental implants
immediately or early after placement.
84
The review determined that a high
degree of primary implant stability or high insertion torque value is a strong
determinant of implant success.
The benefits of immediate loading implants include increased
masticatory function, avoidance of transmucosal loading through cross-arch
stabilization, improvement of psychological well-being, and reduction in
treatment time. Becker et al.
85,86
reported a 93.3% 5 years implant survival
rate and non-significant crestal alveolar bone loss with immediately loaded
implants augmented with barrier membranes. Aalam and Nowzari
87
studied
90 immediate-loaded implants placed in completely edentulous mandibles with
Branemark System Mk III implants (Nobel Biocare). At the 3 year follow-up,
the cumulative success rate was 96.6% (3 failures) and the prosthetic success
rate was 100%, in addition the average bone loss was 1.2 ± 0.1 mm.

80
Piatelli et al, 1998
81
Chiapasco et al. 1997
82
Gatti et al. 2000
83
Yoo et al. 2006
84
Esposito et al. 2007
85
Becker et al. 1999
86
Becker et al. 1994
87
Aalam et al. 2005
15

Similar survival rate between immediate and delayed loading have been
reported. Sennerby et al.
88
found a 97.8% overall survival rate with
immediately loaded implants over 2 to 3 years.

Ganeles et al.
89

demonstrated osseointegrated immediately loaded implants are comparable to
the long-term characteristics of conventionally loaded implants. Also, Chow et
al.
90
provided patients with edentulous mandibles with provisional fixed
prostheses, supported by immediately loaded Brånemark system implants, 27
patients were treated with 115 implants of various lengths and diameters. The
overall implant survival rate was reported to be 98% after 1 year of function.
In addition, Capelli et al.
91
in a multicenter study of 342 immediately
loaded Osseotite NT/Biomet 3i implants (96 mandibular and 246 maxillary
implants) with full – arch, screw-retained prostheses and distal extensions, had
a maxillary cumulative implant survival rate of 97.6% (40 months post-
operative). No failures were observed for the mandibular implants and the
prosthetic success rate was 100%. Dodson
92
reviewed implant survival rates
over 10 years, with 921 subjects and 2,996 implants. Implant survival rates at
one year ranged from 90.3% for immediate-load implants to 96.2% for
implants inserted into grafted sinuses. The 5-year survivals ranged from 87.9%
(sinus graft cases) to 91.2% (all implants). The long-term survival rates of

88
Sennerby et al. 2005
89
Ganeles et al. 2002
90
Chow et al. 2001
91
Capelli et al. 2007
92
Dodson 2006
16

implants indicate that immediate implants are a predictable procedure with a
five-year survival rate approximating 90%.
The present literature does not indicate that premature loading leads to
fibrous tissue encapsulation, rather, it is due to an excessive amount of
micromotion at the bone–implant interface, during the healing phase.
93
In a
study by Horiuchi et al.
94
they determined that 94 of the 96 immediately loaded
mandibular implants (98%) remained osseointegrated during a period of 8–24
months. Similar favorable results were also presented for the maxilla, whereby
42 of 44 immediately loaded implants (96%) remained integrated at 24 months.
The length of immediately loaded implants was suggested to be at least 8.5 mm
(for wide platform) or 10 mm (for regular platform). Implants with good primary
stabilization (placement torque of more than 40 Ncm) can be immediately loaded.
Implants with a placement torque less than 40 Ncm, length less than 8.5 mm
(wide platform) or less than 10 mm (regular platform), or associated with bone
grafting, should be submerged.
Furthermore, clinical and histological studies have indicated that
immediately loaded implants have a higher bone to implant contact (BIC) value
than non-immediately loaded implants. Testori et al.
95
in a case report
attained a 64.2% BIC with immediately loaded Osseotite implants. Histological
comparison of non-submerged unloaded and early –loaded implants in a

93
Szmukler-Moncler et al. 2000
94
Horiuchi et al. 2000

95
Testori et al. 2002
17

monkey model found a tight contact with new bone to implant surfaces in both
study groups.
96
Piattelli et al.
97
examined bony reactions to early-loaded
titanium plasma-sprayed implants in monkeys. They found that the bone of
the loaded implants had a more compact appearance than non-loaded
controls and the mean BIC of immediate-loaded implants was 67.2% in the
maxilla and 80.7% mandible. Frost
98
postulated that both overloading and
unloading of implants results in a negative tissue response.
Also, the original Brånemark implant was a turned or machined surface.
Although studies
99,100
indicate no long-term difference between smooth or
rough surfaces with immediately loaded implants, it has been well documented
that rough surface implants show a faster initial osseointegration than machine
surfaces.
101, 102
The available current research indicate that immediately
loaded implants with moderately rough surfaces have a similar and possibly a
higher BIC compared to delayed-loaded implants.
Implant surface modification alters the bone tissue response to titanium.
It has been demonstrated that early bone formation after implant surgery
occurs directly on the moderately rough oxidized surface, while turned titanium

96
Piattelli et al. 1998
97
Piattelli et al. 1997
98
Frost 2004
99
Sennerby et al. 2008
100
Aalam et al. 2005
101
Burgos et al. 2008
102
Ivanoff et al. 2003
18

surfaces are integrated by the in growth of bone from the adjacent bone
marrow and preexisting bone tissues.
103
Histologic analysis of human
jawbone revealed a significantly higher bone response for anodic oxidized
titanium implants (i.e. TiUnite, Brånemark System) than turned surface
implants.
104
High implant survival rates were observed with immediately
loaded 3i Osseotite implants.
105
Testori et al. 2003 observed 92 immediately
loaded Osseotite implants in 15 patients and obtained only one failure. The
investigators reported a cumulative success rate of 98.9% after 2 years. Also,
the bone loss around immediately loaded implants was similar to the control
group (delayed loading). In addition, Testori et al.
106
conducted a multicenter
study on 325 Osseotite implants (62 patients). The cumulative success rate
was 99.4% over an average of 2.5 years. Again, similar crestal bone loss was
observed between immediate and delayed loaded implants.
Investigations in by Froberg and Erricson et al.
107
compared the treatment
outcome of TiUnite
TM
and turned-surfaced Brånemark immediate loaded implant
with a cross-arch fixed partial dentures in the anterior mandible. The results
showed a highly predictable treatment outcome with immediately loaded
Brånemark implants in the anterior mandible implants. In a prospective study,
108
18 Osseotite implants were placed in 13 patients, using an immediate implant

103
Burgos et al. 2008
104
Burgos et al. 2008
105
Testori et al. 2003
106
Testori et al. 2004
107
Fröberg et al. 2006
108
Guirado et al. 2002
19

placement protocol and immediate loading by provisional crowns. The implant
success rate was 100% at one year. The results indicate that immediate loaded
3i Osseotite implants had a predictable and reliable method after one year follow
up period.

Other studies
109
on immediate loading (microthreaded, TiO2 grit-
blasted implants) indicated that crestal bone was maintained and increased soft
tissue dimension with maintenance of peri-implant papilla was established.
Recently, the utilization of wide-diameter immediate implants (diameter
greater than 4.1 mm) has increased. Wide-diameter implants have been used in
healed bone and extraction sockets with success.
110
Advantages of wide-
diameter implants are that they allow greater occlusal forces in the posterior
dentition and also avoid the use of two standard-size implants.
111,112
In a
study
113
on wide platform Brånemark system implants, with a total of 105
implants in 35 patients, only 3 failures occurred 2–36 months follow-up and the
overall implant survival rate was 97%. The failed implants were distal implants,
which were lost within 3 months of post-insertion. Concerns of placing wide
implants might be the presence of fragile bony walls or concavities in the alveolar
bone may lead to dehiscences or fenestrations. There are few reports on this
topic and more studies are needed to verify the advantages and disadvantages
of wide diameter implants.

109
De kok et al. 2006
110
Degidi et al. 2007
111
Degidi, Marco, Piattelli, Adriano et al. 2007
112
Petrie, Williams 2005
113
Hatano 2001
20

Immediate loading of implants in the anterior region is of particular
importance for patients with esthetic concerns. Present studies generally
indicate a positive treatment outcome with immediately loaded anterior
implants.
114,115,116,117

Maló et al.
118
reported on 49 patients, with a total of 94
Brånemark implants to support 54 fixed prostheses. Of these, 23 were short-
span bridges (14 maxillary and 9 mandibular) and the remainder were single
crowns. The implants were all placed within the esthetic zone, aiming at
bicortical stabilization but avoiding marginal countersinking. After 2 years of
functional loading, the cumulative survival rate was 96% for all inserted implants.
Reported failures mainly occurred in connection with fresh extraction sites, and
consequently the authors recommend extra care to avoid situations with
persisting inflammation when placing implants. Moreover, other clinical
studies
119
have demonstrated that immediate loading has a positive impact on
papilla preservation. Control of peri-implant tissues can be achieved to provide
predictable and esthetic treatment for anterior tooth replacement using dental
implants.
120
Thus, ample data have indicated that immediate loading of single-
tooth implants in the anterior maxilla can result in successful implant
integration.
121

114
Maló et al. 2000
115
Fröberg et al. 2006
116
De kok et al. 2006
117
Turkyilmaz 2006
118
Maló et al. 2000
119
Wohrle 1998
120
Fröberg et al. 2006
121
Lorenzoni et al. 2003
21

BIOLOGICAL WIDTH
Albrektsson
122
and other investigators
123,124,125
demonstrated crestal
bone changes of 1.5–2.0 mm below the implant-abutment junction after the
first year of implant loading. This was reported to be frequently associated
with two-piece implants. Post-operative apical migration of crestal bone
arrested at the first thread of standard 3.75 – 4.0 mm implants.
Berglundh and Lindhe
126
proposed that a minimum width of
approximately 3 mm of peri-implant mucosa is required to create a mucosal
barrier around dental implants. Re-establishment of the 3 mm biological width
is necessary around all implants and is similar to the natural dentition. There
is a requirement of approximately a 1mm sulcus, 1mm epithelial attachment,
and 1 mm supracrestal connective tissue. Thus the establishment of an
adequate biological width occurs through remodeling or resorption of the
crestal bone in order for the new attachment of supracrestal fibers.
127,128
To
create adequate space for biologic soft tissue seal and attachment of soft
tissue to the coronal aspect to the implant, crestal remodeling occurs to the
first implant thread (1.5 to 2.0mm apical to the implant abutment junction).

122
Albrektsson 1996
123
Albrektsson et al. 1986
124
Smith, Zarb 1989
125
Jung et al. 1996
126
Berglundh, Lindhe 1996
127
Berglundh et al. 2007
128
Botticelli et al. 2004
22

Histological evaluations of peri-implant tissues described by Ericsson et
al.
129
demonstrated that after 9 months of healing (dog study model) the
alveolar bone crest was located approximately 1–1.5 mm apical of the
abutment-fixture level. The bone crest was commonly separated from the
abutment inflammatory cell infiltrate by a 1.0 mm wide zone of a normal non-
infiltrated connective tissue. The peri-implant soft tissues have two types of
inflammatory lesions, plaque-associated inflammatory cell infiltrate (associated
with the gingival sulcus) and a 1.0 – 1.5 mm (apical-coronal) zone of
inflammatory cell infiltrate (associated with the implant abutment junction).
Accordingly, the authors concluded that establishment of an abutment
inflammatory cell infiltrate may explain the crestal bone changes during the
first year of loading.
130
Factors controlling crestal bone levels around implants are largely due
to a minimum of 3 mm for biological width, position of abutment inflammatory
cell infiltrate, and implant surface topography.
131
All two-piece implants with
matching diameter healing abutments exhibit a vertical repositioning of crestal
bone or re-establishment of biological width. However, with platform
switching the outer edge of the implant-abutment interface is horizontally
repositioned inward and away from the outer edge of the implant platform.

129
Ericsson et al. 1995
130
Ericsson et al. 1995
131
Lazzara, Porter 2006
23

Hermann et al.
132,133,134
described the biologic response of crestal bone
around the coronal aspect of two-piece implants post-abutment connection
and showed that crestal bone remodels to an approximately 2 mm apical to
the implant abutment junction. Also, the authors reported that following
second stage surgery the distance between the implant abutment junction and
the resulting remodeled crestal bone position remained fairly constant. Other
studies
135,136,137
indicate that if the implant abutment junction is placed deeper
within bone, an increase in vertical crestal bone loss occurs, yet the crestal
bone position remains approximately 2 mm apical to the implant abutment
junction.
138

Differences in bone resorption pattern within individual implants were
also observed. Experimental animal study indicated that remodeling and
resorption following implant placement

was more pronounced at the buccal

than at the lingual aspect of the

alveolar bone crest. Several crestal bone
remodeling theories have suggested that post-restorative crestal bone level is
due to localized inflammation within the soft tissue located at the implant-
abutment interface or the establishment of the biological width (mucosal
barrier). Previous experimental animal studies indicated the transmucosal

132
Hermann et al. 1997
133
Hermann, Schoolfield et al. 2001
134
Hermann, Schoolfield et al. 2001
135
Todescan et al. 2002
136
Piattelli et al. 2003
137
Hermann 2000
138
Botticelli et al. 2004
24

attachment revealed a junctional epithelium and connective tissue, resulting in
a 2 – 4 mm wide zone of biological soft tissue coverage of the implant
supporting bone
139,140,141
Other causes of resorption may be due to the high
stress concentration at the coronal portion of the implant.
142

PLATFORM SWITCHING
Platform switching or the horizontal inward re-positioning of the implant-
abutment interface has been suggested to overcome the problems of alveolar
bone loss. In 1991, 3i Implant Innovations introduced wide diameter implants
(5 – 6 mm) with a matching wide diameter platform. However, no matching
wide diameter prosthetic devices were available. Thus practitioners were
forced to use standard diameter (4.1 mm) healing abutments and prosthetic
components. Lazzara and Porter
143
and Gardner
144
first introduced the
concept of platform switching to minimize bone loss. Lazzara and Porter
conducted the research in a private practice setting that spanned over 13
years. Histological and radiographic observations of the biologic dimension of
the surrounding bone and soft tissue around implants were documented. The
horizontal mismatch was either 0.45 mm (4.1 mm prosthetics with a 5.0 mm
implant platform) or 0.95 mm (4.1 mm prosthetics with a 6.0 mm implant

139
Berglundh et al. 1991
140
Abrahmsson et al. 1998
141
Berglundh, Lindhe 1996
142
Pillar et al. 1991
143
Lazzara, Porter 2006
144
Gardner 2005
25

platform). The authors suggested that wide diameter implants restored with
platform switched abutments show less vertical crestal bone loss in
comparison to conventional matching diameter prosthetic components.
Theoretically, platform switching may increase the distance between the
abutment inflammatory cell infiltrate and the alveolar crest, thus decreasing its
bone-resorptive effect. Abrahamsson et al.
145,146
and Ericsson et al.
147

described a matching implant- abutment interface with the outer edge of the
implant abutment junction in direct approximation to the crestal bone. The
close proximity of the abutment inflammatory cell infiltrate to the bone may
result in the gradual bone loss around exposed two-piece implants. In
consequence, platform switching with smaller diameter healing abutment and
prosthetic components act to horizontally inwardly reposition the implant
abutment junction and therefore decreases the bone loss.

In addition, few animal studies exist on the evaluation of platform
switching for preservation of crestal bone around endosseous titanium
implants. Becker et al.
148
investigated the influence of platform switching on
crestal bone changes with non-submerged wide-body implants in the beagle
dog model. Histomorphometric analysis of difference in crestal bone level was
performed on one-stage insertion of sand-blasted and acid-etched screw-type
implants with matching or smaller-diameter healing abutments (platform

145
Abrahamsson et al. 1997
146
Abrahamsson et al. 1998
147
Ericsson et al. 1995
148
Becker J et al. 2007
26

switching). It was observed that platform switching (circumferential horizontal
mismatch of 0.5 mm) was able to prevent the apical downgrowth of the barrier
epithelium over an observation period of 28 days. However, crestal bone level
changes were reduced after 28 days of healing in both matching and smaller-
diameter healing abutments. Thus no advantage to platform switching was
observed.
It has been shown that different implant designs and vertical implant
position influences the crestal bone levels. A Cochrane 2008 animal study
149

aimed to evaluate radiographic crestal bone changes around experimental
dental implants with non-matching implant-abutment diameters placed either
submucosally or transmucosally at various levels relative to the alveolar crest.
Radiographic analysis revealed that implants with non-matching implant-
abutment diameters demonstrated some bone loss and no clinical difference
was found between submucosal and transmucosal approaches. Furthermore,
the greatest bone loss occurred with implants placed 1 mm below the bone
crest.

IMPLANT COMPLICATIONS
A failed implant has been described as one that is clinically mobile or
unable to fulfill its purpose (function, esthetic, or phonetic) due to mechanical
of biological etiologies.
150
In contrast, an implant that shows progressive loss

149
Jung et al. 2008

150
Askary et al. 1999
27

of supporting bone, but that is clinically immobile, is a failing implant.
151
The
current primary factor shown to predispose implants to failure is low bone
density, in 5-year study
152
confirmed high failure rates (44%) in maxillary type
IV bone. Warning signs of implant failure are gingival bleeding and
enlargement, purulent exudates from pockets, pain (uncommon), bone loss
(radiographically), prosthetic connecting screw loosening or fracture.
153

Implant failures are divided into several categories based on the timing
etiology, or biomechanical factors.
The chronology of implant failures are classified into early or late failures.
Early implant failure (lack of osseointegration prior to second-stage surgery or
uncovering of the implant) occurs within weeks to months after implant
placement.
154,155
Systemic factors play a prominent role for early failures.
156,157
Early failures are due to the interaction of an etiologic agent during the wound
healing process or host susceptibilities. The mechanisms that normally lead to
wound healing by means of bone apposition do not occur, and rather a fibrous
scar tissue is formed in between the implant surface and surrounding bone.
158

This can lead to epithelial downgrowth, a so-called saucerization of the implant,
which often results in mobility or even implant loss.

151
AAP 2000
152
Jaffin et al. 1991
153
Jung et al. 2008
154
Wood et al. 2004
155
Maurizio et al. 1994.
156
van Steenberghe et al. 2002, 2003
157
Mombelli, Gionca 2006
158
Esposito et al. 1999
28

Demonstrated causes of early failures include: surgical trauma,
insufficient quantity or quality of bone surrounding the implant, premature
loading of the implant, and bacterial infection.
159
Surgical technique is also a
factor in early implant failure that leads to bone necrosis. Improper implant
site preparation with high-torque, slow-speed hand pieces and increased
friction or heat has lead to bone necrosis and implant failure. Mobilization of
mucoperiosteal flaps may cause injury to the periosteum, leading to crestal
resorption of the alveolar bone.
160
The formation of peri-implant tissues was
shown to be independent of the surgical approach.
161,162,163
There is a low
rate of postoperative infections associated with early loading.
164
However,
there are documented case reports
165,166
of infection from an adjacent
endodontic lesion affecting implants in the initial stage of osseointegration.
During the initial stage of osseointegration, the bone surrounding the implant
resorbs and osteogenesis occurs 3 - 4 weeks after.
167
Studies indicate that
implant failure tend to occur soon after placement and the probability of failure
decreases from 5 years post-surgery.
168,169

159
Wood et al. 2004
160
Philstrom et al. 1983
161
Abrahamsson et al. 1996
162
Ericsson et al. 1996
163
Weber et al. 1996
164
Rams et al. 1983
165
Sussmand, Moss 1993
166
Sussman 1997
167
Branemark et al, 1985
168
Weyant, Burt 1993
169
Weyant 1994
29

Late failure occurs after second-stage surgery and is the loss of
osseointegration or mechanical failure.
170,171
The pathological processes in late
failure involve disturbances in biochemical equilibrium or host-parasite
equilibrium (infection).
172
The major causes for late failures are overloading in
conjunction with poor bone quality or quantity or progressive changes of the
loading conditions.
In addition, the design of the implant has been shown to affect the
amount of bone loss. Nowzari and Rich (2006) determined that the scalloped
Nobel Perfect implant design resulted in more severe bone loss than
conventional dental implants. One-piece implants tend to show minimal to no
marginal bone resorption at the implant-abutment interface (placed 3 mm
above the bone crest).
173
Hemann et al.
174
concluded that the height of
tissues is more similar to natural teeth in one-piece implants compared to two-
piece implants. Studies
175
on two-piece implants report a crestal bone loss of
1.5 to 2mm after 1 year of implant exposure and loading. Several reasons
may contribute to the bone loss seen around two-piece implants, the position
of the implant-abutment interface relative to the bone crest at time of surgery.
This is due to the high association of the implant-abutment interface with
inflammatory cell infiltrate. Also, the magnitude of inflammation is

170
Jaffin, Berman 1991
171
Wood, Vermilyea 2004
172
Wood, Vermilyea 2004
173
Hermann et al. 2000
174
Hermann 2000
175
Jemt, Lekholm, 2005
30

proportionally dependent upon the interface position relative to the alveolar
crest. Thus subcrestal implant-abutment interfaces promoted a greater
inflammatory reaction correlated with more bone loss in comparison to
supracrestal interfaces.
176
However, the more apical position of the implant-
abutment junction would enhance the emergence profile thus contribute to a
more esthetic prosthetic result.
Several other major causative factors attributed to dental implant
failures are implant microgap, occlusal overload, micromovement, peri-
implantitis, and systemic/patient factors.

IMPLANT COMPLICATIONS: MICROGAP
Microgaps at the implant-abutment interface allow the entrance of
microorganisms which results in bone resorption and subsequent implant
failure. There is known documentation of bacterial microleakage and
colonization with poor implant-abutment connections however, inflammatory
cells occur approximately 0.50 mm coronal to the microgap. The location of
the microgap between the abutment and the coronal aspect of the implant
determines the final coronal height of bone contact.
177

176
Todescan et al. 2002
177
Hermann et al. 1997
31

To help facilitate communication and diagnosis, Kano et al.
178
devised
an implant-abutment microgap classification system. The proposed
classification system consisted of the following four categories: Type I: No
horizontal or vertical gap measured (Ideal class); Type II: Only horizontal
misfit (abutment under or overcontoured); Type III: Only vertical misfit; Type
IV: Both horizontal and vertical misfit. The results showed that only 23% of
all sites had a Type I or ideal implant-abutment relationship.
Numerous studies
179,180,181
have reported on microbial leakage resulting
in a mucosal inflammatory reaction which leads to marginal bone resorption.
Poorly adapted implant-abutment connection can lead to several biological
and mechanical complications.
182,183,184
Biological complications include
microleakage, inflammation, and subsequent bone loss. Mechanical
complications, results from increased abutment rotation or breakage, screw
loosening, and preload reduction. In particular, the microgap at the implant–
abutment interface allows bacterial colonization of the implant
sulcus.
185,186,187,188
Implants exhibiting bacterial leakage along the implant–
abutment interface have marginal bone resorption resulting in a compromised

178
Kano et al. 2007
179
Hermann 2001
180
Mombelli 1987
181
King et al. 2002
182
Jansen et al. 1997
183
Guindy et al. 1998
184
Broggini et al. 2003
185
Mombelli et al. 1987
186
Ericsson et al. 1995
187
Hermann et al. 2001
188
King et al. 2002
32

mucosal barrier and a more apically positioned zone of connective tissue.
189

Microgaps can result in approximately 2 mm alveolar bone loss.
190

IMPLANT COMPLICATIONS: OCCLUSAL OVERLOAD
Occlusal trauma may be defined as an injury to the attachment apparatus
as a result of excessive occlusal force.
191
Occlusal overload may result in
progressive marginal bone loss or loss of osseointegration, and when traumatic
occlusion is combined with inflammation, bone destruction is accelerated.
192

There is generalized agreement that early implant failure may be associated with
overload.
193
The loss of osseointegration by occlusal overload was observed in
animal studies (monkeys).
194
Implants may be more susceptible to crestal bone
loss by mechanical force. The cortical bone is least resistant to shearing forces,
which is significantly increased by bending overload.
195

In addition, the modulus of elasticity of titanium is approximately five
times greater than the cortical bone.
196
When materials of different elasticity are
in contact and one material is loaded, a stress contour increase is observed
where the two materials first come into contact.
197
According to Roberts et al.
198

189
Abrahamsson et al. 1997
190
Hermann 2001
191
Glossary of Prosthodontic Terms, 1999
192
Isidor 1996
193
Adell et al. 1981
194
Miyata et al. 2000
195
Reilly et al. 1975
196
Misch 2008
197
VonRecum 1986
198
Roberts et al. 1989
33

crestal regions around the implant are high stress bearing areas and if the crestal
region is overloaded during bone remodeling, cervical cratering is created around
dental implants. Occlusal stress applied through the implant and prosthetic
components can transmit stress to the BIC.
199
The bone strain at the BIC is
therefore positively related to the amount of stress applied through the implant
prosthesis.
Also, non-submerged implants allow interface strains during mastication.
Masticatory forces involves a repeated pattern of cyclical forces that load both
the implant components and the bone-implant interface, and results in
craniofacial bones being exposed to rapid but periodic regimens of cyclical
loading.
200
The masticatory loads have been described as being brief (0.23 to
0.3 second per tooth contact) and occur at a rate of 1 to 2 Hz for a total period of
approximately 540 to1,020 s/day.
201
However, bruxism, a non-physiological
parafunctional habit is more significant than the forces associated with normal
mastication. In addition, the optimal level of occlusal stresses on the bone-
implant interface for osseointegration has not yet been validated.

199
Cowin et al. 1976
200
Yacoub et al. 2009
201
Graf 1969
34

IMPLANT COMPLICATIONS: MICROMOTION
Micromotion or lack of implant stability can jeopardize the primary
stability of implants.
202,203
It indicates increased load or torque on the implant
and its components. Excessive micromovement creates stress or occlusal
overload and leads to soft tissue encapsulation and prevents osseointegration,
thus causing implant failure.
204
To avoid fibrous encapsulation and
subsequent implant failure, implants must withstand functional load with less
than 150 microns.
205
Preventive measures have been utilized to enhance the
success of immediately loaded implants. Various studies demonstrated
successful immediate loading in edentulous mandibles by means of fixed
superstructures or bar-retained overdentures thereby preventing any
movement or non-axial loading by rigidly splinted implants.
206
Methods such
as splinting of dental implants to reduce the occlusal load was studied by Aka
et al.
207
they concluded that early mechanical force in the bone surrounding
implants may impair initial healing in unsplinted implants. Therefore, the
investigators recommended that splinted implants are more advantageous
than unsplinted immediately loaded implants. However, studies on immediate
loading of unsplinted mandibular implants reported equally high survival
rates.
208

202
Chiapasco 2004
203
Ganeles et al. 2004
204
Brunski et al. 1979
205
Schincalglia et al. 2007
206
Lorenzoni et al. 2003
207
Aka et al. 2007
208
Fischer et al. 2004
35

In addition, micromotion does not occur all at once over the entire
implant. Mobility normally occurs during the osseous remodeling process.
209

Remodeling is a variable process with balanced osteoclastic and osteoblastic
activity, so that a stable implant is preserved during osseointegration.
210

However, clinically stable implants may exhibit mobility on the micro - level
when loaded. Sennerby and Meredith
211
revealed that all implants display
varying degrees of stability or resistance to load. During function, loading is
applied in an axial, lateral, and rotational directions. Lateral loads can occur
in any 360 degrees direction around the implant. Axial loads can be intrusive
or extrusive and rotational loads can be either clockwise or counter-clockwise.
Bending forces are the most common type of loading.

Currently, there is no convincing evidence that non-axial loading is
detrimental to the bone-implant interface; however, occlusal overloading will
adversely affect the various components of implant supported prosthesis.
212

There are limited data regarding the benefits of splinting implants to counteract
the occlusal load.
213,214
Splinting of implants to natural teeth has been shown
to cause intrusion of splinted teeth and pronounced vertical bone loss around
implant abutments are potential sequelae; however, the majority of patients

209
Ganeles et al. 2002
210
Schnitman et al. 1997
211
Sennerby et al. 2008
212
Cochran 1996
213
van Steenberghe 1989
214
Ericsson I et al. 1986
36

(8 out of 10) in Ericsson et al.
215
study suffered no adverse effects.
216
Also,
several investigators indicated a good prognosis for implants splinted to
natural teeth in a fixed prosthesis.
217,218

IMPLANT COMPLICATIONS: PATIENT FACTORS
The American Academy of Periodontics report confirmed no absolute
medical contraindications for dental implants, although relative
contraindications are a concern.
219
No studies have shown that age affects
implant survival. However, for adolescents, it has been suggested that
implants be placed after age 15 in girls and after age18 in boys due to
differences in growth patterns.
220
Adverse effects on implant survival have
been attributed to uncontrolled diabetes, alcoholism, heavy smoking, post-
irradiated jaws, and poor oral hygiene.
Uncontrolled diabetes mellitus does not affect implant failure directly,
however, studies indicate that patients with diabetes experience more
infections. Fiorellini and Nevins
221
studied diabetics’ biological responses to
implant placement and determined an impairment of bone healing exists. The
biological rationale is a decrease in vascularity due to microangiopathies

215
Ericsson et al. 1986
216
Ericsson et al. 1986
217
Wennström et al. 1994
218
Mericske-Stern et al.1994
219
AAP 2000
220
Oesterle et al. 1994
221
Fiorellini et al. 2000
37

reducing host defense and collagen production exhibits an adverse increase in
collagenase activity. Well-controlled diabetic patients are at no higher risk of
implant failure than the general population. Also, successful osseointegration
can be achieved with immediately loaded Brånemark implants in diabetic
patients (insulin-controlled).
222

Multiple studies (Lindquist 1997, Klokkevold 2007, Ekelund 2003) have
demonstrated that smoking has an adverse affect on implant survival and
success. In a prospective (12-15 years) study with Brånemark implants, it was
determined that bone resorption around the implants was negatively
influenced by smoking and poor oral hygiene. A systematic literature review
on the effect of smoking on implant survival demonstrated that areas of poor
bone quality and type II diabetes may have an adverse effect on implant
survival rates.
223
Bain and Moy
224
in a retrospective study revealed that
implant failure was considerably greater in smokers (11.3%) in comparison to
nonsmokers (4.8%). Caffesse
225
in a prospective case series divided smokers
into high (> 20cigs/day) or moderate to low smokers. A 15.8% overall greater
implant failure rate was determined in smokers. Heavy smokers had a 30.8%
failure rate while moderate to low smokers showed a lower implant failure rate
of 10.1%.

222
Balshi et al. 2007
223
Klokkevold et al. 2008
224
Bain, Moy 1993
225
Sanchez-Perez et al. 2007
38

IMPLANT COMPLICATIONS: PERI-IMPLANTITIS
Peri-implantitis is an inflammatory process affecting the tissues around
an osseointegrated implant with bone loss.
226
The etiology of peri-implantitis
or peri-implant mucositis is attributed to microbial infection of either bacterial or
viral origin.
227
The prevalence of peri-implant mucositis is approximately 80%
and peri-implantitis is between 28% and 56% of patients.
228,229
Rapidly
progressing peri-implantitis is comparable to aggressive periodontitis while
slowly progressing peri-implantitis resemble chronic periodontitis.
230
The wide
range of peri-implantitis reported may partly be due to differences in defining
the two entities, and different lengths of the studies.
The clinical appearance of peri-implantitis is normally asymptomatic,
usually detected at routine recall appointments. Indicators of pathology in peri-
implant tissues usually are an increased clinical probing pocket depth,
bleeding on probing (BOP), and suppuration. The criteria for peri-implantitis
are based on probing depth ≥4mm, BOP, and bone level at the third to fourth
thread (3.1-3.7mm). Radiographically, the peri-implant defects are saucer or
rounded beaker shape, well demarcated, encompass the full circumference of
the implant, and the bony defects can develop around single or multiple
implants. Furthermore, Tabanella, Nowzari, and Slots (2008) determined that

226
Albrektsson, Isidor 1994
227
Lindhe et al. 2008
228
Lindhe et al. 2008
229
Roos-Jansaker 2006
230
Tabanella et al. 2003
39

peri-implant bone loss was associated with the absence of radiographic crestal
lamina dura, peri-implant pocket depth, and pain on chewing.
Histologically, 60% of peri-implantitis lesions occupied by inflammatory
cells were predominantly plasma cells and numerous polymorphonuclear cells
in connective tissue adjacent to pocket epithelium. Also, the developing
microbiota around implants closely resembles the miroflora of natural teeth.
Mombelli et al.
231
studied microbial colonization of ITI implants. They
determined that the microbes shortly after surgery were similar to the mucosal
flora, with over 85% coccoid cells and 80% gram-positive facultative cocci.
Other longitudinal studies
232,233,234
determined that the microflora is stable
with osseointegrated implants. Organisms cultured were predominantly
facultative anaerobic cocci (50%) and facultative anaerobic rods (17%). Only
7% of the microbes were gram-negative anaerobic rods. Thus, irrespective of
time from post-surgical implant placement, successful implants have normal
microbial flora that is dominated by facultative anaerobic and gram-positive
cocci.
However, the bacteriology of failing implants is similar to periodontitis
lesions of natural teeth. The deep pockets around natural teeth act as
reservoirs of microorganisms for the colonization of implants. Rams et al.
235

231
Mombelli et al. 1988
232
Mombelli et al.1990
233
Lekholm et al. 1986
234
Apse et al. 1989
235
Rams et al. 1991
40

was the first to report the microbiota associated with failed implants. The
investigators found predominantly coccoid microbiota with elevated levels of
spirochetes. Also, Mombelli et al.
236
showed that failing implant sites contain
gram-negative anaerobic rods, black-pigmented bacteriodes, and
Fusobacterium sps. Under dark field microscopy the predominant species
were spirochetes, fusiform spp., motile and curved rods. Also, observed in
failing implant sites were similar microbiota to control sites of successful and
unsuccessful patients. Thus, peri-implantitis is considered a site specific
infection, similar to chronic periodontitis.
Quirynen and Lisgarten (1990) investigated periodontitis impact around
remaining teeth and probing depth around implants. The results showed that
subgingival mircroflora around implants harbor increased spirochetes and
motile rods in comparison to teeth present in the same jaw. Also deep peri-
implant pockets (≥ 4mm) in residual dentition of chronic or refractory
periodontitis patients had higher spirochetes and motile rods. In addition,
Papaioannou (1996) examined the prevalence of putative periodontal
pathogens in partially edentulous and fully edentulous patients with a history
of periodontal disease. The results indicated that pockets around teeth can
serve as a reservoir for putative periodontal pathogens and a similar
microbiologic profile existed between teeth and implants of equal pocket

236
Mombelli et al.1987
41

depth. Also, pathogens can be detected around implants as early as one
month after implantation.
The microbiota of successfully osseointegrated implants is dependent
on the length of time the implant had been in function, patients with a history of
periodontal or peri-implant infections.
237
The major influence on the peri-
implant microbiota is the microbiota on remaining teeth. Also, patients with a
history of periodontitis had a greater impact on the peri-implant microbiota than
implant loading time.
238
Osseointegrated implants in function are shown to be
colonized principally by oral Streptococci, Capnocytophagae, Veillonella
parvula, Peptostreptococcus micros, and Fusobacterium nucleatum. Few
periodontal pathogens (P. gingivalis, T. forsythia, P. intermedia, P. nigrescens,
and C. rectus) are normally detected.
239

Factors associated with peri-implantitis include patients susceptible to
periodontal disease, existing bone loss, and the absence of keratinized
tissue.
240,241,242
Karoussis
243
compared failure, success, and complications
rates in patients who lost their teeth due to periodontitis and concluded that
patients with a history of chronic periodontitis had a higher incidence of peri-
implantitis (28.6%) in comparison to no history of periodontitis (5.8%). Also, in

237
Lee et al. 1999
238
Baelum et al. 2004
239
Baelum et al. 2004
240
Van der Weijen et al. 2005
241
Warrer et al. 1995
242
Roos-Jansaker et al. 2006
243
Karoussis 2003
42

a comparison study of attachment loss around either implants, healthy teeth,
or periodontitis (generalized aggressive or generalized chronic) it was
determined that attachment loss was greater around implants than natural
teeth and patients with aggressive periodontitis demonstrated the greatest
bone loss.
244
Furthermore, Wennstrom
245
in a 5-year retrospective
radiographic study of implants in healthy and periodontally involved subjects
determined that early implant failures were more frequent with greater bone
loss (>2mm) in the periodontitis group.
However, periodontally compromised patients can still be successfully
treated with implants.
246
Ellegaard et al.
247
looked at implant success rates in
periodontally compromised patients and demonstrated a 3-year survival rate of
95-100% (ITI implants). After 5 years, 45% of the ITI implants showed an
increased bone loss. The authors suggested that periodontally compromised
patients with considerable loss of alveolar bony support can be successfully
treated with implants. Hardt et al.
248
examined 97 partially dentate patients
who received 356 implants in the posterior maxilla. Patients with no reported
periodontal disease had a 96.7% survival rate. The survival rate was 92% for
patients with a history of periodontal disease. Tarnow in 1997 reported similar
survival rates in periodontally compromised patients and healthy patients.
249

244
Mengel et al. 2005
245
Hardt et al. 2005
246
Nevins et al. 1995
247
Ellegaard et al.1997
248
Hardt et al. 2002
249
Tarnow et al. 1997
43

Wennstrom et al.
250
reported implants to be stable in periodontitis patients in a
5-year prospective study. The group found few implant losses and small
marginal bone loss in periodontally susceptive subjects. All study patients had
an individualized maintenance care program. However, other reports
251

showed a much lower 10-year survival rate or 78% for one-stage implants
placed in periodontitis patients.
Controversies still remain over the benefits of keratinized mucosa
around implant sites. Nevertheless, a minimum width of peri-implant mucosa
is required to allow a stable epithelial-connective tissue attachment to form
around the implant (biological width or height).
252
Warrer and Karring et al.
(1995) supported the idea that the absence of keratinized mucosa around
dental endosseous implants increases the susceptibility of the peri-implant
region to plaque-induced tissue destruction. Keratinized mucosal provides a
soft tissue seal against bacteria and lack of keratinized mucosa results in
recession and attachment loss. Furthermore, the absence of adequate
keratinized mucosal in endosseous dental implants, especially in posterior
implants, was associated with higher plaque accumulation and gingival
inflammation but not with more annual bone loss, regardless of their surface
configurations.
253

250
Wennstrom et al. 2004
251
Baelum, Ellegaard 2004
252
Berglundh, Lindhe 1996
253
Chung et al. 2006
44

However, other studies
254,255
failed to demonstrate that an adequate
width of keratinized mucosa is essential in order to maintain a clinical healthy
condition at dental implants. There is no evidence of Sharpey’s fibers between
an implant or implant abutment and bone. Furthermore, Adell et al. 1981 and
Albrektsson et al. 1986 demonstrated that implant surrounded by mucosa
showed similar survival rates compared to implants placed in keratinized
mucosa.
Furthermore, peri-implant bacterial or viral infection has been shown to
elicit an immune response regulated by cytokines (TNF-α, interleukin [IL]-1ᵦ,
Transforming Growth Factor (TGF)-ᵦ, IL-10) that control the inflammatory
reaction. High levels of proinflammatory cytokines may lead to the breakdown
of periimplant tissues.
256
Existing teeth with periodontal involvement may
harbor periodontal pathogens and affect adjacent implants. Nowzari et al.
257

examined bacterial, viral, and pro-inflammatory cytokine levels in clinically
healthy peri-implant and periodontal sites. The results indicated that
periodontopathic bacteria were higher around teeth, however; cytokines (IL-10,
TNF-a) were noticeably elevated around implants.

254
Wennström et al. 1994
255
Mericske-Stern et al. 1994
256
Nowzari et al. 2008
257
Nowzari et al. 2002
45

MEASUREMENT OF IMPLANT STABILITY
Successful implant osseointegration is dependent on the degree of
primary implant stability. Historically, surgeons have relied on subjective
clinical perceptive tests to determine primary implant stability. Poor qualitative
methods to measure implant stability include the clinical perception of the
cutting resistance or the sense of opposition when seating of the implant.
Other potentially destructive methods such as the reversal or unscrewing
torque stress test and percussion test were initially utilized to measure
stability. The reverse torque test applies a shear force to assess the strength
of the implant interface, thus the implant may fracture under applied stress.
The percussion test aimed to elicit a ringing sound from the implant to denote
primary stability, this test unfortunately only yielded information about the
tapping instrument and not the stability of the implant.
However, techniques such as resonance frequency analysis (RFA)
allow an objective and noninvasive measurement of implant stability,
osseointegration at different implant stages, and determine implant success
rates.
258
The RFA value is a measure of the stiffness of the implant/
transducer/bone complex and is affected by the length of the transducer
implant complex above the bone crest. RFA measures implant stability by
applying a bending force or fixed lateral force on the implant (mimics the
clinical load and direction) thus provides information about the stiffness of the

258
Sennerby, Meredith 2008
46

implant-bone junction.
259
In essence, the failure of the implant to seat
increases the effective length above the bone crest and this reduces the RFA
value.
260

RFA is dependent on 3 main factors: design of the transducer, stiffness
of the implant fixture and its interface with the tissue and surrounding bone,
and also the total effective length (above the marginal bone level).
261
Evaluation of the stiffness of the implant bone interface can be influenced by
several factors such as bone density, jaw healing time, and exposed implant
height.
The third generation RFA instruments were the first to be made
available for clinical chair-side measurements. The RFA (Osstell
TM
; Osstell
AB, Gothenburg, Sweden) is a battery-driven device with a transducer that
was pre-calibrated from the manufacturer. Several transducers are available
for different implant systems and abutments. Currently, the newest RFA
version is wireless, with a metal rod or peg connected to the implant (Osstell
Mentor;
TM
Osstell AB). The rod vibrates in two directions and gives two
readings (high and low RF).
Originally, the resonance frequency measurements were recorded in
hertz, however, the measurements were later converted into implant stability
quotient (ISQ) units. ISQ values are based on the underlying resonance

259
Mericske-Stern t al. 1994
260
Meredith et al. 1996a
261
Sennerby, Meredith 2008
47

frequency and ranges from 1 (lowest stability) to 100 (highest stability).
Generally, stability quotient values of 50 and 60 are seen in osseointegrated
implants in maxillary bone, and 60 to 80 in mandibular bone.
262

Sennerby and Meredith
263
suggested that if implants have a primary
stability greater than an ISQ value of 60-65 then immediate loading is a viable
option. Olsson et al.
264
reported a mean primary ISQ of 60 in maxillary early
loaded implants in fully edentulous patients.
Several researchers have documented the correlation between bone
quality and ISQ values.
265,266
Lower ISQ values is indicative of ongoing failure
or marginal bone loss. Sennerby et al.
267
demonstrated a negative correlation
between radiographic bone loss and resonance frequency. Fischer found no
correlation during the first year in function, between marginal bone loss and
RFA.
268
However, after 3 to 5 years lapse the same group noted a positive
correlation between marginal bone loss and ISQ values.
269
Fischer et al.
270

measured 139 maxillary implants in 24 patients at 3 and 5 years and
determined the average ISQ values and corresponding failure rates to be
below 44 (100%), 53 (6.7%), 54 (9.5%).

262
Sennerby, Meredith 1998
263
Sennerby, Meredith 1998
264
Olsson et al. 2003
265
Jansson, Lavstedt 2002
266
Ostman et al. 2006
267
Sennerby et al. 2005
268
Fischer, Backstrom et al. 2008
269
Fischer, Stenberg et al. 2008
270
Fischer 2008
48

However, other studies found no relation with ISQ values and bone
stability and determined that ISQ measurements rarely correlated with implant
survival.
271,272
Furthermore, Andersson et al.
273
found an inverse
relationship between cutting torque (bone density) and implant stability,
however all implants in the study reached a comparable level of stability after
one year. Implants in soft bone with low primary stability showed increase
stability in comparison to implants initially placed in dense bone. A slight
decrease in stability was observed with implants placed in dense bone (type I
or II). The stiffness of implant-bone interface is high in dense bone and low in
soft bone; however, with normal bone remodeling process, soft trabecular
bone increases in stiffness post-surgically.
274
In addition, the drawbacks to
RFA are the need to remove the prosthetic restoration prior to analysis;
however, RFA allows a non- detrimental feedback.

Dental implants are a highly successful treatment option in partial and
fully edentulate patients. Innovations in implant dentistry have allowed for an
increased understanding of implant failures and success; however, new
avenues for improvements are needed. Immediate loading is a viable
alternative to the conventional loading protocols; yet regardless of reported
high success rates, there is a lack of well-controlled prospective longitudinal
studies to adequately document the success of immediate loading.

271
Ottoni et al. 2005
272
Becker, Becker et al. 2003
273
Andersson et al. 2008
274
Sennerby, Meredith 2008
49

CHAPTER 2: MATERIALS AND METHODS
A prospective, observational research design was proposed to study the
immediate occlusal loading of the 3i (Implant Innovations, Inc., Palm Beach
Gardens, FL) Osseotite Certain IOL (Integrated Osseous Lateralization) implant
system. The University of Southern California Health Sciences Institutional
Review Board (HSIRB) approved the study (IRB # 047003) and written informed
consent was obtained from all subjects. Enrollment period was limited to 13
months, from March 2005 to April 2006. An initial screening was performed to
establish if dental implant treatment was suitable and if patients met the inclusion
and exclusion criteria (Table 2 and 3).

Table 2. Patient Inclusion Criteria

INCLUSION CRITERIA

 Patients of either sex, all race, 18 years of age or
older

 Patients for whom a decision has already been
made to use dental implants for treating existing
partial edentulism in the posterior mandible or
maxilla using a short span implant supported fixed
prosthesis of 2 to 4 units.

 Patients physically able to tolerate conventional
surgical and restorative procedures.

 Requirements for implant placement include: at
least 1mm of bone at the buccal, lingual, and apex
of implant.

50

Table 3. Patient Exclusion Criteria

EXCLUSION CRITERIA

 Patients with active infection or severe inflammation in the
area intended for implant placement.

 Smokers ≥ 10 cigarettes/day

 Patients with uncontrolled diabetes or metabolic bone
disease.

 Patients with a history of therapeutic radiation to the head.

 Patients in need of bone grafting at the site of the intended
study implant.

 Patients who are known to be pregnant.

 Patients with para-functional habits with evidence of
severe bruxing or clenching.

 Placement of implants into sites with < 16 weeks of post-
extraction healing. For 3-and 4-unit cases one implant
site may have < 16 weeks of healing prior to implant
placement.

 Cantilevers and/or > 1 pontic per bridge.

 Inter-arch distances of < 7 mm (planned location of
implant seating platform to the opposing occlusal
landmark).

51

TEST DEVICE
The 3i Osseotite Certain IOL implant system (Figure 1) consists of a
threaded titanium alloy with an internal connection. An Osseotite dual acid –etch
(phosphoric and sulfuric acid) surface is present from the apex to the maximum
diameter (area where the platform tapers inward); with a 0.9 mm thread pitch.
The IOL implant system is a combination of three existing 3i design elements
(natural taper (NT), expanded platform (XP), and platform switching).
The NT design refers to the gradual tapering of the implant whereby the
apical portion is 2.5 mm (D). The coronal portion incorporates the XP design
whereby the implant platform expands 1 mm wider than the implant body. The
expanded platform, at the coronal portion, allows a rigid stabilization with
enhanced emergence profile with the larger platform. The device also
incorporates the concept of platform switching at the coronal aspect. The largest
coronal diameter is 4.8, 5.8, and 6.8 mm. For a regular (4 mm) diameter implant,
the platform is 4.8 mm and post is 4.1mm diameter. The implant is lateralized
where the seating surface tapers at a 15 degree angle. The implants are
available in diameters of 4, 5, and 6 mm (mid-portion of implant diameter
dimension) and in lengths of 10, 11.5, and 13 mm.

52

STUDY PROCEDURES
The examination protocol (including inclusion and exclusion criteria)
corresponded with the recommendations presented by Lekholm et al.
275

Periapical radiographs and clinical measurements were taken on the day of
surgery and at 3, 5, 12, 24, and 36 months post-implant placement. To ensure
confidentiality of patient information, each patient enrolled in the study were
assigned a numeric code (#1- 8). The clinical visits are specified below:
Visit 1: Patient screening session
 Patients were evaluated for medical and dental conditions (Figure 2).

 A panoramic and peri-apical radiograph was collected to assess
patient’s admissibility and then a CT scan was ordered for the
participants that qualified for the study.

 All patients’ medical and demographic information were obtained.

 Pre-surgical procedures for the restorative dentist (post-doctorate USC
resident or faculty) consisted of:

 Impressions, articulated casts, and a diagnostic wax-up of the
intended restorations

 Fabrication of a clear vacuum-formed surgical template and a
splinted provisional restoration (based on the wax-up)

 Fabrication of the temporary prosthesis

275
Lekholm et al. 2003
53

Visit 2: Implant Surgery & Provisional Prosthesis
 All implants, for each patient, were placed during the same visit.

 Surgical equipment, type of irrigation, and duration of the time required
to complete the surgical procedure were documented (Figure 3).

 Provisional prostheses were inserted the day of implant placement.

Visit 3 (Week 1): Healing Assessment
 Patients were examined for any signs of implant failure or infection.
The clinical evaluation determined the presence of any gingival
inflammation status, suppuration, implant mobility, and peri-implant
radiolucency.

 Prosthesis evaluation was based on the following criteria: retention,
stability, esthetics, phonetics, vertical occlusion, and pain on chewing.

 The patients were given a visual analog scale where they were to
indicate the status of the prosthesis based on: comfort, fit, speech,
appearance, ability to chew and taste food, general satisfaction, and
any pain on chewing.

Visit 4 (3 months): Clinical examination and impression, fabrication of
permanent prosthesis

 Impression taking and fabrication of the permanent prosthesis were
competed between three and five months post-implant placement.

 The prosthesis were processed according to the standard procedures
for a fixed bridge

Visit 5 (6 months): Permanent prosthesis loading
 The permanent prostheses were loaded by 6 months post-implant
placement.

 Peri-apical radiographs were taken.

 Gingival and plaque indices were evaluated (Table 3, Figure 4)
54

 RFA analyses were measured and for each implant two ISQ values
were recorded.

 The prostheses were evaluated for retention, stability, esthetics,
phonetics, vertical, and horizontal occlusion.

 Also, the patients were asked of their experience with the prosthesis.
A visual analog scale was provided to the patients to evaluate their
prosthesis for the following criteria: prosthesis retention, prosthesis
stability, esthetics, phonetics, vertical occlusion, and pain on chewing.

Visits 6-8 (12, 24, and 36 months): Follow-up evaluations
 Follow-up evaluations were carried out at 1-year intervals following
implant surgery for 3 years.

 Peri-apical radiographs were obtained for all study implants.

 A clinical examination was performed to evaluate the general area
surrounding the implant based on gingival and plaque indices (Figure
4).

 Prosthesis function was assessed (Figure 5) and the patients were
interviewed to determine if they had any problems or difficulties with
their prosthesis. Patients were asked if they had episodes of pain or
numbness.

 All implant sites were examined for any evidence of implant failure
including peri-implantitis, suppuration, or erythema. Implants that show
signs of failure (radiolucency, infection, pain, or neuropathy) were
assessed for implant mobility. Any overt indication of mobility will be
recorded as a failure.

55

Table 4. Gingival and Plaque Index

Gingival Index

0 Normal Gingiva
1 Mild inflammation
2 Moderate inflammation, redness, edema, and
bleeding on probing
3 Severe inflammation, marked redness and edema,
ulcerations, tendency towards spontaneous
bleeding

Plaque Index
1 No plaque in gingival area.

2
No plaque visible by the unaided eye, but plaque
is made visible on the point of the probe after it
has been removed across surface at entrance of
gingival crevice.
3
Marginal area is covered with a thin to moderately
thick layer of plaque; deposit is visible to the naked
eye.
4
Heavy accumulation of soft matter, the thickness
of which fills out a niche produced by gingival
margin and tooth surface, and interdental area is
stuffed with soft debris.

56

Figure 2. Baseline Clinical Conditions Form

Patients’ demographic, medical, and dental conditions were obtained prior
to surgery.

57

Figure 3. Implant Placement Form

Implant bone status, bone fit, RFA, and drill torque information were
documented at implant surgery.

58

Figure 4. Clinical Evaluation Form

Clinical form used to evaluate patients’ gingival indices, and presence
or absence of suppuration, implant mobility, and/or peri-implant
radiolucency.

59

Figure 5. Prosthesis Evaluation Form

At prosthesis delivery, patients’ dentition status, type of prosthesis design,
and clinical evaluation was documented.

60

SURGICAL PROCEDURES
Implants were placed according to manufacturer’s protocol by a single
experienced board certified periodontist (H.N.). All surgeries were performed
under controlled sterile conditions. Patients were given antibiotic prophylaxis
one hour prior to implant surgery. Implants were placed crestal or subcrestal to
the platform to assure engagement of the tapering expanded portion (platform
switch) with the bone crest. Specific shaping drills were provided by the
manufacture for each implant diameter-length. The drills ensure that the
osteotomy site is created to exactly match the implant dimension and allows the
expanded platform to seat correctly on the crestal bone margin. The surgical site
was prepared under high-speed and copious irrigation. Minimal alveoloplasty
was performed to achieve a suitable bone surface with sufficient width and all
attempts were made to avoid over-reduction of the alveolar bone recipient site.
Also, to avoid unnecessary soft-tissue damage, use of surgical retractors was
minimized. Information on bone status and bone fit were recorded (Figure 3).
Specific Surgical Procedures:
 Open flap surgery with a mid-crestal incision.

 Placed all implants with a surgical guide and standard drilling
sequence for crestal placement.

 The final shaping drill (specific for each implant dimension) was
used to prepare the apical and cortical profiles to attain initial
primary stability.

 If threads were exposed during implant placement, they were
covered with autogenous bone and documented.

61

The implant length was limited by the height of remaining alveolar bone,
sinus level, and proximity of nerves. The diameter of the implant was determined
by the available width of the bone and final prosthetic restoration. Implant sites
consisted of premolars and molars of the maxillary and mandibular posterior
positions. Patients 1 – 7 received 2 implants each and patient 8 received 3
implants. The length and diameters of each implant were determined on a case-
by-case basis. The length of the implants varied from 8 to 13mm and the
diameter were either 4/5mm XP or 5/6mm XP. No threads were exposed on any
of the implants.

RESTORATIVE PROCEDURES
Prosthetic treatment was performed according to the manufacturer’s
manual, and an immediate fixed partial denture was delivered within 24 hours of
surgery. Two – or 3-unit fixed partial dentures were made in all patients. A
centric contact was achieved on each provisional crown and all lateral
interferences were removed. GingiHue abutment posts were used to restore the
final prosthesis. Along with prosthetic loading, implant stability was individually
checked.
Specific Restorative Procedures
 GingiHue abutment posts were selected by matching the seating
surface of the implant (IAPP454G or IAPP452G) for 4 mm diameter
implants and (IWPP554G or IWPP552G) for 5 mm implants.

62

 The GingiHue post was placed on the implant to check if the
external hex of the post lined up with the internal implant post. A
Gold-Tite Hexed Screw (IUNIHG) was placed through the opening
at the top of the GingiHue post. Initial tightening of the screw was
done manually.

 Preparation of the GingiHue post (height, angulation, and gingival
counters) was performed. The flat side of the GingiHue post was
adapted to face the buccal to allow for better retention.

 The collar of the GingiHue post was polished with a rubber cup to
increase the roughness of the surface for cement adherence.

 Cotton pellets were placed on top of the abutment screw to prevent
acrylic adhesion into the access hole.

 Acrylic resin was placed inside the temporary bridge.

 The temporary provisional prosthesis was adjusted with a narrow
occlusal table (at least 6 mm but not greater than 10 mm) in order
to provide at least one centric contact on each tooth but no lateral
contacts.

 Occlusion was checked with Accufilm 120 micron paper during
normal biting in light clenching force. To avoid super-occlusion,
Shimstock metal foil 8 micron tape was used.

 The implant torque was checked prior to sealing the access hole.
The screw was torqued to 45 - 50 Ncm with the 3i torque indicating
wrench.

 Full alginate upper and lower impressions with bite registration
were taken.

 Temporary bridge was cemented with temporary cement

 Periapical radiographs were taken.

63

CLINICAL MEASUREMENTS
All patients were monitored appropriately with regular 3 months cleaning
and evaluations.
Periapical radiographs were obtained with a dental radiograph machine
operating at 60kVp taken on film or digital format. A standardized long-cone
paralleling projection, with a ring film holder was utilized at each appointment.
Film radiographs were digitized by scan with a resolution of 600 x 1,200 dots per
inch (Epson Perfection 1260, Espon, Meerbusch, Germany). Linear mesial and
distal measurements between the total implant length and height of the alveolar
crest was determined to characterize the amount of bone loss. Radiographic
analysis was performed with ImageJ 1.38x, a public domain, Java-based image
processing program provided by the National Institute of Health (NIH).
Computerized evaluation of radiographic interproximal bone level was
performed at time of implant placement and time intervals of 3, 6, 12, 24, and 36
months post-surgically. Crestal bone levels observed at all follow-up intervals
were compared to radiographs obtained immediately post-implantation. For each
follow-up interval, the increase or decrease in bone height will be expressed as
an absolute value in tenths of a millimeter.
The periapical radiographs obtained immediately after implant placement
was the baseline radiographs used to compare all follow-up evaluations. Figure 6
depicts how the radiographs were measured with ImageJ. The length of each
implant was imputed into ImageJ as a set scale thus changes in crestal bone
64

level was calculated in comparison to the known implant length. Each
measurement was performed three times and the average of the three was
recorded. Also, radiographs were evaluated for presence or absence of any peri-
implant radiolucencies or abnormalities.
Resonance frequency analysis measurements were taken at the time of
implant placement and at final prosthesis insertion to determine implant stability.
For each study implant two implant stability quotient (ISQ) values were obtained
at placement and final prosthesis insertion using the Osstell
TM
Mentor
instrument, Integration Diagnostics AB, Gothenburg, Sweden.
Evaluation of the patient peri-implant mucosa was performed by assessing
the gingival and plaque indices at baseline and at 3, 6, 12, 24, 36 months post-
implant placement. Gingival and plaque indices (Table 3) were based on Loe
and Sillness Index (1967).

VISUAL ANALOG SCALE
The current study evaluated patient satisfaction via questionnaires with a
visual analog scale (Figure 7). Patients’ were asked to evaluate the implants
based on: comfort, fit, speech, appearance, ability to chew food, ability to taste
food, general satisfaction, and pain chewing. Investigator evaluation (Figure 8)
assessed the prosthesis retention, prosthesis stability, aesthetics, phonetics,
vertical occlusion, and pain on chewing. The scales range from 1 to 100 (1,
65

excellent; 100, poor). Measurements were taken at baseline and at 1, 2, 3 years
of follow-up.

MICROBIOLOGICAL SAMPLING
Peri-implant bacterial samples were obtained at baseline and at 1 week
and 3 months. Baseline microbiological sampling included pooled samples from
natural teeth at day of implant placement and samples from implants at 1 week
(7 subjects) and 3 months (4 subjects).
Microorganisms examined consisted of Aggregatibacter
actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis,
Tannerella forsythia, Campylobacter species, Eubacterium species,
Fusobacterium species, Peptostreptococcus micros, Enteric Gram-negative rods,
Eikenella corrodens, yeast, Staphylococcus species, and Beta hemolytic
Streptococcus. Anaerobic microbiological isolation and identification of putative
periodontal pathogens were carried out with no knowledge of the source (natural
vs. implant site) of the specimens.
Supragingival plaque was first removed, followed by insertion of three fine
endodontic paper-points (Johnson & Johnson, East Windsor, NY, USA) into the
depth of each implant site for 10 seconds and then transferred to viability
medium Göteborg anaerobic III (VMGA III) transport medium.
276
All samples
were processed within 2 hours of collection.

276
Moller 1966
66

Microorganisms were mechanically isolated from the paper points with a
vortex mixer (at maximal setting) for 45 seconds and then diluted 10-fold serially
in VMG I anaerobic dispersion solution. Using a sterile bent glass rod, 0.1 ml
aliquots from 10
3
to 10
5
dilutions were plated onto a nonselective 4.3% brucella
agar (BBL Microbiology Systems, Cockeysville, MD, USA) supplemented with
0.3% bactoagar, 5% defibrinated sheep blood, 0.2% hemolyzed sheep red blood
cells, 0.0005% hemin, and 0.00005% menadione.
Absolute viable counts and magnitude of specific microorganism in
association to the total viable counts were determined. Aliquots diluted in VMGA
III medium were plated onto TSBV medium for culture of A.
actinomycetemcomitans, enteric Gram-negative rods, and yeasts. The non-
selective blood agar was incubated at 35°C in an anaerobic chamber

(Coy
Laboratory Products, Ann Arbor, MI, USA) containing 85% N
2
– 10% H
2
– 5%
CO
2
for 10 days. TSBV (tryptic soy – serum – bacitracin – vancomycin) medium
was incubated in 10% CO
2
under aerobic conditions at 35°C for 4 days.
Colonies were identified by morphological resemblance to the study species
according to methods described by Slots
277
and utilization of the micromethod
system (API
®
20°, bioMerieux, Marcy l’Etoile, France). The percentage recovery
of periodontal pathogens was determined by the colony counts of each microbial
taxon in relation to total viable counts.

277
Slots 1986
67

EVALUATION CRITERIA
A procedure success constitutes the completion of implant placement and
prosthesis insertion within 24 hours and with prosthesis function scores of good
or better. The duration of failure-free function were recorded for both the
temporary and permanent prostheses. Prosthetic failure will be declared if there
is damage or fracture of the prosthesis that requires repair that cannot be
completed at chair side. Additionally, if implant failure results in the need to
discontinue use of the prosthesis the duration of time from prosthesis insertion to
the time of implant failure will be recorded.
An implant is considered successful as long as it supports the prosthesis
and satisfies the following criteria based on Albrektsson et al. (1986) criteria for
implant success:
 Lack of mobility
 No peri-implant radiolucency on radiograph
 Absence of persistent and/or irreversible signs and symptoms such
as pain, infections, neuropathies, paraesthesia, or violation of the
mandibular canal

STATISTICAL ANAYLSIS
A prospective longitudinal descriptive and comparative study design was
used to examine the characteristics of integrated and failed implants. Descriptive
statistics were computed for all study variables and absolute and relative
68

frequency distributions for qualitative variables and mean ± SD for all quantitative
variables were calculated. Implant loss and changes in crestal bone level were
the principal variables under study. Cumulative survival rates were estimated
through Kaplan-Meier methods. Implant survival as a function of time was
analyzed using Kaplan-Meier analysis, comparing the survival rates among the
different variables with the Breslow statistic.
Estimation in bone level changes for all implants were described using
means and standard deviations, overall, by duration of implant, implant status,
distal versus mesial surface, and according to adjacency (implant adjacent to a
tooth, another implant, or an edentulous space). Nonparamentric tests of group
differences (Mann-Whitney U or Kruskal-Wallis) were used to compare bone loss
by the above-listed characteristics. To estimate bone level changes from
baseline to 40 months an associated 95% confidence interval was computed.
VAS completed by investigators and patients were described using means and
standard deviations. Pearson correlations between patients and investigators
VAS scores were examined. A statistical analysis based on means and
standard deviations of the microbiological parameters was reported. All data
analysis was performed with SPSS v.15.0 by an independent research
company.
278
Alpha was set at p ≤ 0.05.

278
Vital Research, LLC
69

Figure 6. Crestal Bone Analysis

A.

B.

Crestal bone loss was analyzed with Image J. Measurements were
performed from the most coronal portion of the bone level to the apex of
the implant. A) Example of crestal bone measurement at surgical
placement (baseline). The mesial site of #12 was measured from the
platform to the apex. B) Crestal bone measurement at 24 months. The
mesial site of #12 was measured from the most coronal portion of the
bone level to the apex.

70

Figure 7. VAS Patient Evaluation Form

Patients were asked to indicate how they regarded the implant
comfort, fit, speech, appearance, ability to chew and taste food,
general satisfaction, and pain on chewing.

71

Figure 8. VAS Investigator Evaluation Form

Investigators examined the status of the patients’ prosthesis in regards to
retention, stability, esthetics, phonetics, vertical occlusion, and pain on
chewing.

72

CHAPTER 3: RESULTS
Eight patients, (F = 4, M = 4) age 28 to 83 years old (mean, 60)
participated in the study. A total of 17 immediately loaded Osseotite Certain IOL
implants were placed and there were no surgical complications associated with
implant placement. The mean follow-up period was 30 months (range, 24 – 40
months). All implants were placed in the posterior regions (premolar and molar
sites). Thirteen implants were placed in the mandible and 4 implants were
placed in the maxilla. The implant lengths were 10 mm (17.7%), 12 mm
(29.4%), and 13 mm (52.9%). A summary of patient and implant descriptive
statistics is presented in Table 5.
The overall survival rate was 70.6% (12/17). The survival rate at 12
months was 82.3%, with 70.6% survival between 12 and 40 months. Based on
the Kaplan-Meier analysis 100% of the maxillary implants survived to 36 months,
and 61.5% of the mandibular implants survived to 40 months (Figure 9). The
statistical analysis for equality of survival distributions for the maxillary and
mandibular sites showed no significant difference in survival between the two
groups. Five of 17 implants failed 3 and 14 months post-operatively and 2
implants failed twice, in 4 of the 8 patients (mean age, 64 years old). Three
implants (60%) were deemed early failures due to detection of mobility at 3
months and 2 more implant failures occurred at 14 months with mobility and peri-
apical radiolucencies.

73

Table 5. Descriptive Statistics

Variable N %
Demographic
Mean age (n=8) 59.9 -
Sex (n=8)
Female 4 50
Health Status
Smokers 0 0
Diabetics 0 0
Post-menopausal (n=4) 3 75
Anatomic (n=17)
Maxillary Posterior 4 23.5
Mandibular Posterior 13 76.5
Bone Quality (n=17)
Type 1 0 -
Type 2 10 58.8
Type 3 7 41.2
Type 4 0 -
Implant (n=17)
Implant length
10 mm 3 17.7
11.5 mm 5 29.4
13 mm 9 52.9
Implant diameter
4/5 mm 9 52.9
5/6 mm 8 47.1
Prosthetic
Total no. units (n=17)
2 14 82.4
3 3 17.6
74

Figure 9. Implant Survival Graph

A comparison of maxillary and mandibular cumulative survival times was
performed by a Kaplan-Meier survival anaylsis. Vertical axis denotes the
percentage of cumulative survival (1.0 = 100%) and the horizontal axis
measure the time of follow-up in months.

75

All failures occurred in the mandibular molar sites. No suppuration,
implant mobility or peri-apical radiolucencies were observed during follow-up
visits up to 12 months. At 14 months, peri-apical radiolucency and mobility was
observed for 2 implants (40%). All loaded implants had a tight implant bone fit
and overall, type II bone density accounted for 58.8% of the total implants, with
41.2% exhibiting type III/IV bone density. The bone density in failed implants
consisted of 60% type II and 40% type III/IV bone. No statistically significant
relationship was observed between bone density and implant failure. However,
a trend was detected in which type III/IV bone showed an association with early
failures whereas late failures had a type II bone density.
The mean crestal bone loss was 1.80 mm (±1.12) for the first year in
function and 2.04 mm (±1.26) 3 years post-operatively. Figure 10 depicts the
changes in radiographic crestal bone levels over time. A Mann-Whitney U test
showed no significant differences in bone loss by duration. No radiologic
difference regarding crestal bone loss was observed between the tested
platform switched implants and standard implants.
No statistically significant difference was found between mesial and distal
sites of implants, however, as shown in Figure 11 the mesial implant sites
demonstrated an average greater bone loss (2.22 ± 1.66 mm) than the distal
sites (1.85 ± 0.67 mm). Based on the Kruskal-Wallis test, implants adjacent to
implants, on average demonstrated slightly higher bone loss compared to
implants adjacent to teeth or edentulous areas (Table 6) however, the
76

differences were not significant. Table 6 demonstrates changes in crestal
bone along the mesial and distal implant site. The distal implant sites exhibited
more bone loss when adjacent to an edentulous area (2.04 mm) than next to
implants (1.84 mm) or teeth (1.80 mm). However, on the mesial sites, implants
adjacent to implants demonstrated the highest bone loss (2.40 mm ± 1.99).
RFA at implant placement had a mean ISQ of 74 (range, 63 – 79.50) and
at final prosthesis delivery, the ISQ reduced to a mean of 64 (range, 59 – 69). A
high interclass correlation (0.849, p<.001) was found between ISQ
measurements at implant placement, but not at the time of prosthesis delivery
(ICC=.239, p>.05) and statistically significant decreases in ISQ were found
between the average baseline ISQ and each of the two ISQ values at time of
prosthesis delivery using a Wilcoxon signed ranks test, showing that ISQ
decreased.
In the present study, healthy peri-implant mucosal conditions were
maintained throughout the follow-up period with minimal changes in the
parameters measured. Gingival index remained consistent (range, 0 – 2) with an
average mild inflammation (score 1) from baseline and follow-up 1- 3 years.
Plaque index showed a statistically significant (p<0.008) increase of plaque with
time.

77

Figure 10. Mean Crestal Bone Level

Comparison of mean implant bone level is measured across different time
periods; initial implant placement, 1 year, 2 years, and 3 years. Implant
crestal bone stabilizes at 2 – 3 years.

0
2
4
6
8
10
12
14
16
1 2 3 4 5 6 7 8
Bone Level
(mm)
Patients
Implant Bone Level
Initial
1 year
2 years
3 years
78

Figure 11. Comparison of Overall, Mesial, and Distal Implant Sites

The mesial implant sites demonstrated an average greater bone loss
(2.22 ± 1.66 mm) than the distal sites (1.85 ± 0.67 mm); however; the
difference is not statistically significant.

0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Overall Distal Mesial
2.04
1.85
2.22
79

Table 6. Crestal Bone Loss

The amount of crestal bone loss was compared across different time
periods (1 year, 2 – 3 years, and overall). Implant status (integrated and
failed), implant surface (distal and mesial), adjacency (edentulous area,
implant, and tooth), and surface by adjacency (distal and mesial) were
compared to levels of crestal bone loss. No significant differences were
observed across all measurements.

N Crestal
Bone Loss
(mm)
SD 95% CI p value
Time
1 Year
2 – 3 Years
Overall

14
20
34

1.80
2.20
2.04

1.12
1.36
1.26

1.22-2.38
1.61-2.79
1.62-2.46

.372
Implant Status
Integrated
Failed

24
10

2.11
1.85

1.35
1.08

1.57-2.65
1.19-2.51

.597
Implant Surface
Distal
Mesial

17
17

1.85
2.22

0.67
1.66

1.53-2.16
1.43-3.01

.796
Adjacency
Edentulous
Implant
Tooth

2
18
14

2.04
2.12
1.93

0.10
1.52
1.00

1.90-2.18
1.42-2.82
1.41-2.45

.924
Surface by
Adjacency
Distal
Edentulous
Implant
Tooth

Mesial
Implant
Tooth

2
9
6

9
8

2.04
1.84
1.80

2.40
2.02

0.10
0.88
0.40

1.99
1.31

1.90-2.18
1.26-2.42
1.48-2.12

1.11-3.69
1.12-2.92

.753

.810
80

Samples cultured from14 implants at 1 week and 8 implants at 3 month
intervals revealed similar periodontal pathogens compared with baseline pooled
samples (Table 7). Common organisms presented include P. gingivalis, P.
intermedia, T. forsythia, Campylobacter species, and Fusobacterium species.
Five integrated and 3 failed implants had microbial samples performed at
3 months. Microbial samples of the 3 failed implants showed similar bacterial
loads and types of microorganisms when compared with the baseline pooled
sample and the adjacent integrated implants (Tables 8 -11). Table 8 and 9
demonstrates cultivable periodontal pathogens at 1 week and 3 months,
revealing similar quantity and composition when compared with the pooled
samples from natural teeth. Also, comparison between failed and integrated
implants within the same patient and between patients showed similar bacterial
profiles and loads (Table 10, 11). For example, subject 3 had P. gingivalis, T.
forsythia, Campylobacter species, and Fusobacterium species detected in both
failed and integrated implants.
A Mann-Whitney U test was performed to determine the differences in
microbial load between failed and integrated implants. No statistically significant
differences were observed between integrated and failed implants for any of the
pathogens tested. Figure 12 –14 demonstrates the microbial counts at baseline,
1 week, and 3 months with integrated and failed implant sites.

81

Table 7. Microbial Results

The percentages of all periodontal pathogens at each measured time points
(baseline, 1 week, and 3 months) are recorded in the above table.

A.a P. g P. i T. f Cam
p.
Eu
b.
Fus
o.
P. m E.
rods
Str
ep.
Ye
ast
E.c Sta
ph.
Subject 1
(teeth)
0 0 0 0 4 3 5 4 0 0 0 0 0
Implant
1 week
0 4.5 0 5.5 6.4 0 7.3 4.5 0 0 0.8 0 0
Implant
3 months
0 2 0 3 0 2 0 0 0 0 0 0 0
Subject 2
(teeth)
0 5.7 0 0 4.3 0 5.7 0 0 0 0 7.1 0
Implant
1 week
0 3.8 0 0 4.6 0 6.2 5.4 52.5 0 0 0 0
Implant
3 months
0 3 0 2 5 0 2 0 0 0 0 0 0
Subject 3
(teeth)
0 0 0 0 0 0 4 0 0 0 0 0 0
Implant
1 week
0 4.2 0 8.4 6.3 0 5.3 0 0 0 0 0 0
Implant
3 months
0 4.5 0 6.1 3.2 2 1.5 0 0 0 0 0 0
Subject 4
(teeth)
0 0 5 2 7 0 3 4 0 0 0 0 0
Implant
1 week
0 0 0 0 0 0 0 0 13.5 0 0 0 0
Implant
3 months
0 3.8 6.2 3.1 4.6 3.8 5.4 0 0 0 0 0 0
Subject 5
(teeth)
0 2.3 0 1 0 0 0 0 0 0 0 0 0
Implant
1 week
0 3 2.6 1.8 0 0 0 2 0 0 0 0 0
Subject 6
(teeth)
0 2.7 3.6 6.4 2.7 3.6 5.5 0 0 0 0 0 0
Implant
1 week
0 3.1 6.9 4.6 5.4 0 3.1 0 0 0 0 0 0
Subject 7
(teeth)
0 2 0 2 0.2 0.4 5 0 0 0 0 0 0
Implant
1 week
0 0 0 3.2 2.1 0 8.4 4.2 0 0 0 0 0

82
82

Table 8. Percentages of Cultivable Periodontal Pathogens for Pooled Natural Teeth at Baseline
and Integrated Implant Sites at 3 Months

Comparison of periodontal pathogens at baseline and integrated implants measured
at 3 months, show no significant differences.

A. a P. g P. i T. f Camp. Eub. Fuso. P. m E. rods Strep. Yeast E. c Staph.
Subject 1-
Pooled
0 0 0 0 4 3 5 4 0 0 0 0 0
Integrated
Implant
0 2 0 3 0 2 0 0 0 0 0 0 0
Subject 2-
Pooled
0 5.7 0 0 4.3 0 5.7 0 0 0 0 7.1 0
Integrated
Implant
0 3 0 2 5 0 2 0 0 0 0 0 0
Subject 3-
Pooled
0 0 0 0 0 0 2 0 0 0 0 0 0
Integrated
Implant
0 4.5 0 6.1 3.2 2 1.5 0 0 0 0 0 0
Subject 4-
Pooled
0 0 5 2 7 0 3 4 0 0 0 0 0
Integrated
Implant
0 3.8 6.2 3.1 4.6 3.8 5.4 0 0 0 0 0 0

83
83

Table 9. Percentages of Cultivable Periodontal Pathogens for Pooled Natural Teeth at Baseline
and Failed Implant Sites at 3 Months

Comparison of the microbial sampling of 3 patients with failed implants at 3 months shows
no statistically significant difference.

A. a P.g P. i T. f Camp. Eub. Fuso. P. m E. rods Strep. Yeast E. c Staph.
Subject 1-pooled
0 0 0 0 4 3 5 4 0 0 0 0 0
Failed implant
0 4.5 0 5.5 6.4 0 7.3 4.5 0 0 0.8 0 0
Subject 3-pooled
0 0 0 0 0 0 2 0 0 0 0 0 0
Failed implant
0 2.6 0 1.5 2.6 0 4 0 0 0 0 0 0
Subject 4-pooled
0 0 5 2 7 0 3 4 0 0 0 0 0
Failed implant 0 0 0 3.3 3.3 0 5 0 0 0 0 0 0

84
84

Table 10. Percentages of Cultivable Periodontal Pathogens for Integrated vs. Failed Implants
at 3 Months

A. a P. g P. i T. f C. Eub. F. P. m E. rods Strep. Y. E. c Staph.
Subject 1-
Integrated implant
0 2 0 3 0 2 0 0 0 0 0 0 0
Failed implant 0 4.5 0 5.5 6.4 0 7.3 4.5 0 0 0.8 0 0
Subject 3-
Integrated implant
0 4.5 0 6.1 3.2 2 1.5 0 0 0 0 0 0
Failed implant 0 2.6 0 1.5 2.6 0 4 0 0 0 0 0 0
Subject 4-
Integrated implant
0 3.8 6.2 3.1 4.6 3.8 5.4 0 0 0 0 0 0
Failed implant 0 0 0 3.3 3.3 0 5 0 0 0 0 0 0

Comparison of the microbial sampling of 3 patients with integrated and failed implants at 3 months
show no statistically significant difference across measured periodontal pathogens.

85

Table 11. Comparison of Overall Periodontal Pathogens

Comparison of predominant periodontal pathogens (P. gingivalis, P.
intermedia, T. forsythia, Eubacterium sps., Campylobacter sps., and
Fusobacterium sps.) from natural teeth at baseline and failed and integrated
implant sites (3 months). No statistically significant differences were observed
between integrated and failed implants in the pathogens tested.

P.g P.i T.f Camp. Eub. Fuso.
Subject 1 – pooled

0 0 0 4 3 5
Integrated Implants

2 0 3 0 2 0
Failed Implants

4.5 0 5.5 6.4 0 7.3
Subject 2 – pooled

5.7 0 0 4.3 0 5.7
Integrated Implants

3 0 2 5 0 2
Subject 3 – pooled

0 0 0 0 0 2
Integrated Implants

4.5 0 6.1 3.2 2 1.5
Failed Implants

2.6 0 1.5 2.6 0 4
Subject 4 – pooled

0 5 2 7 0 3
Integrated Implants

3.8 6.2 3.1 4.6 3.8 5.4
Failed Implants

0 0 3.3 3.3 0 5

86

Figure 12. Microbial Count: P. gingivalis, P. intermedia,
and T. forsythia

The distribution of P. gingivalis, P. intermedia, and T. forsythia at baseline,
1week, and integrated and failed Implants at 3 months is shown above.
Similar levels of microorganisms were found between integrated and failed
implants (except P. intermedia). No significant differences were observed
between the microorganisms at baseline or integrated and failed implants.

0.00%
1.00%
2.00%
3.00%
4.00%
5.00%
6.00%
7.00%
8.00%
9.00%
10.00%
P. gingivalis P. intermedia T. forsythia
1.81%
1.23%
1.63%
2.66%
1.36%
3.36%
3.33%
1.55%
3.55%
2.37%
3.43%
Baseline 1 week Integrated 3 month Failed 3 month
0%
87

Figure 13. Microbial Count: Campylobacter sps.,
Eubacterium sps., and Fusobacterium sps.

The distribution of Campylobacter sps., Eubacterium sps., and
Fusobacterium sps. at baseline, 1 week, and integrated and failed
implants at 3 months is shown above. Similar levels of microorganisms
were found between integrated and failed implants (except Eubacterium
sps.). Campylobacter and Fusobacterium species were higher in failed
implants; however, the difference was not statistically significant.

0.00%
1.00%
2.00%
3.00%
4.00%
5.00%
6.00%
7.00%
8.00%
9.00%
10.00%
Campylobactor Species Eubacterium Species Fusobacterium Species
2.60%
1.00%
4.02%
3.54%
4.33%
3.20%
1.95%
2.23%
4.10%
5.43%
Baseline 1 week Integrated 3 month Failed 3 month
0%
0%
88

Figure 14. Microbial Count: P. Micros, Enteric Gram Negative
Rods, Yeast, and E. Corrodens

Levels of P. Micros were higher in failed implant sties than integrated
sites; however the results were not statistically significant. Enteric Gram
negative rods showed high quantities at 1 week, and minimal levels of
yeast and E. Corrodens were detected.

0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
14.00%
16.00%
18.00%
20.00%
P. Micros Enteric Gram
Negative Rods
Yeast E. Corrodens
1.14%
1.01%
2.30%
9.42%
0.11%
1.50%
0.27%
Baseline 1 week
0%
0%
0% 0%
0%
0% 0% 0% 0%
89

The qualitative outcome was measured by a visual analog scale. No
significant difference was determined in the investigator VAS scores across
different time points for prosthesis retention, prosthesis stability, esthetics, and
vertical occlusion. The investigator evaluation showed significantly lower
phonetics scores at baseline (4.0) than at 3 years follow-up (5.4) and pain on
chewing scores was less at 3 years (4.0) than at baseline (28.9).
Generally, patient overall satisfaction was highly correlated (r >0.91,
p <0.002) with the ability to chew, pain on chewing, and comfort (Table 10).
Patient VAS scores did not differ significantly across the 4 measurement periods
for any of the 8 variables. Patient VAS scores of fit and investigator scores of
prosthesis stability were moderately correlated at baseline and 12 months and
highly correlated at 24 months with a correlation coefficient of r >.62 and r >.92,
respectively.
Patients with no failed implants were compared with patients who had one
or more implant failure(s) on their investigator and patient VAS scores. No
significant differences were found in the investigator VAS scores for any variable
at all measurement periods. At 12 months patient’s self-rated comfort,
appearance, ability to chew food, and pain on chewing were significantly higher
among patients with integrated implants compared to those with 1 or more failed
implants, as shown on Table 11.

90

Table 12. Patient VAS Correlations

Patients’ general satisfaction was compared against comfort, fit, speech,
appearance, ability to chew or taste food, and pain on chewing. Patients’
general satisfaction was highly correlated with comfort, ability to chew
food, and pain on chewing (p <.002).

Variable

Statistical
Analysis

Patient General
Satisfaction
Comfort Pearson Correlation .913
Sig. (2-tailed) .002
N 8
Fit Pearson Correlation .319
Sig. (2-tailed) .442
N 8
Speech Pearson Correlation .552
Sig. (2-tailed) .156
N 8
Appearance Pearson Correlation .518
Sig. (2-tailed) .188
N 8
Ability to chew food Pearson Correlation .902
Sig. (2-tailed) .002
N 8
Ability to taste food Pearson Correlation .165
Sig. (2-tailed) .695
N 8
Pain on Chewing Pearson Correlation .970
Sig. (2-tailed) .002
N 8
91

Table 13. Comparison of Patients’ VAS Results

Variable
Integrated
Implants
(n = 4)

SD
Failed
Implants
(n = 4)

SD

p Value
Comfort 11.5 6 .40 3.0 3.30 .032
Appearance 9.75 3 .86 2.33 3.22 .05
Ability to Chew Food 11.00 1 .23 1.67 1.53 .05
Pain on Chewing 6.00 3. 46 1.67 1.53 .048

Comparison of patients’ self-evaluation with integrated and failed
implants (n = number of patients). Patients with no failed implants
reported higher satisfaction with comfort, appearance, ability to chew
food, and pain on chewing.

92

CHAPTER 4: DISCUSSION

Implant dentistry have evolved from a traditional two stage functional
therapy to a highly esthetic and immediate load driven discipline. Initially, the
rationale behind delayed loading was to limit implant micromovements during
wound healing, which may induce fibrous tissue encapsulation rather than bony
contact, leading to clinical failure.
279,280
The original Brånemark protocol of
delayed 3 – 6 months submerged healing period was based on a selected
patient pool with poor bone quality, limited implant design (machine surface and
only two lengths were available), and the surgical protocol of raising a muco-
periosteal flap.
281
In addition, submerged implants were thought to prevent
infection and epithelial downgrowth.
282,283
However, currently, similar treatment
outcomes have been reported for submerged and non-submerged
implants.
284,285,286

The two-stage implant protocol has yielded high success rates; however,
patients have found the prolonged healing period to be uncomfortable and
inconvenient. Consequently, clinicians have sought to implement techniques to
shorten the restorative phase with methods such as immediate placement of
implants at time of extraction, immediate load, and flapless surgical procedures.

279
Adell et al. 1981
280
Esposito et al. 2007
281
Brånemark et al. 1977
282
Branemark et al. 1977
283
Akagawa et al. 1986
284
Ericsson et al.1994
285
Becker et al. 1997
286
Collaert, De Bruyn 1998
93

Moreover, modifications of implant shape, surface characteristics, and
advancements in implant technology have made it possible to restore implants
predictably with shorter healing periods.
287

Preliminary studies have claimed that a one-step Brånemark implant may
be considered a viable alternative to conventional loading of implants.
288
Several
investigators have demonstrated successful immediate loading in edentulous
mandibles by means of a fixed cross-arch splinted superstructure.
289,290,291
Also,
direct bone-to-implant contact was observed with screw and hydroxyapatite
coated immediately loaded implants.
292
Immediately loaded implants have
reduced the healing period and provided patients with an esthetic prosthesis
during the restorative period. Accordingly, the present study aims to investigate
immediate occlusal loading in relation to long-term, clinical and microbiological
outcomes with the 3i Osseotite Certain IOL implant.
The cumulative survival rate, observed in this study, was 70.6% over a 3
year period. This is lower than the generally reported cumulative survival rates
of immediate (85 – 100%) and delayed (94 – 100%) loading implants.
293,294,295

Early studies on immediate loading demonstrated high

287
Cochran et al. 2002
288
Becker et al. 1997
289
Randow et al. 1999
290
Salama et al. 1995
291
Tarnow et al. 1997
292
Sagara et al. 1993
293
Ostman 2008
294
Chiapasco et al. 1997
295
Erakat et al. 2008
94

success rate with mandibular hybrid prosthesis (97.4%),
296
implant- retained
mandibular overdentures (97.5%),
297
and splinted-fixed partial dentures
(100%);
298
however, the success rates with immediate occlusal loading of single
implant restorations vary significantly (79 – 100%).
299

Similar low survival rates with immediately loaded implants were observed
in current literature. Tawse-Smith et al.
300
examined immediate and delayed
loading with implant supported overdentures and found a 70.8% success rate
with immediately loaded machine implants and 100% with rough surface
implants, although the difference was not statistically significant. Oddly, the
success rate of rough surface delayed loaded implant was only 83.3%. The
authors attributed the low success rate to the machined surface characteristics of
the implants, which had 7 of the 8 early implant failures. Also, a clinical study
conducted by Glauser et al.
301
revealed low success rates (66%) when implants
were placed in poorly mineralized trabecular bone in the posterior maxilla. Oh et
al.
302
investigated the effects of flapless immediately loaded Zimmer implants in
the maxilla and determined a 75% survival rate for immediate loaded versus
100% for conventional loaded implants. The authors attributed the high failure
rate (25%) to patient selection and different permanent loading times, whereby

296
Testori et al. 2004
297
Chiapasco et al. 2001
298
Degidi et al. 2006
299
Attard et al. 2005
300
Tawse-Smith et al. 2002
301
Glauser et al. 2001
302
Oh et al. 2006
95

the permanent prosthesis was delivered within 10 – 14 days after surgery while
other studies delivered the permanent crowns at 6 months.
303,304
Also, Chaushu
et al.
305
reported an 82.4% survival rate with immediately loaded single-unit
hydroxyapatite - coated implants in fresh extraction and healed sites, within a 13
month period. All failures (3/28) were in the fresh extraction sites. In addition,
Susarla et al.
306
demonstrated that immediately loaded implants were 2.7 times
more likely to fail at 1 year when compared with delay-loaded implants. They
also determined certain risk factors associated with failure, such as smoking,
maxillary sites, and short implant lengths. Given the retrospective nature of the
authors’ study, loss to follow-up and lack of a uniform recall time period may be
significant factors affecting the results.

However, other studies
307,308,309,310,311
demonstrated comparable survival
rates (greater than 90%) with immediate and delayed loading protocol.

Tarnow
et al.
312
observed 10 patients (1 – 5 years) with immediately loaded and splinted
full-arch maxillary and mandibular prosthesis and the cumulative survival rate
reported was 97%. In addition, a review of 8 published studies was conducted
on 1,446 immediately loaded implants (184 patients) in the

303
Lorenzoni et al. 2003b
304
Andersen et al. 2002
305
Chaushu et al. 2001
306
Susarla et al. 2008
307
Buser et al. 1988
308
Salama et al. 1995
309
Chiapasco et al. 1997
310
Gatti et al. 2000
311
Malo et al. 2000
312
Tarnow et al. 1997b
96

completely edentulous maxilla and a 97.3% total implant survival rate was
obtained.
313
The results from these studies suggest that immediate implant
loading can provide high success rates.
The large discrepancy observed between the survival rates in the present
study and generally reported high survival rates on immediate implant loading
may be attributed to the study duration, different case selection criteria (i.e.
patient factors, bone quality, or location of implant site), occlusal factors, time of
functional loading (permanent crown placement), implant device, and surgical or
prosthodontic protocols. The present study is a prospective 3 year study
whereby most clinical immediate load studies report survival rates at only one
year. Balshi and Wolfinger
314
confirmed that the occlusal scheme may
jeopardize the success rates of immediately loaded implants; they found that
75% of failures in immediately loaded implants occurred in patients with bruxism.
Also, the literature indicates more favorable results with immediate load single
units compared to the present study cases with 2 – 3 units interim fixed partial
dentures. In addition, several studies
315,316
attributed high success rates to the
specific implant design used. When studying particular implant designs,
Scortecci et al.
317
concluded that the cortically anchored disk implants studied,
allowed increased stress distribution and Jo et al.
318
used an expandable implant

313
Ostman 2008
314
Balshi, Wolfinger 1997
315
Scortecci et al. 1999
316
Jo et al. 2001
317
Scortecci et al. 1999
318
Jo et al. 2001
97

with high success rates. Long-term data on immediate-loading is scarce and
thus quantitative assessment for long-term outcomes for immediately loaded
implants is difficult.
In the present study, 60% of failed implants were deemed early failures
due to detection of mobility at 3 months prior to final prosthesis placement, while
40% of implants were categorized as late failures due to the peri-apical
radiolucencies detected at 14 months with mobility. An early implant failure
results from the inability to establish an intimate bone-to-implant contact.
319,320

Both systemic and local factors can interfere with the early cellular events of
osseointegration. On the other hand, late implant failures are influenced by both
the microbial environment and the prosthetic rehabilitation. These later failures
have been associated with peri-implantitis resulting from plaque-induced
gingivitis and/or occlusal overloading.
321,322
In addition, the long-term exposure
of the implants and superstructures to the microbial environment and occlusal
forces are supplementary risk factors, for late failures.

All failures in the present investigation occurred in the mandibular molar
sites. Previous studies have reported a wide range of failure rates (0 to 25%)
with immediately loaded implants.
323,324,325,326
Generally, higher implant failures

319
Esposito et al. 1998
320
Quirynen et al. 2002
321
van Steenberghe et al. 1990
322
Quirynen et al. 2002
323
Ericsson et al. 2000
324
Oh et al. 2006
325
Lorenzoni et al. 2003
326
Andersen et al. 2002
98

occur in the maxilla than the mandible and the posterior vs. the anterior region;
which reflects the influence of the thin cortical bone combined with less dense
trabecular bone often observed in the maxilla.
327
Distal regions are also prone
to greater occluding forces when compared to the anterior; with triple the
clenching forces present in the molar vs. the incisor regions.
328
This natural
distribution of occlusal forces may explain why the molar sites had a significantly
higher failure rate in this study.
Also, mandibular anterior implants typically have the highest reported
success rate, while the posterior maxilla shows the lowest success rate.
329

Interestingly, all maxillary posterior implants survived in this study. However,
contrary to previously reported studies some data claim no difference in success
rate between maxillary and mandibular arches with immediately loaded
implants.
330,331
Oh et al.
332
even reported higher failure rates in the first premolar
region, with an implant size of 3.7 x 13 mm. Thus no generalized conclusive
evidence on the propensity of implant site failures can be determined from the
present study.

327
Jacobs 2003
328
Helkimo et al. 1977
329
Cochran 1999
330
Horiuchi et al. 2000
331
Buchs et al. 2001
332
Oh et al. 2006
99

Several studies have determined that quality of bone is the greatest
influence in primary implant stability and lower bone quality is more prone to
implant failure.
333,334
The bone density, in this study, consisted of 60% type II
and 40% type III/IV bone; also a trend existed, whereby type III/IV bone showed
an association with early failures, while late failures had a type II bone density.
These findings are in agreement with earlier reports of the association of implant
failure and bone density. Jaffin et al.
335
determined that type IV bone had fixture
loss rates of 44% (maxilla), 37% (posterior mandible), and 10% (anterior
mandible). This was in contrast to type I, II, and III bone with fixture loss rates of
3.6% (maxilla), 6.8% (posterior mandible), and 1.2% (anterior mandible). It is
difficult to obtain primary stability with poor quality bone or class IV bone
(Lekholm and Zarb 1985). Reports of implant failure rates in class IV bone are
as high as 35%.
336
A successful outcome of immediate-loaded implants can be
highly expected if adequate primary stability can be obtained in medium to dense
bone quality.
337

In the present study, all implants had high primary stability, with an
insertion torque of 45 Ncm and an ISQ value of 74. The initial RFA
measurements were all within the expected range of osseointegrated implants
and compare favorably with other reported values on success with early or

333
Jaffin, Berman 1991
334
Van Steenberghe et al. 1990
335
Jaffin, Berman 1991
336
Jaffin, Berman 1991
337
Ostman 2008
100

immediate loading. Ostman
338
recommends a final torque of 30 Ncm and an
ISQ above 60 for optimal stability with immediately loaded implants. Also, as
successful integration of the implant occurs, the RFA value may increase.
339
The
ISQ and insertion torque are not necessarily related, however, based on the final
implant torque and RFA obtained in this study, all implants had a high initial
stability and a good prognosis.
340

Declining ISQ values are indicative of ongoing marginal bone resorption.
Meredith

et al.
341
reported that variations in implant stability after 5 years in
function could be explained by differences in marginal bone height.

Low failure
rates in immediate loaded maxillary and posterior mandibular implants had an
ISQ value of 60.
342,343
Glauser et al.
344
monitored the RFA of 81 immediately
loaded implants and found 9 failures with an initial high ISQ of 70. It was
observed that implants that failed later in function (after 1 year) showed a
continuous decrease in implant stability and ISQ values of 49–58 were
associated with an 18.2% risk of failure. Evidently, the lower the ISQ value after
1 month of immediate loading, the higher the risk for future failure. This
observation is in accordance with the present study whereby a decline in ISQ
(64) was observed at final prosthesis delivery, and 3 implants were deemed
failures at that time.

338
Ostman 2008
339
Meredith et al. 1997b
340
Friberg et al. 1999
341
Meredith et al. 1997
342
Ostman et al. 2008
343
Meredith et al. 1997
344
Glauser et al. 2004
101

CRESTAL BONE LOSS
It has been demonstrated that immediately loaded implants are within the
normal range of crestal bone loss.
345,346
The overall, mean bone loss in the
present study was 2.04 mm and 1.80 mm during the first year in function, which
is slightly higher compared to reported immediate and standard delayed loading
protocols. The conventional mean crestal bone loss for the delayed protocol is
0.9 – 1.6 mm during the first year of function.
347,348,349
Comparison of crestal
bone loss by Randow et al.
350
with immediate and delayed loading of Brånemark
implants at 18 months, found 0.4 mm and 0.8 mm, respectively. Olsson et al.
351

reported a mean marginal bone loss of 1.3 mm after 1 year of function with
immediately loaded maxillary oxidized titanium implants. Also, Yoo et al.
352

investigated 347 immediately loaded Bicon implants and found 92.5% of implants
had ≤ 1.5 mm of crestal bone loss (at 12 months) and suggested that crestal
bone level changes for immediately loaded implants are comparable to delayed
loading. The results of this study demonstrated slightly higher levels of bone loss
compared to reported immediate placement studies, the variation observed may
be due to different methods of crestal bone loss measurements and radiographic
inaccuracies.

345
Branemark et al. 1999
346
Randow et al. 1999
347
Adell et al. 1986
348
Cox, Zarb 1987
349
Weber et al. 1992
350
Ericsson et al. 2000
351
Olsson et al. 2003
352
Yoo et al. 2006
102

Another finding in this analysis was that implants adjacent to implants
demonstrated higher bone loss (compared to implants adjacent to teeth or
edentulous areas) and mesial implant sites had greater bone loss (2.22 mm) than
distal sites (1.85 mm) but the differences were not statistically significant. Also,
the distal implant sites exhibited more bone loss when adjacent to an edentulous
area (2.04 mm) than next to implants (1.84 mm) or teeth (1.80 mm). However,
on the mesial sites, implants adjacent to implants demonstrated the highest bone
loss (2.40 mm). These findings may be explained by the observation that
differences in mesial/distal crestal bone loss may be due to the variation in
thickness of the alveolar crest, between regions as well as between patients.
Most studies show no difference in mesial/distal bone loss. Nordin et
al.
353
examined radiographic measurements after 2 – 3 years and determined no
differences in mesial and distal bone height. Bragger et al.
354
reported a median
bone loss of 0.7 mm for both the mesial and distal surfaces using nonsubmerged
implants (Straumann, Switzerland). Vela Nebot et al.
355
examined platform
switched vs. standard implants and determined no differences between
mesial/distal sites and actually found higher bone loss with standard implants.
The mean value of bone resorption observed in the mesial sites for the standard
and platform switched implants was 2.53 mm and 0.76 mm, respectively.

353
Nordin et al. 2007
354
Bragger et al. 1998
355
Vela Nebot et al. 2006
103

The bone resorption on the distal sites for the standard and platform switched
implants were 2.56 mm and 0.77 mm, respectively. In a retrospective cohort
study, conducted in MGH (Boston, MA), revealed comparable crestal bone level
changes between immediate or standard loading and showed that the mandible
had a higher susceptibility to crestal bone loss.
356

The results from this study suggest that platform switching does not
prevent crestal bone loss. The crestal bone loss of the platform switched
implants was actually slightly higher than reported standard non-platform
switched implants. This study does not support the findings from previous
reports of reduced bone loss with platform switched implants.
357,358,359,360

Computer-assisted finite element analysis studies indicate that reduced diameter
implant prosthetic abutments resulted in less stress translated to the crestal bone
and subsequently less bone loss.
361
Cappiello et al.
362
examined platform
switched 3i Osseotite Certain Prevail and standard 3i Osseotite Certain implants
and determined less bone loss with platform switching implants (0.95 mm and
1.67 mm, respectively). However, the reported results are only at one year
follow-up and long term studies are needed to accurately determine the effects of
platform switching. Hurzeler et al.
363
found that the mean crestal bone level

356
Yoo et al. 2006
357
Lazzara, Porter 2006
358
Baggi 2008
359
Maeda et al. 2007
360
Gardner 2005
361
Schrotenboer et al. 2008
362
Cappiello et al. 2008
363
Hurzeler et al. 2007
104

reduction after one year follow-up was 0.12 mm for the platform switched
implants and 0.29 mm for the non-platform switched implants. However, the
authors recommended cautionary interpretation of the results due to limited
sample size.
The most likely account of the variation observed between this study and
reported positive studies on platform switching may be due to the difference in
study design (finite analysis vs. clinical studies), method of radiographic
measurement, and length of follow-up of the studies, whereby the present study
is a three year prospective study in comparison to other retrospective or short-
term clinical investigations. However, other investigations are in accordance
with the present study and determined no longitudinal difference between
platform switching and conventional implants.
364
The clinical implications of
these findings suggest platform switching implants may not preserve crestal bone
and cautionary use of the implant device with other means of bone preservation
should to be considered in highly esthetic areas. In addition, platform switching
requires a deeper placement of the implant to allow for a natural emergence
profile thus more bone loss may result due to physiologic bone resorption to
create space for biologic width development.
The crestal implant bone reduction observed in this study may be a
consequence of a microgap with bacterial invasion, implant design, natural
remodeling of the marginal bone, and/or early implant loading. Crestal bone

364
Becker et al. 2007
105

resorption primarily occurs during the first 4 weeks after implant uncovery.
365

The mechanism responsible for the induced crestal bone loss may be the
existence of a microgap at the implant abutment interface that allows microbial
leakage and elicitation of an inflammatory reaction which leads to marginal bone
resorption.
366,367,368

In addition, bone remodeling is not dependent on early or immediate
loading of implants.
369
Bone resorption is considered a physiologic bone
response to second-stage implant uncovering.
370
It has been demonstrated that
lamellar bone was present around implants as early as 6 weeks.
371
Wound
healing after implant placement begins with angiogenesis, osteoprogenitor cell
migration, woven bone scaffold formation, deposition of parallel – fibered or
lamellar bone, and secondary bone remodeling.
372
Also, similar to natural teeth,
implants have a biologic width with peri-implant mucosa that ensure adequate
junctional epithelium and supraalveolar connective tissue to maintain an optimal
seal around the implant, and provide protection from mechanical and external
biological agents.
373,374
Under an inflammatory reaction, the biologic width
responds by migrating beyond the insult in order to isolate and create a

365
Hermann, Buser et al. 2001
366
Hermann 2001
367
Mombelli et al. 1987
368
King et al. 2002
369
Piattelli et al. 2003
370
Adell et al. 1981
371
Roberts et al. 1984
372
Schenk, Hunziker 1994
373
Vacek et al. 1994
374
Berglundh et al. 1991
106

defensive distance which results in bone resorption and reestablishment of the
biologic width.
In addition, the present study implant is a two – piece implant and current
research have found more crestal bone loss with two – piece vs. one- piece
implants.
375,376,377
Accumulated evidence from side-by-side comparisons of
various implant designs indicate that under even healthy conditions, crestal bone
levels significantly remodel apically (1 – 1.5 mm) for two – piece implant designs,
dependent on the location of the microgap and the re-establishment of the
biological width.
378
Studies confirmed that a microgap between an implant and
abutment allows for bacterial colonization of the microgap and implant
components.
379,380
Overall, two – piece submerged implants placed with the
microgap/interface below the alveolar crest experience the greatest amount of
crestal bone loss.
381
Hermann et al.
382
demonstrated that significant crestal bone
loss occurs in two – piece implant configurations, even with the smallest-sized
micro-gaps (<10 µm). Also, when implants and abutments are placed
transmucosally, interruption of the blood supply occurs which may contribute to
bone loss.
383

375
Hermann et al. 2001
376
Piattelli et al. 2003
377
Ericsson et al. 1995
378
Ericsson et al. 1995
379
Quirynen, van Steenberghe 1993
380
Hermann et al. 1997
381
Piattelli et al. 2003
382
Hermann et al. 2001
383
Cochran et al. 1996
107

However, findings by Todescan et al.
384
were contradictory and claimed
no additional bone loss when implants and abutments are placed deeper in bone.
Pontes et al.
385
evaluated the clinical and radiographic changes that occur
around dental implants inserted at different levels in relation to crestal bone.
Results indicated that further apical positioning of the first BIC did not negatively
influence the height of the peri-implant soft tissues and ridge. In relation to the
present study, the implants were placed either crestal or subcrestal to engage
the platform-switching element of the implant design. Contrary to the findings by
Todescan et al.
386
and Pontes et al.
387
the bone loss observed in this study was
always evident to at least to the first thread and further apical positioning of the
implant may have induced more bone loss.
Another plausible cause of the crestal bone loss observed may be
attributed to occlusal loading.
388
Early occlusal loading may induce more crestal
bone loss compared to the two – stage unloaded implants.
389
Investigators have
speculated that early loading may interfere with the ability of new bone formation
to restore the necrotic bone at the implant – bone interface.
390

A significant difference between immediately loaded and unloaded
implants was reported by Lorenzoni et al.
391
in a prospective study evaluating 14

384
Todescan et al. 2002
385
Pontes et al. 2008
386
Todescan et al. 2002
387
Pontes et al. 2008
388
Pillar et al. 1991
389
Sagara et al. 1993
390
Albrektsson et al. 1981
391
Lorenzoni et al. 2003
108

immediately loaded Frialit-2 (Friadent, Mannheim, Germany) and 28 unloaded
implants. They reported the mean value of bone level changes at 6 months
postoperatively was 0.9 mm (loaded), 0.33 mm (unloaded), and a combined 0.75
mm mean bone loss. The most probable explanation for the differences
observed may be a more reproducible radiographic technique was employed for
the immediately loaded implants.
However, long term detrimental effects of occlusal forces on implants have
not been adequately supported by literature.
392
Other studies of immediately
loaded implants have demonstrated that an osseointegrated interface can form
between the implant and bone, despite the absence of a healing period before
loading.
393,394
A long term comparison study of crestal bone loss between
immediate and delayed loading protocol showed no difference in bone level
changes over a 7 year period between immediately loaded and submerged
adjacent implants.
395
Also, similar bone loss between immediate and delayed
loading was found in a prospective study
396
with immediately loaded implant
supported overdentures (Brånemark System). The median bone loss was 0.7
mm (1 year) and 1.5 mm (2 years) with immediately loaded implants and 0.8 mm
(1 year) and 1.2 mm (2 years) for delayed loading. Ostman et al.
397
investigated
123 oxidized immediately loaded and 120 delayed loaded implants. A screw-

392
Sasaki et al. 2008
393
Gapski et al. 2003
394
Proussaefs 2003
395
Schnitman et al. 1997
396
Chiapasco et al. 2001
397
Ostman et al. 2005
109

retained temporary bridge was delivered within 12 hours of implant placement.
The marginal bone resorption for the immediately loaded and two-stage implants
was 0.78 mm and 0.91 mm, respectively. Thus the detrimental effect of occlusal
load is not adequately substantiated and no conclusive evidence can support that
the failures in this study was due to early occlusal loading.

MICROBIOLOGY
The microbiota detected in this study consisted of P. gingivalis, P.
intermedia, T. forsythensis, Campylobacter sps., Eubacterium sps.,
Fusobacterium sps., enteric Gram negative rods, yeasts, and E. corrodens
(Table 6). Fusobacterium species were reported in high percentages; however,
the bacterium is known to co-aggregate and form an anaerobic polymicrobial
community with other periodontal pathogens (i.e. P. gingivalis and P. intermedia)
and may not be pathogenic itself.
398
A. actinomycetemcomitans was not
recovered from any implant sites. Slots
399
first reported A.
actinomycetemcomitans in 50% of progressing periodontitis lesions and only 6%
in non-progressing sites. This study differed from previous findings by Leonhardt
et al.
400
who obtained high levels of A. actinomycetemcomitans along with P.
gingivalis and P. intermedia around peri-implant lesions. The differences in

398
Socransky et al. 1988
399
Slots et al. 1986
400
Leonhardt et al. 1993
110

study populations and difficulty of detecting A. actinomycetemcomitans may
explain for the dissimilarity in findings.
Rams et al.
401
first described the microbiota associated with failing
implants to be predominantly spirochete rich whereas coccoid bacteria were
abundant around healthy implants. The present study is in accordance with
other reported studies on the microbiology detected around implants. Rosenberg
et al.
402
determined that the majority of periodontopathic bacteria around failing
implants consist of P. micros, Fusobacterium species, enteric gram-negative
rods, and yeasts. Tabanella et al.
403
studied the clinical and microbiological
determinants in ailing implants and identified the presence of several putative
periodontopathogens (T. forsythia, Campylobacter species, and P. micros)
associated with failing implants. Furthermore, Mombelli et al.
404
detected P.
gingivalis, P. intermedia, Fusobacterium species, and spirochetes in peri-implant
deep pockets at 3 to 6 months post-operatively. Presently, in this study, a
greater amount of P. micros, Campylobacter species, and Fusobacterium
species were detected at failed implant sites, however, the findings were not
statistically significant (p=.248, p=.724, p=.157; respectively).
Findings in the present investigation differ from previous findings in that
similar loads of periodontal pathogens were discovered in both healthy and
failing implant sites, including baseline pooled samples which had similar levels

401
Rams et al. 1983
402
Rosenberg et al. 1991
403
Tabanella et al. 2008
404
Mombelli et al. 1995
111

of P. gingivalis, P. intermedia, T. forsythia, Campylobacter species, and
Fusobacterium species. An explanation of the similarity observed may be due to
bacterial contamination shared between neighboring implants as well as natural
teeth. Therefore, other local or systemic factors may have superseded the affect
of periodontal pathogens. It can be speculated that local factors may contribute
to early failures related to primary stability and premature loading.
Also, the present study’s limited sample size and technical variations may
account for the differences observed. The technical difficulties associated with
microbial studies include: location of plaque sample, tendency of various
methods of dispersing bacterial plaque to favor growth of one species over
another, and unavailability of a single culture media/method capable of
recovering all bacterial species in subgingival plaque. Selective media may
disenfranchise important species and purportedly non-selective media may
actually select for different segments of microbiota. These factors may be
partially responsible for the variety of microbiological findings reported by
different laboratories.
Furthermore, probing accuracy may present a problem when attempting to
associate culture findings with probing depth. The time and expense associated
with culturing presently limit its use to a diagnostic tool in periodontal research.
Evian et al.
405
suggested that pooling samples from individual patients, may be
possible to minimize sampling errors and still yield pertinent data. However,

405
Evian et al. 1982
112

spirochetes are ubiquitous in nearly all forms of periodontal disease and its
presence in bacterial sample is of limited diagnostic value.
The present study suggests that immediately loaded dental implants
undergo a process of microbial colonization that is similar to implants loaded in a
delayed manner. This is demonstrated by the comparable microbial profiles of
the natural dentition at baseline and implants at 1 week and 3 months post-
operatively. In addition, the microbial composition was similar for both failed
and integrated implants within and across subjects (Table 6). For example,
subject 4 had 2 implants (#30 and 31) placed and only the mesial implant (#30)
failed to osseointegrate. The failed implant (#30) demonstrated presence of P.
gingivalis (3.8%), P. intermedia (6.2%), T. forsythia (3.1%), Campylobacter
species (4.6%), Eubacterium species (3.8%), and Fusobacterium species (5.4%).
The distal implant (#31), which was osseointegrated at 3 months, demonstrated
the presence of T. forsythia (3.3%), Campylobacter species (3.3%), and
Fusobacterium species (5%). Thus, within the same subject, the failed implant
showed similar quantity and species of periodontal pathogens when compared
with neighboring integrated implant. In addition, the integrated implants showed
no signs of peri-implantitis.
The microbiology between adjacent implants within the same patient can
differ dramatically whereby integrated implants can survive amongst failed
implants. Partially edentulous patients with periodontitis harbor anaerobic
113

pathogenic bacteria in deep peri-implant sites
406
and periodontal pathogens
have been shown to translocate from natural teeth to implants.
407
It has been
shown that within the same patient, peri-implantitis can be localized to one
implant among other healthy implants, with no clinical manifestation of peri-
implantitis.
408,409,410,411
Microorganisms may be present in the peri-implant
sulcus for a prolonged period of time without causing detectable
destruction.
412,413,414,415,416
A possible alternative explanation is that other local
or systemic factors may be involved in the cause of implant failure and that the
pathogens are merely acting in tandem in the breakdown of peri-implant tissue of
failed implants.

According to available implantology literature, implant failures are mostly
addressed retrospectively, thus making it difficult to determine whether microbial
infection was the cause or result of implant instability.
417,418,419,420
In the present
study, 3 of the implant failures occurred at 3 months and the most probable
causes of these early failures are surgical trauma, premature loading and/or

406
Edwardsson et al. 1999
407
Lee et al. 1999
408
Mombelli et al. 1995
409
Apse et al. 1989
410
Kees et al. 2002
411
Adell et al. 1986
412
Mombelli et al. 1995
413
Apse et al. 1989
414
Kees et al. 2002
415
Adell et al. 1986
416
Rbordone et al. 1999
417
Mombelli et al. 1987
418
Papaioannou et al. 1996
419
Quirynen et al. 1990
420
Listgarten et al. 1990
114

bacterial infection. However, it is not possible to determine whether the
recovered putative periodontal pathogens are the cause of the failures or
whether the microorganisms are the result of surgical trauma or premature
loading.
According to Persson et al.
421
there are two known possible sources of
bacterial contamination around dental implants; either contamination of the
fixture and abutment components (during first or second stage surgery) and/or
transmission of microorganisms from the oral environment (during function
subsequent to permanent prosthesis installation).

On examination of possible
implant contamination, Quirynen et al.
422
cultivated microbial species from the
internal surfaces of submerged implants or their restorative component parts and
found coccoid cells (86.2%) and non-motile rods (12.3%). Motile organisms
(1.3%) or spirochetes (0.1%) were infrequently registered. The investigators
concluded that a microbial leakage from the microgap between the
abutment/fixture interfaces in submerged implants is the most probable origin for
this contamination.
The present study confirmed the presence of putative periodontal
pathogens around peri-implant soft tissue; however, it cannot be determined
whether the source of contamination is from a microgap leakage. The initial
colonization of peri-implant pockets with bacteria associated with periodontitis

421
Perrson et al. 2002
422
Quirynen M, van Steenberghe

D 1993
115

occurs within two weeks.
423
Similar putative periodontal pathogens existed
around immediately loaded fixtures compared to baseline pooled data from the
natural dentition. In addition, preliminary data indicated that periodontal
pathogens can be retained for a prolonged period of time in non-dental sites,
from where they can later colonize and compromise existing implants.
424

Another explanation for the peri-implant microbiota is the difficulty in
maintaining post-surgical oral hygiene. Contamination can occur from the lack of
oral hygiene due to post-surgical sensitivity or presence of sutures. However, in
this study, gingival indices showed consistently normal to mild inflammation with
only minimal plaque observed; however plaque accumulation increased with
time. Previous research has established that plaque formation on titanium
implants results in the establishment of inflammatory lesions in the adjacent
mucosa. However, according to Ericsson et al.
425
the presence of inflammatory
cells adjacent to the microgap is not related to the presence of plaque.

VISUAL ANALOG SCALE
In the present study, the VAS results indicated that patient satisfaction
scores at baseline and follow-up were overall the same. All patients’ responded
with near excellent ratings with regards to surgical and prosthodontic comfort,
appearance, and function (chewing and speech). Only one patient responded

423
Quirynen M et al. 2005
424
Ermani et al. 2008
425
Ericsson et al. 1995
116

with poor rating, due to pain and discomfort, and the implant was later removed.
Patient satisfaction was found to be highly correlated (r >0.91, p <0.002) with the
ability to chew, pain on chewing, and comfort. In addition, patients reported
higher phonetics satisfaction and none/less pain on chewing at 3 years follow-up.
The investigator evaluation showed significantly higher phonetic scores at three
years follow-up while pain on chewing scores decreased with follow-up. The
VAS scores indicate an overall high patient satisfaction with implant therapy.

CAUSES OF IMPLANT FAILURE
The nature of implant failures proposed by Rosenberg et al.
426
introduced
the notion of an infectious or traumatic type of implant failure. Implants were
categorized as infectious failures when they exhibited clinical and/or radiographic
signs of failure (bleeding, suppuration, pain, paraesthesia, mobility, peri-implant
radiolucency, and/or loss of crestal alveolar bone). Traumatic etiology was
suspected in the absence of these signs. They reported that the difference
between the two types of failure is reflected in the composition of the microbiota.
Failing implants categorized as infectious exhibited a subgingival flora with
42% spirochetes and motile rods. Traumatic causes of failure showed no signs
of infection and have a microflora more consistent with gingival health, composed
primarily of streptococci. When time of failure was taken into account, failure due
to infection occurred most often between initial implant placement and second-

426
Rosenberg et al. 1991
117

stage surgery, prior to any occlusal loading. The failed implants in the present
study likely reflect both infectious and traumatic profiles since both harbor
periodontal pathogens and show clinical signs of infection (mobility and peri-
apical radiolucency).
Other causes of implant failures, in the present study, may be attributed to
a combination of factors such as surgical protocol, early occlusal loading,
micromotion, inflammatory reaction, site specificity, and implant design.
Excessive surgical trauma and thermal injuries can cause osteonecrosis and
fibrous encapsulation.
427,428
Some studies documented almost doubled the
failure rate of implants placed by inexperienced vs. experienced clinicians
(greater than 50 implants).
429,430
Proper surgical technique, with adequate
irrigation and adherence to manufacture protocol was followed in this study.
Also, to limit confounding factors only a single highly experienced surgeon (H.N)
placed all the implants in the present study.
Ample evidence support the viability of immediately loaded implants,
however, early loading may still be a causative factor in the failures observed in
our study. The impact of occlusal forces on the peri-implant structures are unlike
natural teeth, which have periodontal ligament. Implants are rigidly attached and
it has been demonstrated that implants can only be displaced 3 – 5 µm vertically

427
Satomi et al. 1988
428
Gapski et al. 2002
429
Lambert et al. 1997
430
Morris et al. 1997
118

and 10 – 50 µm laterally.
431
Occlusal overload can result in marginal bone loss
around implants with no signs of peri-implant tissue inflammation.
432
Some
researchers hold that immediate loading results in the formation of a fibrous
connective tissue (pseudoperiodontium) around the implant.
433

In addition, the continuous load progressively weakens the structural
strength of bone and threatens implant stability and vitality. Existing documented
cases of implant mobility indicate that occlusal trauma may contribute to
progressive peri-implant bone loss.
434
Studies have shown that even if implants
are initially integrated, excessive force can lead to microfractures and mobility
resulting in bone loss and fibrous tissue repair.
435,436
A 6 week healing period is
required for implant stability, due to the amount of time required for lamellar bone
formation. Thus Brunski et al.
437
postulated that immediate loading causes
micromovement, destroys the three - dimensional lattice of woven bone, and
impedes the normal healing process.

Although there may be certain biological risks with immediate loading,
histological animal studies with immediate loading actually show no adverse
effects in the osseointegration process or bone morphology.
438,439
Orthopedic
studies report that fractured immobilized bones can be loaded immediately after

431
Kim et al. 2005
432
Isidor et al. 1998
433
Haanaes 1990
434
Isidor et al. 1998
435
Roberts et al. 1989
436
Uhthoff et al. 1977
437
Brunski 1992
438
Piatelli et al. 1997
439
Piatelli et al. 1998
119

surgery.
440,441
Furthermore, some data have advocated the concept of
mechanical stimulation of bone around implants and that early loading increase
BIC and allows a faster remodeling process.
442,443
A significant increase in blood
vessel formation and active remodeling in fractures sites has been observed
under loading.
444
Thus, contrary to speculated beliefs, immediate loading may
accelerate bone formation.
445

Mechanical stress induces metabolic bone remodeling. A lack of bone
stimulus (50–100 microstrain) results in bone remodeling with a net loss of
bone.
446
Melsen and Lang
447
reported a significantly higher threshold (6600
microstrain) for bone apposition around loaded implants, however, the
dimensions of the applied load does not appear to affect the peri-implant alveolar
bone turnover. It has been shown that bone surrounding mechanically - loaded
oral implants is denser than surrounding non-loaded implants in monkeys.
448

Misch
449
stated that the applied load on bone after 1 year alters the stress-strain
relationship and reduces the risk of microfracture.
Changes in bone metabolic activity are dependent on mechanical stress
such as the direction, quality, and duration of loading conditions. According to

440
Kenright et al. 1991
441
Romanos 2004
442
Piatelli et al. 1998
443
Rubin, McLeod 1994
444
Hert et al. 1972
445
Gapski et al. 2003
446
Frost 1992
447
Melsen, Lang 2001
448
Piattelli et al.1997,1998
449
Misch 1999
120

Miyata et al.
450
long-term implant occlusal stress (without surpassing
physiological tolerance) can stimulate blood circulation and thus enhance bone
metabolism and remodeling. Mechanical loading is crucial in the formation and
maintenance of bone architecture. According to Warden et al.
451
mechanical
loading induced bone adaptation in the rat ulna and an increased resistance to
fatigue was observed in more advanced bone loading than control groups.
Bone metabolic activities are affected by the magnitude of the mechanical
loading on implants. Sasaki et al.
452
utilized a nuclear medical approach to
determine the dynamic changes in bone metabolic activity around
osseointegrated implants using bone scintigraphy in rat models. Two titanium
implants were placed parallel to each other on the tibiae of 23 rats and a
continuous lateral load (0.5, 1.0, 2.0, 4.0 N) with coil springs was applied after 8
weeks of integration. A gamma camera was used to examine the radionuclide
bone scanning. The results attained revealed that bone metabolic activity first
increased and, subsequently, gradually decreased to baseline after
osseointegration. Although, bone metabolic activity rose around implants when
the same level of loading was applied, the metabolic activity still decreased over
time. Thus the magnitude and period of loading affects the bone metabolism
around implants. Periimplant alveolar bone adapted to the mechanical stress of

450
Miyata et al. 1998
451
Warden et al. 2005
452
Sasaki et al. 2008
121

long-term loading by structurally changing and the responsiveness to loading
gradually decreased with time.
In addition, histological evaluations of various loading protocols have
yielded different findings, depending on the type of implant used. Sagara et al.
453
showed that early occlusal loading led to incomplete bone apposition on implants
with machined or turned surfaces. On the other hand, a case report by Testori et
al.
454
demonstrated successful osseointegration with immediately loaded splinted
Osseotite rough surface implants. This suggests that immediate loading does
not impede osseointegration. However, evaluations were performed at 4
months after functional loading and no long-term results were given.

In the present study, despite the challenges of immediate loading, the
achievement of osseointegration indicated that immediate provisionalization did
not prevent peri-implant tissues from forming lamellar bone. The temporary
prosthesis delivered for all patients in the study consisted of a splinted acrylic
implant-supported prosthesis. Several studies
455,456
have shown that splinting
reduces the occlusal load transfer in comparison to individual implant units.
Splinted implants reduce micromotion at the bone-implant interface thus
enhancing osseointegration. In the present study, a splinted provisional fixed
partial denture was delivered after implant placement and should in theory
reinforce biomechanical properties. However, 2 splinted implants will not be as

453
Sagara et al.1993
454
Testori et al. 2001
455
Ostman 2008
456
Glantz 1984
122

beneficial in reducing occlusal load as 3 splinted implants due to a lack of a
tripod configuration, which reduces lateral forces. Occlusal adjustments were
made to eliminate lateral contacts and to provide at least once centric contact on
each tooth. Directing the masticatory forces towards the long axis of an implant
can favorably enhance the prognosis of the implant.
457

The 3 early failures in this study may not have achieved primary stability
and, therefore, may have been subject to micromotion within the osteotomy sites.
Micromotion is difficult to measure clinically and several researchers have
postulated that rough surface implants may tolerate micromotion up to 150 µm.
458

It can be postulated that the implants may have been inadvertently subjected to
undue lateral forces or eccentric mandibular movements. However, all implants
in this study had a high insertion torque, ISQ value, and were splinted in a 2 – 3
unit short-spanning fixed partial denture and sufficiently immobilized to
counteract micromotion.
In addition, 2 of the implants resulted in a second failure shortly after re-
implantation with wide diameter (5 mm) implants. Several studies
459
have
reported on the phenomenon of site specificity as the cause of failure. Re-
implantation sites show lower success than first-time implant placements.
460,461

Machtei et al.
462
determined an 83.5% survival rate with redo implant sites and

457
Hsu et al. 2007
458
Brunksi 1992
459
Machtei et al. 2008
460
Davierwala et al. 2006
461
Alsaadi et al. 2006
462
Machtei et al. 2008
123

attributed the low survival to the possible negative effects associated with the
specific implant site. The site-specific theory is mainly supported by the finding
that failed implants are often found in patients where other implants were
successfully osseointegrated and in function.
463

Another probable determinant of implant failure may stem from an
inflammatory response to microbial presence which elicits an autoimmune
response regulated by cytokines (TNF-α, IL-1ᵦ, IL-10, or TGF-ᵦ). Cytokines
trigger an inflammatory response and stimulates bone resorption and subsequent
implant failure. Socransky
464
identified key bacteria in periodontal infections
which included the presence of putative pathogens (close to periodontal lesions)
and in high numbers compared to either the absence of bacteria or presence of
smaller numbers in healthy subjects. Patients infected with these periodontal
pathogens often develop high levels of antibody in serum, saliva, and gingival
crevicular fluid and may also develop a cell-mediated immune response to the
putative pathogen.
The microbiology and cytokine levels around healthy implants and teeth
were evaluated by Nowzari et al. 2008. It was determined that both the
frequency and levels of periodontopathic bacteria were elevated around natural
dentition in comparison to implant sites. Also, pro-inflammatory cytokine
production was found to be unrelated to bacterial infiltration. However, when
periodontopathic bacteria were cultured, the cytokine levels (TNF-α and IL-1ᵦ)

463
Miyamoto et al. 2005
464
Socransky1977
124

were increased in peri-implant sites and natural dentition. Thus the increased
cytokine level in healthy sites indicates an existing microbial challenge around
teeth and implants.
If microbial infection is not the cause of implant failure, the implant
composition and design may affect the longevity of the implant.
465
Improper
implant design can depreciate the success rates of dental implants. Avenues to
improve implant design and enhance stability are of growing concern in dental
implantology. Numerous investigators have conducted studies on the effect of
various surface types or implant designs on immediate load. Implant surface
quality is known to be one of several important factors to obtain osseointegration
predictably.
466
Surface quality includes chemical, physical, mechanical, and
topographical properties. The implant structure has been shown to be a potential
parameter in peri-implant bone loss.
467

Titanium and titanium alloy implants have proven to be biocompatible,
however, should not be considered completely inert. An inherent problem with
titanium and other biomaterials is the inevitable growth of bacteria biofilms. The
surface characteristics of implants determine the adhesion potential of bacteria
and inflammatory mediators due to an oxide layer (2 – 5 nm) over the surface of
titanium implants, which supports cationic and anionic adsorption exchange.
468

Also, the biodegradation of titanium and titanium alloy stimulates the release of

465
Nowzari et al. 2008
466
Albrektsson et al. 1981
467
Tabanella et al. 2003
468
Grossner-Schriber et al. 2001
125

cytokines.
469
In vitro analysis has demonstrated that titanium particles influence
the release of IL-1, TNF-α, and IL-6.
470

Implant surface properties may affect cell accumulation and production of
cytokines and growth factors which in turn modulates bone formation.
471

Experimental studies have shown that a modified implant surface structure is
beneficial to osseointegration.
472
Rough surface implants obtain faster bone
apposition and lower prevalence of early implant failure compared to machined
titanium, screw-shaped implants.
473
Rough surface implants show a significantly
higher success rate and demonstrate greater amounts of bone-to-implant contact
compared to smooth surface implants.
474,475

Meyle
476
reported a rough titanium surface delays the spread and
adhesion of epithelial cells, while enhancing fibroblasts and osteoblasts
proliferation. Thomas and Cook
477
confirmed that surface roughness enhances
osseointegration by increasing the contact surface area and biomechanical
interlocking between the implant and bone; thus enhancing the metabolic activity
of osteoblasts, leading to earlier lamellar bone formation. Also, a higher removal

469
Nowzari et al. 2008
470
Wang 1996
471
Schwartz 1999
472
Wennerberg 1996
473
Esposito et al. 1998
474
Cochran 1999
475
Buser et al. 1991
476
Myele 1999
477
Thomas, Cook 1985
126

torque is required for rough surface implants because of increased surface area
and interlocking between the growing bone and implant surface.
478

A dual-acid etch (Osseotite) rough surface, produced by thermal etching
of machined titanium and titanium alloy implant surfaces was employed in the
present study. Previous studies found a high success rate with immediately
loaded double acid-etched surface implants.
479.480
Abrahammsson et al.
481

performed an experimental study in dogs, comparing the Osseotite rough surface
and a turned surface. The histological results indicated a significantly larger
bone to implant contact with the rough Osseotite surface. A human study
482
on
experimental titanium implants, with both a turned and rough Osseotite side
(mesial or distal), was placed in the maxillary posterior regions. Histological
examinations at 6 months, verified animal study findings that Osseotite surfaces
had double the amount of bone-to-implant contact than turned surfaces (34% vs.
73%). In addition, long-term analysis of acid-etched (Osseotite) implants
indicated a 100% success rate after 2 – 3 years.
483
In a study of immediate
occlusal loading of double acid-etched titanium implants, with 41 maxillary and
mandibular full-arch cases, found a 99.42% survival rate (within 6 – 74 months
follow-up).
484

478
Abrahmsson et al. 2001
479
De kok et al. 2006
480
Ibanez et al. 2005
481
Abrahamsson et al. 2001
482
Lazzara et al.1999
483
De kok et al. 2006
484
Ibanez et al. 2005
127

Furthermore, Rocci et al.
485
examined immediately loaded TiUnite and
turned surfaces, with implant – supported fixed partial dentures (44 patients), and
demonstrated higher success rates with the rough Ti-Unite surfaces (95.5%)
compared to the machined or turned surfaces (85.5%). Three TiUnite and 8
turned-surface implants failed during the first 7 weeks of loading. The authors
concluded that rough surface implants provided a 10% lower failure rate
compared to machine implants. Buser et al.
486
compared 6 different implant
surfaces in miniature pigs and determined that surfaces with increased
roughness had greater bone-to-implant contact. Also, the sandblasted large-grit
acid etch surface showed the highest bone-to-implant contact.
In contrast, few studies support high primary stability for machined
surfaces, however, comparison studies between implant designs determined that
the Brånemark MKIV turned surface was the most beneficial with regard to
primary implant stability for immediate load with fixed partial dentures (90.7%
success rate).
487,488
Froberg et al.
489
found no difference between immediately
loaded Brånemark implants with either the traditional turned or anoxidized
(rough) implant surface. The discrepancy between this study and previously
reported data most probably is the result of the location (mandibular anterior) of
the implants placed, which have demonstrated a high level of healing and

485
Rocci et al. 2003
486
Buser et al. 1991
487
Glauser et al 2001
488
Rocci, Martignoni et al. 2003
489
Froberg et al. 2006
128

predictability,
490
therefore outweighing the influence of implant surface variables
on primary stability.
The prototype 3i IOL implant utilizes a self-tapping tapered body design, to
enhance initial primary stability. It has been suggested that the use of self-
tapping implants, may improve primary stability by removing the need for a
separate surgical tap to prepare the implant site.
491,492
Tapered implants were
originally designed to closely approximate root anatomy and, in theory, facilitate
immediate implant placement after extraction.
493,494
The Osseotite NT design
was first introduced in 2002, as a threaded tapered implant that mimics the taper
of natural tooth roots. They were indicated for use in areas of poor or limited
bone quality and quantity. Also, the original Osseotite NT had a greater thread
pitch (0.9 mm) than the cylindrical or parallel –wall Osseotite Certain (0.6 mm).
Tapered implants have shown promising results with failure rates
comparable to standard implants in healed sites and fresh or recent extraction
sockets.
495
The screw design minimizes micromotion and improves the initial
stability with higher mechanical retention.
496
Reported cumulative survival rates
of tapered implants range from 91.1% (maxilla), 89.1% (mandible), and 90.8%
(immediate placement).
497,498
In addition, tapered screw implants show similar

490
Branemark et al. 1977
491
Lekholm 1992
492
Ivanoff et al. 2000
493
Perry et al. 2004
494
Callan et al. 2000
495
Davarpanah 2005
496
Gapski et al. 2003
497
Perry et al. 2004
498
Drago et al. 2006
129

crestal bone loss as cylindrical implants.
499
Drago et al.
500
demonstrated a high
cumulative survival rate of 96% with immediately loaded tapered implants and a
mean bone loss of 0.63 mm at one year follow-up.
However, there is currently no conclusive evidence that the tapered
implant design is superior to cylindrical standard-implants.
501
Tapered implants
have less surface area than similar sized cylindrical implants. NT implants have
20% less surface area than similar-sized 3.75 mm diameter cylindrical implants,
and 30% less than 4 mm diameter parallel-wall implants.
502
Also, selected
tapered implants have a design flaw that concentrates all forces in one portion of
the implant leading to failure, especially when immediately loaded, thus the
implant demonstrates a high insertion torque but low stability.
The angle of the taper is an important design variable in reducing the peak
stress. However, extremely tapered angles should be avoided, as they cause
stress concentrations to the implant itself, which may cause problems relating to
stability and possible implant fracture.
503
In addition, Perry et al.
504
reported a
low survival rate with the Frialit-2 tapered implants system, with the majority of
failures occurring prior to loading. The authors attributed the early failures to the
design flaw of the implant, which may be a common problem of the tapered

499
Ormianer, Palti 2006
500
Drago et al. 2006
501
Lang et al. 2007
502
Meltzer 2003
503
Shi et al. 2002
504
Perry et al. 2004
130

implant design.
505,506

Within the limitations of this study, the 3i IOL design may
have attributed to the high failure rate observed, however, no absolute
conclusions can be drawn due to the small sample size.
Generally, the longer and wider the implant the more bone to implant
contact and, thus, enhanced osseointegration. For every 3 mm increase in
length, the surface area of a cylindrical implants increase by 20 – 30%
average.
507
Several reports have suggested that implants should be ≥ 10 mm in
length to ensure high success rates.
508,509
Schnitman et al.
510
reported a 50%
failure rate with immediate loaded implants with ≤ 10 mm lengths. Therefore, the
implant length and width may also influence the success rates of immediately
loaded implants. However, no definitive implant length or diameter is known for
immediately loaded implants and most data published are generated based on
clinical experience and limited human research. In the present study, no
correlation between implant length and survival was found; the failed implants
lengths were 40% (13 mm) and 20% (10 mm and 11.5 mm). In addition, one
study found the maximum bony stress around implants was virtually constant,
independent of implant length and bicortical anchorage.
511
The maximum
implant stress, however, increased with implant length and bicortical anchorage.

505
Perry et al. 2004
506
Gomez-Roman et al. 1997
507
Misch 1999
508
Buser et al. 1988
509
Tarnow et al. 1997
510
Schnitman et al. 1997
511
Pierrisnard et al. 2003
131

Another factor which may affect implant success is whether or not the
patient is completely or partially edentulous. Immediate loading in partial
edentulism is considered more challenging compared to fully edentulate cases
since fewer implants are required in partial edentulism and the implants are
normally placed in a straight line and thus exposed to lateral forces. Partially
edentulous maxillary and mandibular sites were immediately loaded in this study.
All patients received immediate provisional restorations supported by 2 – 3
posterior implants indicating that both immediate occlusal and continuous
bending loads were introduced.
Biomechanically, it is more favorable to immediate load completely
edentulous ridges, in comparison to posterior partially edentulous ridges, due to
the ability to establish cross-arch stability. Posterior partial restorations have a
higher susceptibility to bending loads due to the presence of lateral forces.
Unlike forces acting along the long axis of an implant, where stress is well
distributed, lateral bending forces apply load mainly at the terminal portions of the
implant. This bending motion gives rise to higher stress levels in both the implant
and surrounding bone.
Other studies
512,513,514,515
have shown predictable treatment for both
complete and partially edentulous patients, however, implants placed in dentate
patients harbor the same bacteria as their natural teeth and the likelihood of peri-

512
Jemt et al. 1996
513
Lindquist et al. 1996
514
Buser et al. 1997
515
Lambrecht et al. 2003
132

implant breakdown may be increased.
516
Also, past literature reported high
implant survival rates of 96 – 100% with immediate and early loading with fixed
prosthesis in the partially edentulous maxilla/mandible.
517
Cochran et al.
518
in a
prospective multicenter study of 383 sandblasted large-grit acid-etched implants;
reported a one year survival rate of 99.1%. These results demonstrate that
implant restorations in partially edentulous, immediately-loaded patients are
feasible and further prospective studies are warranted.

STUDY LIMITATIONS
Study limitations included the small sample size, radiographic technique,
and study design. The available clinical trial is limited in number and has a small
sample size, thereby exhibiting a high risk of bias. In addition, one patient failed
to return for the two – year follow-up and the failure to return for re-examination
may potentially be related to failure. However, to help compensate for the
limited sample size, non-parametric tests of group differences (Mann-Whitney U
and/or Kruskal-Wallis) were used for the statistical analysis.
The accuracy of crestal bone level measurements is influenced by the
precision of the radiographic technique and the reproducibility of the
measurement technique used. In the past, periapical films were extremely
susceptible to operator error, especially in the maxillary molar regions; however,

516
Apse et al. 1989
517
Ostman 2008
518
Cochran et al. 2002
133

with advent of parallel-positioning devices, the likelihood of misangulation has
reduced considerably.
519
In this study, proper projection geometry was applied
(perpendicular right-angle technique with beam indicator ring and bite block) to
reduce projection errors.
In comparison to open surgery measurements, intraoral radiographs may
underestimate bone loss from 9 - 20%.
520
Periapical radiographs do not provide
a perfect measurement; however, it is a noninvasive technique and provides
accurate longitudinal assessment of crestal bone level. In addition, the accuracy
of standardized periapical radiography is reported to be within 0.2 mm in 89% of
cases.
521
Presently, periapical radiographs are commonly utilized in clinical
practice and research to evaluate the status of implants.
522
The practicality and
significantly reduced rate of radiation exposure of periapical radiographs, in
comparison to conventional CT, are favorable for patient care.
Another study limitation is that some radiographs were digitized, which
may have resulted in magnification errors. To help control for this, the
radiographs were analyzed with the ImageJ software and the measurements
were performed three times and the average of the three results was used for
study analysis. Since, dental implants have known lengths, this helped serve as
a reliable reference when assessing marginal bone height. It should be noted
that some subjects in the present study returned for radiographic follow-up at

519
Hausmann et al. 1989
520
Akesson et al. 1992
521
Hermann et al 2001
522
Bragger 1994
134

different time points (i.e. 13 months vs. 12 months), thus it was difficult to
standardize the absolute amount of crestal bone loss for comparison at specific
time points.
In addition, the study design lacked a control group of standard implants
and only healthy patients and non-smokers were included in the study. Although,
the patient selection controls for potential confounders and effect modifiers; a
sample population of healthy, non-smokers does not necessarily reflect the
population variability that exists in clinical practice and may limit the generality of
these study results.

135

CHAPTER 5: CONCLUSION
The results of the present study suggest that the 3i Osseotite Certain IOL
implant system did not provide a viable and predictable method of treatment.
No conclusive evidence has been presented to support immediate loading as
the cause of implant failure. However, the relatively high failure rate (29.4%), in
this investigation, suggests that a thorough assessment of patient history, site
evaluation, surgical and prosthodontic protocol, and implant device is essential
to minimize implant failure.
Within the limitations of this study, it can be concluded that platform
switching did not meet the expectations of previous reported studies and failed
to preserve crestal bone. In addition, immediate loading did not notably
influence the composition and quantity of periodontal pathogens. Based on the
findings of this study, it can be concluded that the quantity and microbiological
profiles of immediately loaded implants is similar to the natural dentition,
measured at baseline. Moreover, the presence of periodontal pathogens does
not predict implant failure. The role of periodontal pathogens in causing implant
failure requires further investigation.
Cautionary interpretation of these results is advised due to the limited
sample size. More longitudinal prospective multi-center studies are required to
further evaluate the clinical outcomes and other determining factors of
immediate loading with the 3i IOL implant system. The benefits of immediate
136

loading for patients, with shorter treatment time and improved psychological
factors, warrant further research.

137

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Asset Metadata

Creator Chi, Jackie (author)

Core Title A prospective observational study of immediately loaded platform switched 3i implants

Contributor Electronically uploaded by the author (provenance)

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 04/13/2009

Defense Date 03/04/2009

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag dental implants,immediately loaded implants,OAI-PMH Harvest,platform switched implants,platform switching

Language English

Advisor Nowzari, Hessam (committee chair), Navazesh, Mahvash (committee member), Rich, Sandra (committee member)

Creator Email chijackie@hotmail.com,Jackie.chi@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-m2083

Unique identifier UC1451146

Identifier etd-Chi-2717 (filename),usctheses-m40 (legacy collection record id),usctheses-c127-229589 (legacy record id),usctheses-m2083 (legacy record id)

Legacy Identifier etd-Chi-2717.pdf

Dmrecord 229589

Document Type Thesis

Rights Chi, Jackie

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Repository Name Libraries, University of Southern California

Repository Location Los Angeles, California

Repository Email uscdl@usc.edu

Abstract (if available)

Abstract The present prospective clinical study investigated immediate occlusal loading in relation to long-term, clinical outcomes with the 3i Osseotite Certain IOL implant. Radiographs, bacterial sampling, and clinical measurements were obtained at baseline and at follow-up (up to 3 years). The overall survival rate was 70.6% (12/17) and mean crestal bone loss was 2.04 mm (SD = 1.26). Mesial implant sites had an average greater bone loss (2.22 ± 1.66 mm) than distal sites (1.85 ± 0.67 mm). Microbiological sampling of integrated and failed implants revealed similar periodontal pathogens compared with baseline and pool. VAS indicated patient satisfaction was highly correlated (r >0.91, p <0.002) with the ability to chew, pain on chewing, and comfort. 3i IOL implants did not provide a viable and predictable method of treatment and platform switching did not prevent crestal bone loss. Immediate loading did not notably influence the composition and quantity of periodontal pathogens.