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

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

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Content 1

MAXILLARY SINUS FLOOR AND
ALVEOLAR CREST ALTERATIONS
FOLLOWING EXTRACTION OF
MAXILLARY MOLARS AND RIDGE
PRESERVATION
A RETROSPECTIVE CBCT ANALYSIS

A Thesis Presented to the Graduate School of the
University of Southern California
In Partial Fulfillment of the Requirements for the Degree of
MASTER OF SCIENCE IN CRANIOFACIAL BIOLOGY
By
ESSA ALWAZAN
August 2018
2
TABLE OF CONTENTS

Authors and Affiliations. ..................................................................................................... 3
Table Legends ..................................................................................................................... 4
Figure Legends ....................................................................................................................4
Abstract … ............................................................................................................. 8
1. Introduction … ................................................................................................... 10
2. Materials and Methods … ................................................................................... 13
3. Results …........................................................................................................... 18
4. Discussion ..................................................................................................................... 20
5. Conclusions ................................................................................................................... 26
6. Tables …............................................................................................................ 27
7. Figures … ........................................................................................................ 32
8. References ............................................................................................................... ….44
3
Authors and Affiliations
Essa Alwazan BDS, MFDS
Graduate student, Candidate for Master of Science in Craniofacial Biology ( CBY)..
Division of Periodontology, Diagnostic Sciences and Dental Hygiene.
Herman Ostrow School of Dentistry, University of Southern California (USC).
925 W 34th St Room 4278 Los Angeles CA 90089.

Homayoun H. Zadeh DDS, PhD
Associate Professor.
Division of Periodontology, Diagnostic Sciences and Dental Hygiene.
Herman Ostrow School of Dentistry, University of Southern California (USC).
925 W 34
th
St Room 4278 Los Angeles CA 90089.

Correspondence:
Alwazan@usc.edu

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Table Legends
Table 1. Clinical characteristics of study patients and sites.
Table 2. Mean pre-operative and post-operative measurements (mm) for each root:
a) Reference line to sinus floor (SF1 and SF2).
b) Total vertical alveolar height (MBL1 and MBL2).
c) Reference line to crest of alveolar bone (AC1 and AC2).

Table 3. Mean height changes (mm) for individual root:
a) Vertical Height Change (VHC).
b) Crest Height Change (CHC).
C) Sinus Floor Change (SC).

Table 4. Pearson’s correlation results for the height changes after maxillary molar extraction
and ridge preservation at each root.

Table 5. Pearson’s correlation for the Vertical Height Change (VHC) and healing time after
maxillary molar extraction and age of patients.

Table 6. Pearson’s correlation results for Sinus Floor Change (SC) and root parameters:
Root inclination.
Root width.
Root apex to sinus.
Periapical lesion diameter.
Sinus membrane thickening.

Figure Legends
Figure 1A. A Diagram depicting the radiographic landmarks used for measurements made on
pre- and post-extraction CBCT images:
Horizontal occlusal red line indicates reference line drawn using anatomic landmarks that
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were unchanged in pre- and post- operative CBCT images.
SF1 (red arrow)- measured as the distance (mm) from the red reference line to sinus floor
(light blue line) in pre- operative CBCTs.
MBL1 (purple arrow)- measured as the distance (mm) from alveolar crest indicated
by the green line to sinus floor which is indicated by the light blue line in pre-
operative CBCTs.
AC1 (blue arrow)- measured as the distance (mm) from the red occlusal reference
line to alveolar crest which is indicated by the green line in pre-operative CBCTs.
SF2 (red arrow)- measured from the red reference to the sinus floor light blue line
in post- operative CBCTs (mm).
MBL2 (purple arrow) - measured from alveolar crest indicated by the green line to
sinus floor which is indicated by light blue line in post-operative CBCTs (mm).
AC2 (blue arrow)- measured from the red occlusal reference line to alveolar crest
which is indicated by the green line in post-operative CBCTs (mm).
SC (Sinus Change) = SF1-SF2.
VHC (Vertical Height Change) = MBL1-MBL2.
CHC (Crest Height Change) = AC2 –AC1.

Figure 1B-A. Representative CBCT series taken before and after extraction of a
maxillary molar, illustrating the measurements made according to the anatomic
landmarks designated in figure 1A.

Figure 2. Anatomical parameters measured in pre-operative CBCT images:
Root inclination- measured as the angle (degree) formed between a line passing
through each root axis with a second horizontal line drawn through the inferior
boarder of the maxillary sinus.
Root width (mm)- measured at 2 mm coronal from the radiographic apex of the
root.
Root apex-to-sinus floor distance (mm)- measured as the shortest distance from the
radiographic apex of each root to the maxillary sinus floor.
Periapical lesion (mm)- measured at its widest points (diameter).
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Sinus membrane thickening (mm)- which is the sinus membrane width measured
superior to each root apex.

Figure 3. A pie chart illustrates the reasons for extracting the maxillary molar in the
study.

Figure 4. The Total Vertical Height of the alveolar bone measured for individual roots
before and after extraction. Each point designates the value for the root of an
individual tooth. The horizontal lines and the corresponding orange box denote the
mean values (mm) of the pre-and post-operative total vertical height.

Figure 5. The changes to total vertical height (VHC), alveolar crest height (CHC) and
sinus floor (SC) measured for individual roots for pre- and post-molar extraction.
Each point designates the value for the root of an individual tooth. The horizontal
black lines designate the mean values and orange lines denote median values (mm).
The yellow and the orange boxes represent the mean and the median values for three
roots.

Figure 6. The cumulative percentage of sites showing the total Vertical Height
Change (VHC) detected after extracting maxillary molars for individual roots within
the population analyzed.

Figure 7. The cumulative percentage of sites showing the alveolar Crest Height
Change (CHC) detected after extracting maxillary molars for individual roots within
the population analyzed.

Figure 8. The cumulative percentage of sites showing the Sinus Floor Change
(SC) detected after extracting maxillary molars for individual roots within the
population analyzed.

Figure 9. A scatter plot showing the relationship between Sinus Floor Change (SC) and
alveolar Crest Height Change( CHC) after extracting maxillary molars for individual roots.
7
Figure 10. A scatter plot showing the relationship between Sinus Floor Change (SC)
after extraction of maxillary molars and the inclination of each root to the sinus floor.

Figure 11. A scatter plot showing the relationship between Sinus Floor Change (SC)
after extraction of maxillary molars and the width of each root within 2mm of the
apex.

Figure 12. A scatter plot showing the relationship between Sinus Floor Change (SC)
after extraction of maxillary molars and the distance of each root apex to the sinus
floor (mm) .

Figure 13. A scatter plot showing the relationship between Sinus Floor Change (SC)
after extraction of maxillary molars and the diameter of periapical lesions (mm).

Figure 14. A scatter plot showing the relationship between Sinus Floor Change (SC)
after extraction of maxillary molars and the thickness of the maxillary sinus
membrane (mm) .

Figure 15. A scatter plot showing the relationship between healing time (months)
after extraction of maxillary molars and Sinus Floor Change (SC).

Figure 16. A scatter plot showing the relationship between healing time (months)
after extraction of maxillary molars and alveolar Crest Height Change (CHC).

Figure 17. A scatter plot showing the relationship between age (years) of patient and
Sinus Floor Change (SC) after the extraction of maxillary molars.

Figure 18. A scatter plot showing the relationship between age (years) of patient and
alveolar Crest Height Change (CHC) after the extraction of maxillary molars.

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Abstract

Introduction
Maxillary sinus pneumatization has been proposed to occur after maxillary molar extractions.
Dimensional changes occurring at the alveolar crest after extraction have been extensively studied.
Maxillary sinus pneumatization and its possible relationship with maxillary molar extraction has
not been investigated using CBCT imaging modality. The aim of this retrospective radiographic
study was to investigate post-extraction spatial and dimensional changes in the maxillary sinus floor
and alveolar ridge crest in extracted molar sites managed with ridge preservation using Anorganic
Bovine Bone Minerals (ABBM).

Materials and Methods
23 pre-and post-operative CBCT images of 23 patients who had maxillary molar extraction were
analyzed using Simplant 17.0 software. Pre-and post-operative CBCT images were oriented and
aligned by utilizing co-incident reference lines and then superimposed subsequently. Linear
measurements were then calculated for the mesiobuccal (MB), distobuccal (DB) and palatal (P)
roots for the height of alveolar crest, the distance from the reference line to the maxillary sinus
floor, and the distance from the reference line to the alveolar ridge. As a result, changes in the total
vertical height of the alveolar crest, to the location of the alveolar crest, and to the maxillary sinus
floor were obtained. Root anatomical factors including root inclination, root width at 2 mm from
the radiographic apex, periapical lesion diameter and sinus membrane thickening were also
investigated in relation to post-extraction sinus floor change. Statistical analysis was done using
SPSS software. Paired-sample t-tests and Pearson’s correlations were used. Results were reported
as means and standard deviations. Significance was sought at p = 0.05.

Results
The results revealed a statistical significant difference (p<0.05) between the mean pre-extraction
and post-extraction values for the total vertical height, sinus floor and alveolar crest. The mean
changes from pre-extraction to post-extraction were calculated. The mean for all three roots for the
Vertical Height Change (VHC) of the alveolar crest = -1.44 + 1.53 mm. This change was related to
the Crest Height Change (CHC) having a mean = -0.71+1.51 mm whereas the mean Sinus Floor
Change (SC) = 0.54 + 0.26 mm for all three roots.
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No statistically significant correlation was found between any root anatomical factors and sinus
floor change. No statistically significant correlation was found between sinus floor change and
vertical alveolar crest height change or between alveolar crest height change and sinus floor change
for MB, DB and P roots at the p > 0.05 level. There was however significant correlation between
CHC and VHC for each root (p < 0.05).

Conclusions
Within the limitation of the study, the result of this retrospective analysis demonstrated minimal
linear dimensional changes in marginal bone height as well as maxillary sinus floor following
maxillary molar extraction and ridge preservation grafting with Anorganic Bovine Bone Minerals
(ABBM). The results also demonstrated that root anatomical factors did not seem to significantly
affect sinus floor change. This study has important clinical implication suggesting that maxillary
molar extraction managed by ridge preservation can lead to stable alveolar crest outcomes. The
relative effect of ridge preservation on sinus floor and alveolar crest should be further
experimentally substantiated in future randomized control clinical trials which should also include
a non-grafted control group.

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1. Introduction
Alveolar ridge resorption occurs after tooth extraction. Following maxillary molar extraction,
this resorption is believed to be bi-directional and was found to take place at the alveolar crest
in an apical direction and at the floor of the maxillary sinus coronally towards the alveolar
crest.
Changes in the alveolar ridge crest have been shown to occur during the remodeling phase of
the healing process of extraction socket and have been well documented in the literature.
Studies of canine and premolar models in dogs (Araujo & Lindhe 2005) have demonstrated
marked dimensional changes of the alveolar ridge occurred in the first 2–3 months post-
extraction. This reduction was seen to be histologically accompanied with osteoclasts present in
lacunae in the buccal and the lingual plates with a relatively enhanced osteoclastic activity
observed on the buccal plate. Schropp et al. 2003 in their reviews of human studies have
concluded that a substantial horizontal ridge reduction accounted for 50 % of the original
alveolar ridge width occurred within the first 12 months where two thirds of the reduction took
place during the first 3 months. In addition to the horizontal resorption, vertical resorption of the
alveolar ridge seems to be inevitable but to a lesser extent. The alveolar ridge undergoes a mean
vertical reduction in height of 1.24 mm within 6 months after tooth extraction. (Hammerle &
Araujo 2012). Human re-entry studies have shown a marked horizontal resorption of 29-63%
and a vertical resorption of 11–22% after 6 months following tooth extraction. These studies
demonstrated initial rapid volumetric reduction during the first 3–6 months followed by a
gradual reduction in the overall dimension thereafter (Wah Lay Tan et al. 2012).

The periodontium is an important structure which supports the tooth and was found to be
affected by changes the tooth may undergoes such as eruption and extraction (Pietrokovski &
Massler 1967). Following teeth extraction, the periodontium undergoes atrophy (Schropp et
al.2003) with a complete loss of attachment apparatus including the periodontal ligament and its
Sharpey’s fibers insertions in cementum and bone (Araujo & Lindhe 2005). The quantitative
(thickness) and the anatomical (composition) variations within the alveolar socket have also
shown to contribute to the magnitude of alveolar ridge resorption (Araujo et al. 2005). The
buccal plate is solely made of bundle bone whereas the oral plate contains both bundle and a
thicker compact bone. Chappuis et al. 2013 showed that the pre-extraction thickness of the
buccal plate was the most important determining factor in horizontal dimension loss. This has
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been further elicited that greater alveolar resorption took place in the buccal plate (solely bundle
bone) when compared to the thicker oral (Chappuis et al. 2013).

Ridge preservation is a procedure proposed to preserve the volume of alveolar ridge present at
the time of tooth extraction via the application of various biomaterials. Several studies have
utilized different techniques included the use of different bone graft materials and occlusive
membranes. Hammerle et al. 2012 have shown that the incorporation of bone biomaterials (Bio-
Oss) into fresh extraction sockets is a suitable technique for socket dimensional preservation.
Cardaropoli et al. 2014 concluded that application of Anorganic Bovine Bone Minerals (ABBM)
and porcine collagen membrane in fresh extracted molar and premolar sockets can considerably
limit the amount of horizontal bone resorption compared to tooth extraction alone irrespective to
thickness of the buccal plate. In an experimental dog study describing the efficacy of ridge
preservation with Bio-Oss in fresh extraction sockets, Fickl et al. 2008 found that the
incorporation of Bio-Oss bone material and collagen membrane can limit but do not entirely
prevent post-extraction contour shrinkage. Thus, ridge preservation of fresh extraction sockets
seems to limit the reduction of alveolar crest dimensional change but does not stop the process.
In a 6 months’ experimental canine study in dogs, Araujo & Lindhe 2009 compared the
dimensional changes of alveolar ridge following tooth extraction and Bio-Oss collagen grafting
with non-grafted control group. Their histological and histomorphometrical analysis showed that
the amount of volumetric reduction of the crestal portion of the socket in the non-grafted sites
was three times greater compared to grafted sites. The dynamics of incorporating Bio-Oss
collagen in extraction socket when attempting to counteract volumetric shrinkage was further
examined and confirmed by the same group in another experimental study in dogs (Araujo &
Lindhe 2010). Human studies have shown that the incorporation of (ABBM) can maintain the
alveolar ridge height through the formation of new bone within well integrated and virtually
intact Bio-Oss graft granules (Araujo et al 2015). The kinetics of crestal remodeling following
unassisted healing tooth extraction in canine model has been estimated to be 0.21 to 0.28 mm
per week. Comparatively, following extraction and ridge preservation with (ABBM), the rate of
crestal bone loss was found to be between 0.003 to 0.13 mm per week (Ryu, et al. 2015). Three-
dimensional CBCT analysis in human as well as in non-human primate models have indicated
that the volumetric changes mainly occur at the crestal 3-6 mm of the alveolar bone. Thus, ridge
preservation with (ABBM) was found to be correlated with reducing the magnitude of alveolar
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bone volumetric changes at crestal region (Abdelhamid et al. 2015, Omran et al. 2015).

Maxillary sinus pneumatization is a normal physiological process that is essential to increase the
sinus volume. This process occurs after birth to the age of 20 when the pneumatization process
is almost completed. By this time, the maxillary sinus floor becomes 5 mm inferior to the nasal
floor. (Shea, J.J 1936, Thomas et al. 1989, Kanda, S 1992, Maresh, M 1940, Nowak, R 1975,
Scuderi, A.J 1993, Misch, C.E 1999, Peterson, L.J 1993, Ritter, F.N 1978).

The etiology of the progressive maxillary sinus is poorly understood. Wehrbein, H & Diedrich,
P 1992 justified this phenomenon because of the accelerated osteoclastic activity in the cortical
walls of the sinus and its inferior osteoid layers. Sharan et al. 2008 reported that pneumatization
of the maxillary sinus occurs in response to different local and general factors. These factors
were genetics, the mechanical drive of the mucous membrane of the nose, the craniofacial
configuration, the alveolar bone density, growth hormones, sinus air pressure, sinus surgery and
teeth extraction.

Maxillary sinus pneumatization after extractions in the posterior maxilla has been termed as the
“Fourth Expansion Phenomenon of The Maxillary Sinus” and has been explained as a type of
disuse atrophy (Misch 1999, Wehrbein, H & Diedrich, P 1992). This atrophy is thought to be
the result of decreased functional forces on the alveolar bone following tooth extraction causing
a shift in the remodeling process toward bone resorption. This eventually results in an increase
in the maxillary sinus volume at the expense of the edentulous alveolar area.

The effect of ridge preservation in reducing maxillary sinus pneumatization is currently unknown.
If ridge preservation is found to minimize sinus pneumatization and reduce bone resorption at the
apical region of extracted molar sockets, it may therefore reduce the need for sinus augmentation
procedures prior to implant placement. As previously mentioned, significant data are available
regarding the dimensional changes at crestal portion of the alveolar ridge. In contrast, post-
extraction alveolar ridge atrophy that may take place at the apical regions of maxillary molar
extraction sockets and its potential relationship with maxillary sinus pneumatization has not been
investigated.

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Therefore, the aim of this study is to investigate the association between tooth extraction and
ridge preservation using Anorganic Bovine Bone Minerals (ABBM) and the degree of maxillary
sinus pneumatization while defining specific risk factors that modulate these volumetric changes.
The association between ridge preservation and crestal as well as apical alveolar ridge resorption
and sinus pneumatization in single extraction of maxillary molars will also be studied.

The null hypotheses are as follow:
Null hypothesis 1: following extraction of maxillary molars and ridge preservation grafting with
ABBM, there are no significant changes to either the maxillary sinus floor or alveolar ridge crest
positions when comparing pre- and post-op values.
Null hypothesis 2: post-extraction maxillary sinus floor change is not related to pre-extraction
root anatomical parameters such as root inclination, root width, root apex to sinus distance,
presence of periapical lesions and sinus membrane thickening.
Null hypothesis 3: post-extraction sinus floor changes are not correlated with alveolar height
changes following maxillary molar extraction managed with ridge preservation.

2. Materials and Methods
The study was conducted in the Advanced Periodontology Department of Herman Ostrow School
of Dentistry of the University of Southern California. The protocol was approved by the
Institutional Review Board (IRB) allowing access to patients records and radiographic images.
The recruitment of patients for data screening and analysis included all patients who met the
inclusion criteria and who have been treated in the Advanced Periodontology Department of the
school and in the private practice of one practitioner (H.Z). All patients were initially referred for
CBCT scans for diagnosis and treatment planning purposes including teeth extractions, dental
implants and other restorative or endodontic reasons.
The initial screening yielded a total of 800 patients needed extractions of maxillary molars and
bone grafting (ABBM) having pre-and post-extraction CBCT images. After meeting the inclusion
and exclusion criteria, the final screening identified 23 patients and 23 scans whom their DICOM
files were obtained from the imaging facility of (H.Z) private practice. The final DICOM files
were then uploaded into Simplant Pro 17.0 software (Dentsply Implants, Waldham, MA, USA)
for linear measurements, calculation and data analysis.
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Inclusion criteria:

Adult patients aged 18-90 years old who had maxillary molar extractions.
Ridge preservation with Bio-Oss following maxillary molar extractions.
The availability of diagnostic pre-and post-extraction CBCT images.
Exclusion criteria:
Third molar extractions.
History of sinus or other dento-alveolar surgery at the extraction site.

Pre-and post-extraction CBCT images were carefully oriented and then superimposed to allow for
measurements accuracy. Image superimpositions were done manually by creating screenshots for
each of the steps below for each pre- and post-operative CBCT image.
a) CBCT image orientation:
Pre-operative CBCT images were orientated in the coronal, axial, sagittal and frontal views so
that the Frankfort and axial planes were horizontal and the frontal view was symmetrical. Post-
operative CBCTs were then orientated to match the pre-operative scans.
b) Creation of a panoramic curve:
The creation of the panoramic curve was done by drawing a line passing through the central
fossa of the teeth at the most coronal level of the alveolar crest for each pre- and post-operative
image. This was done meticulously to ensure both images panoramic curves have identical
representation. Once the panoramic curves were matched, final panoramic views were obtained
and post-operative panoramic views were then screenshot and copied into a keynote
presentation for superimposition and accuracy check. In cases of panoramic curves
superimposition error, the pre- and post-operative CBCT were re-orientated and new
panoramic curves were drawn until both images are superimposed precisely.
c) Co-incident reference line (Red line: Figures 1.A):
A reproducible co-incident reference line was drawn on both the pre- and post- operative
CBCT scans in the panoramic view using multiple fixed references points such as cusp tips of
teeth.
15
d) Referencing of the extracted maxillary molar tooth (Figure 1.A):
This was done on the pre-operative scans to accurately locate the extracted tooth site on the
subsequent post-operative CBCT image.
On the pre- operative CBCT image (Panoramic view), the width of the tooth to be extracted was
measured from fixed landmarks such as contact points. Each root (mesiobuccal, distobuccal,
and palatal) was then identified on the axial and the sagittal views. Once identified, a vertical
line was drawn (on the Panoramic view) bisecting each root apex and the reference line. The
distance from the fixed width- reference points and the long axis of each root was then
measured. A second point of reference (per root) was done on the coronal view. This involved
drawing a line bisecting the long axis of the root (from the root apex) and measuring the
distance (the same coronal view) to the previously obtained sagittal bisecting line. Screenshot
images of each root in both the panoramic and the sagittal views were transferred into Keynote
presentation for later superimposition.
On the post-operative CBCT image, the site of the extracted tooth and the coincident reference
lines were identified by reproducing both pre-operative panoramic and coronal view reference
measurements (as described above). Screenshot images were taken for the post- operative root
sites (MB, DB and P) and superimposed on the pre-operative sites for accuracy matching.

Linear measurements:
Root Anatomical Parameters (measured from pre-operative CBCT scans only, Figure 2):

Root Inclination (coronal view; Figure 2):
This was measured as the angle internal angle formed from two bisecting lines, a first line
drawn through the apex and down the long axis of the root and a second horizontal line
drawn through the lowest bony point of maxillary sinus floor.

Root width (coronal view; Figure 2):
Measurement of root width was done by first denoting the location of each root on the axial
view. Once the correct locations were identified, the width was measured at 2 mm coronal to
root apex.

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Root apex-to-sinus floor distance (coronal view; Figure 2):
Measured as the linear distance from the root apex to most inferior point of cortical border of
the sinus floor.
Periapical area diameter (coronal view; Figure 2):
In cases where periapical radiolucency was evident, the diameter of the periapical lesion was
calculated by measuring the widest distance of the radiolucent area.

Sinus membrane thickening (coronal view; Figure 2):
Sinus membrane thickening (mm) was measured by calculating the distance from the highest
thickened point of the sinus to the most inferior point of the sinus floor at the corresponding
mid-root apex.

Mean inter-radicular distance (coronal view; Figure 2):
The mean inter-radicular distance was calculated in the axial view by locating the first point
visible of the apices of each root and then drawing a line connecting all apices. The sum of
these measurements was then divided by a factor of 3 to obtain the total mean inter-radicular
distance.

Sinus and bone crest parameters (coronal view; Figure 1.B):

The quantification of the changes in the pre- and post- operative bone crest and sinus floor was
done by first establishing three horizontal lines drawn in the cross-sectional view per root in
CBCT images. The distance between these lines were then measured, and the difference
between these measurements were calculated pre-and post-operatively.

Horizontal Lines on pre- operative CBCT Scans (Figure 1.B):

The following horizontal lines were drawn for each root on the pre- operative CBCT scans on the
coronal view:
Co-incident reference (red) line.
Pre- operative marginal bone level (green line) drawn at the most coronal point of the
alveolar bone level corresponding to the long axis of the root.
17
Pre- operative maxillary sinus floor level (light blue line) drawn at the most coronal point
of the bony maxillary sinus floor level corresponding to the long axis of the root.

Distances measured on pre- operative CBCT Scans (coronal view; Figure 1.B):

SF1: measured from pre-operative reference (red) line to pre- operative sinus floor (light
blue) line.
MBL1: measured from pre- operative marginal bone level (green) line to pre- operative
sinus floor (light blue) line.
AC1: measured from reference (red) to pre-operative marginal bone level (green) line.

Horizontal lines on Post- operative CBCT Scans (coronal view; Figure 1.B):

Co-incident reference (red).
Post- operative marginal bone level (green line) drawn at the most coronal point of the
alveolar bone level corresponding to the long axis of the root.
Post- operative sinus floor level (light blue line) drawn at the most coronal point of the
bony maxillary sinus floor level corresponding to the long axis of the root.
Distances measured on Post-operative CBCT Scans (coronal view; figure 1.B):

SF2: measured from post-operative reference (red) line to post -op sinus floor (light
blue) line.
MBL2: measured from post- operative marginal bone level (green) line to post- op
sinus floor (blue) line.
AC2: measured from pre- operative reference (red) line to post- operative marginal
bone level (green) line.

Sinus floor and alveolar bone height changes:

The following linear changes were calculated from the pre- and post-operative distances:
SC (Sinus Change): calculated by subtracting SF2 from SF1;
SC = SF1-SF2.
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This measurement (mm) quantifies the change in the position of the sinus floor from pre-to post extraction.

VHC (Vertical Height Change): calculated by subtracting MBL2 fromMBL1;
VHC = MBL1-MBL2.
The measurement was done to quantify the total vertical height changes from pre- to post
extraction.
The negative sign of the change indicates the that the location of alveolar crest has moved
further apically following extraction and ridge preservation.

CHC (Crest Height Change): calculated by subtracting AC2 from AC1;
CHC = AC1 – AC2
This measurement (mm) indicates the change in the location of the alveolar crest from Pre- to
Post-extraction. The negative sign of the change indicates the that the location of alveolar crest
has moved further apically following extraction and ridge preservation.

Statistical analysis
Descriptive statistical analysis was carried out using SPSS (Version 24, IBM Corporation, New
York, USA). The pre-extraction and post-extraction measurements were compared using paired-
sample t-tests and independent sample t-tests were utilized for inter-group comparisons.
Pearson ’s correlation was used to assess the association between the parameters and the outcome
measures. Results were reported as means and standard deviations. Significance was sought at
the p = 0.05 level.

3. Results

Table 1 shows the clinical characteristics of patients and their teeth included in this study. A total of
23 patients met the inclusion and exclusion criteria. The mean age was 60.34 + 14 years old. There
were 10 males and 13 female patients, 19 were non-smokers and 4 were smokers.
Patients had positive history for various medical conditions including: 1 patient had
hypothyroidism, 2 patients had history of cancer (melanoma and leukemia), 6 patients had allergies
(penicillin, codeine, betadine and latex allergy), 7 patients were diagnosed with arthritis
(osteoarthritis and rheumatoid arthritis), 8 with type II diabetes mellitus (under glycemic control).
Each patient contributed only with 1 tooth for the analysis. First (n=17) and second (n=6) maxillary
19
molars were included. The mean healing time from extraction to the time of post- extraction CBCT
scan was 8.60 + 6.35 months, with a range from 3 to 27.24 months. The reasons for extraction of the
maxillary molar teeth in the study (Table 1 and Figure 3) were: dental caries (8/23), advanced
periodontitis (3/23) and endodontic failure (12/23).

Comparison of CBCT imaging at pre- and post-extraction periods (Table 2) showed statistically
significant difference in total vertical alveolar height in the region of (MB) mesiobuccal (pre-op:
13.10+ 6.82 mm; post-op: 11.91 + 6.36 mm; p < 0.001), (DB) distobuccal (pre-op: 11.73 + 2.70
mm; post-op:10.02+ 3.18 mm; p < 0.001), and (P) palatal (pre-op: 12.95+ 5.44 mm; post-op: 11.54
+ 5.86mm; p <0.001) roots. Collectively, the mean vertical alveolar height for all three roots were
12.59 +5.23 mm at pre-op and 11.16 + 5.31mm at post-op, the difference being statistically
significant (p < 0.001).

The Vertical Height Change (VHC) which is the change in the total vertical height from pre- to
post-extraction (Table 3 and Figure 5) had a mean of -1.16 + 1.69, -1.72+ 1.68 and -1.43 +
2.04 mm for the (MB) mesiobuccal , (DB) distobuccal and (P) palatal roots respectively. The
mean (VHC) for all three roots was -1.44 +1.53 mm. The range of VHC included gain
(denoted as positive values) of 1.57, 0.81, and 1.79 mm for the (MB) mesiobuccal, (DB)
distobuccal and (P) palatal roots, respectively. On the other side of the range, loss (denoted as
negative values) of -5.22,-5.64 and -6.74 mm for (MB) mesiobuccal, (DB) distobuccal and (P)
palatal roots respectively were noted. The median (VHC) were -0.98, -1.11 and -1.21 mm for
the (MB) mesiobuccal , (DB) distobuccal and (P) palatal roots respectively.
In examining the position of the sinus floor (SC) in pre- and post-extraction CBCT images (Table
2-3 and Figure 5), there was a small, albeit, statistically significant (p< 0.001) change in areas
directly superior to (MB) mesiobuccal (0.61 + 0.46 mm), (DB) distobuccal (0.57 + 0.34 mm) and
(P) palatal (0.45 + 0.46 mm) roots respectively. Altogether, for the three roots, the mean sinus
floor change (SC) was 0.54 mm +0.26 in inferior direction. The median values were 0.47, 0.54,
0.26 mm in the regions of (MB) mesiobuccal , (DB) distobuccal and (P) palatal roots respectively.
These measured changes were in inferior direction.

The mean changes of the alveolar crest (CHC) (Table 3 and figure 5) were -0.52+ 1.49, -1.16 +
1.82 and -0.47 + 1.80 mm in the regions of the (MB) mesiobuccal , (DB) distobuccal and (P)
20
palatal roots respectively. The mean change for all three roots was -0.71 + 1.51 mm in apical
direction (p< 0.01). The range of alveolar crest height changes included loss (denoted as negative
values) of -3.80, -4.78, and -6.28 mm for the alveolar crest in the regions of (MB) mesiobuccal ,
(DB) distobuccal and (P) palatal roots respectively. On the other end of the spectrum, gain (denoted
as positive values) of 2.98, 2.38 and 2.13 mm in the region of (MB) mesiobuccal , (DB) distobuccal
and (P) palatal roots were noted, respectively. The median alveolar crest height changes were -0.16,
-1.67 and - 0.45 mm for the (MB) mesiobuccal , (DB) distobuccal and (P) palatal roots
respectively.

The cumulative percentage of sites exhibiting changes in total vertical alveolar bone height (VHC)
(Figure 6), alveolar crest position (CHC) (Figure 7) and sinus floor position (SC) (Figure 8) are
shown. These data provide additional insights into the distribution of changes of individual sites
examined.
The cumulative percentage of sites examined for their total vertical height changes (VHC) showed
that 50% of sites exhibited only minor changes in the range of approximately 1 mm. Within this
group, 25% of total sites, gained up to 1mm (positive values on the Y-axis) and another 25% lost
up to 1mm of bone (negative values on the Y-axis). The other 50% of cases, lost between 1.5 to
6.7 mm of vertical height, during the healing period.
Examination of the cumulative percentage of alveolar crest height position (CHC), showed that 50%
of sites exhibited either no change or a gain of up to 2 mm in their alveolar crest (positive values on
the Y-axis). The bottom 30% of cases lost between 1 to 4.8 mm in their alveolar crest.

Assessment of the sinus floor position (SC) revealed that 50% of sites had a change in the sinus floor
position of 0.43 mm or less. The other 50% of cases exhibited changes in the sinus floor which
ranged from 0.43 to 1.30 mm. The changes in the sinus floor position were all in an inferior
direction.
To better understand factors that are associated with changes in the sinus floor position (SC), a
series of correlation analyses were performed between sinus floor position changes and
demographic, anatomic, temporal or spatial changes. To that end, correlations between sinus
floor position changes (SC) and alveolar crest position(CHC) (Figure 9), root inclination with
sinus floor (Figure 10), root width (Figure 11), distance between root apex to sinus floor (Figure
21
12), periapical lesion diameter (Figure 13), sinus membrane thickness (Figure 14) and patient
age were analyzed. None of these analyses resulted in statistically significant correlations.
However, changes in the crest height position were statistically significantly correlated to total
vertical height changes (R= 0.84, 0.73 and 0.76; p<0.001) for (MB) ) mesiobuccal, (DB)
distobuccal and (P) palatal roots, respectively (Table 4).
The healing period from tooth extraction to the post-op CBCT imaging date (months) was
found to be statistically correlated with the total vertical height change (VHC) (Table 5) in the
region of (MB) mesiobuccal (R= -0.41, p=0.05), (DB) distobucaal (R= -0.47, p = 0.03) and (P)
palatal roots (R= -0.48, p= 0.02). When considering the mean of the three roots, the healing
time was found to be statistically correlated with total vertical height change (VHC) (R= -0.53,
p =0.01). The alveolar crest position changes (CHC) were also found to be statistically
significantly correlated with the healing time in the region of (MB) mesiobuccal (R= -0.46, p =
0.02) and (P) palatal roots (R= -0.53, p = 0.01). The mean changes of the alveolar crest (CHC)
for all three roots was also correlated with the healing time (R= -0.50, p = 0.01) (Table 5 and
figure 16). No statistically significant correlation was found between the sinus floor position
change and the healing time at any root

4. Discussion
Maxillary sinus pneumatization and alveolar crest alterations are important biological events
that require careful clinical and radiographic assessment due to the major impact they could
have on maxillary dental implant rehabilitation. It has been widely believed that there is
significant pneumatization of the sinus following extraction of maxillary molars (Rosen &
Sarnat 1955, Weherbien & Dedrich et al. 1992, Harorh & Bocutoglu 1995, Ohba et al.2001).
Despite this dogmatic belief, there has been very little evidence in support of this relationship.

In a recent study, Hameed, et al. 2018 have reported that maxillary sinus floor only undergoes
very small post-extraction positional changes (0.47mm + 0.32). On the other hand, it was
observed that following spontaneous healing after maxillary molar extraction, a significant
alveolar crest remodeling takes place (3.07 mm + 2.53). The question addressed in the present
study was whether sinus floor or alveolar crest position changes are influenced by alveolar ridge
preservation. To the best of our knowledge, this is the first report utilizing CBCT images to
compare and evaluate the magnitude of post-extraction maxillary sinus floor pneumatization
22
and alveolar crest dimensional changes in sites treated with alveolar ridge preservation (ARP).

The results of the present study showed that the post-extraction and alveolar ridge preservation
(ARP) relative changes in the position of the maxillary sinus floor were small (mean=0.54 mm +
0.26) but statistically significant (p<0.001). The magnitude of post-extraction change in the
sinus floor obtained in the current study was not in agreement with the values reported in
previous studies. In a twelve month, radiographic volumetric comparative study in dog, Rosen &
Sarnat 1955 found that following the extraction of maxillary posterior teeth, the sinus exhibited
an increase in volume with a range between 3 to 27 % compared to the contralateral un-operated
side. However, the author has concluded that this study was conducted only to highlight the
volumetric change phenomena in dog and may not necessarily be applicable for human. The
anatomy and the intimate relationship of the roots of the maxillary molars to the sinus in dog are
different than in human. Maxillary molar roots in dogs do not invaginate in the sinus and are
usually confined within the alveolar ridge housing, therefore extraction may increase the risk of
trauma contributing to the enlargement of the sinus volume. Harorh & Bocutoglu 1995 have
compared the vertical height and width of maxillary sinuses using “Waters’ View” radiographs.
A statistical significant difference was found in the height of the maxillary sinus between dentate
and edentulous cases in favor of the edentulous group. Moreover, Ohba et al.2001 have found in
a panoramic transparent-paper tracing study that the maxillary sinus floors of edentulous patients
were significantly inferiorly positioned compared with those of dentate subjects. However, in
both studies, the pre-and post-extraction sites of the same subject were not investigated. Tracing
superimposition of panoramic radiographs (Orthopantomogram) of pre- and post-extraction sites
according to the study conducted by Weherbien & Dedrich et al. 1992 have shown that the sinus
does inferiorly pneumatize with a magnitude up to of 30 % from baseline value. They also found
that the degree of pneumatization was significantly correlated with molar teeth compared with
premolar teeth. This study has a major shortcoming. Image distortions when comparing pre- and
post-extraction sites in panoramic views is crucial and may result in compromising the final
accuracy measurements. Thus, the use of referencing lines utilizing different anatomical
landmarks within the oral cavity has been proposed by Sharan and colleagues 2008 to improve
the accuracy using panoramic radiographs. In their analysis, a progressive inferior migration of
the sinus floor was detected and exhibited a magnitude of 2.18 mm for dentate patients and 1.83
mm for edentulous patients when comparing pre- and post-extractions values of the sinus floor
23
over a healing period ranging between 6-53 months.

The use of CBCT scan images is well suited for imaging the craniofacial region. It provides
clear and accurate view with less distortions that are usually found in panoramic radiographs.
Currently, the only study that has examined the volumetric changes of the sinus in a
retrospective design was conducted by Arijii & colleagues 1994. Their data have shown that the
change of the sinus volume was statistically correlated with age only until an individual reaches
the age of 20. They have also found no statistical correlation with maxillary volume changes and
the presence or absence of posterior maxillary teeth. However, this study looked at volume of
the maxillary sinus and not specifically post-extraction changes in the sinus floor position.

The reasons cited for progressive post-extraction sinus pneumatization have not been clearly
explained. It has been hypothesized that following extraction of maxillary molar in adults, the
alveolar ridge at the extraction site undergoes disuse atrophy where decreased functional stresses
transmitted into the alveolar ridge causes a shift in the remodeling process and subsequently
increases in the resorption rate driven by high osteoclastic activity (Wehrbein and colleagues
1992). The magnitude of post-extraction resorption and the degree of sinus floor pneumatization
(Wehrbein and colleagues 1992) may be influenced by multiple factors. Maxillary posterior
teeth sometimes protrude in the maxillary sinus and their roots are usually surrounded by thin
cortical lining. It has been hypothesized that extraction may be accompanied by damage to this
thin cortical lining, allowing the sinus to expand inferiorly (Wehrbein and colleagues 1992).
Secondly, larger teeth with subsequent larger size residual defect after extraction requires a
longer healing time before complete closure of the socket, thus allowing the sinus to
progressively pneumatizes (Wehrbein and colleagues 1992). Despite these hypotheses, very little
concrete data have been offered in their support. Therefore, the present study examined the
validity of some of these hypotheses.

With regards to root anatomical factors, we have found that none were correlated with sinus
change. Specifically, the present data observed that the proximity of the roots to the sinus floor
was not correlated with the degree of sinus floor position changes. Moreover, the present data
did not find any correlation between root apical dimensions and sinus floor position changes. It
has been found that the inclination of roots affects post extraction crestal bone resorption
24
(Araujo 2015). However, this doesn’t seem to be the case for sinus floor change.
Unlike scan data regarding post-extraction sinus floor changes, there are ample data examining
post-extraction alveolar crest changes. However, many studies examining post-extraction
dimensional changes have specifically excluded molars. Very limited data are available about
maxillary molar alveolar crest changes with or without alveolar ridge preservation. The result of
our study showed that after a mean follow-up of 8.6 months, alveolar crest underwent mean of -
0.71+1.51mm changes which was in agreement with the results reported in the literature. In a
RCT by Cardaropoli, D et al. 2012 evaluating the use of (ABBM) covered with porcine collagen
membrane following extraction molar and premolar teeth, a statistically significantly less
reduction in ridge width (1.04 ± 1.08 mm vs 4.48 ± 0.65 mm, p < 0.001) and height (0.46 ± 0.46
mm vs 1.54 ± 0.33 mm, p < 0.001) were found in grafted sockets compared with non-grafted
sockets. It has also been shown that after 4 months of healing, ridge preservation resulted in
horizontal ridge width reduction that was significantly limited to 0.71 mm and a vertical
reduction of 0.58 mm. The impact of socket grafting on crest dimension alterations in molar
teeth was further investigated by Barone et al. 2014. In their prospective RCT, two types of
socket preservation were performed on two groups of patients treated via either full-thickness
mucoperiosteal flap or flapless procedure using (ABBM). The result of their analysis showed
that when flapless ridge preservation approach was used, a statistical significant bucco-lingual
and bucco-vertical reductions were obtained accounted for 1.7 + 0.6 mm and 1.1 + 0.9 mm
respectively. Moreover, the efficacy of ARP and socket repair in maintaining alveolar crest
dimension in intact sockets and sockets with facial dehiscence has also been elicited in the
literature. In a quantitative 3D CBCT analysis, the application of SocketKAP
TM
+ABBM in
intact post-extraction sockets has shown to preserve a statistically significant greater percentage
of remaining mineralized tissue volume at the 0-3 mm zone of the alveolar ridge when compared
to the negative control group (75 Vs 32.6%, p< 0.05) during a healing period of 6 months
(Abdelhamid et al. 2016). Similarly, for extraction sockets with facial dehiscence, a statistically
significant difference of (76 Vs 37.5%, p< 0.05) favoring SocketKAP
TM
+ SocketKAGE
TM
+
ABBM treated group over the control was observed during a healing period of 6 months at the
crestal 0-3 mm zone (Abdelhamid et al. 2016). The systematic reviews and meta- analysis on
human studies which included molar extraction have shown that resorption of the alveolar ridge
cannot be totally stopped by ARP, while it still can be significantly prevented. ARP accounted
for a statistically significant (p<0.0001) mean reduction difference of 1.31-1.54 mm (95% CI:
25
0.30-2.31 mm) in the bucco-oral dimension and 0.91-1.21 mm (95% CI: 0.55-1.27 mm) in the
vertical dimension (p<0.0001) (Wilenbacher et al. 2016). When ARP was implemented and
compared with control unassisted healing groups, Macbeth and colleagues 2016 found that the
mean linear and volumetric difference was 0.74 mm (95% CI: 0.332-1.147mm) in the vertical
bone height and 1.2 mm (95% CI: 0.0374-2.433mm) in the bucco-oral dimension (p<0.0001).

Currently, there are no studies considered the impact of ridge preservation in preventing or
reducing the magnitude of sinus pneumatization following tooth extraction. The question of
whether crestal resorption is associated with apical resorption of the alveolar ridge also
remained unanswered. The current retrospective radiographic study did not find any correlation
between sinus floor change and change in total alveolar crest height post-extraction and ridge
preservation, indicating that the use of socket grafting did not prevent the inferior migration of
the maxillary sinus.

CBCT scans accuracy could affect the final precision of the results. Motion artifacts have been
shown to deteriorate the precision of CBCT image as they could destroy the isometric
representation of a tomographic image with a range between 1-4 mm from the actual
representation (Marmulla et al. 2006). Lascala et al. 2004 found that despite being neither
statistically nor clinically significant, the real measurements on human skulls were always
greater than those obtained from CBCTs. Inherited geometric errors of CBCT scan devices have
also shown to affect the mean absolute measurements and the final accuracy. Mischkowski et al.
2007 found that the average absolute percentage error (APE) for CBCT imaging on the Galileo
CBCT unit is 0.98%.
Human errors during CBCT scans orientation, superimposition, and detection could affect the
accuracy of the results. Previous studies examined intra-examiners reliability and
reproducibility of linear measurements of CBCT scans in mandibular jaw objects. The intra-
examiners reliability in CBCT has an overall absolute mean error of 0.40 mm with the
percentage of error exceed 1 mm to be 6.7% of the objects (Tomasi et al. 2011). In this study,
one examiner did all 23 CBCT image measurements. Each measurement was repeated three
times to ensure the accuracy of the final measurements. It is therefore possible to attribute the
change observed in the maxillary sinus position (0.54 mm + 0.26) to the error rate of CBCT
quantitative measurement.
26
There are several limitations in the current investigation. The first is that the sample size was
small, with only 23 teeth and patients with pre- and post- extraction CBCT images. It is
however, worthy to note that this sample size was found from 800 patients records that were
screened. The reason for this small sample size was since CBCT’s are not routinely taken in pre-
extraction cases to minimize radiation exposure.
The result of our study can safely reject the first null hypothesis, and accept the second and third
null hypotheses. We found there to be a significant change to the maxillary sinus floor position
of maxillary molars, as well as alveolar crest position, following maxillary molar extraction and
ridge preservation with Anorganic Bovine Bone Minerals. However, as the magnitude of this is
very small, it may be clinically insignificant. We also found that post extraction maxillary sinus
floor change was not correlated with pre-operative root anatomical parameters such as root apex
to sinus distance, root width, root inclination, presence of periapical lesions, and thickening of
the sinus membrane. Additionally, we found that post-extraction sinus floor changes were not
correlated with alveolar height changes.The significant findings of the present study coupled
with the clinical significance of the proposed hypothesis merit a prospective randomized
controlled clinical trial.

5. Conclusions
Within the limitation of the study, the result of this retrospective analysis demonstrated minimal
linear dimensional changes in marginal bone height, as well as maxillary sinus floor following
maxillary molar extraction and ridge preservation grafting with Anorganic Bovine Bone Minerals.
The results also demonstrated that root anatomical factors did not seem to significantly affect sinus
floor change. This study has important clinical implication, suggesting that maxillary molar tooth
extraction managed by ridge can lead to stable alveolar crest outcomes. The relative effect of ridge
preservation on sinus floor and alveolar crest dimensional changes should be experimentally
substantiated in a future randomized control clinical trial which will also include a non-grafted
control group.

27
6. Tables

Table 1

Parameter Value
Population (n) Subjects (n) 23
Teeth (n) 23
Mean Age (years) 60.34 + 14
Age range (years) 34-89
Male 10
Female 13
Sites Max right second molar 3
Max right first molar 11
Max left first molar 6

Max left second molar 3
Mean healing time of extraction
sites (months)
8.6 + 6.35

Healing Range (months) 3 – 27.24
Reason for extraction Caries 8

Endodontic lesion 12

Periodontal disease 3
Medical History Non-smokers 19
Smokers 4
Hypothyroidism 1
Cancer 2
Asthma 1
Anxiety and depression 3
Hypertension 7
Heart disease (Angina, heart
murmur, irregular heartbeat,
heart attack )
8
Allergy (Penicillin, codeine,
betadine, latex)
6
Arthritis (Rheumatoid arthritis,
osteoarthritis)
7
Diabetes mellitus II 8
Anemia 2

28
Table 2

*Negative values denote changes in apical direction.

Table 3

Height Changes (mm)

a) Vertical Height Change (VHC)

b) Crest Height Change (CHC)

c) Sinus Floor Change (SC)
Root MB DB P Mean of 3
roots
MB DB P Mean
of 3
roots
MB DB P Mean
of 3
roots
Mean -1.16
+
1.69
-1.72
+
1.68
-1.43
+
2.04
-1.44
+
1.53
-0.52
+
1.49
-1.16
+
1.82
-0.47
+
1.80
-0.71
+
1.51
0.61
+
0.46
0.57
+
0.34
0.45
+
0.46
0.54
+
0.26
Min. -5.22 -5.64 -6.74 -5.04 -3.80 -4.78 -6.28 -4.41 0.00 0.01 0.00 0.12
Max. 1.57 0.81 1.79 0.60 2.98 2.38 2.13 2.50 1.46 1.26 1.68 1.26
Median -0.98 -1.11 -1.21 -1.43 -0.16 -1.67 -0.45 -0.62 0.47 0.54 0.26 0.50

*Negative values denote changes in apical direction.

a) Reference line to
Sinus floor

b) Total vertical
alveolar bone height

c) Reference line to crest of
alveolar bone

Root

MB

DB

P

Mean of
3 roots

MB

DB

P

Mean of
3 roots

MB

DB

P

Mean of
3 roots

Mean Pre-

23.09

21.26

22.28

22.21

13.10

11.73

12.95

12.59

10.27

9.32

9.10

9.56
Op (mm) + + + + + + + + + + + +
6.32 2.90 5.26 5.02 6.82 2.70 5.44 5.23 3.21 1.90 2.09 2.36

Mean Post-

22.47

20.57

21.80

21.61

11.91

10.02

11.54

11.16

10.79

10.64

9.57

10.33
Op (mm) + + + + + + + + + + + +
6.22 3.04 5.25 5.00 6.36 3.18 5.86 5.31 3.21 2.67 2.60 2.85
Paired
sample
T test

6.22

5.17

5.29

10.13

3.30

4.92

3.30

4.47

-1.68

-3.26

-1.29

-2.39
Significance
p value

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.05

0.00

0.04

0.01
29
Table 4

CORRELATION
PEARSON ’S

SINUS FLOOR CHANGE (SC)

CREST HEIGHT CHANGE
(CHC)
Root MB DB P MB DB P

CREST
HEIGHT
CHANGE
(CHC)
MB R = 0.18
p = 0.40

DB R = 0.46
p = 0.20

P R = 0.17
p = 0.43

VERTICAL
HEIGHT
CHANGE
(VHC)
MB R = 0.17
p = 0.43
R = 0.84
p =0.00

DB R = 0.20
p = 0.35
R = 0.73
p = 0.00

P R = 0.01
p = 0.96
R = 0.76
p =0.00

30
Table 5

CORRELATION ROOT
PEARSON ’S

HEALING TIME
(MONTHS)

AGE (YEARS)

VERTICAL HEIGHT CHANGE
(VHC)
MB R = -0.41
p = 0.05
R = 0.13
p = 0.60
DB R =-0.47
p = 0.03
R = 0.06
p = 0.78
P R = -0.48
p = 0.02
R = 0.04
p = 0.84
3 roots R= -0.53
p = 0.01
R = 0.20
p = 0.85

SINUS FLOOR CHANGE (SC)
MB R = 0.08
p = 0.70
R = -0.23
p = 0.30
DB R = 0.07
p = 0.74
R = -0.19
p = 0.40
P R = 0.06
p = 0.80
R =-0.06
p = 0.80
3 roots R= 0.12
p = 0.10
R = -0.24
p = 0.76

CREST HEIGHT CHANGE
(CHC)
MB R = -0.46
p = 0.02
R = 0.14
p = 0.54
DB R = -0.34
p = 0.11
R = -0.20
p = 0.40
P R = -0.53
p = 0.01
R = -0.13
p = 0.57
3 roots R= -0.50
p = 0.01
R =-0.34
p = 0.48

31

Table 6

CORRELATION
PEARSON ’S

SINUS FLOOR CHANGE (SC)

Root parameter
Root MB DB P

Root Inclination
MB R = 0.29
p = 0.17

DB R = 0.36
p = 0.08

P R = -0.06
p = 0.77

Root Width
MB R = -0.22
p = 0.32

DB R = 0.10
p = 0.63

P R = -0.30
p = 0.18

Root apex to sinus
distance (mm)
MB R = 0.01
p = 0.97

DB R = 0.24
p = 0.25

P R = 0.13
p = 0.53
Mean Inter-
radicular
distance
R = 0.33
p = 0.12
R = 0.12
p = 0.57
R = 0.21
p = 0.34
Periapical
lesion
diameter
MB R =-0.05
p = 0.78

DB R = 0.34
p = 0.11

P R = 0.06
p = 0.76
Sinus membrane
thickness
MB R = -0.13
p = 0.54

DB R = -0.30
p = 0.16

P R =- 0.02
p = 0.91

32

7. Figures
Figure 1 A-B

33
Figure 2

Figure 3

34
Figure 4
35
Figure 5

36
Figure 6

Root Mean Median SD
MB -1.16 -0.98 +/-1.69
DB -1.72 -1.11 +/-1.68
P -1.43 -1.21 +/-2.04
Mean of 3 roots -1.44 -1.43 +/- 1.53

*Negative values denote changes in apical direction.

37
Figure7

Root Mean Median SD
MB -0.52 -0.16 +/-1.49
DB -1.16 -1.67 +/-1.82
P -0.47 -0.45 +/-1.80
Mean of 3 roots -0.71 -0.62 +/- 1.51

*Negative values denote changes in apical direction.

38
Figure 8

*Positive values denote changes in coronal direction.

Root Mean Median SD
MB 0.61 0.47 +/-0.46
DB 0.57 0.54 +/- 0.34
P 0.45 0.26 +/-0.46
Mean of 3 roots 0.54 0.50 +/- 0.26
39
Figure 9

Figure 10

40
Figure 11

Figure 12

41
Figure 13

Figure 14

42

Figure 15

Figure 16

43
Figure 17

Figure 18

44

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Creator Alwazan, Essa (author)

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

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 08/05/2018

Defense Date 07/29/2018

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

Tag alveolar crest,cbct,maxillary molar extraction,OAI-PMH Harvest,ridge preservation

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Alwazan, Essa (committee member)

Creator Email alwazan@usc.edu,haysoos.dr@hotmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c89-52582

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

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

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