Close
About
FAQ
Home
Collections
Login
USC Login
Register
0
Selected
Invert selection
Deselect all
Deselect all
Click here to refresh results
Click here to refresh results
USC
/
Digital Library
/
University of Southern California Dissertations and Theses
/
Prevalence of TMJ morphological changes and scoring system based on CBCT imaging
(USC Thesis Other)
Prevalence of TMJ morphological changes and scoring system based on CBCT imaging
PDF
Download
Share
Open document
Flip pages
Contact Us
Contact Us
Copy asset link
Request this asset
Transcript (if available)
Content
1
Prevalence of TMJ Morphological Changes and
Scoring System based on CBCT Imaging
Nehi Ogbevoen, DDS
May 2018
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)
2
Table of Contents
I. Abstract 4
II. Introduction 5
III. Literature Review 6
A. 2-Dimensional Imaging in Orthodontics 6
B. CBCT Imaging in Orthodontics 8
C. TMJ Specific Imaging 11
i. Conventional radiographs 12
ii. Ultrasound 13
iii. MRI 14
iv. Arthrography 15
v. CT/CBCT 16
D. TMJ and Relationship to Orthodontics 16
E. TMJ Normal Anatomy and Remodeling 18
i. Normal TMJ Anatomy 18
ii. Normal radiographic anatomy of the TMJ 20
iii. Temporomandibular disorders(TMD) 21
iv. TMJ remodeling and prevalence. 22
F. Current Classification for TMJ and TMJ Reporting 24
IV. Materials and Methods 24
Sample 24
Protocol for CBCT Image Acquisition 25
Protocol for CBCT Image Reconstruction 27
3
TMJ Morphology and Position Assessment 27
TMJ Morphology and Position Classification and Scoring System. 29
Statistical Analysis 29
V. Results 30
VI. Discussion 47
VII. Conclusion 51
VIII. References 53
4
I. Abstract
Background: The introduction of cone beam computed tomography (CBCT)
to the field of orthodontics has been a great tool for imaging of the
temporomandibular joint (TMJ). CBCT imaging eliminates many of the
disadvantages associated with previous modalities of imaging the TMJ. The
health of the TMJ should be assessed prior to beginning orthodontic treatment
as it can be a precursor to temporomandibular mandibular joint disorders.
There are only a few studies focused on the prevalence of various condylar
osseous changes and position. Additionally, there are currently no efficient or
effective ways to quantify the severity of changes in the TMJ.
Purpose: The purpose of this study is to further understand the prevalence of
the morphologic changes to the condyle and to establish a scoring system of
the morphological changes and position of the TMJ based on CBCT images to
quantify the changes.
Materials and Methods: The sample consisted of 100 patient CBCT images
from a single practitioner’s office in Santa Monica, CA. The condylar osseous
changes (flattening, erosion, osteophyte, sclerosis, and subchondral cyst) and
position were evaluated and recorded by the UCLA Radiology Department
and an USC 3
rd
Year Resident. Prevalence and descriptive statistics were
performed to test for significance and correlation to gender and anatomical
side.
Results: 58% of condyle showed no radiographic changes to morphology or
position of the joint. Changes observed: flattening (23%), posterior position of
5
condyle (15.5%), erosion (14.5%), sclerosis (8.5%), osteophyte (4.5%), and
subchondral cyst (3%). Only sclerosis and posterior position of the joint
occurred significantly more often in females as compared to males(p<.05). No
significant differences in changes to the joint between left and right condyles.
No significant correlation between condyle health score and age, side, or
gender.
Conclusion: 42% of condyles evaluated by CBCT imaging showed at least
one change in condylar morphology or position. The most prevalent changes
seen were flattening (23%) and posterior position of the condyle (15.5%). A
scoring system (scores from 0-11) to quantify changes and degree of severity
in the health of each condyle was developed. In our sample showed no
statistically significant association between a condyle’s health score and
gender, side, or age.
II. Introduction
Imaging the temporomandibular joint(TMJ) is a very important aspect in
the diagnosing and treatment planning of orthodontic patients
(Krishnamoorthy et al., 2013). The TMJ has a very important role in the
function of the masticatory system. Understanding the health and prognosis of
the joint can help a clinician make more educated decisions in regard to
treatment options for the patient.
Historically, a variety of imaging modalities have been used to image the
morphology of the TMJ. Options included panoramic x-rays, magnetic
resonance imaging(MRI), computed tomography (CT) scans, and
6
arthrography. Many of these options had inherent disadvantages to imaging
the TMJ such as overlapping of cranial structures and excessive radiation. A
more recent imaging modality, cone beam computed tomography (CBCT), has
gained popularity for imaging the TMJ due to many advantages not previously
present.
Previous studies have reported the prevalence of different morphological
changes in the TMJ such as flattening, erosion, sclerosis, osteophyte,
subchondral cyst, and joint position for various sample groups. Although it has
become easier to diagnosis these changes with CBCT imaging, it is still
difficult to classify the varying degrees of the change. Additionally, current
studies cannot be compared because there is an evident lack of agreement.
This lack of agreement can be due to many reasons including differences in
sample characteristics and differences in imaging protocols. Futhermore, no
one has developed a system to categorize and score the extent of changes
present in the TMJ.
The purpose of this study is to further understand the prevalence of
these morphologic changes to the condyle and to establish a scoring system of
the morphological changes and position of the TMJ based on CBCT images to
quantify the changes. This will allow efficient and effective communication in
regard to the findings and health of the joint.
III. Literature Review
A. 2-Dimensional Imaging in Orthodontics
7
One of the most important tasks in orthodontics is to properly diagnose
each patient and case. The diagnostic process needs to be comprehensive and
not limited to singular findings. More often than not, a case will have many
components that together become a complex situation. Orthodontic diagnosis
requires a broad overview of the patient’s situation and must take into
consideration both objective and subjective findings. The diagnostic process
includes both a clinical and radiographic examination. Currently, two-
dimensional (2D) digital imaging is the system of choice. The standard
diagnostic records routinely taken by most orthodontics practices are
panoramic and lateral cephalometric radiographs, dental models, intraoral
photographs, and extraoral photographs.
The 2D digital radiographs are used primarily to assess the skeletal and
dental relationship throughout the different phases of orthodontic treatment
including initial diagnosis, treatment planning, observation of growth and
development, progress of treatment, and final outcomes. A lateral
cephalometric radiograph is used primarily to assess the relationship of the
jaws to the cranial base and the relationship of the teeth to the jaw. A
panoramic radiograph is valuable for orthodontic evaluation at most ages
beyond the early mixed dentition years. With a panoramic radiograph the
clinician is able to have a better understanding of the broad picture and view
findings such as impacted teeth, supernumerary teeth, and pathological lesions
easier all while using less radiation than a FMX (Proffit, William R.
Contemporary Orthodontics. Mosby, 2013). In addition, when there is
8
evidence or suspicion of root resorption additional periapical radiographs are
needed.
Conventional orthodontic radiographic imaging provides a 2-D image
of a 3-D object. It is impossible with these images to visualize all the
dimensions of the structures within the skull. Additionally, with
superimposition of important structures in 2D images, precise intracranial
landmark identification is difficult and greatly alters the consistency and
reliability of the findings.
B. CBCT Imaging in Orthodontics
As in every other medical and dental specialty, accurate and reliable
diagnostic imaging is essential in the field of orthodontics for many reasons
including: detailed and comprehensive diagnosis and treatment planning, and
assessment of treatment progress and outcomes. As this demand has steadily
increased so has the utilization of CBCT imaging in orthodontics.
CBCT was initially designed to offset some of the limitations of
conventional CT scanning devices. CBCT has many advantages for
orthodontist over a conventional CT including: it is less expensive and
involves a smaller system. The x-ray beam is limited, scan time is rapid,
lower radiation dose is used, display modes are exclusive to dentofacial
imaging, and there are fewer imaging artifacts (Kapila and Nervina, 2015) .
CBCT technology utilizes a cone-shaped X-ray beam that is directed through
the patient and the remnant beam is captured on a flat two-dimensional (2D)
detector (Grauer et al., 2009). The X-ray sources and detector are able to
9
revolve about a patient’s head, and a sequence of 2D images are generated.
These 2D images are then converted into a 3D image using computer software.
The rapid movement of the X-ray tube and digital detector through 180
degrees, or more frequently 360 degrees, produces essentially instantaneous
and precise 2D and 3D radiographic images of an anatomical structure. Once a
CBCT scan has been acquired, the information can be exported as a digital
imaging and communications in medicine (DICOM) file.
The decision to perform a CBCT scan on a patient should be made only
after the clinician has evaluated the patient history, chief complaint, and
performed a clinical examination. This careful selection will ensure maximum
benefit balanced against radiation risk (American Academy of Oral and
Maxillofacial Radiology 2013; Kapila and colleagues 2011). A recent study
completed by the University of Minnesota on 200 consecutive orthodontic
patients showed that 18% of patients had incidental TMJ findings by a dental
radiologist that required further testing or referrals (Larson, 2012). CBCT
imaging uses ionizing radiation, therefore clinical benefits should be balanced
against radiation risks and this type of imaging will only be used when the
clinical question cannot be answered adequately by lower dose conventional
radiograph of non-ionizing imaging modality. On the contrary, if the
clinician’s judgement indicates that a CBCT is indicated, avoid taking
additional conventional 2D radiographs (American Academy of Oral and
Maxillofacial Radiology 2013).
10
Although doses from CBCT are relatively low compared to other
imaging options, it is always important to try to minimize radiation for
patients. There are several factors that must be considered when taking at
CBCT. Techniques to help reduce the effective radiation dose include
reducing the size of the irradiated area known as field of view (FOV), and
modifying settings such as peak kilovoltage (kVp) and millampere (mA). The
use of lower mAs and/or collimation can reduce the amount of radiation the
patient receives, although these settings can also reduce image quality.
It is important to understand that the term CBCT does not refer to a
single imaging protocol. There are several parameters that influence the
quality of CBCT images, including X-ray beam factors, the size of the field of
view (FOV), the detector type and the size of the reconstructed voxels. All of
these parameters vary between CBCT units and can be adjusted in most
machines. It is important for the clinician to have a good understanding of
these parameters and adjusts them accordingly to produce optimal images for
the specific diagnostic goal. It is important to consider that with larger FOV
and higher voxel sizes, the image resolution is decreased and this could
potentially compromise the ability to detect early osseous changes.
Despite the numerous publications on the use of CBCT imaging in
orthodontics, very few authors have presented high levels of evidence or have
even measured the impact of CBCT in altering treatment planning decisions
(American Academy of Oral and Maxillofacial Radiology 2013). The AAO
recognizes that only in some clinical cases does this 3D imaging be of value,
11
and it is not required routinely for orthodontic care. Since its use has not yet
been supported by rigorous scientific studies, its utilization is being justified
by published case reports showing its potentially significant contribution to
diagnosis, treatment planning, and monitoring various cases (Kapila and
colleagues 2011).
CBCT has demonstrated clinical efficacy in treatment planning of
impacted and unerupted teeth, monitoring root resorption and angulations,
obtaining accurate measurements of airway volume, assessing skeletal
asymmetries, determining the skeletal jaw relationship and growth, and
viewing the condyle position and temporomandibular joint (TMJ) in three
dimensions. It can also be applied to evaluate other supplementary findings
like periodontal issues, post treatment TMD and placement of temporary
anchorage devices (American Academy of Oral and Maxillofacial Radiology)
C. TMJ Specific Imaging
When focusing specifically on the temporomandibular joint a variety of
modalities can be used for imaging the anatomy. This includes non-invasive
options such s conventional radiographs, ultrasound, magnetic resonance
imaging(MRI), computed tomography (CT), and cone-beam computed
tomography (CBCT) to more invasive imaging such as arthography (Barghan
et al., 2012).
12
i. Conventional radiographs
Conventional radiographs have a limited role in the imaging of the
TMJ. The biggest disadvantage conventional radiographs pose for imaging of
the TMJ is the problem of superimposition of adjacent structures (Figure 1 and
Figure 2). In order to view the obscured joint many different views including
the submentovertex, transmaxillary, and transcranial are used to reduce
superimposition of structures. Unfortunately, these projections do not always
show the condyle directly along its transverse axis which is the view most
valuable for diagnosis. Additionally, they can only be used to evaluate the
bony elements of the TMJ. They do not give useful information when it
comes to non-bony elements such as cartilage or adjacent soft tissues
Figure 1 Panoramic x-ray Image from:
http://www.banningorthodontics.com/orthodontic-records/panoramic-x-rays/
13
Figure 2 Lateral cepholometric x-ray
Image from: https://www.americanboardortho.com/orthodontic-professionals
ii. Ultrasound
Ultrasound is an easily performed imaging modality that can be used to
evaluate the TMJ. In the available literature, it was found that ultrasonography
as an acceptable diagnostic tool for detection of joint effusion, disc
displacement with both open and closed mouth imaging, and condylar erosion.
The principle of ultrasonography is based on the fact that ultrasonic
sound waves emitted by a device (transducer), travel through the tissue against
which they are aimed, and are partly reflected on transiting through dissimilar
anatomical structures. The reflected sound waves are then read by the same
emitting device, and translated into images. The patient should be lying
14
supine with the transducer placed parallel to a line extending from the tragus
of the ear to the lateral surface of the nose over the TMJ.
Figure 3. Ultrasound image of TMJ. Image from http://www.anatomy-
physiotherapy.com/tmj
iii. MRI
MRI is considered the most effective imaging tool for evaluation of the
TMJ soft tissues, the disc-condyle relationship, and for determination of disc
displacement. During the last decade, the introduction of dynamic(cine-mode)
MR imaging has made function evaluation feasible in addition to the
morphologic study of the joint. The major advantage of MRI is its ability to
study the articular disc and congruity as well as its location relative to the
condyle in both closed and open mouth positions. Due to its high contrast
resolution, MRI is unique in demonstrating joint effusion, bone edema and
sclerosis, rupture of the retrodiscal layers and impairment of the lateral
pterygoid muscle.
15
Figure 4. MRI of the TMJ. Image from:
https://radiopaedia.org/articles/temporomandibular-joint-dysfunction
iv. Arthrography
Arthrography is an invasive imaging technique to evaluate the TMJ.
This imaging modality requires injection of radiopaque contrast into the TMJ
under fluoroscopic guidance. Once the contrast is injected, the joint can be
evaluated for adhesions, disk dysfunction, as well as disk perforation based on
how contrast flows in the joint. This modality is rarely used today because
MRI can be used to evaluate the TMJ without being invasive, exposing the
patient to a possibility of allergic reaction to the contrast, or possibility of
infection.
16
Figure 6. Arthrography image of the TMJ. Image from:
https://www.urmc.rochester.edu/imaging/patients/procedures/tmj-imaging.aspx
v. CT/CBCT
Computed tomography provides excellent visualization of a broad
spectrum of osseous pathological changes such as osteophytes, condylar
erosion, fractures, ankylosis, dislocation, growth abnormalities. Studies on
autopsy specimens have found CT to have a sensitivity of 75% and specificity
of 100% for detecting bony changes. However, the high cost, access to
equipment and the relatively high radiation dose have limited the widespread
use of CT for TMJ evaluation. With the advent of cone beam CT(CBCT)
these barriers have been overcome. CBCT offers several advantages over
17
medical CT with the same diagnostic efficacy including lower cost, better
access to equipment, and lower radiation for the patient.
Figure 5. CT scan including TMJ region. Image from: https://ct-dent.co.uk/justification-for-
x-ray/
D. TMJ and Relationship to Orthodontics
Historically, the relationship between the temporomandibular joints
(TMJs) and orthodontics has been very important and complex. In the 1980s
there was a heightened awareness by the orthodontic community following
multiple lawsuits claiming a negative association between temporomandibular
joint disorder (TMD) and orthodontic care. Patients were asserting that their
occlusion and orthodontic treatment increased their likelihood of having TMD
symptoms including popping and discomfort. However, it is very prevalent in
the literature today that TMD is a heterogenous group of complex disorders of
varied and often multifactorial etiologies. These disorders can affect the
18
masticatory musculature, the osseous components of the TMJ and the soft
tissue components of the TMJ(Caruso et al., 2017).
Many studies show that orthodontic treatment performed during
adolescence does not change the odds of developing TMD, there is no elevated
risk of developing TMD with any specific orthodontic mechanic or protocols,
and not achieving an ideal occlusion does not result in TMD signs and
symptoms. Although it is known that orthodontic treatment does not cause
TMD it is imperative for clinicians to evaluate the TMJs as a routine part of
the initial comprehensive radiologic analysis of the craniofacial structures.
For example, an important component of assessment of facial asymmetries in
patients is the evaluation of TMJ morphology because manipulation of the
occlusal relationships could alter the loading and usage of the joints.
E. TMJ Normal Anatomy and Remodeling
i. Normal TMJ anatomy
The temporomandibular joint is a modified-hinge synovial joint formed by
the condylar process of the mandible and the glenoid fossa of the temporal
bone (Bag, 2014). The TMJ is considered a ginglymoarthrodial joint because
it has both a hinging movement of a ginglymoid joint and a gliding movement
of an arthrodial joint. Separating the two bones of the joint from direct
articulation is the articular disc. This fibrous, saddle shaped structure also
known as the meniscus serves as a non-ossified tissue that allows for the
simple and complicated action of the joint. It sits directly between the condyle
and the articulating surfaces of the glenoid fossa. The articular disc is
19
composed of dense collagenous tissue this is avascular, hyaline, and devoid of
nerve tissues in the central area (Shaefer et al., 2012). During function of the
joint the disc is elastic to some extent and will adapt to the needs of the
articular surfaces. Overall, the disc is designed to maintain its shape and
function unless excessive forces or structural changes occur in the joint. These
atypical forces or changes can cause the morphology of the disc to be
permanently altered which in return will produce biomechanical changes
during function.
The temporal bone has two sections to the articulating surfaces: (1) the
mandibular fossa is the poster concave portion and (2) the articular eminence
is the anterior convex portion. Additionally, what makes the articular surfaces
of the bones unique is the face they are covered by fibrocartilage instead of the
usual hyaline cartilage (Krishnamoorthy et al., 2013). Furthermore, the
condyle is barreled shape and average measurements are 15-20mm
mediolateral and 8-10mm anteroposterior. It is situated perpendicular to the
ascending ramus of the mandible and orient 10-30 degree with the frontal
plane (Petscavage-Thomas and Walker, 2014).
20
Figure 7. Basic anatomy of the temporomandibular joint. Image from:
https://www.slideshare.net/drtonypious/tmj-anatomy
ii. Normal radiographic anatomy of the TMJ
The radiographic appearance of healthy TMJs has been evaluated.
Ideally a healthy condyle should be centered in the fossa in the sagittal plane,
the surface should have regular, smooth, and intact cortication and the shape
should be rounded, resembling the shape of the fossa (Larheim et al., 2015).
21
Figure 6. CBCT reconstruction of TMJ (Machado, 2015)
iii. Temporomandibular disorders(TMD)
Temporomandibular disorders(TMDs) can affect either the muscular soft
tissue, bony components of the temporomandibular joint, or both. They present with
a wide range of signs and symptoms including but not limited to pain, clicking,
limited opening, popping, headaches, malocclusion, and muscle tenderness
(Khojastepour et al., 2017). Unfortunately, they are multifactorial in origin and
results from several predisposing factors. Most TMD specialists believe there are
three main dimensions to TMD including the biological, psychosocial, and structural
dimensions (Laplanche et al., 2012). Dr. Jeffrey Okeson, Director of the Orofacial
Pain Center at University of Kentucky, classifies TMDs into four main categories.
The categories are masticatory muscle disorders, TMJ disorders, chronic mandibular
hypomobility, and growth disorders. Within the TMJ disorders category Okeson had
22
subcategories of derangements of the condyle-disc complex and structural
incompatibilities (Okeson, Jeffrey. Management of Temporomandibular Disorders
and Occlusion. 2013) TMDs are often associated with bony degenerative changes of
the TMJ. For diagnosis of TMD it is important to take into consideration the
patient’s history, clinical examination, and imaging of the TMJ.
iv. TMJ remodeling and prevalence
The temporomandibular joint has many anatomic and functional features
that make it unique and complex among the joints of the human body. One
unique feature it demonstrates is the ability to remodel. Condylar remodeling is a
physiologic process that aims to adapt the structure of the TMJ to meet the
functional demands (Mathew et al., 2011). This process is based on adaptive
capacities of the condyle and the mechanical forces sustained by the joint.
Although it is known that the TMJ does have the ability to remodel the
mechanism of these structural changes is not completely understood. There are
many radiographic findings that have been reported to be associated with
condylar remodeling including: flattening, osteophyte formation, erosion,
sclerosis, and formation of subchondral cysts. The prevalence of these
radiographic findings have been reported in several articles with flattening being
the most common finding (80%), followed by osteophyte (16%), sclerosis (12%),
erosion (8%), and subchondral (7%) (Hiltunen et al., 2002; Mathew et al., 2011;
Sato et al., 2009; Takayama et al., 2008). These radiographic condylar changes
were also reported to increase with age and were seen more frequently in patients
with signs and symptoms of TMD (Hansson, 2004). Remodeling is only
23
considered abnormal or an issue if it is indeed accompanied by alterations in
function of pain of the joint at 79% of TMJs have some form of remodeling(Al-
Ekrish et al., 2015).
Figure 8. Lateral slices of the temporomandibular joint (TMJ) in maximum
intercuspation. The classification of the condyle morphology was (a) no bone change;
(b) osteophyte; (c) flattening (d) sclerosis; (e) erosion and (f) subchondral cysts. (Anjos
Pontual et al., 2012)
Figure 9. Lateral slices of the temporomandibular joint (TMJ) in maximum. The
classification of the condyle morphology was (a) no bone change; (b) flattening; (c)
sclerosis; (d) osteophyte and (e) erosion ((Lee et al., 2010)
24
F. Current Classification for TMJ and TMJ reporting
Currently, there are no widely accepted or prevalent techniques to
classify or score changes of the TMJ based on radiographs. One classification
for the TMJ is called Piper’s Classification. This system focuses on
intracapsular TMDs and progressive patterns that routinely occur as TMJs go
through stages from health to severe degeneration (Dawson, Peter E.
Functional Occlusion: From Tmj to Smile Design. Edinburgh: Elsevier
Mosby, 2006). Another classification system developed focuses on describing
the surface of the condyle head and placing them into one out of three
categories: smooth, irregular, and unclear (Vidra et al., 2002).
TMJ radiology reports drafted by radiologist are presently only
qualitative in nature. Qualitative reports have a tendency to be subjective in
nature as they are often based on the reporters’ findings and do not have any
quantitative support.
G. Materials and Methods
Sample
142 consecutive patient records were screened for this study from a single
practitioner’s office in Santa Monica, CA. To protect the patients’ identity,
patients were anonymized by assigning an arbitrary code number that
corresponded to their patient record number. The criteria for inclusion were:
18-60 years of age, CBCT records available and of diagnostic quality, and a
radiographic report from University of California Los Angeles (UCLA)
available. The criteria for exclusion from the group were: occlusal
25
interferences resulting in functional shift or deviation of the mandible, history
of previous orthodontics, signs and symptoms consistent of TMD or history of
TMD treatment, history of facial trauma, or general conditions potentially
affecting the TMJ. Of the 142 patients screened, 100 fulfilled all inclusion
criteria. All CBCT images were taken by the radiology team at a private
orthodontics practice in Los Angeles. The team was able to image all 100
patients (200 TMJs) using the same iCAT CBCT machine. (Imaging Sciences
International, Hatfield, PA) to minimize environmental error.
Protocol for CBCT Image Acquisition
Patients were guided by the private practice radiology technician to
obtain consistent images. All patients stood beside the iCAT machine and
were asked to look straight ahead into the horizon to assess for symmetry.
Afterwards, the technician was able to guide the patient to be seated into the
machine. Once seated, the head was supported by a temple support that goes
across the forehead and rests on either side of the temple.
26
Figure 3. Patient being oriented in a ICAT CBCT imaging machine *Image
adapted from: https://henryschein.com.au/equipment/imaging/cone-beam/i-cat-flx
Next, to register true horizontal and vertical lines laser light beams
were projected on to the patient. Proper alignment on the face of the patients
was ensured by adjusting the seat heights to properly accommodate each
individual patient. The horizontal line was placed in front of the condyle on
both the right and left side, with best attempts to align the heights. The light
was projected on and off until a stable repeatable position was achieved. The
vertical line was then projected on the patient to align the mid-sagittal plane.
27
Protocol for CBCT Image Reconstruction
The TMJ images were isolated and created utilizing the Dolphin
imaging software. The primary reconstruction of the raw data was restricted to
the TMJ region (approximately 1 cm superior to the mandibular fossa and 1
cm inferior to the condylar neck) and a series of axial views of 1 mm thickness
were automatically generated. The long axial view of the examined condyle
was traced with the TMJ tool and the software generated lateral and frontal
cross-sectional reconstructions perpendicular and parallel to the long axis of
the condyle, respectively. The thickness of the image slices was 1 mm and the
distance between slices was 1 mm for both lateral and frontal reconstructions.
Figure 4. Reconstructed image of left and right TMJ used to assess osseous changes.
TMJ Morphology and Position Assessment
All 100 patient images were sent to the University of California Los
Angeles (UCLA) Radiology department. The patient images received a CBCT
28
TMJ assessment by a trained radiologist. A detailed qualitative report was
returned outlining the TMJ findings for each patient and condyle. These
reports were used independently to extract data in regard to age, gender,
osseous changes, and TMJ position within the fossa for each patient.
The reconstructions were also assessed by a 3
rd
year orthodontic
resident looking for changes of the bone surfaces and position of the TMJ.
Right and left TMJs were assessed independently, resulting in a total of 200
TMJs. Gender, age, side, osseous changes, and TMJ position within the fossa
were recorded and compiled within an excel document arranged by patient
code number. Findings of the TMJ had to be present in at least two
consecutive slices to be recorded. The hard tissue changes evaluated were
flattening (a flat bony contour deviating from the convex form; loss of an even
convexity), erosion (an area of decreased density of the cortical bone and the
adjacent subcortical bone), osteophytes (marginal bony outgrowths on the
condyle), sclerosis (an area of increased density of cortical bone extending into
the bone marrow) and subchondral cysts (well-circumscribed osteolytic
adjacent subcortical bone area without cortical destruction) (Anjos Pontual et
al., 2012; Muir and Goss, 1990). The condyle position was only assessed in
the anterior-posterior direction. After the findings of all 200 TMJs had been
evaluated and recorded, classifications and scoring system were made for each
bone change category.
29
TMJ Morphology and Position Classification and Scoring System
Each TMJ morphology category was divided into three categories. Grade 0
represented no change or a healthy assessment of the joint and was rewarded
zero points. Grade I represented a mild to moderate change of the joint and
received one (1) points. Grade II represented a severe change in the joint and
received two (1) points. In addition, for the position of the joint any change
either anterior or posterior received one (1) point. Each joint then received a
scored based on the sum of the points from each category. Each TMJ could
receive a score ranging from 0-11 that would reflect the radiographic health of
the joint.
Statistical Analysis
Descriptive statistics including frequencies of occurrence for flattening,
erosion, osteophytes, sclerosis, subchondral cysts and posterior condylar
position were calculated.
To evaluate whether, generally, there was any correlation between
flattening, erosion, osteophytes, sclerosis, subchondral cysts, posterior
condylar position, and gender, Pearson correlation tests were used. Results
were considered significant at P<0.05. The same Pearson correlation tests were
used to evaluate correlation between flattening, erosion, osteophytes, sclerosis,
subchondral cysts, posterior condylar position, and the specific anatomical
30
side of the condyle. All statistical analyses were performed with software
(SPSS Inc. of IBM, Chicago, IL).
H. Results
The demographic characteristics of the subjects for our study can be
found in Table 1. Aside from the number of male and female subjects, the
range and mean for the males and females in this study are not significantly
different. The male to female ratio is 3:5
N Range of Age (years) Average Age (years)
Male 38 19-59 38
Female 62 19-59 37
Total 100 19-59 38.2
Table 1. Demographic characteristics
The number of individual condyles with a present condylar change or
posterior position was 84 out of the 200 evaluated(42%). Table 2 shows how
many condyles demonstrated a certain number of changes. The majority of
condyles (58%) showed no radiographic changes to morphology or position of
31
the joint. Below, images of the 20 condyles with the highest scores are
presented (Images x-x). Scores ranged from 0-8pts.
# of present
changes
0 1 2 3 4 5 6
# of condyles 116 46 24 12 2 0 0
Percentage 58 23 12 6 1 0 0
Table 2. Number of joints with detected changes.
Pt. 170941. The left TMJ received a score of 8 (Flattening =2, erosion =2, osteophyte =2,
scleoris =2).
32
Pt. 171048. The right TMJ received a score of 6 (Flattening =1, erosion =2, osteophyte =2,
sclerosis =1).
Pt. 171010. The right TMJ received a score of 5 (Osteophyte =2, sclerosis =1, subchondral
=2).
33
Pt. 171180. The left TMJ received a score of 5 (Flattening =2, osteophyte =2, scleoris =1).
Pt. 170919. The right TMJ received a score of 4 (Erosion =1, scleoris =1, subchondral
cyst=2).
34
Pt. 170965. The right TMJ received a score of 4 (Flattening =2 erosion =1, posterior
position=1)
Pt. 171218. The left and right TMJ received a score of 4 (Flattening =2 osteophyte =1,
posterior position=1)
35
Pt. 171243. The right TMJ received a score of 4 (Erosion =2 subchondral cyst =1, posterior
position=1)
Pt. 170930. The left TMJ received a score of 3 (Flattening =2, erosion =1)
36
Pt. 171117. The left and right TMJ received a score of 3 (Erosion =2, sclerosis =1)
Pt. 171208. The left TMJ received a score of 3 (Erosion =2, sclerosis =1)
37
Pt. 171258. The left TMJ received a score of 3 (Flattening =2, sclerosis =1)
Pt. 171264. The right TMJ received a score of 3 (Flattening =1, sclerosis =1, subchondral
cyst =1)
38
Pt. 171141. The left TMJ received a score of 3 (Sclerosis =1, subchondral cyst =1, posterior
position =1)
Pt. 171189. The left and right TMJ received a score of 3 (Flattening=1, erosion =1, posterior
position =1)
39
Pt. 171208. The right TMJ received a score of 3 (Flattening=1, sclerosis =1, posterior
position =1)
Pt. 170907. The left TMJ received a score of 2 (Flattening=1, erosion =1)
40
Tables 3-8 represent the frequency of occurrence for each variable
monitored for the joints. The most frequent change observed of the condyle
evaluated was flattening (46 joints, 23%), followed by posterior position on
the condyle in the sagittal plane (31 joints, 15.5%). Erosion of the condylar
surface was the next most common (29 joints, 14.5%), followed by sclerosis
(17 joints, 8.5%). The two least common findings were osteophytes (9 joints,
4.5%) and subchondral cysts (6 joints, 3%).
Frequency Percentage
Flattening Not Present 154 77
Flattening Present 46 23
Total 200 100
Table 3. Frequency table of condylar flattening.
Frequency Percentage
Erosion Not Present 171 85.5
Erosion Present 29 14.5
Total 200 100
Table 4. Frequency table of condylar erosion.
41
Frequency Percentage
Osteophyte Not Present 191 95.5
Osteophyte Present 9 4.5
Total 200 100
Table 5. Frequency table of condylar osteophyte formation.
Frequency Percentage
Sclerosis Not Present 183 91.5
Sclerosis Present 17 8.5
Total 200 100
Table 6. Frequency table of condylar sclerosis.
Frequency Percentage
Subchondral cyst
Not Present
194 97
Subchondral cyst Present 6 3
Total 200 100
Table 7. Frequency table of condylar subchondral cyst formation.
42
Frequency Percentage
Centered 169 84.5
Posterior 31 15.5
Anterior 0 0
Total 200 100
Table 8. Frequency table of condylar position.
Descriptive statistics were also performed on the data to evaluate the
correlation between the condylar variables and gender of the patient. Only
sclerosis and the posterior position of the joint had a significant correlation
with female joints with P values of .004 and .006 respectively (Table 14).
Gender Flattening
Not Present
Flattening
Present
Total
Female 90 34 124
Male 64 12 76
Total 154 46 200
Table 8. Frequency table of condylar flattening by gender.
Gender Erosion
Not Present
Erosion
Present
Total
Female 102 22 124
Male 69 12 76
Total 171 29 200
Table 9. Frequency table of condylar erosion by gender.
43
Gender Osteophyte
Not Present
Osteophyte
Present
Total
Female 116 8 124
Male 75 1 76
Total 191 9 200
Table 10. Frequency table of condylar osteophyte by gender.
Gender Sclerosis
Not Present
Sclerosis
Present
Total
Female 108 16 124
Male 75 1 76
Total 183 17 200
Table 11. Frequency table of condylar sclerosis by gender.
Gender Subchondral Cyst
Not Present
Subchondral Cyst
Present
Total
Female 119 5 124
Male 75 1 76
Total 194 6 200
Table 12. Frequency table of condylar subchondral cyst by gender.
Gender Centered
Position
Posterior
Position
Total
Female 98 26 124
Male 71 5 76
Total 169 31 200
Table 13 Frequency table of condylar position by gender.
44
Variable Value df Asymp. Sig
(2-sided)
Flattening 3.599 1 .058
Erosion 2.766 1 .096
Osteophyte 2.892 1 .089
Sclerosis 8.135 1 .004
Cyst 1.195 1 .274
Position 7.448 1 .006
Table 14. Table of Pearson Chi- Square Tests for gender. *Statistically significant at P<.05
The same descriptive statistics were also performed on the data to
evaluate the correlation between the condylar variables and anatomical side of
the condyle. There were no condylar variables that had any significant
correlation with the anatomical side of the joint being evaluate (Table 21).
Both right and left joints experience change in the morphology and position of
the condyle at similar rates.
Anatomical
Side
Flattening
Not Present
Flattening
Present
Total
Right 77 23 100
Left 77 23 100
Total 154 46 200
Table 15. Frequency table of condylar flattening by anatomical side.
45
Anatomical
Side
Erosion
Not Present
Erosion
Present
Total
Right 86 14 100
Left 85 15 100
Total 171 29 200
Table 16. Frequency table of condylar erosion by anatomical side.
Anatomical
Side
Osteophyte
Not Present
Osteophyte
Present
Total
Right 95 5 100
Left 96 4 100
Total 191 9 200
Table 17. Frequency table of condylar osteophyte by anatomical side.
Anatomical
Side
Sclerosis
Not Present
Sclerosis
Present
Total
Right 92 8 100
Left 91 9 100
Total 183 17 200
Table 18. Frequency table of condylar sclerosis by anatomical side.
46
Anatomical
Side
Subchondral Cyst
Not Present
Subchondral Cyst
Present
Total
Right 96 4 100
Left 98 2 100
Total 194 6 200
Table 19. Frequency table of condylar subchondral cyst by anatomical side.
Anatomical
Side
Centered
Position
Posterior
Position
Total
Right 83 17 100
Left 86 14 100
Total 169 31 200
Table 20. Frequency table of condylar position by anatomical side.
Variable Value df Asymp. Sig
(2-sided)
Flattening 0.000 1 1.000
Erosion 0.040 1 .841
Osteophyte 0.116 1 .733
Sclerosis 0.064 1 .800
Cyst 0.687 1 .407
Position 0.344 1 .558
Table 21. Table of Pearson Chi- Square Tests for anatomical side. *Statistically significant at
P<.05
47
Statistical tests were run to assess the difference between groups in regard to the
condyle health score and to evaluate if there was a correlation between age and health score.
Variables Test Significance
Gender & Condyle Health Score T-Test .589
Side & Condyle Health Score T-Test .953
Age & Condyle Health Score Pearson Correlation .180
Table 22. Table of condyle health score statistical tests *Statistically significant at P<.05
I. Discussion
CBCT imaging has been proven to have very distinct advantages over
other modalities of TMJ imaging including more accurate anatomical detail of
the TMJ. CBCT has shown to have a high diagnostic accuracy for the
detecting TMJ bone changes and analyzing condyle position (Ma et al.,
2016)((Dalili et al., 2012). It is important to be able to visualize various
osseous changes and the positon of the TMJ as they may be indicative of
degenerative adaptions of the joint. This information can inform the clinician
on the severity of future possible temporomandibular joint disorders. It can
also help with the accurate diagnosis and referring of patients to the
appropriate specialists prior to commencing orthodontic treatment(Kapila and
Nervina, 2015).
48
In the present study, the prevalence of condylar morphological changes
based on this specific sample group were reported. We found that 42% of the
condyles evaluated had at least one finding associated with joint remodeling or
posterior positioning of the joint. It has been previously reported that 79% of
joints present with at least one type of joint remodeling finding not including
posterior positioning of the joint that would most likely increase the
prevalence (Al-Ekrish et al., 2015). Mathew et al(2011) found that 81.3% of
the condyles they studied had radiographic changes in the condylar
morphology. This disparity in prevalence in the number of joints with at least
one finding could be due to the imaging method or exclusion criteria for these
studies. In our study we used of only CBCT imaging while Mathew et al. used
panoramic radiographs. The diagnostic capabilities of CBCT is far greater and
more accurate as compared to panoramic x-rays. There may have been some
false positive findings in their study that did not contribute to the prevalence in
our study. Additionally, in our sample we excluded occlusal interferences
resulting in functional shift or deviation of the mandible, history of previous
orthodontics, signs and symptoms consistent of TMD or history of TMD
treatment, history of facial trauma, or general conditions potentially affecting
the TMJ. It was shown that joints with signs and symptoms of TMD and
history of TMD as well as occlusal interferences are at a higher risk of
showing osseous condylar changes (Talaat et al., 2016). Additionally, the
mean age of sample evaluated was 38.2 years while in previous studies it was
older. Older populations are known to have a higher incidence of TMD,
49
osteoarthrosis, and degenerative changes of the joint (Schmitter et al., 2010).
Lastly, our sample consisted of patients seeking orthodontic care. These
patients may inherently differ from the general population and it would be
beneficial to repeat the study with a larger sample size from a more random
group such as a general dentistry practice.
According to previous studies based on CBCT imaging and other
imaging modalities, prevalence of changes to the condyle differ depending on
the type of change being evaluated. The few studies that have reported on the
prevalence report flattening being the most common finding (80%), followed
by osteophyte (16%), sclerosis (12%), erosion (8%), and subchondral (7%).
The prevalence values in our study definitely differed. Flattening was found to
be 23% as compared to 80% in previous studies. Osteophyte was found to be
4.5% as compared to 16%. Sclerosis was found to be 8.5% as compared to
12%. Erosion was found to be 14.5% as compared to 8%. Lastly, subchondral
cyst was found to be 3% as compared to 7%. The order of prevalence in our
study was flattening (23%), erosion(14.5%), sclerosis(8.5%),
osteophyte(4.5%), and subchondral cyst(3%). The prevalence values may
differ for several reasons. In the study by Mathew et al. (2011) their patient
demographics included patients over the age of 60 years while our study the
patient age was 18< X >60. They found that patients in the 61 years and above
group actually had the highest prevalence of flattening and sclerosis as
compared to the other two groups of 21-40 years and 41-60 years. Had our
study had patients above the age of 60 it can be estimated that the prevalence
50
of flattening and sclerosis would have increased. The opposite is true for
osteophyte and subchondral cyst formation. Mathew et al. (2011) found these
changes to have a lower prevalence as the age of the patient advanced. With
our sample having a lower average age we would have expected to see a.
higher prevalence of osteophytes and subchondral cysts. Additionally, these
disparities could also be due to the difference in imaging protocol. It has been
reported that CBCT images based on field of view(FOV) of 6 inches have the
highest diagnostic efficacy as compared to FOV of 12 inches with the lowest
(Librizzi et al., 2011).
In our study, only sclerosis and posterior position of the condyle
occurred significantly more frequently in the female sample compared to the
male sample. The other categories did not have a significant difference in
regard to gender. When looking at differences in prevalence correlated with
the specific anatomical of the joint, none of the categories has a significant
difference in prevalence between the left or right sides. Past studies have
found most morphologic changes to occur significantly more frequent in
females compared to males and no significant difference between the sides for
the joint (Locker and Slade, 1988).
Furthermore, when we looked at the correlations between our new
scoring system and gender, anatomical side, and age we found that there were
no significant differences. With our results it appears that all condyles have a
similar likelihood of having changes in the position or morphology of the
joint. There could again be an inherent difference between our sample, patients
51
seeking orthodontic treatment, and those who do not seek orthodontic care.
According to the National Institute of Dental and Craniofacial Research, TMD
and osseous changes of the condyle affect women significantly more than
men. Although our sample size was relatively the same size as previous
studies, further studies may need to increase the sample size and have different
sites for sample selection.
As a clinician it is important know the prevalence of various
morphologic changes and atypical positioning of the condyle. Although
patients may not have any current signs or symptoms of TMD or issues with
the joint, according to our study 42% of joints will show at least one change on
a CBCT evaluation. While our study does not show any significant difference
between sexes, women are proven to be more prone to TMD and bony
adaptations in the joint. With this information the standard of care may need to
change from traditional 2D radiographs (panoramic and lateral cephalogram)
to a full CBCT to image the TMJ and synthesize the traditional radiographs.
J. Conclusion
The following were the conclusions from our study. The prevalence of
changes in condylar morphology and position based on CBCT imaging was 42% with
flattening (23%) and posterior position of the condyle (15.5%) being the most
common. Only sclerosis and posterior position of the condyle occurred significantly
more frequently in females as compared to males. There was no difference in
prevalence of changes between the left and right condyles.
52
The scoring system that was developed helps quantify the changes and the
degree of severity in the health of each condyle. The scoring system ranges from 0-11
with each morphologic change earning a score of 0-2 and the condyle’s position
earning a score of 0 or 1. Our sample showed no correlation between age and condyle
score and no significant difference between gender or side and condyle score.
Since there appears to be no statistically significant association between a
condyle’s health score and gender, side, or age, clinicians should expect the same risk
of radiographic changes to the morphology and positon of the condyle for all patients.
A thorough clinical and radiographic examination of the condyle is essential for all
patients seeking orthodontic care prior to commencing treatment.
53
K. References
Al-Ekrish, A.A., Al-Juhani, H.O., Alhaidari, R.I., and Alfaleh, W.M. (2015). Comparative
study of the prevalence of temporomandibular joint osteoarthritic changes in cone beam
computed tomograms of patients with or without temporomandibular disorder. Oral Surg
Oral Med Oral Pathol Oral Radiol 120, 78–85.
Anjos Pontual, dos, M.L., Freire, J., Barbosa, J., Frazão, M., Anjos Pontual, dos, A., and
Fonseca da Silveira, M.M. (2012). Evaluation of bone changes in the temporomandibular
joint using cone beam CT. Dentomaxillofacial Radiology 41, 24–29.
Bag, A.K. (2014). Imaging of the temporomandibular joint: An update. Wjr 6, 567–17.
Barghan, S., Tetradis, S., and Mallya, S.M. (2012). Application of cone beam computed
tomography for assessment of the temporomandibular joints. Australian Dental Journal 57,
109–118.
Caruso, S., Storti, E., Nota, A., Ehsani, S., and Gatto, R. (2017). Temporomandibular Joint
Anatomy Assessed by CBCT Images. BioMed Research International 2017, 1–10.
Dalili, Z., Khaki, N., Kia, S.J., and Salamat, F. (2012). Assessing joint space and condylar
position in the people with normal function of temporomandibular joint with cone-beam
computed tomography. Dent Res J (Isfahan) 9, 607–612.
Dawson, P. E. (2006). Functional occlusion: from TMJ to smile design. Edinburgh, Elsevier
Mosby.
Grauer, D., Cevidanes, L.S.H., and Proffit, W.R. (2009). Working with DICOM craniofacial
images. Am J Orthod Dentofacial Orthop 136, 460–470.
Hansson, L.-G. (2004). A Comparison between clinical and radiologic findings in 259 TMJ
patients. The Journal of Prosthetic Dentistry 1–6.
Hiltunen, K., Vehkalahti, M.M., Peltola, J.S., and Ainamo, A. (2002). A 5-year follow-up of
occlusal status and radiographic findings in mandibular condyles of the elderly. Int J
Prosthodont 15, 539–543.
Kapila, S.D., and Nervina, J.M. (2015). CBCT in orthodontics: assessment of treatment
outcomes and indications for its use. Dentomaxillofacial Radiology 44, 20140282.
Khojastepour, L., Vojdani, M., and Forghani, M. (2017). The association between condylar
bone changes revealed in cone beam computed tomography and clinical dysfunction index in
patients with or without temporomandibular joint disorders. Oral Surg Oral Med Oral Pathol
Oral Radiol 123, 600–605.
Krishnamoorthy, B., Mamatha, N.S., and Kumar, V. (2013). TMJ imaging by CBCT:
Current scenario. Annals of Maxillofacial Surgery 3, 80.
54
Laplanche, O., Ehrmann, E., Pedeutour, P., and Duminil, G. (2012). TMD clinical diagnostic
classification (Temporo Mandibular Disorders). Journal of Dentofacial Anomalies and
Orthodontics 15, 202.
Larheim, T.A., Abrahamsson, A.-K., Kristensen, M., and Arvidsson, L.Z. (2015).
Temporomandibular joint diagnostics using CBCT. Dentomaxillofacial Radiology 44,
20140235–12.
Larson, B.E. (2012). Cone-beam computed tomography is the imaging technique of choice
for comprehensive orthodontic assessment. Am J Orthod Dentofacial Orthop 141, 402–404–
406passim.
Lee, D.-Y., Kim, Y.-J., Song, Y.-H., Lee, N.-H., Lim, Y.-K., Kang, S.-T., and Ahn, S.-J.
(2010). Comparison of bony changes between panoramic radiograph and cone beam
computed tomographic images in patients with temporomandibular joint disorders. The
Korean Journal of Orthodontics 40, 364–372.
Librizzi, Z.T., Tadinada, A.S., Valiyaparambil, J.V., Lurie, A.G., and Mallya, S.M. (2011).
Cone-beam computed tomography to detect erosions of the temporomandibular joint: Effect
of field of view and voxel size on diagnostic efficacy and effective dose. American Journal
of Orthodontics and Dentofacial Orthopedics 140, e25–e30.
Locker, D., and Slade, G. (1988). Prevalence of symptoms associated with
temporomandibular disorders in a Canadian population. Community Dentistry and Oral
Epidemiology 16, 310–313.
Ma, R.-H., Yin, S., and Li, G. (2016). The detection accuracy of cone beam CT for osseous
defects of the temporomandibular joint: a systematic review and meta-analysis. Nature
Publishing Group 1–8.
Machado, G.L. (2015). CBCT imaging - A boon to orthodontics. Saudi Dent J 27, 12–21.
Mathew, A.L., Sholapurkar, A.A., and Pai, K.M. (2011). Condylar Changes and Its
Association with Age, TMD, and Dentition Status: A Cross-Sectional Study. International
Journal of Dentistry 2011, 1–7.
Muir, C.B., and Goss, A.N. (1990). The radiologic morphology of asymptomatic
temporomandibular joints. Oral Surgery, Oral Medicine, Oral Pathology 70, 349–354.
Petscavage-Thomas, J.M., and Walker, E.A. (2014). Unlocking the Jaw: Advanced Imaging
of the Temporomandibular Joint. American Journal of Roentgenology 203, 1047–1058.
Proffit, William R, Henry W. Fields, and David M. Sarver. Contemporary Orthodontics. St.
Louis, Mo: Mosby Elsevier, (2007). Print.
55
Sato, H., Österberg, T., Ahlqwist, M., Carlsson, G.E., Gröndahl, H.-G., and Rubinstein, B.
(2009). Association between radiographic findings in the mandibular condyle and
temporomandibular dysfunction in an elderly population. Acta Odontologica Scandinavica
54, 384–390.
Schmitter, M., Essig, M., Seneadza, V., Balke, Z., Schroder, J., and Rammelsberg, P. (2010).
Prevalence of clinical and radiographic signs of osteoarthrosis of the temporomandibular
joint in an older persons community. Dentomaxillofacial Radiology 39, 231–234.
Shaefer, J.R., Riley, C.J., Caruso, P., and Keith, D. (2012). Analysis of Criteria for MRI
Diagnosis of TMJ Disc Displacement and Arthralgia. International Journal of Dentistry
2012, 283163–283168.
Takayama, Y., Miura, E., Yuasa, M., Kobayashi, K., and Hosoi, T. (2008). Comparison of
occlusal condition and prevalence of bone change in the condyle of patients with and without
temporomandibular disorders. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 105, 104–
112.
Talaat, W., Bayatti, Al, S., and Kawas, Al, S. (2016). CBCT analysis of bony changes
associated with temporomandibular disorders. Cranio 34, 88–94.
Vidra, M.A.L., Rozema, F.R., Kostense, P.J., and Tuinzing, D.B. (2002). Observer
consistency in radiographic assessment of condylar resorption. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 93, 399–403.
Abstract (if available)
Linked assets
University of Southern California Dissertations and Theses
Conceptually similar
PDF
Comparison of facial midline landmark and condylar position changes following orthognathic surgery
PDF
Three-dimensional quantification of post-surgical condylar displacement
PDF
Operator-determined and reoriented natural head position in three-dimensional imaging
PDF
Orthodontic rotational relapse: prevalence and prevention
PDF
Three-dimensional assessment of tooth root shape and root movement after orthodontic treatment: a retrospective cone-beam computed tomography study
PDF
Three dimensional analysis of maxillary retromolar alveolar bone before and after en‐masse distalization
PDF
The effect of cone beam computed tomography (CBCT) imaging on orthodontic diagnosis and treatment planning
PDF
The mesiodistal angulation and faciolingual inclination of each whole tooth in three dimensional space post non-extraction orthodontic treatment
PDF
Root shape frequency and direction of dilaceration: a CBCT study
PDF
Three-dimensional immediate post-surgery condylar displacement
PDF
An assessment of orthognathic surgery outcomes utilizing virtual surgical planning and a patented full-coverage 3D-printed orthognathic splint
PDF
Classification of 3D maxillary incisor root shape
PDF
An evaluation of bond strength using sham lingual brackets with differences in base morphology and preparation
PDF
Comparison of HLD CAL-MOD scores obtained from digital versus plaster models
PDF
3D ssessment of bracket position accuracy for lingual appliances using CAD/CAM technology: a pilot study
PDF
Relationship between key cephalometric parameters and tooth tip and torque
PDF
Monitering of typodont root movement via crown superimposition of single CBCT and consecutive iTero scans
PDF
Utilizing voxel based superimposition to asses orthognathic surgical treatment
PDF
Maxillary sinus floor and alveolar crest alterations following extraction of maxillary molars: a retrospective CBCT analysis
PDF
Shear bond strength comparison of mesh, sandblasted and laser-etched orthodontic brackets
Asset Metadata
Creator
Ogbevoen, Nehi Jeffrey
(author)
Core Title
Prevalence of TMJ morphological changes and scoring system based on CBCT imaging
School
School of Dentistry
Degree
Master of Science
Degree Program
Craniofacial Biology
Publication Date
03/14/2018
Defense Date
02/27/2018
Publisher
University of Southern California
(original),
University of Southern California. Libraries
(digital)
Tag
CBCT imaging,OAI-PMH Harvest,orthodontics,temporomandibular joint
Language
English
Contributor
Electronically uploaded by the author
(provenance)
Advisor
Sameshima, Glenn (
committee chair
), Grauer, Dan (
committee member
), Paine, Michael (
committee member
)
Creator Email
ogbevoen@usc.edu
Permanent Link (DOI)
https://doi.org/10.25549/usctheses-c40-485602
Unique identifier
UC11267282
Identifier
etd-OgbevoenNe-6108.pdf (filename),usctheses-c40-485602 (legacy record id)
Legacy Identifier
etd-OgbevoenNe-6108.pdf
Dmrecord
485602
Document Type
Thesis
Rights
Ogbevoen, Nehi Jeffrey
Type
texts
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...
Repository Name
University of Southern California Digital Library
Repository Location
USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA
Tags
CBCT imaging
orthodontics