University of Southern California Dissertations and Theses

Prevalence and distribution of facial alveolar bone fenestrations in the anterior dentition: a cone beam computed tomography analysis

(USC Thesis Other)

Prevalence and distribution of facial alveolar bone fenestrations in the anterior dentition: a cone beam computed tomography analysis

PDF

Download a page range

Download transcript

Copy asset link

Request this asset

Transcript (if available)

Content
PREVALENCE AND DISTRIBUTION OF FACIAL ALVEOLAR BONE
FENESTRATIONS IN THE ANTERIOR DENTITION: A CONE BEAM COMPUTED
TOMOGRAPHY ANALYSIS

by

Jana Lampley

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

August 2010

Copyright 2010 Jana Lampley

ii

TABLE OF CONTENTS

List of Figures iii

Abstract iv

Chapter 1: Introduction 1
Prevalence of Fenestrations 4
Etiology of Fenestrations 12
Problems with Detection of Fenestrations 15
History of Computed Tomography 17
The Advent of Cone Beam Computed Tomography 19
Objectives & Hypothesis 21

Chapter 2: Materials and Methods 22
Statistical Analysis 32

Chapter 3: Results 34

Chapter 4: Discussion 42
Limitations 52

Chapter 5: Conclusion 54

Bibliography 56

iii

LIST OF FIGURES

Figure 1: Frontal View with Soft Tissue 24

Figure 2: Skeletal View 25

Figure 3: View of Facial Fenestration 26

Figure 4: Sagittal View 27

Figure 5: Axial View 28

Figure 6: Point Locators 29

Figure 7: Axial View with 1mm Incremental Cuts 30

Figure 8: Cross Sectional View 31

Figure 9: Fenestration Measurement 32

Figure 10: Demographics by Gender 34

Figure 11: Reason for CBCT Scan 35

Figure 12: Mean Age (Years) 37

Figure 13: Number of Fenestrations by Tooth 38

Figure 14: Number of Fenestrations by Location 39

Figure 15: Mean Length of Fenestrations by Location 40

Figure 16: Mean Length of Fenestrations by Tooth Number 41

iv

ABSTRACT

Cone beam computed tomography scans can provide valuable information to
dental surgeons. This information can help to alleviate the unexpected encounter of an
alveolar bone defect and assist in proper treatment planning when reviewed prior to
surgical procedures. Additionally, awareness of potential complications may help to
optimize the success of treatment when mucogingival surgeries are performed in these
areas. The objective of this study was to detect facial alveolar bone fenestrations of the
anterior teeth using NewTom CBCT scans and to report the incidence and distributions of
these defects. It was hypothesized that the incidence and distributions would be
comparable to previously reported studies. The secondary objective was to measure and
describe the vertical length of the fenestrations.
Cone beam computed tomography (CBCT) scans were consecutively selected
from the USC School of Dentistry active database (Redmond Imaging Center, Los
Angeles, CA). The database consisted of CBCT scans of patients who were interested in
receiving orthodontic treatment, dental implant therapy, analysis of TMJ pathology, or
participating in a sleep apnea study. The one hundred and twenty-five CBCT scans
selected for the current study were taken between March 2009 and November 2009.
Most of the CBCT scans selected provided twelve teeth for analysis, the anterior
dentition (maxillary and mandibular). Scans were not included if the roots of the anterior
teeth could not be visualized due to scattered images. Classifying information including
the age, gender, and the reason for the scan were included for comparison purposes.
v

The CBCT scans were evaluated for facial alveolar bone fenestrations. When
fenestrations were detected, the location was recorded using the CEJ and the root apex as
a reference. The location was listed as coronal, middle, or apical. The apicocoronal
length of the fenestrations were also measured and recorded.
The majority of the patients included in the present study did not have detectable
fenestrations (n=96). In the remaining twenty-nine patients, fenestrations were more
prevalent in females (62.1%). The twenty-nine patients provided a total of thirty-seven
fenestrations for analysis. The mean age of the patients with fenestrations was slightly
higher than the mean age of patients without fenestrations (25.8 years vs. 22.9 years). In
general, fenestrations were more commonly found on the maxillary anterior teeth
compared to the mandibular anterior teeth, with tooth #9 having the most occurrences of
fenestrations, followed by #10. Twenty-two of the fenestrations were found to be
located in the middle third of the root, nine in the coronal third, and six in the apical third.
The mean length of all fenestrations was 1.6mm±0.8mm. The largest fenestration
measured was 3.9mm. This measurement was detected on a maxillary right lateral
incisor. The smallest fenestration measured was 0.5mm. This measurement was detected
on a mandibular right lateral incisor and a maxillary right canine. The overall percentage
of teeth with fenestrations was 2.5%. The overall percentage of patients with
fenestrations was 23%. There were three patients that had fenestrations on two teeth and
two patients with fenestrations on three teeth.
vi

This study provides clinical relevance because it introduces the novel approach of
pre-surgically using CBCT images to detect alveolar bone defects, particularly
fenestrations. Although CBCT scans are often unnecessary for many periodontal
surgeries, it is becoming the standard of care for patients that are undergoing orthodontic
therapy or receiving dental implants to have pre-operative three-dimensional scans. The
presence of fenestrations can cause implant placement to be contraindicated in a
particular site and orthodontic therapy may actually make the fenestration increase in size
if treatment is not planned strategically. Further studies should be conducted to confirm
and expand the results of the present study on anterior teeth and to determine
predictability of the detection of fenestrations of posterior teeth using CBCT scans as
well as measuring the length of those fenestrations.

1

CHAPTER 1: INTRODUCTION
Mucogingival surgical procedures require the dental surgeon to have a precise
knowledge of both normal and abnormal anatomic features of the alveolar process. The
reflection of the alveolar bone during surgical procedures may inadvertently expose
underlying alveolar defects, including dehiscences and fenestrations. Alveolar
dehiscences and fenestrations are defects of the alveolar cortical plates which are most
frequently observed by periodontists during mucogingival surgery (Abdelmalek and
Bissada, 1973). They are also encountered during oral surgery and endodontic
procedures when a surgical flap is reflected. Fenestrations and dehiscences of the
alveolar plate of bone are often detected during mucogingival surgical procedures.
Deformities of the alveolar process discovered during these procedures can present
surgical dilemmas which may seriously affect the outcome of treatment. Although
dehiscences and fenestrations are considered non-pathological conditions, and a variation
within the range of periodontal normalcy, their undiagnosed or unexpected presence may
complicate periodontal surgical procedures or require changes in implant placement
protocols (Nimigean et al. 2009).
There has been general agreement in previous studies in describing a fenestration
as a circumscribed defect of the alveolar radicular bone exposing the underlying root
surface but not involving the alveolar margin (Edel, 1981). Carranza et al. (2002),
defined a fenestration as an isolated area in which the root is denuded of bone, and the
root surface is covered only by periosteum and overlying gingiva. Stahl et al. (1963)
classified fenestrations from 1-3 where 1 represented the smallest opening seen with the
2

naked eye and 3 represented buccal vertical loss extending into the alveolar crest. This
lesion is a denuded area of bone, exposing the root surface and is usually found about
2mm below the crest on the buccal surface (Bradin, 1962). Nabers et al. (1962) reported
that fenestrations do not offer too many clinical therapeutic complications, because they
are not associated with periodontal pathosis due to bone being occlusally or incisally to
the alveolar fenestrations.
The term dehiscence has been poorly defined in the literature. Definitions for a
dehiscence ranged from stating a deficiency in alveolar bone resulting in a denuded root
to the absence of alveolar cortical plate exceeding one half of the root length (Rupprecht
et al. 2001). Davies et al. (1974) were the first to define the term dehiscence in numerical
terms. They considered a dehiscence to be a defect in which the crest of the radicular
bone was at least 4mm apical to the crest of the interproximal bone, as measured from the
cementoenamel junction (Davies et al. 1974). Although this definition sets an arbitrary
distance, there is conformity with the generally accepted clinical impression of a
dehiscence. The inherent weakness in this definition is that bone loss on the interproximal
surface due to periodontal disease could eliminate the presence of a dehiscence as defined
in this way (Edel, 1981). These differences in definitions could explain some of the
variability in incidence and distribution of defects found between studies.
The alveolar process consists of an external plate of cortical bone and the inner
socket wall formed by the alveolar bone proper, which is seen as the lamina dura on
radiographs. Alveolar bone architecture may vary from patient to patient in point of
3

thickness, contour and configuration, and all these variations may be both normal and
healthy (Carranza et al. 2002). The cause of these differences is the unique dependence
between the morphology of the alveolar process and the teeth. The bone contour
normally conforms to the prominence of the roots with intervening vertical depressions
that taper toward the margin. Within harmonious dental arches, there is congruence
between the size of the teeth and the size of their bone housing. In a healthy
periodontium, the contour of the marginal bone follows the contour of the
cementoenamel junction and lies approximately 2mm apical to it (Carranza et al. 2002).
The result is that the interproximal bone is more coronal in height than the labial and
lingual/palatal bones. This scalloping of the bone on the facial and lingual/palatal areas
is related to the tooth, the root form and the tooth position in the alveolus. The bony
architecture varies from the anterior to the posterior regions, the molar teeth showing less
scalloping and a more significantly flap profile as compared to the bicuspids and the
incisors.
In a fenestration or dehiscence, a connective tissue covering overlies the osseous
lesion and is firmly attached to the root surface by periosteal fibers. Such bony defects
are probably the result of a slow, progressive absorption of an already thin plate of bone.
Thin bone usually lacks a supporting layer of bone marrow between the outer buccal
plate of compact bone and the alveolar bone proper. Thus, there is dependency on the
periosteum and periodontal connective tissue for adequate nourishment and blood supply.
Mucogingival surgery, which often strips the periosteum, thus could reveal these defects
4

which would not have been clinically noted if the periosteum had been kept intact. This
stripping of the periosteum will encourage even further resorption of the thin overlying
plate of bone, since bone absorption is greater than bone deposition after surgical
intervention. The probability exists that fenestrations are actually a stage in the
development of dehiscence (Nimigean et al. 2009). A fenestration may potentially
progress into a dehiscence due to the necrosis of the remaining thin layer of marginal
bone.
PREVALENCE OF FENESTRATIONS
Early evidence on the interest regarding the correlation between the alveolar
process morphology and the teeth dates back to 1963. Prior to this year, the incidence
and clinical significance of alveolar defects received little attention in the literature. A
pilot study was conducted by Elliott and Bowers (1963) in an effort to determine the
incidence of dehiscence and fenestration and to learn the most frequent locations of these
defects. Fifty-two human skulls from Ohio State University were obtained and a total of
1153 teeth were examined. The defects were observed most frequently in regions where
the anatomical shapes and positioning of the teeth resulted in a thin covering of alveolar
bone proper and cortical plate. The statistics showed an average incidence of defects of
the cortical plates of 20.1% of which 10.9% accounted for fenestrations. The remaining
9.2% of defects were dehiscences. The maxillary left first molar and the mandibular
cuspids had the highest incidence of defects and overall the defects occurred frequently
5

as bilateral defects. In general, fenestrations were commonly observed in the maxilla,
whereas dehiscences were more predominant in the mandibular arch.
A study conducted by Stahl et al. (1963) recorded the presence of fenestrations in
human skulls of various races and attempted to correlate these findings with histologic
observations in cadaver material. The 162 cadaver skulls and autopsy specimens were of
various ethnic backgrounds including Chinese, Americans, and American Indians. All
skulls were surveyed for the presence of alveolar plate fenestrations, which were
recorded per socket site. The wear patterns of teeth associated with the fenestrations
were also recorded. Fenestrations were present in 750 of 4,438 socket sites (16.9%).
Fenestrations were more frequently in the labial alveolar plate of the anterior teeth than in
the posterior teeth. Stahl et al. (1963) observed an increased incidence of fenestration in
jaws exhibiting occlusal wear which was taken to represent excessive occlusal forces.
In addition to clinical observations of fenestrations, Stahl et al. (1963) also
evaluated fenestrations histologically in cadaver material. The histological appearance of
the labial fenestrations was identified in a study of progressive labiolingually-cut sections
of jaw specimens. Areas of resorption were present at the periodontal surface of a thin
labial alveolar plate which at some point resulted in loss of alveolar continuity. This
alveolar interruption was associated with alterations in the periodontal fiber orientation in
the area. As noted clinically, it was observed histologically that periosteum covers these
defects. The histological appearance of fenestrations helps to further explain why these
lesions had been clinically observed during mucogingival surgery (Stahl et al. 1963).
6

Kakehashi et al. (1962) conducted the first study in a contemplated series of
comparative skeletal studies on periodontal disease in the native higher primates. A total
of 292 gorilla skulls were examined for periodontal disease as evidenced by resorptive
lesions of the alveolar process. Measurements (mm) were taken for the following
osseous defects: amount of horizontal bone loss; length, width, and coronal extent of
fenestrations; buccal vertical bone loss (dehiscence) and depth of interproximal craters.
The fenestrations were measured in length from the apical to the coronal margins. A total
of 481 fenestrations were found in the osseous cortical plate over the buccal root contours
of premolars and molars and located within several millimeters of the margin of the
alveolar crests. These fenestrations occurred in 468 areas of the maxilla and 13 areas of
the mandible. The fenestrations were present twice as often in males as in females and
were observed in all age groups. With age, there was an increase in frequency, in length,
and in the distance between the CEJ and the coronal extent of the fenestration. An
analysis of the tooth-to-fenestration relationship shows the maxillary first molar to be
involved more frequently with an osseous fenestration defect. The authors also suggested
that fenestrations may be associated with teeth in severe trauma which have only a thin
labial plate of bone covering the root.
The studies by Larato (1970, 1970, and 1972) were instrumental in providing
knowledge of the incidence and distribution of fenestrations and dehiscences in both
adults and children. The number and location of fenestrations and dehiscences were
recorded for each tooth area in each of 108 skulls. Similar to other studies, occlusal wear
patterns of each tooth were recorded to determine whether a possible relationship
7

between occlusal wear and fenestrations exists. In addition, the prominence of each tooth
root was recorded to determine if root prominence was related to general arch
configuration. There were a total of 3,416 teeth examined, of which 149 (4.3%)
exhibited fenestrations and 109 (3.2%) exhibited dehiscences. This is one of the only
studies in which percentage of bone defects were distinguished as fenestration or
dehiscence instead of being calculated under the broad term of alveolar bone defects.
There were more alveolar bone defects located in the anterior teeth compared to the
posterior teeth. Fenestrations and dehiscences were most frequently found on the cuspids
and first molars of the maxillary arch and on the cuspids of the mandibular arch. In more
than 90% of the teeth that exhibited either alveolar plate fenestrations or dehiscences, the
teeth had prominent roots in relation to the rest of the arch. No relationship could be
shown between fenestration and teeth in excessive trauma because occlusal wear was
present on the majority of the teeth.
Because there was limiting information concerning the incidence of alveolar
defects in children’s jaws, Larato (1972) also conducted a study to determine the
frequency of these defects in children. The 176 child skulls varied between the ages of 2-
5 years and all exhibited 20 erupted primary teeth. Only 21 (12%) of the skulls presented
fenestrations or dehiscences. Out of a total of 3,520 teeth, only 43 (1%) had alveolar
bone defects. Of the 43 teeth, 35 had dehiscences and 8 had fenestrations. This study
concluded that because alveolar defects do occur in children’s jaws, further studies
should be conducted to determine whether trauma from occlusion and/or tooth position
are related to the development of this defects.
8

Another study conducted by Larato (1970) was undertaken to examine the effects
of periodontal disease in the jaws of young children. Human skulls ranging in age from
2-5 years were examined for the presence of bone defects resulting from periodontal
disease. Alveolar plate fenestrations and dehiscences were also noted since these defects
may also influence the course of periodontal pocket formation. Out of 97 skulls, 25 had
one or more bone defects as a result of periodontal disease. Three skulls had dehiscences
on the anterior teeth; however, none of the skulls exhibited fenestrations. A variety of
periodontal bone lesions can be encountered in the child’s jaw as a result of periodontal
disease. These include bone craters, alveolar plate bone resorption, bifurcation and
trifurcation involvements, and intrabony defects. An important finding of this study was
that the types of periodontal bone lesions in children are similar to those found in adults.
Various epidemiological studies showed that periodontal disease is not solely a
disease of adulthood, since the effects of the initial lesion of marginal gingivitis are first
manifested in early childhood. Previous clinical surveys conducted in the United States
have demonstrated that 24%-64% of the children examined were affected by some form
of gingival disease. It has been observed that marginal gingivitis is the most common
periodontal lesion found in children (Goldman et al. 1968). The maxillary and
mandibular anterior regions are the areas of gingival most commonly exhibiting
gingivitis in children (Massler et al. 1952). If the initial marginal lesion continues to
spread, or is not successfully treated, the inflammatory process will extend to and affect
the underlying bone structures resulting in eventual adsorption and destruction of the
alveolar process.
9

Studies concerning the prevalence of dehiscences and fenestrations have been
performed on various ethnic groups: Egyptians, Britons, Bedouins, Mexican Indians,
South African Blacks, etc. The thickness and size of the jaws are genetically determined
and vary among ethnic groups (Morant et al. 1936). A study conducted by Abdelmalek
and Bissada (1973) on human Egyptian skulls correlated somewhat with previous studies.
They evaluated 154 adult jaws (61 maxillary and 93 mandibular) of which fenestrations
were found in 26 of the maxillae and 23 of the mandibles. They found that fenestrations
were found most commonly on the maxillary first molar, which further supports studies
by Elliott and Bowers (1963) and Larato (1970). In agreement with previous studies, the
alveolar bone defects were more predominant in the anterior region. With regards to the
incidence of fenestrations, Elliott & Bowers (1963) reported an incidence of 10.9%. In
the study by Abdelmalek and Bissada (1973), the incidence was only 6.3%, which is
significantly lower. They suggest that this difference may be due to the racial origin of
the human specimens, Egyptians versus Americans. In contrast, the incidence was
comparable to results from studies by Larato (1970).
It has been suggested that the variance in the incidence of alveolar bone defects
reported in human skulls may be due to varying ethnic origin of the specimens. In a
study of South African Bantu mandibles (Volchansky et al. 1978) 40 fenestrations were
found out of a total of 645 teeth, for an incidence of 6.2%. As seen with many other
studies, fenestrations were seen most frequently on the mandibular canine. In addition,
the first premolar also had a high frequency (19%) of fenestrations. Likewise, Edel
(1981) conducted a study with 87 dry Bedouin jaws. A total of 990 teeth were evaluated,
10

of which 106 fenestrations (9.7%) were present. This study could find no conclusive
relationship between the presence of occlusal wear and the incidence of alveolar defects,
since 28.4% of teeth with fenestrations and 50% of teeth with dehiscence showed absence
of occlusal wear. In addition a high percentage of teeth without associated alveolar
defects had occlusal wear patterns. In contrast with other studies, two fenestrations were
located on the lingual surfaces and associated with lingually inclined roots of mandibular
central incisors; however these fenestrations were not included in the data. Edel (1981)
was also one of the few studies that classified the location of the fenestrations. A total of
89.5% of all maxillary fenestrations were located in the apical half of the root and 1.3%
was located in the coronal half. Sixty percent (60%) of mandibular fenestrations were
likewise situated in the apical half and 36% were found in the coronal half of the root.
The remainder of the fenestrations were situated at the junction of the coronal and apical
halves. In agreement with Elliott & Bowers (1963) and Abdelmalek & Bissada (1973),
the maxillary first molar was most frequently involved with fenestration. After the
maxillary first molar, the maxillary canines, mandibular canines and mandibular lateral
incisors were most frequently the site of fenestrations.
In many of the historic studies on fenestrations in human skulls, except for studies
in children by Larato (1972), the age of the specimens were either unknown or not
reported. In a study by Davies et al. (1974), of 398 British skulls evaluated, the age of
approximately 1/3 of the skulls was known. Estimated ages were given to the remaining
skulls. The percentage of teeth with fenestrations was between 6.3% and 9.9% within
three groups, with an average of 8.45%. The percentages of teeth with dehiscences and
11

fenestrations decreased with age. Fenestrations were found most frequently on the
maxillary first molars in all age groups and the mandibular lateral incisors and canines
were also consistently involved.
A more recent study by Rupprecht et al. (2001) sought to examine the prevalence,
distribution, and features of alveolar dehiscences and fenestrations in modern American
skulls. They also correlated their presence with occlusal attrition, root prominence, and
alveolar bone thickness. Of the 3,315 teeth examined, 9.0% (298) had fenestrations. A
fenestration was present in 61.6% of skulls. Fenestrations were most commonly found at
maxillary first molars (37.0%), maxillary canines (13.9%), and mandibular canines
(11.5%). In addition, this was the first study in which the fenestrations and dehiscences
were measured using a dental probe. The mean height and width of the fenestrations was
3.6 ± 1.8 x 2.1 ± 0.7mm. The majority of the defects involved the buccal alveolar plate;
relatively few were found on the palatal (1.6%) or mandibular lingual (3.9%) aspects of
the jaw.
In addition, the apicocoronal location of the fenestrations was determined.
Overall, most fenestrations (72.8%) were located on the apical third of the root. In the
maxilla, 92.0% of fenestrations were found on the apical third of the root and the
remaining were found on the middle third. The alveolar bone thickness was recorded for
the affected teeth. Teeth were classified as having an average bone thickness if visual
examination revealed minimal or no interdental grooves. Teeth that possessed prominent
grooves in the interdental area were classified as thin and those with alveolar bone in
12

excess of average were classified as thick. Root prominence was recorded using the
classification defined by Edel (1981), whereby a root was classified as average if it was
within the alveolar housing, but prominent if it produced a convexity in the external
surface of the jaw bone. It was found that the prevalence of skulls with alveolar defects
was greater in skulls with an overall thin alveolar process compared to skulls with an
average or a thick process. Root prominence was noted in 18% of teeth with
fenestrations. More affected teeth demonstrated no occlusal faceting (22%) compared to
teeth with severe occlusal faceting (7.5%).
ETIOLOGY OF FENESTRATIONS
The published studies are somewhat consistent with regard to prevalence and
distribution of dehiscences and fenestration. In contrast, opinions concerning their
etiology are heterogenous. Clinical predictors of dehiscences and fenestrations have not
been well defined. A number of possible etiologic factors have been examined, including
developmental abnormalities, frenum attachments, orthodontics tooth alignment,
periodontal and endodontic pathosis, trauma from occlusion, tooth size, and tooth
position.
The most common probable etiologic cause for alveolar defects is the
combination of prominent roots with a thin alveolar bone plate. Many studies have not
taken into account the thickness of the alveolar plate, as there were no objective criteria
of defining normalcy with regard to the thickness of the alveolar plate. Great interest also
exits in previous anatomical and clinical studies regarding the influence that the occlusal
13

forces could have on the morphology of the alveolar bone. In an animal study,
Kakehashi et al. (1962) suggested that degenerative causes or excessive trauma may be
possible causative factors. Historically, it was thought that an important etiologic factor
for the development of fenestrations and dehiscences was an excessive occlusal force.
Stahl et al. (1963) found attrition (indicative of excessive occlusal forces) present in
many the teeth identified as having fenestrations. The increased extent of fenestrations
seemed to correlate with an increased extent of wear facets. These correlations are based
on skull material without any evidence of function and thus must be regarded as possible
trend rather than absolute data.
In contrast, Edel (1981) could find no clear relationship between the presence of
occlusal wear and the presence of dehiscences and fenestrations. A study by Rupprecht
et al. (2001) reported that the affected teeth and the entire dentition of the affected skulls
lacked attrition in a high percentage, and this is the reason why it could be considered
that the lack of attrition is a predictor for the presence of dehiscences and fenestrations.
Furthermore, it is well documented that excessive occlusal forces can determine buccal
alveolar bone ledges and exostosis, rather than cortical wedges (Horning, 2000).
In a study by Nimigean et al. (2009), depictions of dehiscences and fenestrations
through CT examinations were performed in order to find out if it was possible to
correlate the presence of alveolar bone defects with teeth arrangement in the jaws. Teeth
that were found to have an alveolar defect were analyzed regarding their bucco-lingual
inclination in the jaws. The angle between the long axis of the tooth and a perpendicular
14

line to the occlusal plane was measured for each tooth. When the values were compared
with those described by Dempster WT et al. (1963) for teeth with normal alignment in the
dental arch, a decrease of the bucco-lingual inclination was noticed in all teeth affected
either by dehiscences or by fenestrations. It was concluded that the more the deviation
from the normal bucco-lingual inclination of the tooth, the more the defect. The results
of this investigation point to the hypothesis issued by Shroeder (1976) and abandoned in
later research, that dehiscences and fenestrations were a consequence of tooth
malalignment.
Certain factors such as the tooth/jaw ratio and the position of the teeth may
influence the incidence of alveolar bone defects. Lundström (1951) has documented the
fact that tooth and jaw size are independently inherited and thus a small jaw size inherited
from one parent together with large teeth inherited from the other parent can result in a
tooth/bone radio discrepancy which manifests itself as crowding of the teeth in the jaws.
This discrepancy can also result in the presence of prominent roots and a corresponding
thin alveolar housing.
In summary of the above discussion, the etiology of dehiscence has yet to fully
clarified. Dehiscences have been regarded as a consequence of tooth malalignment rather
than one of periodontal-inflammatory bone destruction (Schroeder, 1976). Schroeder
(1976) suggests that two mechanisms provide the most likely source of the origin of
dehiscences. One speculation of the origin of dehiscence is that they occur immediately
after the conclusion of tooth eruption as a result of the prominence of the tooth position in
15

relations to the dental arch (Schroeder, 1976). The other proposed origin is that they
undergo a secondary development as a result of the thin alveolar housing of the facial
surface of the root receding due to influences that have yet to be analyzed (Schroeder,
1976).
PROBLEMS WITH DETECTION OF FENESTRATIONS
The presence of fenestrations has been evaluated in vivo during mucogingival
surgery and by inspecting dry human skull specimens. The study of patients undergoing
periodontal surgery or the examination of autopsy specimens limits the investigation to
small groups of older or highly selected individuals. Another problem in studying the
alveolar morphology of human skulls is that some of the defects may have been port-
mortem artifacts which may be mistaken for alveolar defects. Damage of the skulls
encountered during shipping and handling or vigorous cleaning processes may result in
chips, cracks, or breaks in the alveolar process, especially in areas of thin bone.
Radiographic examination is not reliable because the facial and lingual bony plates are
obscured by the density of the tooth structure. Additionally, exploring the area with the
periodontal probe is also unsatisfactory as is digital palpation. Given that there is no
satisfactory method for diagnosing alveolar defects, they can potentially present clinical
therapeutic hazards.
The presence of alveolar defects may complicate outcome during healing since
exposure of alveolar bone commonly occurs during surgical procedures. These
deformities of the alveolar process discovered during mucogingival procedures can
16

present surgical dilemmas which may negatively affect the outcome of treatment. When
an alveolar defects is observed during a surgical procedure, the treatment plan is usually
modified instantaneously. Clinically, the intraoperative discovery of an alveolar
dehiscence or fenestration requires special consideration. If a defect is unintentionally
exposed, root instrumentation which may remove radicular connective tissue fibers
should be avoided, the root surface should not be permitted to become desiccated, and
soft tissue coverage of the defect must be ensured. The possible presence of dehiscence
and fenestration defects also requires attention prior to orthodontic treatment. Teeth
associated with these types of alveolar defects may have prominent roots, thin radicular
bone, or roots that extend outside the bony envelope of the alveolar process. Gingival
augmentation prior to orthodontic therapy should be considered, particularly in cases
where rapid orthodontic movement is expected.
Although it is difficult to predict with certainty when fenestrations or dehiscences
may be encountered during mucogingival surgery, many studies have been conducted to
document the incidence and distribution of such defects utilizing the historical methods.
It would be beneficial to clinicians to be aware of the presence of fenestrations prior to
surgery. Many of the previous studies recognized the limitations in detecting alveolar
defects with the previously used methods and agreed that there is a need to develop a
technique by which the morphology of underlying alveolar bone in living human subjects
may be visualized.
17

Radiography plays an important adjunctive role in periodontal diagnosis,
primarily by providing information regarding the amount and type of damage to the
alveolar bone. Imaging modalities, including periapical radiography and panoramic
radiography have been used in the dentomaxillofacial fields over the past few decades;
however, entirely satisfactory results are not attainable. These modalities produce two-
dimensional images that collapse the three-dimensional structures based on differential
attenuation of x-rays. Thus, important aspects of the alveolar bone may go undetected as
a result of an unfavorable location with respect to other structures or an unfavorable
orientation with respect to the x-ray beam. Concerning radiographic projection errors,
magnification and distortion of skeletal and dental structures play important roles.
Magnification occurs because x-ray beams originate from a source that is not parallel to
all points of the object being examined. Distortion occurs because of different
magnifications between various planes. With the advent of computed tomography scans,
alveolar bone defects can be detected pre-surgically.
HISTORY OF COMPUTED TOMOGRAPHY
Human craniofacial patterns were first analyzed by anthropologists and
anatomists who recorded various dimensions of ancient dry skulls. The first
measurements obtained for craniofacial patterns were based on osteologic landmarks.
With time, measurements were made directly on living subjects by palpating the supra-
adjacent tissues, and, with the invention of the x-ray machine, measurements were made
on cephalometric radiographs (cephalometry). Nevertheless, a cephlaometric analysis is
18

a 2-dimensional (2D) diagnostic rendering from a 3-dimensional (3D) structure, with
measurements subject to projection, landmark identification, and measurement errors.
The theoretical background for tomographic image reconstruction was laid out in 1917
when Radon established that a three-dimensional object can be reconstructed from an
infinite set of two-dimensional projections obtained at varying angles around an object
(Sukovic, 2003).
The first CT scanner was developed in 1967 by Sir Godfrey Hounsfield (Sukovic,
2003). Since then, CT technology has rapidly undergone four developmental
generations. After an initial period of rapid development, CT technology became mature,
and it was not until the early 1990s that CT research began anew. Traditional CT (CAT
scan) uses a narrow fan beam that rotates around the patient acquiring thin axial slices
with each revolution. In order to image a section of anatomy, many rotations must be
completed. Due to these repeated rotations, traditional CT emits a high radiation dose
and leaves a gap or break in information between each rotation. Software must fill in, or
guess the missing information. Conventional CT scanners are large and expensive
systems designed primarily for full-body scanning at a high speed to minimize artifacts
caused by movement of the heart, lungs, and bowels. They are not well suited for in
house use in dentomaxillofacial facilities where cost considerations are important, space
is often at a premium, and scanning requirements are limited to the head (Sukovic, 2003).

19

THEADVENT OF CONE BEAM COMPUTED TOMOGRAPHY
In 1996, Quantitative Radiology (QR), developed the first generation of
dentomaxillofacial Cone Beam systems. This invention, created from a need for superior
3D imaging, remains today’s undisputed industry leader in 3D imaging technology.
Cone beam computed tomography (CBCT) has paved the way for the development of
relatively small and inexpensive CT scanners dedicated for use in dentomaxillofacial
imaging. Cone-beam computed tomography (CBCT) can be used with machines such as
NewTom. The NewTom 9000, a new-generation dental CT machine, is a fixed-anode
cone-beam volumetric scanner that is specifically designed for maxillofacial imaging. A
total of 360 individual images are taken, one per each degree of rotation. Because the x-
ray radiation is not on continuously, the 24-36 second duration of each scan translates to
only 3.6-5.4 seconds of actual radiation exposure. An image intensifier allows images to
be generated with significantly less radiation. When the scan is completed, the New Tom
NNT software reconstructs the 360 images, transforming them into a three-dimensional
database, representing the complete anatomy of the patient. This reconstructed volume
consists of a series of axial images, the thickness of which can be graduated from 0.1 to
5mm.
CBCT scanners utilize a two-dimensional, or panel detector which allows for a
single rotation of the gantry to generate a scan of the entire head, as compared with
conventional CT scanners whose multiple slices must be stacked to obtain a complete
image. Cone Beam 3D imaging uses a cone-shaped beam to acquire the entire image in a
20

single pass, resulting in more accurate imaging without gaps in information, and with
considerably lower radiation exposure. Cone beam technology utilized x-rays much
more efficiently, requires much less electrical energy, and allows for the use of smaller
and less expensive x-ray components. Jaffray and Siewerdsen (2000) noted that the
CBCT approach offers two important features that dramatically reduce its cost in
comparison to a conventional scanner. First, the cone beam nature of the acquisition does
not require an additional mechanism to move the patient during the acquisition. Second,
the use of a cone beam, as opposed to a fan beam, significantly increases the x-ray
utilization, lowering the x-ray tube heat capacity required for volumetric scanning.
Because the head and neck can be sufficiently stabilized for clear imaging at a slower
scanning speed, a dedicated dentomaxillofacial scanner does not require the highly
sophisticated, bulky, and expensive components required for sub-second scanning in full-
body CT scanners to avoid blurring of the images caused by movement of the heart,
lungs, and bowels. CBCT produces a radiation dose that is comparable to a dental peri-
apical full mouth series, thus posing minimal risk to the patient. It also allows secondary
reconstructions, such as sagittal, coronal, and para-axial cuts and 3D reconstructions of
craniofacial structure from an acquired volumetric data set. CBCT is ideally suited for
high quality and affordable in-house or on-site CT scanning of the head and neck in
dentomaxillofacial applications.
The modality that is best suited for 3D imaging of mineralized tissues is
computed tomography. Studies have shown that assessment of alveolar bone height on
CT images is reasonably accurate and precise. However, medical CT examinations are
21

dose intense and have an unfavorable cost-benefit ratio for periodontal purposes. These
drawbacks have largely been overcome with the development of cone beam computed
tomography (CBCT) scanners. CBCT scanners are specifically designed for imaging the
hard tissues of the head and neck. They are much cheaper than medical CT units, impart
a relatively low dose to the patient and are becoming rapidly available to the dental
profession.
OBJECTIVE & HYPOTHESIS
Cone beam computed tomography scans can provide valuable information to
dental surgeons. This information can help to alleviate the unexpected encounter of an
alveolar bone defect and assist in proper treatment planning when reviewed prior to
surgical procedures. Additionally, awareness of potential complications may help to
optimize the success of treatment when mucogingival surgeries are performed in these
areas. The objective of this study was to detect alveolar bone fenestrations of the
anterior teeth using NewTom CBCT scans and to report the prevalence and distributions
of these defects. It was hypothesized that the prevalence and distributions detected from
CBCT scans would be comparable to the previously reported studies. The secondary
objective was to measure and describe the vertical length of the fenestrations.

22

CHAPTER 2: MATERIALS AND METHODS
The University of Southern California Institutional Review Board approved this
study (UP-09-00130).
Cone beam computed tomography (CBCT) scans were consecutively selected from the
USC School of Dentistry active database (Redmond Imaging Center, Los Angeles, CA).
The database consisted of CBCT scans of patients who were interested in receiving
orthodontic treatment, dental implant therapy, analysis of TMJ pathology, or were
participants in a sleep apnea study. The scans of the orthodontic patients consisted of
initial, progress, and final treatment scans. The one hundred and twenty-five CBCT
scans selected for the current study were taken between March 2009 and November 2009.
Most of the CBCT scans selected provided twelve teeth for analysis, the anterior
dentition (maxillary and mandibular). Scans were not included if the roots of the anterior
teeth could not be visualized due to scattered images. Classifying information including
the age (determined from the date of birth and the date of the CBCT scan), gender, and
the reason for the scan (initial, progress, or final orthodontic treatment, sleep apnea study,
or TMJ analysis) were included for comparison purposes. The mean age represented by
the scans was 25.1 years (range: 7-68 years). There were 69 females and 56 males
included.
The cone beam computed tomography computer program used in this study was
NewTom9000. The NewTom 9000, a new-generation dental CT machine, is a fixed-
anode cone-beam volumetric scanner that is specifically designed for maxillofacial
23

imaging. With precise 1:1 scale imaging, NewTom technology eliminates the
magnification errors of conventional cephalometric imaging technology. NNT is
designed to deliver high quality images that can be placed into user-defined templates,
deliverable digitally, on paper, or on film. NewTom images are compatible with most
major third-party software systems. Software segmentation adjusts the amount of soft
tissue relative to underlying hard tissue by peering “into” the skull.
Once the NewTom database was uploaded, the patient’s individual CBCT scan
was selected, starting with the first name available and continuing in alphabetical order.
The first screen generated provided information regarding the specific scan. It included
the following data: the number of axial images, the exposure time, the field size, detector
field, the axial thickness, a panoramic section, and 3D reconstruction. The program
provided the option to display three different views: 1) an axial view, 2) a panoramic
view, and 3) and a three-dimensional view. The 3D view with the patient in maximum
intercuspal postion (MIP) was selected and the image was loaded. The NNT program
allowed the scan to be viewed from the front, rear, left, right, top and bottom views. The
axial palette was also decreased to 35% contrast and the model quality was increased to
the maximum level so that the facial structures could be clearly visualized.
The frontal view of the face was viewed which showed the facial skeletal bones
including the soft tissue structures such as the nose, ears, cheeks, etc. (Figure 1).

24

Figure 1. Frontal View with Soft Tissue

The amount of soft tissue was adjusted to the level that only the facial skeletal bones
were visible (Figure 2).

25

Figure 2. Skeletal View

The image created could be rotated about three different axes, including axially, sagitally,
and coronally. The roots of the maxillary and mandibular anterior teeth were evaluated
for the presence of facial alveolar bone fenestrations. The skeletal view was adjusted to
ensure that the skull was not tilted in any direction and that it was located at the
intersection of an imaginary x and y axes. Each tooth was carefully evaluated and the
image was rotated so that the complete facial surface of the tooth was visible. The
central incisors were evaluated from the frontal view. The lateral incisors and the canines
were viewed after the image was rotated to the left or right and the long axis of the tooth
was perpendicular to the examiner. A fenestration was noted as a discontinuity in the
buccal alveolar bone that was surrounded by bone on all four sides. Due to the delays
26

after the skull was rotated, each scan was viewed for approximately 7 minutes each.
When a fenestration was detected, the root surface was then divided into thirds. The
cementoenamel junction and the root apex were used as reference points and the location
(coronal, middle, and apical) of each fenestration recorded (Figure 3).
Figure 3. View of Facial Fenestration

The CBCT scans in which an alveolar bone fenestration was detected were further
analyzed. The sagittal view of skull was then generated. The cursor was moved to a
level in which the clinical crowns were bisected into two equal halves in the arch in
which a fenestration was detected (Figure 4).

27

Figure 4. Sagittal View

Next, an axial view of the respective arch was uploaded (Figure 5).

28

Figure 5. Axial View

Each tooth in the arch was divided into four quadrants and a point locator was placed at
the junction of the two axes (Figure 6). This was done to ensure that the cross sectional
cuts of the teeth were symmetrical.

29

Figure 6. Point Locators

A line was drawn to connect each of the point locators. At this point, the point locators
could be adjusted in an attempt to be sure that the line followed the arch pattern as
precisely as possible. This was particularly important in the area of the canine and in
cases where there was crowding or malalignment of the teeth. The axial view provided
cross-sectional cuts in increments of 1mm each (Figure 7).

30

Figure 7. Axial View with 1mm Incremental Cuts

The particular tooth with a fenestration was located and the number of the corresponding
cross-sectional cut was determined.
This cross-sectional cut was then located and the cross sectional view of the tooth was
evaluated (Figure 8).

31

Figure 8. Cross Sectional View

The cut corresponding to the most central axis of the tooth was evaluated in most cases.
However, when the fenestration was located on either the mesial or distal surface of the
root, the respective cross sectional cut was evaluated. The fenestration was then located.
The computer program provided a ruler for measuring distances (in mm) with a precision
of one- tenth of a millimeter (Figure 9).

32

Figure 9. Fenestration Measurement

When the fenestration was visualized, the cursor was placed at the most coronal extent
and dragged to the most apical extent of the fenestration and the measurement was
recorded. This process was completed for each tooth on which a fenestration was
detected.
STATISTICAL ANALYSIS
The association between gender and the presence or absence of fenestrations as
well as the association for difference in fenestrations (any/none) by ortho initial vs. ortho
final was determined using the Fishers exact test. Patients with other reasons for CBCT
scans (ortho progress, TMJ analysis, sleep apnea study) were excluded from the latter
analysis. The independent sample t-test was used to calculate the difference in mean age
by fenestration group (any/none) and difference in length of fenestration by gender. The
33

difference in length of fenestration by fenestration location and by tooth calculated using
analysis of variance (ANOVA).

34

CHAPTER 3: RESULTS
A total of one hundred and twenty-five CBCT scans were reviewed for 69 female
and 56 male patients (see Table 1). The CBCT scans were taken for a variety of reasons
including initial and final orthodontic assessment, to analyze the progression of
orthodontic treatment, for the diagnosis of pathological disorders of the TMJ, and for
patients participating in a sleep apnea study (see Table 2). The majority of the CBCT
scans were taken for patients that presented for initial orthodontic evaluation. The mean
age of all patients was 25.1 years, with a range from 7-68 years (see Table 3).
Figure 10. Demographics by Gender
0
10
20
30
40
50
60
70
All Patients Fenestrations No fenestrations
56
11
45
69
18
51
Number of Patients
Demographics by Gender
Male
Female

35

Figure 11. Reason for CBCT Scan
Initial Ortho
62%
Final Ortho
24%
TMJ
4%
Sleep Apnea
7%
Ortho Progress
3%
Reason for CBCT Scan

Of the one hundred and twenty-five CBCT scans selected for evaluation,
one hundred and six each provided a total of twelve anterior teeth (maxillary and
mandibular) for evaluation. In nineteen of the CBCT scans, the complete anterior
dentition was not present. The reasons the thirty-two teeth (from these 19 scans) were
not evaluated were listed as one of the following: missing, impacted, or erupting at the
time of the CBCT scan. The maxillary canines were the teeth that were most commonly
missing, impacted, or erupting and not available for evaluation. Two maxillary right
lateral incisors were missing and one mandibular left central incisor was missing and
replaced with a dental implant. Eight of the CBCT scans were of patients that contained
both primary and permanent teeth, in the mixed dentition phase of dental growth. Of
36

these eight patients, there were a total of 20 unerupted canines in five patients that were
not present for the evaluation. The remaining three patients with mixed dentition
provided canines for evaluation. The remaining missing, erupting, or impacted teeth not
present for evaluation were in adolescent or adult patients in the permanent anterior teeth
were present. Three maxillary canines were listed as impacted. Two maxillary canines
and one mandibular canine were listed as erupting.
The CBCT scans provided a total of 1468 teeth after excluding the teeth that were
missing, impacted, or erupting. The remaining teeth were evaluated for alveolar facial
bone fenestrations. The majority of the patients included in the present study did not
have detectable fenestrations (n=96). However, fenestrations were detected in 29
patients. Eighteen (62.1%) of the 29 patients with fenestrations were female and eleven
were male (see Table 1). The mean age of the patients with fenestrations was 22.9 years.
The range was between 11 and 68 years. This mean age of patients with fenestrations
was slightly lower than the mean age of patients without fenestrations, 22.9 years vs. 25.8
years (see Table 3).

37

Figure 12. Mean Age (Years)
21
21.5
22
22.5
23
23.5
24
24.5
25
25.5
26
All patients No fenestrations Fenestrations
25.1
25.8
22.9
Age
Mean Age (Years)

The twenty-nine patients provided 37 fenestrations for analysis. Alveolar bone
fenestrations were more commonly found on the maxillary anterior teeth compared to the
mandibular anterior teeth. The maxillary left central incisor was the tooth with the most
fenestrations detected (n=7). The maxillary left lateral incisor (n=6) was the next tooth
with the most common occurances followed by the maxillary left canine (n=5). On the
mandible, the mandibular right canine (n=4) was most frequently associated with
fenestrations (see Table 4).

38

Figure 13. Number of Fenestrations by Tooth
0
1
2
3
4
5
6
7
6 7 8 9 10 11 22 23 24 25 26 27
# of Fenestrations
Tooth #
Number of Fenestrations by Tooth

Overall, there were 25 fenestrations detected on the maxillary anterior teeth and 12 found
on the mandibular teeth. At least one alveolar bone fenestration was found on every
anterior tooth type except for the mandibular central incisors. Mandibular central
incisors exhibited no fenestrations in this study.
When a fenestration was detected, its location on the root was recorded. The root
surface was divided into thirds, using the cementoenamel junction and the root apex as
references. The location of the fenestrations was listed as being located in the coronal,
middle or apical third of the root. Over half, 59.5%, of the root fenestrations were
located in the middle third. Nine of the fenestrations, 24.3%, were located in the coronal
third of the root and six, 16.2%, were located in the apical third of the root (see Table 5).
39

Figure 14. Number of Fenestrations by Location
0
5
10
15
20
25
9
22
6
Number of Fenestrations
Number of Fenestrations by Location

After the 37 fenestrations were detected and the location was recorded, the length
of the fenestration was measured. Using a sagittal view of a cross section of the teeth
with fenestrations, a measuring device of the NewTom software was used to measure the
apico-coronal length of the fenestrations in mm. The mean length of all fenestrations was
1.6mm±0.8. The largest fenestration measured was 3.9mm. This measurement was
detected on a maxillary right lateral incisor. The smallest fenestration measured was
0.5mm. This measurement was detected on a mandibular right lateral incisor and a
maxillary right canine. The overall percentage of teeth with fenestrations in this sample
was 2.5%. The overall percentage of patients with fenestrations was 23%. There were
five patients that had two or more fenestrations.
40

According to this study, using Analysis of Variance (ANOVA), there was a
statistically significant difference in the location of fenestration with regard to
fenestration length. The longest fenestrations were located in the apical one-third of the
root surface (p = ≤ 0.5). Although more fenestrations occurred in the middle one-third,
the longer fenestrations were statistically more likely to be present on the apical one-third
(see Table 6).
Figure 15. Mean Length of Fenestrations by Location
0
0.5
1
1.5
2
2.5
Coronal Middle Apical
1.31
1.49
2.28
Mean length of fenestration
Location
Mean Length of Fenestrations by Location
p = ≤ .05

There were no statistically significant differences between the number of fenestrations by
tooth and the length of fenestrations by tooth. Fenestrations on tooth #7 had the longest
mean length, but the standard deviation (SD) was large, so the differences overall
remained insignificant (see Table 7).
41

Figure 16. Mean Length of Fenestration by Tooth Number
0
0.5
1
1.5
2
2.5
6 7 8 9 10 1122232627
0.5
2.35
1.25
1.8
1.63
1.74
1.37
1.4
1.47
1.4
Mean Length of Fenestrations
Tooth #
Mean Length of Fenestrations by Tooth #

There were no statistical significant differences in any of the other variables and
relationships measured.

42

CHAPTER 4: DISCUSSION
Computed tomography scans allow surgeons to visualize alveolar bone in human
patients. The buccal and lingual surfaces are visible on CBCT scans which provide
information that is unavailable on periapical or panoramic radiographs. This information,
if noticed prior to a surgical procedure, can provide valuable information on the presence
and degree of severity of the bone defects. This study was limited to fenestrations and
excluded dehiscences because of the ambiguity in the definition and means of detection
of dehiscences. Davies et al. (1974) defined a dehiscence as a defect measuring at least
4mm apical to the crest of the interproximal bone as measured from the CEJ. They were
the first to define the term dehiscence in numerical terms. Prior to this definition
established by Davies et al. in 1974, the authors used various descriptions to classify an
alveolar bone defect as a dehiscence. Elliott and Bowers (1963) defined a dehiscence as
the absence of alveolar cortical plate exceeding one half of the root length. Stahl et al.
(1963) did not use the term dehiscence but classified fenestrations from 1-3 depending on
the severity of the defect. Larato (1970) did not define the term dehiscence but his
illustration showed buccal bone loss almost to the apex of the tooth. In addition,
Abdelmalek and Bissada (1973) described a dehiscence as the absence of alveolar
cortical plate extending more than half of the root length in some cases. The definition
suggested by Davies et al. (1974) is somewhat arbitrary but is in conformity with the
generally accepted clinical impression of a dehiscence. The weakness in this definition is
that bone loss on the interproximal surfaces due to periodontal disease could eliminate
the presence of a dehiscence as defined in this way. Thus, when a dehiscence is present,
43

the determination of the severity of the dehiscence will not be accurate if there is bone
loss due to periodontal disease (Edel, 1981). Fenestrations; however, are more clearly
defined and hence were evaluated in this study.
The overall percentage of individual teeth with fenestrations present was 2.5%
and the percentage of patients with fenestrations was 23%. This value is somewhat lower
than the previously published percentages. While differences have been observed among
various ethnic groups, overall prevalence of teeth with a fenestration ranges from 0.23%
to 16.9% for fenestrations. There are many possible reasons for the variances in the
reported prevalence of alveolar bone defects. Careful consideration must be taken when
comparing the various reports since criteria for measurements tend to vary from one
group to another and until these criteria are standardized, results must be interpreted with
caution. Ferembach (1975) has shown evidence that nutrition can influence skeletal
morphology in humans. Forurnier (1965) also reported that dietary lactose influences
ossification in rodents. Thus variations in osseous density between groups may
influence the degree of bony erosion of skeletal remains, and the incidence of these bony
defects. In general, the groups of human skulls in each respective study were of the same
racial or ethnic background. Therefore, factors such as nutrition and dietary habits may
also be generalized among the skull populations and may influence the presence of
alveolar bone defects. Both Ubelaker (1978) and Stewart (1979) have stressed the
importance of the water content and pH of the soil in preservation of human skeletal
remains. At death osseous protein undergoes hydrolysis to peptides which subsequently
are broken down to amino acids. The rate of this degradation process is dependent on the
44

local temperature, the amount of water present, and the pH of the soil. The erosive nature
of the soil can also influence skeletal preservation. In addition, a further problem in
studying the alveolar morphology of exhumed material is that some of the defects may
have been post-mortem artifacts, particularly in areas where the alveolar plate was
originally thin. These artifacts may have been mistaken for alveolar bone defects,
increasing the frequency of the defects. All of the above factors may have been
overlooked in previous studies and could be a limiting factor with regard to accurate and
valid measurement of fenestrations taken from skulls.
Only the maxillary and mandibular anterior teeth were evaluated for this study. In
some of the previous studies on the frequency of fenestrations, they were most commonly
detected in the anterior regions. Comparing the anterior and posterior regions in general,
the results of the study by Abdelmalek and Bissada (1973) showed that the defects are
more predominant in the anterior region. Stahl et al. (1963) and Larato (1970) came to a
similar conclusion. These facts were taken into consideration when designing this study
for evaluating the dentition for fenestrations. In addition, the time required for observing
fenestrations using CBCT is considerably longer than that required for observing and
taking measurements in human skulls. In the latter method, the facial surfaces of the
skulls can be viewed relatively quickly and the presence of fenestrations can be
documented. However, when CBCT scans are used to view fenestrations, there is a
significant increase in time that has to be allotted for each tooth. For the reasons listed
above, this study was limited to the facial surfaces of the maxillary and mandibular
anterior teeth. A study conducted by Edel in 1981 and one by Rupprecht et al. (2001)
45

were the only studies in which fenestrations were located on the lingual surfaces. Edel
(1981) noted two fenestrations on the lingual surfaces associated with lingually inclined
roots of the mandibular incisors. Rupprecht et al. (2001) detected only 3.9% of all
fenestrations on the lingual surfaces of the mandibular anterior teeth. The present study
was limited to facial fenestrations because of the low prevalence of lingual fenestrations
reported in the literature.
The studies by Larato (1970 and 1972) were instrumental in reporting the
prevalence and frequency of alveolar defects in children. Prior to these studies, there was
little information in the literature concerning alveolar bone defects in children. The
results of these studies showed that young children between the ages of 2-5 years of age
exhibit bone destruction as a result of periodontal disease and that the types of
periodontal bone lesions in children are similar to those found in adults. Although the
subjects in the present study were older than 5 years of age, there were a significant
amount of children and adolescent patients in the mixed dentition stage of dental growth.
The youngest age was 7 years and of the patients with fenestrations, the over half were 18
years old or younger. In general, over two-thirds of patients were adolescents and
teenagers. Davies et al. (1974) reported that the percentage of skulls affected by
dehiscences and fenestrations decreased with age. One possible explanation is that the
increase in tooth loss with age resulted in fewer teeth being at risk. The increased
percentage of young patients is due to the fact that many of the patients in the database of
CBCT scans used were patients that presented for orthodontic therapy. Younger patients
are more likely to begin orthodontic treatment earlier in life; however, more adult patients
46

are becoming interested in correcting their dentition with orthodontic therapy. In
addition to the CBCT scans that were for orthodontic evaluation, the sample was
comprised of some older patients (n=14) also presented for a sleep apnea study and TMJ
analysis.
Although there have been many historical studies reporting the prevalence and
frequency of alveolar bone defects, few have actually reported the measurements of these
defects. Rupprecht et al. (2001) reported the mean height and width of fenestrations in a
population of modern American skulls to be 3.6±1.8 x 2.1 ±0.7mm. The mean
measurements of fenestrations were slightly smaller than that of dehiscences (5.9±2.4 x
3.3±1.3mm). In the present study, the only the lengths of the fenestrations was measured
(1.6mm ± 0.8). In the sagittal CBCT view which was used to measure the length of the
fenestrations, it was not possible to measure the width as well.
Depending on the type of periodontal surgery that is performed, the location of
the fenestration may be hazardous. For example, if an osseous surgery is performed and
the fenestration is located in the coronal third of the tooth, the amount of ostectomy and
osteoplasty that can be achieved will be greatly limited, and may affect the outcome of
the procedure. It may be impossible to obtain positive architecture without jeopardizing
the affected tooth or adjacent teeth. In the study by Edel (1981), the only study that
reports the location of the fenestration, the severity of the fenestration was not classified
but location (apical or coronal halves of the root) was estimated. He reported that the
majority of fenestrations were located in the apical half of the root.
47

Average tooth length as presented by Ingle (1973) was considered to be
representative of each respective tooth for this purpose and root lengths were calculated
by subtracting the crown length from the total tooth length. In the present study, 59.5%
of fenestrations were located in the middle third of the root and 24.3% were in the
coronal third. Edel (1981) reported the location of 89.5% of maxillary fenestrations and
60% of mandibular fenestrations in the apical half of the root may be racially specific, but
is of interest clinically in that with the trend towards more conservative flap reflection.
Alveolar fenestrations, especially in the maxilla, in cases of early to moderate
periodontitis, may not be exposed and may thus be of less clinical significance than has
been previously reported (Edel, 1981). This is because the majority of fenestrations were
located apically and thus may not be exposed during flap reflection.
An alveolar bone dehiscence is considered to be a prerequisite for the
development of a gingival recession (Lost, 1984). Towards the apices of the teeth, the
facial bone plate becomes thicker and spongy bone fills the interval between the facial
and the lingual cortical plates. In these thicker areas, recession generally stops
spontaneously. With his study performed at the time periodontal flap surgery of 50
recession sites, which included 113 affected teeth, Lost (1984) determined that a
recession depth of 1mm was exceeded by an average of 2.8mm towards the apex by the
alveolar bone dehiscence. Additionally, each 1mm increase in recession depth involved
an average increase of 0.98mm in the alveolar bone dehiscence. While dehiscences could
be made in vivo evident through the above described mechanism, not the same can be
said regarding fenestrations; their existence is usually clinically unexpected. Exposure of
48

alveolar bone commonly occurs during periodontal or oral surgery, and the presence of
fenestrations and dehiscenes is of great importance as they may complicate the outcome
during the healing process. If a defect is unintentionally exposed, root instrumentation
which may remove radicular connective tissue fibers should be avoided, the root surface
should not be permitted to become desiccated, and soft tissue coverage of the defect must
be ensured. Special consideration must also be taken into account with regards to the
current trend in implantology, specifically the flapless approach.
Despite many reports in the literature on the various uses of cone beam computed
tomography, studies on its accuracy and image quality for assessing bone morphology
have been limited. Also, no studies have assessed the use of CBCT to study alveolar
bone morphology in vivo (Leung et al. 2010) as the present study does. Instead, most
studies used artificially created defects on phantoms or dry skulls, which do not
accurately represent some anatomic structures such as tooth sockets and alveolar bone
margins. The problem with evaluating artificially created defects on dry skulls is that the
detection of defects can be overestimated because of the distinct borders created by the
operator (Leung et al. 2010). The literature has reported the accuracy of CT and CBCT
for measuring and identifying artificially created alveolar bone defects; however, no
studies have evaluated the use of CBCT to diagnose naturally occurring bony dehiscences
and fenestrations in human skulls (Leung et al. 2010).
There are numerous studies which support the accuracy of CBCT in detecting
artificially created alveolar bone defects in human and animal jaws. Misch et al. (2006)
49

conducted a study to compare CBCT measurements of periodontal defects to traditional
methods. Artificial osseous defects including infrabony buccal, lingual, and
interproximal defects of varying width and height were created on mandibles of dry
skulls. CBCT scanning, periapical radiography, and direct measurements using a
periodontal probe were compared to an electronic caliper that was used as a standard
reference. For radiographs, most buccal and lingual measures could not be performed;
however, all bony defects were identifiable and measureable directly or with CBCT. For
buccal and lingual measures, the direct measurement mean difference was 0.3 (±0.51
SD), and the CBCT mean difference was 0.7 (±0.68 SD). These results were not
statistically different. The results of this study are evidence that CBCT is as accurate as
direct measurements using a probe and as reliable as radiographs for interproximal areas.
Because buccal and lingual defects could not be diagnosed with radiography, CBCT was
a superior technique.
Using human cadaver jaws, Furhmann et al. (1995) also compared radiographs
with high resolution conventional CT and found that only 60% of infra-alveolar bony
defects were identified on radiographs, whereas 100% could be distinguished using
CBCT. The results of this study were similar to those reported by Misch et al. (2006).
Their measurements resulted in a mean underestimation of 2.2mm using radiographs and
0.2mm using CBCT. They also noted that the assessment of normal alveolar bone and
the artificially created dehiscences was facilitated by the identification of changes in the
topography of the cortex in the root section and the presence of sharp breaks in the bone
lamella. The assessment of bone dehiscences depends on the extent of the defect, the
50

thickness of the adjacent alveolar plates and the visualization of the periodontal ligament
space. Their results suggested that quantitative evaluation of alveolar bone plates is
currently realistic with a bone thickness of 0.5mm. If the periodontal ligament space is
visualized, then measurements on thinner bone will be feasible. It must be mentioned
that this study used modern high-resolution computed tomography (HR-CT) and not
CBCT scans for imaging periodontal defects.
In 2006, Mengel et al., used animal and human mandibles to compare periapical
radiographs, panoramic films, CT and CBCT measurements of periodontal defects,
including fenestrations, dehiscences, and furcations. The defects were artificially created
and gutta percha points were used to aid in visualization. These measurements were
compared to their corresponding histologic specimens. Intraoral radiography was limited
by visibility in the buccolingual direction, and image quality (contrast, brightness,
distortion, clarity of structures, and focus) was superior using CBCT. It has been
suggested that the variation between studies is likely due to differences in the
methodology; however, most differences are minimal.
Although the studies discussed previously report that the use of CBCT to detect
alveolar bone defects is superior to conventional radiography and comparable to direct
measurements, those results may be flawed. Because the defects were artificially created,
the margins are clearly visible and likely more easily detectable on CBCT scans. Leung
et al. (2010) suggests that since natural defects have more gradual and tapering margins,
they may not be visualized on CBCT as easily as those created by an operator, and thus
51

might not provide a true assessment of CBCT for diagnosing alveolar bone defects.
Therefore, Leung et al. (2010) conducted a study to evaluate the accuracy and reliability
of CBCT in the diagnosis of naturally occurring fenestrations and bony dehiscences.
Thirteen dry human skulls with 334 teeth were scanned with CBCT technology.
Measurements were made on each tooth from the cusp or incisal tip to the CEJ and from
the cusp or incisal tip to the bone margin along the long axis of the tooth. The accuracy
of CBCT measurements was determined by comparing the means, mean differences, and
the absolute mean differences with those of direct measurements.
The results of this study showed that the indirect assessment of facial alveolar
bone defects overlying roots was not as accurate as previously reported. There was a
much higher rate of false positives (false fenestrations) with CBCT: 3 times the number
of fenestrations detected on CBCT compared with direct skull examination. There were
also a significant number of false negatives, with true defects missed on CBCT. The
spatial resolution limitations of the CBCT meant that areas with bone less than 0.6mm
thick were seen on the image as areas without bone. The smallest thickness measured on
axial and coronal sections was 0.6mm, suggesting that this was the minimum thickness
required for bone to be measureable and distinguishable from the root surface. This
study reported two incidences when bone was not visualized on the CBCT and suggested
that the bone may be truly missing, or its thickness was less than 0.6mm. The results still
support the use of CBCT for detection of buccal bony defects such as dehiscences and the
fenestrations determined in the present study. The low positive predictive values for
dehiscences and fenestrations are less critical, since the prevalence of these defects are
52

low and less than 10% as reported in most of the studies. Because of the low prevalence,
it is more critical to identify true negative accurately to avoid any unnecessary alarming
data. Overall, the high negative predictive values of 0.95 for dehiscences and 0.98 for
fenestrations in this study provide evidence that when a defect is not found on CBCT, it
is most likely not present.
LIMITATIONS
Variation in the detection and measurements of fenestrations detected on CBCT
scans is a limitation of this study. Of the previous studies performed to evaluate the
accuracy of CBCT measurements, only a few have reported on the reliability of the
method by repeating measurements with a time interval between the first and second
measures. Pinsky et al. (2006) found that the intra-examiner reliability by ICC for CBCT
ranged from 0.75 to 0.99. Baumgaertel et al. (2009) found that the reliability of
measuring variables relating to teeth on CBCT images was highly reliable with an ICC of
almost 1.0. In addition, the study by Leung et al. (2010) also showed high reliability of
both CBCT and direct methods.
Although most of the previous studies evaluating the accuracy of CBCT in
detecting buccal bone defects report CBCT images as being superior to other methods,
there are some limitations in its accuracy. As reported by Leung et al. (2010), there was a
much higher rate of false positives with CBCT of three times the number of fenestrations
detected on CBCT compared with direct skull examination. They also reported that there
were a significant number of false negatives, with true defects missed on CBCT. These
53

findings should be taken into consideration when evaluating the results of studies that
support the notion that CBCT is more accurate the other modalities of detecting bone
defects.
Other limitations of the present study are the fact that this was a retrospective
study and the introduction of possible study population bias. The data (information from
CBCT scans) was retrieved from past records and there was no follow up of patients, as
is the case with a prospective study. In addition, sources of error due to confounding and
bias are more common in retrospective studies, which introduces limitations to the study.
Because most of the patients included in the study were patients of the orthodontic clinic,
this population may not correctly represent the general population. Thus, the results of
this study may be vulnerable to showing skewed findings. Orthodontic patients generally
are periodontally healthy, which is not the case for the general public. Varying severities
of periodontal disease, including gingivitis have a moderately high prevalence in many
populations.

54

CHAPTER 5: CONCLUSIONS
Periodontal diagnosis relies heavily on traditional two-dimensional radiographic
assessment, including periapical radiography and panoramic radiography. Despite the
efforts in improving reliability, current methods of detecting bone level changes over a
period of time or determining three-dimensional architecture of osseous defects are
inadequate. Computed tomography has been explored to address these issues because of
the ability to produce accurate three-dimensional imaging. However, there are inherent
limitations to this method including radiation exposure, machine size, and cost, which
have made the method impractical for routine dental use. The advent of the cone beam
computed tomography has alleviated many of the problems associated with the
conventional CT machines. These relatively lower-cost, smaller machines produce high
quality data and are more amenable to dental use. Compared to radiographs, it has been
reported in most cases that the three-dimensional capability of CBCT offers a significant
advantage to clinical dentistry because defects can be detected on all surfaces and
measured with most software programs.
This study provides clinical relevance because it reports the prevalence and
distribution of facial alveolar bone fenestrations detected utilizing CBCT. In addition,
the apicocoronal location of the fenestrations are determined and measurements are
provided. Although CBCT scans are often unnecessary for many periodontal surgeries, it
is becoming the standard of care for patients that are undergoing orthodontic therapy or
receiving dental implants to have pre-operative three-dimensional scans. The presence of
55

fenestrations can cause implant placement to be contraindicated in sites where
fenestrations and dehiscences are present. As reported in previous studies, these defects
are more prevalent in the maxillary anterior dentition compared to the mandible.
Therefore, it may not be advantageous to treatment plan for immediate implant placement
in the maxillary anterior area until the appropriate CBCT scans are evaluated and it has
been determined that there is adequate bone to house an implant. Additionally,
orthodontic therapy may cause a pre-existing fenestration to increase in size if treatment
is not planned strategically. The presence of these bone defects decreases the bony
support for the teeth. It has been well documented that, under certain conditions such as
plaque-induced inflammation, a lack of bony support during orthodontic movement can
be detrimental to the health of the teeth and the periodontium. Likewise, orthodontic
tooth movement can create alveolar bone defects (Karring et al. 1982).
Future studies should be conducted to confirm and expand the results of the
present study on anterior teeth and to determine the prevalence of fenestrations of
posterior teeth using CBCT scans as well as quantifying those fenestrations. The mesial
and distal roots maxillary first molars are a common site for dehiscences and
fenestrations and this information can help with determining prognosis and treatment
planning.

56

BIBLIOGRAPHY
Abdelmalek RG, Bissada NF. Incidence and distribution of alveolar bone dehiscence and
fenestration in dry human Egyptian jaws. J Periodontol 1973; 44:586-588.
Baumgaertel S, Palomo JM, Palomo L, Hans MG. Reliability and accuracy of cone-beam
computed tomography dental measurements. Am J Orthod Dentofacial Orthop
2009;136:19-28.
Bradin, M. Precautions and Hazards in Periodontal Surgery. J Periodontol 1962; 33:154.
Carranza F, Newman M, Takei H. The tooth-supporting structures. Clinical
periodontology,9
th
ed. W.B. Saunders;2002:36-57.
Davies RM, Downer MC, Hull PS, Lennon MA. Alveolar defects in human skulls. J
Clin Periodontol 1974; 1:107-111.
Dempster WT, Adams WJ, Duddles RA. Arrangement in the jaws of the roots of the
teeth. J Am Dent Assoc 1963; 67:779-797.
Edel A. Alveolar bone fenestration and dehiscences in dry Bedouin jaws. J Clin
Periodontol 1981; 8:491-499.
Elliott JR, Bowers G. Alveolar dehiscence and fenestration. Periodontics 1963; 1:245-
248.
Ferembach D. The effects of diet on the phenotypic expression of humans. In the
archives of anatomy and anthropology institute of anthropologist Professor Souza
Marques 1975; 300.
Fournier P. Influence of lactose on the utilization of calcium and the ossification.
Pathology-Biology 1965;13: 143-151.
57

Fuhrmann R, Wehrbein H, Langen HJ, Deidrich P. Assessment of the dentate alveolar
process with high resolution computed tomography. Dentomaxillofac Radiol 1995;
24:50-54.
Goldman HM, Cohen DW. Periodontal Therapy. St. Louis, C.V. Mosby Company; 1968.
Horning GM, Cohen ME, Neils TA. Buccal alveolar exostoses: prevalence,
characteristics, and evidence for buttressing bone formation. J Periodontol 2000;
71:1032-1042.
Ingle JL. Endodontics. Philadelphia: Lea and Febiger; 1973:181.
Jaffray DA, Siewerdsen JH. Cone-beam computed tomography with a flat-panel imager:
initial performance characterization. Med Phys 2000; 27: 1311-1323.
Jeffcoat M, Jeffcoat RL, Reddy MS, Berland L. Planning interactive implant treatment
with 3-D computed tomography. J Am Dent Assoc, 1991; 122:40-4.
Kakehashi S, Baer PN, White CL. Comparative Pathology of Periodontal Disease. I.
Gorilla. Oral Surgery 1963; 16: 397-406.
Karring T, Nyman S, Thilander B, Magnusson I. Bone regeneration in orthodontically
produced alveolar bone dehiscences. J Periodontol Res 1982; 17:309-315.
Larato DC. Alveolar plate fenestrations and dehiscences of human skull. Oral Surg Oral
Med Oral Pathol 1970; 29: 816-819.
Larato DC. Periodontal bone defects in the juvenile skull. J Periodontol 1970;41:473-5.
Larato DC. Alveolar plate defects in children’s skulls. J Periodontol 1972; 43:502.
Lascala CA, Panella J, Marques MM. Analysis of the accuracy of linear measurements
obtained by cone beam computed tomography (CBCT-NewTom). Dentomaxillofac
Radiol 2004; 33:291-294.
58

Leung C, Palomo L, Griffith R, Hans MG. Accuracy and reliability of cone-beam
computed tomography for measuring alveolar bone height and detecting bony
dehiscences and fenestrations. Am J Orthod Dentofacial Orthop 2010; 137:109-119.
Lost C. Depth of alveolar bone dehiscences in relation to gingival recessions. J Clin
Periodontol 1984; 11:583-589.
Lundström, A. The etiology of crowding of the teeth (based on studies of twins and on
morphological investigations) and its bearing on orthodontic treatment (expansion or
extraction). European Orthodontic Society 1951; 176-191.
Massler M, Schour I, Cohen A. Epidemiology of gingivitis in children. J Am Dent Assoc
1952; 45: 319-324.
Mengel R, Kruse B, Flores-de-Jacoby L. Digital volume tomography in the diagnosis of
peri-implant defects: An in vitro study on native pig mandibles. J Periodontol 2006;
77:1234-1241.
Misch KA, Yi ES, Sarment DP. Accuracy of cone beam computed tomography for
periodontal defect measurements. J Periodontol 2006; 77:1261-1266.
Morant GM, Collet M, Adyanthaya NK. A biometric study of the human mandible.
Biometrika 1936; 28: 84-122.
Nabers CL, Spear GR, Beckham LC. Alveolar dehiscence. Texas Dental Journal 1960;
1:4-6.
Nimigean VR, Nimigean V, Bencze MA, Dimcevici-Poesina N, Cergan R, Moraru S.
Alveolar bone dehiscences and fenestrations: an anatomical study and review. Romanian
Journal of Morphology and Embryology 2009; 50:391-397.
Pinsky HM, Dyda S, Pinsky RW, Misch KA, Sarment DP. Accuracy of three-
dimensional measurements using cone-beam computed tomography. Dentomaxillofac
Radiol 2006; 35:410-416.
59

Rupprecht RD, Horning GM, Nicoll BK, Cohen ME. Prevalence of dehiscences and
fenestrations in modern American skulls. J Periodontol 2001; 72:722-729.
Schroeder HE. Oral Structural Biology. Thiem: Stuttgart; 1976.
Stahl SS, Cantor M, Zwig E. Fenestration of the labial alveolar plate in human skulls.
Periodontics 1963; 1:99.
Stewart TD. Essentials of Forensic Anthropology. Springfield, Illinois: Charles C.
Thomas; 1979: 74-75.
Sukovic P. Cone beam computed tomography in craniofacial imaging. Orthod Craniofac
Res 2003; 6 (Suppl) 1:31-36.
Ubelaker DH. Human Skeletal Remains. Chicago: Aldine Publishing Co; 1978: 18.
Volchansky A, Cleaton-Jones P. Bony defects in dried Bantu mandibles. Oral Surg Oral
Med Oral Pathol 1978; 45:647-653.

Abstract (if available)

Linked assets

University of Southern California Dissertations and Theses

Conceptually similar

PDF

Detrimental effects of dental encroachment on secondary alveolar bone graft outcomes in the treatment of patients with cleft lip and palate: a cone-beam computed tomography study

PDF

Cone beam computed tomographic measurements of buccal alveolar bone widths overlying the maxillary premolars

PDF

The effect of cone beam computed tomography (CBCT) imaging on orthodontic diagnosis and treatment planning

PDF

Rate of bone loss in furcation-involved molars: a retrospective analysis

PDF

3D volumetric analysis of post extraction maxillary sinus floor changes: a retrospective CBCT analysis

PDF

Cone-beam computed tomography images: applications in endodontics

PDF

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

PDF

Longitudinal analysis of peri-implant keratinized mucosa using computer imaging

PDF

A cone beam CT evaluation of the maxillary dento skeletal complex after rapid palatal expansion

PDF

Human histological analysis of autogenous block grafts

PDF

Dimensional changes in alveolar bone following extraction of maxillary molars in humans: a retrospective CBCT analysis

PDF

Alveolar process inclination as related to tooth inclination on near normal patients -- in three dimensional space

PDF

A randomized controlled clinical trial evaluating the efficacy of grafting the facial gap at immediately placed implants in the anterior maxilla: 3D analysis of bone and soft tissue changes

PDF

Relationship of buccal bone plate thickness and healing of extraction sockets with or without alveolar ridge preservation: a systematic review

PDF

A cone beam-ct evaluation of the availability of bone for the placement of miniscrews

PDF

Three-dimensional assessment of tooth root shape and root movement after orthodontic treatment: a retrospective cone-beam computed tomography study

PDF

Marginal bone response of implants placed in post-extraction sites following ridge preservation with bovine anorganic bone

PDF

Radiographic analysis of bone gain from guided bone regeneration utilizing tenting screws

PDF

A cone beam-CT evaluation of the proximity of the maxillary sinus to commonly used TAD sites

PDF

Maxillary sinus floor and alveolar crest alterations following extraction of maxillary molars: a retrospective CBCT analysis

Asset Metadata

Creator Lampley, Jana L. (author)

Core Title Prevalence and distribution of facial alveolar bone fenestrations in the anterior dentition: a cone beam computed tomography analysis

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 06/04/2010

Defense Date 06/02/2010

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

Tag anterior dentition,cone beam computed tomography,facial fenestrations,OAI-PMH Harvest

Language English

Contributor Electronically uploaded by the author (provenance)

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

Creator Email jlampley711@gmail.com,jlampley711@yahoo.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-m3113

Unique identifier UC1214229

Identifier etd-Lampley-3835 (filename),usctheses-m40 (legacy collection record id),usctheses-c127-334234 (legacy record id),usctheses-m3113 (legacy record id)

Legacy Identifier etd-Lampley-3835.pdf

Dmrecord 334234

Document Type Thesis

Rights Lampley, Jana L.

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 cisadmin@lib.usc.edu