THESIS – SYNOPSIS
DR. NIKITHA
POST GRADUATE STUDENT
DEPARTMENT OF ORTHODONTICS AND
DENTOFACIAL ORTHOPAEDICS
K.V.G. DENTAL COLLEGE & HOSPITAL
KURUNJIBAGH, SULLIA – 574327
DAKSHINA KANNADA
RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES
BANGALORE, KARNATAKA
ANNEXURE II
PROFORMA FOR REGISTRATION OF SUBJECT FOR
DISSERTATION
1. NAME OF THE CANDIDATE
: DR. NIKITHA
POST GRADUATE STUDENT,
AND ADDRESS
DEPT OF ORTHODONTICS AND
DENTOFACIAL ORTHOPAEDICS,
K.V.G DENTAL COLLEGE & HOSPITAL,
KURUNJIBAGH, SULLIA – 574 327
2.
NAME OF THE INSTITUTION
: K.V.G. DENTAL COLLEGE & HOSPITAL,
KURUNJIBAGH, SULLIA – 574 327.
3.
COURSE OF THE STUDY AND
: MASTER OF DENTAL SURGERY
ORTHODONTICS, BRANCH –V
SUBJECT
4.
DATE OF ADMISSION TO
:
28/05/2013
COURSE
"EVALUATION OF MANDIBULAR
5.
TITLE OF THE TOPIC
: SYMPHYSIS MORPHOLOGY AND
DIMENSIONS AMONG DIFFERENT
DENTOSKELETAL AND GROWTH
PATTERNS IN DAKSHINA KANNADA
POPULATION"
6
BRIEF RESUME OF THE INTENDED STUDY
6.1 Need for the study
In orthodontics , mandibular symphysis (MS) morphology has an impact on diagnosis and
treatment planning in patients; it serves as a reference anatomical landmark for esthetic and
beauty of the face in general and of the lower part in particular. Mandibular symphysis
morphology may also be used to predict the direction of mandibular growth rotations.1-4
It has been reported that morphological changes in the mandibular symphysis are
associated with malocclusions & orthodontic treatment. Tooth eruption plays a critical role
in continuous growth of the mandibular symphysis , resulting in an increase in the height of
the mandibular body 2 and the center of the cross section of the symphysis which can be
used to determine changes in the position of the mandibular teeth within the mandible .5
Factors such as vertical jaw relation and inclination of the lower incisors may have
indirect affect on the shape of mandibular symphysis during growth period; hence
dentoalveolar compensation which occurs during this period might be reflected in the
morphology and dimension of mandibular symphysis.1
According to Siciliani et al it is found that the symphysis is thin and elongated in
patients with long faces, whereas it is thicker in those with short faces.6
The purpose of the study is to assess the morphology and dimensions of mandibular
symphysis among different dentoskeletal and growth patterns and to determine whether
craniofacial parameters have any correlation with its shape and/or dimensions in Dakshina
Kannada population.
6.2 Review of the Literature:
A study was performed to determine whether symphysis morphology could be used as a
predictor of the direction of mandibular growth and assess growth changes of symphysis.
Cross-sectional data included lateral cephalometric radiographs of 115 adults, the direction
of mandibular growth was evaluated with seven cephalometric measurements that included
Y-axis ,SN to mandibular plane, palatal plane to mandibular plane, gonial angle, sum of
saddle, articulare and gonial angles, percentage lower facial height and posterior /anterior
face height. The symphysis morphology was found to be associated with the direction of
mandibular growth, especially in male subjects with symphysis ratio having the strongest
relationship. A mandible with an anterior growth direction was associated with a small
height, large depth, small ratio and large angle of the symphysis .3
Another study was conducted to clarify symphysis morphological characteristics in skeletal
class
III
malocclusion
requiring
orthognathic
surgery
and
their
relationships
with symphysis morphology and inclination of the long axis of the lower incisor. The
materials were pretreatment lateral cephalometric radiographs from 50 subjects diagnosed
as requiring orthognathic surgery. Controls were 30 adults with normal occlusion and wellbalanced faces. Detailed cephalometric measurements on the mandibular symphysis
(angular, linear and proportional measurements) were recorded and analyzed statistically.
In the surgical group, the long axis of the lower incisor demonstrated a significant lingual
inclination in relation to the mandibular plane and symphysis. Moreover, because
the symphysis demonstrated lingual inclination everywhere except in the basal bone region
in relation to the mandibular plane, the curvature between the alveolar and the basal bone
region was significantly smaller than that of normal occlusion group.7
A study was conducted to verify, via computed volumetric tomography, a correlation
between the morphology of the mandibular symphysis and the various facial types from a
sample of 148 digital volumetric tomographs, the subjects were classified as either short
face, normal face & long face according to the average values of their Frankfort-mandibular
plane angle between 12 and 40 years of age. The parameters measured on the sections
corresponding to the 4 mandibular incisors are: height, thickness, and area of the entire
symphysis; height, thickness, and area of the cancellous bone of the symphysis; distance of
the vestibular and lingual cortices from the apices of the 4 incisors; and possible inclination
of each mandibular incisor, expressed in degrees. conclusion obtained from the study was
there is a statistically significant relationship between facial type and the total thickness of
the mandibular symphysis.6
A study was conducted to evaluate mandibular morphology in different facial types using
various parameters. This study was conducted on lateral cephalograms of a total of 110
subjects. The sample was divided into normodivergent, hypodivergent, and hyperdivergent
subgroups based on Jarabak's ratio. Symphysis height, depth, ratio (height/depth) and angle,
antegonial notch depth, ramal height and width, mandibular depth, upper, lower, and total
gonial angle, and mandibular arc angle were analyzed statistically and graphically. It was
found that the mandible with the vertical growth pattern was associated with a symphysis
with large height, small depth, large ratio, small angle, decreased ramus height and width,
smaller mandibular depth, increased gonial angle, and decreased mandibular arc angle in
contrast to mandible with a horizontal growth pattern. Sexual dichotomy was found with
mean symphysis height and depth in the female sample being smaller than in the male
sample, but symphysis ratio was larger in the female sample; males having greater ramus
height and width, mandibular depth than females.8
A study was done to investigate the alveolar and symphysis region properties
in hyper-, hypo-, and normodivergent Class II division 1 anomalies. Pretreatment lateral
cephalograms of 111 young adult female patients with skeletal Class II division 1
anomalies were compared to those of 54 Class I normal subjects (control group).
Class II cases were divided into hyperdivergent, hypodivergent , and normodivergent
groups . The heights and widths of the symphysis and alveolus and the depth of maxillary
palate were measured on the lateral cephalograms. Mean symphysis width was wider in the
hypodivergent Class II group than in the other groups, while mean symphysis height was
similar among all groups. The study concluded that symphysis width is the main factor in
the differential diagnosis of Class II division 1 anomaly rather than symphysis height and
hypodivergent Class II division 1 anomaly is more suitable for mandibular incisors
movements. 9
Another study was aimed to establish cephalometric reference values for mandibular
symphysis in adults. Dentoalveolar, skeletal and soft tissue variables were measured
considering the influence of gender and facial type. The sample consisted of sixty
cephalometric radiographs of white Brazilian adult patients, with a mean age of 27 years
and 6 months, who had not undergone orthodontic treatment and who presented wellbalanced faces and normal occlusion. Result of the study showed that the brachyfacial
group showed broader symphysis in the dentoalveolar and basal areas and a greater buccal
dentoalveolar inclination. The projection of the chin was 6.67 mm below the subnasal
vertical line and there was no significant difference between the genders or facial types.10
A study performed to assess the morphology and dimensions of mandibular symphysis in
different anteroposterior jaw relationships and to investigate whether craniofacial
parameters have any correlation with its shape and/or dimensions. Lateral cephalograms of
subjects with Class I, Class II, and Class III skeletal relationships were traced. Several
craniofacial and mandibular symphysis parameters were measured. Mandibular symphysis
parameters were compared between the three groups using analysis of variance and were
correlated with the craniofacial parameters using the Pearson correlation coefficient. Result
obtained was larger angle of concavity of the chin, more inclination of the alveolar bone
toward the mandibular plane, and larger mandibular symphysis dimensions and area were
found with a Class III skeletal relationship compared to Class I and Class II relationships
.So the conclusion was the dimensions and configuration of mandibular symphysis in the
Class III relationship were different than those in Class I and Class II relationships; the
alveolar part of mandibular symphysis compensated for the skeletal relationship in the
Class III pattern. Mandibular symphysis dimensions were strongly correlated to anterior
facial dimensions.1
6.3 Aims & objectives of the study:
1. To assess the morphology and dimensions of mandibular symphysis in class I, class II,
class III skeletal patterns.
2. To assess
the morphology and dimensions of mandibular symphysis in average,
vertical & horizontal growth patterns.
3. To investigate whether craniofacial parameters have any correlation with its shape
and/or dimensions.
7
MATERIAL & METHODS
7.1 Source of the Data:
Pre-treatment records of the subjects native to Dakshina Kannada population visiting the
Department of Orthodontics, of various Dental Colleges of Dakshina Kannada.
7.2 Method of Collection of Data:
Pre-treatment records of 270(135 males & 135 females) patients will be collected from the
Department of orthodontics of various Dental Colleges of Dakshina Kannada.
Selection Criteria:
Criteria for the selection of samples.
Inclusion Criteria:
1. All subjects should be in the age group of 18-26 years.
2. Acceptable radiographic quality.
3. The radiographs are selected according to their skeletal AP jaw relationship (Class I,
Class II, or Class III relationship). Class I skeletal relationship is considered when ANB
angle =3±1°, Class II skeletal relationship was considered when ANB angle is >4°, and
class III skeletal relationship is considered when ANB angle is <2°.
4. The radiographs are selected according to their growth patterns (average, horizontal
and vertical). Average is considered when Y-axis is 64.5-67.4°, horizontal growth is
considered when Y-axis is <64.5° and vertical growth is considered when Y-axis is
≥67.5° .
Exclusion Criteria:
1.History of orthodontic treatment.
2.Orthognathic surgery.
3. Craniofacial anomalies.
4.History of trauma to the mandible.
Materials Required:
 Standardized lateral cephalogram
 Matt acetate tracing paper
 0.5 mm 2B microtip pencil(camlin)
 Metal scale
 Set sqare(camlin)
 Red colour pencil(camlin)
 Software Autocad (version 2010)
Methodology:
A total of 270 (135 males & 135 females) Subjects will be divided into three groups as
follows :class I (average, vertical growth & horizontal growth skeletal pattern) ,class II
(average, vertical growth & horizontal growth skeletal pattern), and class III (average,
vertical & horizontal growth skeletal pattern) comprising 90 in each group on the basis of
ANB angle & Y-axis measured on lateral cephalogram.
Dental Lateral Cephalometric radiographs will be obtained and analysis will be done
on matt acetate tracing paper & software (Autocad .version 2010) will be used to measure
the area of mandibular symphysis.
Measurements
Lateral cephalometric measurements:
Lateral cephalometric measurements will be obtained by manual tracing and software
Autocad (version 2010) in this study. The cephalometric measurements are as follows :
SNA: Angle formed by intersection of Sella-Nasion and Nasion-A point.
SNB :Angle formed by intersection of Sella-Nasion and Nasion-B point.
ANB: Angle formed by intersection of Nasion-B point and Nasion-A point.
L1/Md: Angle formed by intersection of long axis of the most prominent mandibular
incisor and mandibular plane.
UAFH: The distance from Nasion to Anterior nasal spine.
LAFH :The distance from Anterior nasal spine to Menton point.
TAFH: The distance from Nasion to Menton.
Y-Axis: The angle formed between the points Nasion, Sella & Gnathion.
Mandibular symphysis points and parameters:
Point B: The most posterior point on the profile of the mandible between the chin point
and the alveolar crest.
Pogonion (Pog): The most anterior point of the mandibular symphysis in the midline.
Gnathion (Gn): The most anterior inferior point of the mandibular symphysis in the
midline.
Menton (Me) :The lowermost point of the mandibular symphysis in the midline.
Point B1: A point formed by the intersection between a perpendicular line dropped from
point B to the tangent drawn on the inner contour of mandibular symphysis at the shortest
distance from point B.
Point Id: The most anterior superior point of the labial mandibular alveolar crest, situated
between the lower central incisors.
Angular measurements:
B-B1-Gn :The angle between point B, point B1, and Gnathion; It gives an indirect
reflection of the vertical dimension of the mandibular symphysis.
B-Pog-Me: The angle formed between point B, Pogonion, and Menton; It reflects the
convexity of the mandibular symphysis.
Id-B-Pog: The angle between point Id, point B, and Pogonion; It reflects the concavity of
the mandibular symphysis.
Id-B/Md: The angle between a line connecting Id to Point B and the mandibular plane; It
reflects the inclination of the alveolar part of the mandibular symphysis in relation to the
mandibular plane.
B-Pog/Md: The angle between a line connecting Point B to Pogonion and the mandibular
plane; It reflects the inclination of the skeletal part of the mandibular symphysis in relation
to the mandibular plane.
Linear measurements:
Id-B: The linear distance from Id to point B.
B-Pog :The linear distance from point B to Pogonion.
Pog-Me :The linear distance from Pogonion to Me.
Id-Me: The linear distance from Id to Me, representing the total length of Mandibular
symphysis.
Perpendicular distance from Pog to B-Me line: The perpendicular distance from Pogonion
to the line connecting point B and Menton to represent the anterior prominence of
mandibular symphysis.
Area, mm2 :The total area confined within the outer border of mandibular symphysis and
bounded superiorly by the line connecting Id and the most superior point of the lingual
mandibular alveolar crest.
Error study:
After the first measurement, 40 randomly selected lateral cephalograms will be retraced by
the same examiner to determine measurement error in this study. The casual error will be
calculated using Dahlberg's double determination formula. The Houston coefficient of
reliability will also be calculated.
Statistical analysis:
The statistical analysis will be performed using the SPSS software package(version.17.0).
Unpaired t-test will be used to find the difference between males and female subjects and
Pearson correlation coefficient will be calculated to assess the relationship between
mandibular symphysis parameters and craniofacial & dentoalveolar parameters. p<0.05
will be considered as significant. General linear model analysis will be employed to
investigate differences of mandibular symphysis parameters between the 3 groups.
ANOVA (Fishers test) and Tukeys test will be used to compare means of measurements
between different dentoskeletal patterns and growth patterns.
7.3
DOES
THE
STUDY
REQUIRE
ANY
INVESTIGATIONS
OR
INTERVENTIONS TO BE CONDUCTED IN PATIENTS OR OTHER HUMAN?
NO, Previously recorded cephalometric radiographs will be utilized for the study .
7.4.
HAS
ETHICAL
CLEARANCE
BEEN
INSTITUTION?
YES, Institutional Ethics Committee clearance enclosed.
OBTAINED
FROM
YOUR
8.
LIST OF REFERENCES
1. Al-Khateeba SN, Maaitahb EFA, Alhaija ESA , Badrand SA. Mandibular symphysis
morphology and dimensions in different anteroposterior jaw relationships. Angle
Orthod 2013;Aug 5:doi:10.2319/030513-185.1
2 . Endo T, Ozoe R, Kojima K ,Shimooka S. Congenitally Missing Mandibular incisors
and mandibular symphysis morphology. Angle Orthod 2007;77:1079-1084
3. Aki T, Nanda RS, Currier GF, Nanda SK. Assessment of symphysis morphology as a
predictor of the direction of mandibular growth. Am J Orthod Dentofacial Orthop
1994;106:60-69.
4. Buschang PH, Julien K, Sachdeva R, Demirjian A. Childhood and pubertal growth
changes of human symphysis. Angle Orthod 1992;62:203–210.
5. Rosenstein SW, Chicago, Illinois.A longitudinal study of Anteroposterior Growth Of
The Mandibular symphysis. Angle Orthod 1964; 34:155-167
H. Suzuki, H. Maeda, and
6. Gracco A, Luca L, Bongiorno MC, Siciliani G. Computed tomography evaluation of
mandibular incisor bony support in untreated patients. Am J Orthod Dentofacial Orthop
2010; 138:179-187.
7.Nojima
K, Nakakawaji
K, Sakamoto
T, Isshiki
YR.
Relationship
between mandibular symphysis morphology and lower incisor inclination in skeletal class
III malocclusion requiring orthognathic surgery. Bull Tokyo Dent Coll 1998;39(3):175181.
8. Mangla R, Singh N, Dua V, Padmanabhan P, Khanna M. Evaluation of mandibular
morphology in different facial types.Contemp Clin Dent 2011; 2(3): 200–206
9. Esenlik E, Sabuncuoglu A. Alveolar and symphysis regions of patients with skeletal
class II division 1anomalies with different vertical growth patterns. Eur J Dent 2012;6:123132.
10. Karine EMA, José VN, Guilherme de AA. Assessment of the mandibular symphysis of
Caucasian Brazilian adults with well-balanced faces and normal occlusion: The influence
of gender and facial type. Dental Press J Orthod 2012;17(3):40-50.
Tanaka, H. Suzuki, H. Maeda, and
9.
SIGNATURE OF CANDIDATE
10.
REMARKS OF THE GUIDE
11.
NAME AND DESIGNATION OF
11.1 GUIDE
DR. SHARATH KUMAR SHETTY, M.D.S.
DIRECTOR OF PG STUDIES,
PROFESSOR AND HOD,
DEPARTMENT OF ORTHODONTICS AND
DENTOFACIAL ORTHOPAEDICS,
K.V.G DENTAL COLLEGE AND HOSPITAL,
KURUNJIBAGH, SULLIA, D.K -574327
11.2 SIGNATURE
11.3 REMARKS OF HOD
11.4 HEAD OF THE DEPARTMENT
DR. SHARATH KUMAR SHETTY, M.D.S.
DIRECTOR OF PG STUDIES,
PROFESSOR AND HOD,
DEPARTMENT OF ORTHODONTICS AND
DENTOFACIAL ORTHOPAEDICS,
K.V.G DENTAL COLLEGE AND HOSPITAL,
KURUNJIBAGH, SULLIA, D.K -574327
11.4 SIGNATURE
12.
REMARKS OF THE PRINCIPAL
DR. MOKSHA NAYAK, M.D.S.
PRINCIPAL,
K.V.G. DENTAL COLLEGE AND HOSPITAL,
KURUNJIBAGH, SULLIA.
12.1 SIGNATURE