ALVEOLAR AND SYMPHYSIS REGION CHARACTERISTICS OF …

I

“ALVEOLAR AND SYMPHYSIS REGION CHARACTERISTICS OF

PATIENTS WITH SKELETAL CLASS III MALOCCLUSION –A

CEPHALOMETRIC STUDY”

By

DR. KISHOR KUMAR

Dissertation Submitted to the

Rajiv Gandhi University of Health Sciences,

Bengaluru, Karnataka

In partial fulfillment

of the requirements for the degree of

MASTER OF DENTAL SURGERY

In

ORTHODONTICS

&

DENTOFACIAL ORTHOPAEDICS

Under the guidance of

Dr. ASHOK KUMAR TALAPANENI M.D.S

Professor & Head

DEPARTMENT OF

ORTHODONTICS & DENTOFACIAL ORTHOPAEDICS

AL-BADAR RURAL DENTAL COLLEGE AND HOSPITAL,

GULBARGA.

2015 - 2018

ACKNOWLEDGEMENT

At the very outset, I would like to thank the Almighty for making this task possible with

his blessings, providing and infusing me with enough strength to carry out this work and being

with me in all my endeavours.

My respects and deepest gratitude to my guide Dr. Ashok Kumar Talapaneni

Professor & Head,, Department of orthodontics and dentofacial orthopaedics, Al- Badar

Rural Dental College & Hospital, Kalaburagi. I have been very fortunate to have an advisor

who gave me the freedom to explore on my own and at the same time the guidance to recover

when my steps faltered.

I take this opportunity to express my gratitude to him for his keen interest and constant

encouragement during every stage of this library dissertation. He stood as pillar by me

throughout the inscription of this library dissertation and guided me throughout my work.

I cannot forget the support provided to me by, Dr.Prasad Konda, Professor, Dr.Avinash

kumar MDS Reader, Dr.Saravanan MDS, Reader, Dr Arshad MDS, Reader, Dr. Chandrika

MDS, Assistant Professor, Dr. Laeque MDS, Assistant Professor, Dr. Asma MDS, Assistant

Professor, Dr. Ayub MDS, Assistant Professor from the department of Orthodontics and

dentofacialorthopaedics, Al-Badar Rural Dental College and Hospital, Gulbarga, for whom I

remain always thankful.

I thank the librarian Mr.Jagannath Maski and the library staff for giving their valuable

support to utilize the library facility for my study.

My sincere thanks to my seniors Dr. Arifa, Dr. Meenakshi, Dr.Suresh, Dr.Rajesh,

Dr.Shreyas and Dr. Imran, Dr.Abdul Saleh, Dr.Nisar, Dr. Hajra, Dr. Samiullah

and my batchmates Dr Faiza, Dr. Kirmani, Dr. Mujeeb and Dr.Meghna who kept me aloft

during the entire course, and I am also thankful to my beloved juniors, Dr. Kamala, Dr. Rekha,

Dr. Javeria, Dr.Praveen, Dr. Mujtaba, Dr. Rony, Dr.Sujith, Dr. Fareed, Dr. Aftab, Dr.

Archana and the non-teaching staff of my department Mr.Gani, Mr.Chandru, and Mr. Noor

whose association was a source of great help.

V

LIST OF ABBREVATIONS USED

PP - Palatinal plane

MP - Mandibular plane

L1–AH - Mandibular incisor dentoalveolar height

L6–AH - Mandibular molar dentoalveolar height

U1–AH - Maxillary incisor dentoalveolar height

U6–AH - Maxillary molar dentoalveolar height

Id – Anterosuperior

Id′- Posterosuperior

B′ - Lingual projection of the B point at the lingual symphysis border

VI

LIST OF TABLES

SI.No Tables Pages

1. Landmarks and Definition 18

2. Intergroup comparison of skeletal parameters 21

3. Intergroup comparison of various maxillary parameters 22

4. Intergroup comparison of mandibular parameters 23

5. Intergroup comparison of symphysis parameters 24

VII

LIST OF FIGURES

SI.No Figures Pages

1. Dentoalveolar and Symphysis Parameters 19

Abstract

IX

ABSTRACT

Title: “Alveolar And Symphysis Region Characteristics Of Patients With Skeletal

Class

III Malocclusion – A Cephalometric Study”.”

Objectives: To investigate the differences in the properties of the alveolar and

symphysis regions of patient with skeletal class III malocclusion and a Class I control

group.

.Materials and methods: Pretreatment lateral cephalograms of 80 patients is divided

into 50 lateral cephalograms from subject of class-І malocclusion (control group) and,

30 lateral cephalograph of skeletal class-ІІІ malocclusion. The heights and widths of

the symphysis and alveolus and depth of maxillary palate is measured on the lateral

cephalograms and analyzed.

All cephalograms are traced manually by a single examiner using a protractor 0.5°

and with 0.5 mm accuracy. The data obtained will be evaluated and subjected to

statistical analysis. The cephalometric data of the control and Class III groups were

presented as a mean ± SD. The results were inferred by analysis of variance

(ANOVA) using statistical software (SPSS version 23). P < 0.05 was considered

significant.

Results: The skeletal Class III cross bite group showed a larger SNB, ANB and AO-

BO measurements compared with the control group. The maxillary incisal dento

alveolar height has an insignificant difference between the two groups. Class I control

group had a significantly lesser mandibular plane angle than the Class III. Mandibular

Abstract

X

incisal inclinations were significantly greater in Class I control group than in Class III

cross bite group (P<0.001**).

Conclusion: Mandibular incisal dento alveolar height and mandibular molar dento

alveolar height were significantly greater in the Class III cross bite group than in the

Class I control group. Symphysis height and width were significantly greater in the

Class III cross bite group than in the Class I control group.

Keywords: Lateral cephalograms, symphysis, maxillary palate

Introduction

1

INTRODUCTION

Class III malocclusion is a significant problem that can be disturbing both

socially and functionally. Many factors have been implicated in its etiology and a

strong genetic background has been established in literature. The prevalence of class

III malocclusion varies according to ethnicity; it is high among Asians of the Far East

(12%) and low in Caucasians (1-4%).1

Facial types of a multidimensional nature are derived from the combination of

anteroposterior and vertical dimensions. Teeth, muscles, and bones interact intimately

during growth, increasing or masking initial deformities.2 Disproportions and

malpositions of the structures often lead to malocclusions or facial deformities.3

In orthodontics, knowledge of mandibular growth is highly beneficial in

diagnosis and treatment planning and is critical in the development of balanced

dentofacial structures4. Mandibular rotation types have been well defined by several

authors.5,6

It was stated that some additional growth at the major growth sites

accompanied by mandibular rotation and remodeling tend to reshape the mandible.

These remodeling changes described for the inferior mandibular border have been

related to rotational changes in the mandible.7 Anterior rotation is generally associated

with deposition in the inferior aspect while posterior\ rotation is associated with

resorption.8 These remodeling processes were thought to be indirectly related to the

nature of the stresses generated by the supra-hyoid musculature.3

It is believed by some authors that the symphysis region properties could be a

good indicator of mandibular rotation.4,5,9,10

The symphysis is one of the most

important regions of the craniofacial complex for clinical orthodontists, and it serves

as a primary reference for esthetic considerations in the lower one-third of the face.7

Introduction

2

Furthermore, the vertical and sagittal positions of the mandibular incisors are

important determinants in planning occlusal and skeletal relations for orthodontic

treatment and orthognathic surgical procedures.3

It is known that the facial growth pattern influences not only the morphology

of the mandibular symphysis, but also the thickness of the alveolar process in this

area, and consequently, the position of the mandibular incisors. The wider the

symphysis, the greater the possibility to tip forwards the mandibular incisors11

.

Moreover, one speculates that the negative vertical overlap is another factor

influencing the symphysis morphology.12

The region of the mandibular symphysis is involved in delicate and limited

movements, not only in esthetics, but with regard to bone and tooth resorptions.

Therefore, knowledge of the adequate limits of tooth movement and establishment of

parameters for the thickness of the alveolar process in the mandibular symphysis

region may have a significant influence on the diagnosis, and consequently, the end

result of orthodontic treatment. Previous studies have shown that individuals with a

vertical growth pattern have a longer and narrower symphysis; in those with

horizontal growth it is shorter and wider.13,14

Thus, the facial pattern may help

diagnose the shape of the symphysis.15

The morphology of mandibular symphysis is important because it serves as

the primary reference for the esthetics of the facial profile and is a determinant in

planning the lower incisor position during orthodontic and orthognathic surgery.7,16

The factors associated with the symphyseal growth and morphology include the

functional neuroskeletal balance,13

masseter muscle thickness,17

mandibular plane

Introduction

3

angle,16,18

overbite,13,15,19

lower incisor angle,20

occlusal hypofunction and its

recovery,21

inheritance.22

During orthodontic treatment, limiting incisor movement within the bone

structure is believed to be essential for achieving better results, stability, and

periodontal health, as well as for avoiding root resorption.23,24

In particular, in the case

of a severe adult skeletal Class III malocclusion, the proper amount of

decompensation including the labial inclination of the lower incisors is necessary

before orthognathic surgery.24

On the other hand, lingual inclination of the lower

incisors is needed for camouflage treatment. Either way, incisor movement confined

within the bone is recommended.25

Studies12,16

have shown morphology of the symphyseal region based on the

divergence of the mandibular plane angle and reported that the alveolar bone and

symphyseal thickness negatively correlated with the mandibular plane angle.

However Ceylan I et al19

and Nojima et al

20 from their studies have concluded Patients

with a vertical growth pattern, open bite, and high mandibular plane angle were

reported to have a similar or larger vertical dimension of the symphysis.

However substantial literature correlating and comparing the morphological

characteristics of symphysis and alveolus in brachyfacial class I and class III skeletal

subjects has not been evaluated. Therefore this study focused on the morphological

characteristics of symphysis and alveolus in Adult skeletal class III malocclusions

with cross bite and compared them with normal occlusion in brachyfacial structural

patterns.

Aims and Objectives

4

AIMS AND OBJECTIVES

The objective of this study is to measure the

1. Difference in the maxillary dentoalveolar properties of skeletal class III

cross bite malocclusion and class I control group.

2. Difference in the mandibular dentoalveolar properties of skeletal class III

cross bite malocclusion and class I control group.

3. Difference in the symphysial properties of skeletal class III cross bite

malocclusion and class I control group.

Review of Literature

5

REVIEW OF LITERATURE

Schudy F F (1963)26

conducted a cephalometric study of 400 malocclusions, in

which 19 average angles and measurements were calculated. A group of 57

malocclusions with high occluso mandibular angles (OM) were selected from the

group of 400. This group was studied and compared with other groups of 44

malocclusions with low OM angles which were selected from the group of 400 and

compared with other group. The OM angle was discussed and an attempt was made to

show its diagnostic value. This study contains documented evidence to support the

study that the relationship of the mandibular plane to the occlusal plane is very

important. The evidence strongly suggests that the OM angle is significantly related to

overbite. And by orthodontic treatment the OM angle is quite subject to change. There

is a consistency between facial type, OM angle and vertical overbite. In treated cases

attention should be given to the relationship of the incisor teeth to the occlusal plane.

The OM angle is a useful tool for describing one aspect of the morphology of the

mandible.

Robert J, et al (1977)

27 evaluated the position of the lower incisor with respect to

hard tissue references. Two samples were used for this purpose one containing 78

patients with post-treatment records having a post-retention period of at least 4 years,

and the other composed of 82 normal occlusions. They concluded that there was no

significant difference in relapse of lower incisor crowding between cases, where the

lower incisor had been moved lingually, labially, or held in the same relative position

during treatment. The position of the maxilla should be considered when placing the

lower incisor. The A-Po plane (A point to Po [Pog point]) adequately serves as a

guide to this purpose, whereas other reference lines such as mandibular plane or facial


6

plane do not. The positions of the incisors with respect to popular cephalometric

reference lines such as A-Po, N-B, or mandibular plane were not correlated with the

relapse of mandibular crowding. Therefore other clinical guides might be more

successful for determining stability.

Handelman C S (1996)23

studied 107 cephalometric films which were measured to

determine the width of alveolar bone anterior and posterior to the incisor apex in each

arch. Thin alveolar widths were found both labial and lingual to the mandibular

incisors in groups of Class I, II, and III individuals with high SN-MP angle and in a

group of Class III average SN-MP individuals. Thin alveolar widths were also found

lingual to the maxillary incisors in Class II high angle group. Clinical cases were

presented showing that orthodontic tooth movement may be limited in patients with

narrow alveolar bone widths and that these patients are likely to experience increased

iatrogenic sequelae.

Bibby R E (1980)28

studied how the incisors were accommodated and whether there

is any consistent pattern operating. Sella-nasion is a stable reference plane for this

sample. Skeletal classification based on the relative prognathism of A and B points to

the cranial base indicates that Class II skeletal types, are produced due to a relatively

retruded mandible. Similarly, skeletal Class III types are due to a relatively retruded

maxilla. A compensation mechanism exists which allows upper and lower incisors ‘to

be accommodated in a normal relationship regardless of skeletal class. This

compensation is effected by both upper and lower incisors in skeletal Class III types

and mainly by the upper incisors in skeletal Class II types.

Perera P S G (1987)29

conducted a cephalometric and dental serial study of 29

untreated subjects over 9 years (11.21+/-1.1 years to 19.90+/-1.41 years), using


7

Bjork's method of superimposition, and found a statistical relationships between

rotational growth of the mandible and anterior mandibular crowding. The results

indicate that closing rotational growth in the mandible is closely related to the incisor

crowding that commonly occurs during this period of 9 years. These changes appear

to be mediated through a compensatory proclination of the mandibular incisors within

the symphysis that is associated with this rotation.

Kilpeläinen P V J (1993)30

473 parents of children being screened at an orthodontic

graduate clinic completed a self-report form about the child’s dental/facial

appearance, reasons for seeking care and referral paths. Almost all (85%) of the 313

parents of children under the age of 16 years expressed concern about the appearance

of the child’s teeth, and 44% reported the child had been teased about this. Only 14%

of the parents reported that it was the child who had first noticed the need for

treatment. The rank order of reasons for seeking treatment were appearance of teeth

(85%), advice of dentist (73%), and appearance of face (46%). Using logistic

regression, overjet and malalignment were observed to be significant predictors of the

parent report of the child being teased (odds ratios [OR] 5.5 and 2.4, respectively).

Overjet predicted citing facial appearance as the reason for seeking treatment (OR

2.9), while age predicted patient-referral (OR 2.2) and overjet predicted parental

referral (OR 3.0). Increased overjet is an important focus for early treatment and

might accordingly be expected to influence the value of early intervention.

Beckmann S H, et al (1998)

15 conducted a study to investigate whether in the maxilla

and in the mandible the structure of the anterior medial sagittal alveolar and basal

bone is related to the overbite. A total of 460 untreated adult subjects were divided

into four groups with either deep bite, normal overbite, end to-end bite, or open bite


8

and were compared. The overbite, lower face height, and anterior alveolar and basal

midsagittal cross-sectional areas from the maxilla and the mandible were assessed on

lateral cephalometric radiographs. A deeper bite coincided with smaller lower face

height, larger alveolar and basal areas, and a more widened shape of the symphysis. If

the lower face height was introduced as a covariable, the open bite group showed

significantly smaller maxillary and mandibular alveolar and basal cross-sectional

areas compared with the end-to-end group, the normal overbite group, or the deep bite

group. Vertical variation of the overbite probably coincides with a relative

hyperdevelopment or hypodevelopment of the symphysis.

McIntyre GT, Millett D T (2003)31

determined whether the lateral cephalometric

crown-root shape differs among the permanent maxillary central incisor in Class I,

Class II division 1, Class II division 2 and Class III malocclusions and to identify the

nature of any differences. Of the 499 lateral cephalograms recorded at a university

orthodontic clinic during 2001, 361satisfied the inclusion criteria. Sixty cephalograms

were selected from the four malocclusion groups and were digitized in random order.

The configurations of the 10 landmarks characterizing the crown root shape of the

permanent maxillary central incisor were then the optimal superimposed using

Procrustes algorithms. Discriminant analysis of the principle components of shape

determined the incisor shape differences between the malocclusion groups. The

crown-root shape of the permanent maxillary central incisor did not differ

significantly among the Class I, Class II division 1, and Class III groups (P > .05);

however, the crown-root shape of the Class II division 2 permanent maxillary central

incisor was significantly different (P < .001) from that of the Class I, Class II division

1 and Class III. The shape discrimination involved axial bending of the Class II

division 2 incisors. Principle components 1=incisor crown tip, 2=incisor root apex,


9

and 3=palatal amelocemental junction accounted for 63% of the Class II division 2

incisor shape variance, encompassing a shorter root, a longer crown, and axial

bending of the incisor, in addition to a reduced labiopalatal thickness. These shape

features could precipitate the development of a deep overbite in Class II division 2

malocclusions and may limit the amount of palatal root torque during fixed appliance

therapy.

Ochoa B K, Nanda R S (2004)32

carried a study on lateral cephalometric radiographs

to compare growth patterns of the maxilla and mandible, with hand-wrist radiographs

which are used to assess skeletal maturity. The sample comprised of 28 untreated

subjects (15 female, 13 male) who were followed from ages 6 to 20 years. All

subjects had Class I malocclusions without anterior crossbites. Absolute values and

incremental changes for linear and angular cephalometric measurements were

recorded and analyzed, and the relative growth-rate formula was used to provide an

accurate index of acceleration and deceleration of growth. The SNA angle did not

change significantly with age, but the SNB angle increased significantly in the male

subjects. The ANB angle decreased continuously until age 14. The palatal plane

descended significantly from the horizontal plane. The anterior and posterior nasal

spines moved at about the same rate. The mandible grew in length twice as much as

the maxilla from ages 6 to 20. With growth, the facial profiles of the male subjects

became straighter as the chin became more prominent. The female subjects had less

incremental growth and duration of growth of the mandible, so that the profiles

remained more convex. Overall, skeletal and chronologic ages did not differ

significantly, except at ages 10 and 16 in the female subjects. Individual variability

pointed to the need for assessing each patient's pattern in the general guidelines of the

group pattern.


10

Yamada C, et al (2007)23

conducted a study to examine if there was any correlation

between the labio-lingual inclinations of the mandibular central incisor and the

associated alveolar bone, and to investigate the labio-lingual position of the

mandibular central incisor root apex in the associated cancellous bone in adults with

untreated mandibular prognathism. High-resolution computed tomography images of

the mandible were recorded in 20 adult patients with mandibular prognathism. They

concluded, in adults with untreated mandibular prognathism, when the mandibular

central incisor was more lingually inclined, the associated alveolar bone was also

more lingually inclined and thinner. The mandibular central incisor root apex was

closer to the inner contour of the labial cortical bone than to the lingual cortical bone.

Chung C J, Jun S, Baik H (2008)12

conducted a study to evaluate the relationship of

the morphological characteristics of the symphyseal region of adult Class III

malocclusion to the differences in overjet and overbite. The basal and symphyseal

widths along with the alveolar and symphyseal heights were evaluated using data

from the lateral cephalograms of skeletal Class III, divided into crossbite (n = 28) and

openbite (n = 41) groups. Male normal occlusion samples (n =32) were used as

controls. He concluded, An openbite, rather than a negative overjet, is the major

factor influencing the symphyseal morphology in an adult Class III malocclusion.

Buschang P H (2008)7 established reference data for anterior and posterior

dentoalveolar heights of growing French-Canadians with untreated normal occlusions

and malocclusions. The mixed longitudinal sample includes 227 French- Canadians,

119 male and 108 female, with cephalograms taken annually between 10-15 years of

age. Maxillary and mandibular dentoalveolar heights were measured as the

perpendicular distances of the incisor tips and first molar mesial cusp tips to the


11

palatal (ANS-PNS) and mandibular (Go-Me) planes. Male dentoalveolar heights were

significantly (P < .05) greater than female heights at all ages. Dentoalveolar heights at

15 years of age were significantly larger (P < .05) than at 10 years of age, with

differences ranging from 2.1–4.2 mm in male subjects and from 2.1–3.8 mm in

female subjects. The greatest difference in dentoalveolar heights between the 10- and

15-yearold age groups was for the maxillary first molar; the maxillary central incisor

height showed the smallest age effects. The coefficients of variation were greater for

the maxillary than the mandibular dentoalveolar heights. Correlations of dentoalveolar

heights within jaws ranged from 0.53 to 0.82; correlations between jaws ranged from

0.30 to 0.44. The mandibular heights showed the strongest associations. French-

Canadian adolescents require age- and sex-specific reference data for dentoalveolar

heights.

Kim Y, Park J U, Kook Y (2009)34

conducted a study to test the hypothesis that

there is no difference in the vertical alveolar bone levels and alveolar bone thickness

around the maxillary and mandibular central incisors in surgically treated skeletal

Class III malocclusion patients. The study sample comprised patients with skeletal

Class III malocclusion with anterior crossbite and openbite. Three dimensional cone

beam computed tomography images were taken at least 1 month before the

orthognathic surgery, and sagittal slices chosen at the labio-lingually widest point of

the maxillary and mandibular right central incisor were evaluated. Measurement of

the amount of vertical alveolar bone levels and alveolar bone thickness of the labial

and lingual plate at the root apex was made using the SimPlant Pro 12.0 program. The

hypothesis was rejected. For the skeletal Class III patients undergoing orthognathic

surgery, special care should be taken to prevent or not aggravate preexisting alveolar

bone loss in the anterior teeth, especially in the mandible.


12

Gracco A (2009)

35 studied the correlations between the morphology of the upper jaw,

the position of the upper incisors, and facial type. From a sample of 191 patients, the

FMA angle was used to select 20 short face type, 20 normal face type, and 20 long

face type patients, aged 12 to 40 years. Using cone-beam computed tomography

(CBCT); tomography was carried out on sagittal sections corresponding to the four

upper incisors. Some parameters defining the dentoskeletal relationships, the alveolar

thickness, the alveolar height, and the dental movement were measured. The

measurements were processed using analysis of variance and Tukey'stest. At the

upper central incisors, short face type patients presented a greater alveolar bone

thickness than long face type patients. In short face type and normal face type subjects

the root apex of the upper incisors was farther away from the lingual cortex than in

the long face type patients. At the central incisors the alveolar thickness was greater

and the lingual cortex was higher with respect to the lateral incisors in all three facial

types. With respect to the upper incisors, facial types are correlated statistically

significantly with both alveolar bone thickness and distance between the root apex

and lingual cortex.

Esenlik E, Sabuncuoglu F A (2012)

3 conducted a study 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 (n = 58), hypodivergent (n = 19), and normodivergent groups (n = 34).

The heights and widths of the symphysis and alveolus and the depth of maxillary

palate were measured on the lateral cephalograms. He concluded that Symphysis

width is the main factor in the differential diagnosis of Class II division 1 anomaly


13

rather than symphysis height and hypodivergent Class II Division 1 anomaly is more

suitable for mandibular incisors movements.

Baysal A, Ucar F I , BuyukS K, Ozer T , Uysal T (2013)

36 study was conducted

to evaluate lower incisor position and bony support between patients with Class II

average- and high-angle malocclusions and compare with the patients presenting

Class I malocclusions. CBCT records of 79 patients were divided into 2 groups

according to sagittal jaw relationships: Class I and II. Each group was further divided

into average- and high-angle subgroups. Six angular and 6 linear measurements were

performed. They concluded that Mandibular anterior bony support and lower incisor

position were different between average- and high-angle Class II patients. Range of

lower incisor movement in high-angle Class II patients is limited compared to average

angle class II patients.

Krishana N, Shetty A, Girija M. P, Nayak R (2013)37

Conducted a study to

Evauated change in alveolar bone as a result of maxillary and mandibular incisor

retraction in patients with bimaxillary protrusion by means of using lateral

cephalogram and computed tomography (CT)scans and to investigate any occurance

of bony defect like dehiscence and fenestration. Ten patients (age 15 ± 3 years) with

bimaxillary protrusion treated by extraction of four first premolars were investigated

by lateral cephalograms and CT scans during pre‑ treatment (T1) and after 3 months

of completion of incisor retraction (T2). In the mandibular arch, after lingual

movement of the incisors, the bone labial to the anterior teeth decreased in thickness

at the coronal level of the left lateral and left central incisors. In the maxilla the

change in the labial bone thickness was not statistically significant.He concluded,

when incisors are retracted, the risk of adverse effect is present. This must be

carefully monitored to avoid negative iatrogenic effects.


14

Nahás-Scocate A C (2014)38

evaluated the amount of buccal and lingual supporting

bone tissue of 60 upper central incisors and the relationship with their inclination.

Thirty healthy adult patients with no previous orthodontic treatment were evaluated

using cone-beam computed tomography. Cross-sectional views were analyzed to

check the amount of the bone tissue on the cervical (cervical buccal thickness/CBT;

lingual/CLT), middle (middle buccal thickness/MBT; lingual/MLT), and apical

regions (apical buccal thickness/ABT; lingual/ALT). The Pearson correlation, linear

regression, and analysis of variance tests were used (P < .05). For both surfaces

(buccal and lingual), the amount of bone tissue in the apical region was significantly

higher than the middle and cervical regions, and the middle region was significantly

higher than the cervical region. In relation to the upper central incisor's inclination,

the higher the U1/PP the higher was ABT. However, the coefficient values for both

upper central incisors were low.

Gutermanna C (2014)39

reassessed the inclination of lower incisors and evaluated

possible associations with gender, age, symphyseal parameters, and skeletal pattern.

Twelve hundred and seventy-two (605 females, 667 males) cephalograms of untreated

subjects of a craniofacial growth study (8–16 years) were evaluated. Correlations

between the angulation of the lower incisors and age, symphyseal distances (height,

width, and depth), symphyseal ratios (height-width, height-depth), and skeletal angles

(divergence of the jaws and gonial angle) were investigated for all ages separately and

for both sexes independently. Lower incisor inclination was linked to the subject’s

sex, age, and skeletal pattern. The inclination of lower incisors increased over age,

correlated with the divergence of the jaws for all ages significantly or highly

significantly, except for boys and girls 9 years of age and girls 11 and 12 years of age,

for which only a tendency was observed. Similarly, a strong correlation to gonial


15

angle was observed. No correlation was found between the inclination of lower

incisors and any symphyseal parameters (absolute measurements and ratios), except

for symphyseal depth. The inclination of lower incisor was not associated with

symphyseal dimensions, except symphyseal depth. Factors related to natural

inclination of lower incisors should be respected when establishing a treatment plan.

Dayoub N S, Al- Sabbagh R (2015)40

conducted a study to assess the supporting

bone tissue thickness of 68 lower central incisors and to investigate the impact of

gender on the alveolar bone thickness. Thirtyfour healthy patients with no previous

orthodontic were evaluated by Cone Beam Computed Tomography. Sagittal sections

views were analyzed to check the thickness of supporting bone on the cervical, middle

of the root and apical for both surfaces buccal and lingual. The results showed that

buccal apical and lingual apical regions had the greatest values of bone tissue

thickness, and the lowest values were in lingual cervical, buccal cervical and buccal

middle of the root for both lower central incisors. There was no significant effect of

gender on supporting bone thickness.

Arriola-Guille´n L E, Flores-Mir C (2015)

41 conducted a study to compare the

anterior dentoalveolar and skeletal maxillary cephalometric factors involved in

excessive upper incisor crown exposure (UICE) in subjects with skeletal open bite

Class II (SOBCIIG) and Class III (SOBCIIIG) against an untreated control group

(CG). Seventy pretreatment lateral cephalograms of orthodontic young adult patients

(34 men, 36 women) were examined. The sample was divided into three groups

according to both sagittal and vertical growth pattern and occlusion. Several

cephalometric measurements were considered (skeletal and dental). Princicipal

component analysis (PCA) showed that a nondental component—including vertical


16

maxillary height (VMH) and upper lip height (ULH)—was the only component

significantly associated with upper incisor crown exposure (UICE). Although the

upper incisor crown exposure (UICE) was statistically different in skeletal open bite

Class II (SOBCIIG), the values were within the esthetic standards. The upper incisor

crown exposure (UICE) was mainly influenced by vertical maxillary height (VMH)

and upper lip height (ULH).

Methodology

17

MATERIAL AND METHODS

Material required:

In this study a total of 80 lateral cephalograms of adult patients over the age of

18years (50 of patients with skeletal class I malocclusions and 30 lateral

cephalograph of patients with skeletal class-ІІІ malocclusion) referred to the

department of orthodontics and dentofacial orthopedics, Al-Badar dental college and

hospital, Gulbarga were evaluated.

The skeletal Class III sample was selected in accordance with the following

inclusion criteria

Class III intermaxillary jaw base relationship (ANB below 0O, AO – BO ≤ -

0.5mm)

Class III molar relationship, negative overjet, positive overbite and deep

vertical incisal overlap.

Brachyfacial pattern with low mandibular plane angle (angular value of FMA

< 20o and SN GO-GN < 29

o)

The skeletal Class I control group exhibited normal ANB angle, normal

overjet and acceptable occlusion.

Cephalometric Analysis:

The lateral cephalograms were taken with the head locked in position by ear

rods and nasal support. The Frankfort horizontal plane was set parallel to the floor

and teeth were in centric occlusion. The x-rays were taken with a focus coronal plane

distance of 200cm and an enlargement of 7.5 %.

Methodology

18

All cephalograms were traced manually by a single examiner using a

protractor with 0.5° and 0.5 mm accuracy as described in, (Table 1 and fig.1).

Duplicate tracings of 30 landmarks on 15 randomly chosen cephalograms were done

at a 2month interval by the same examiner. The systematic error was evaluated with a

paired t Test at P < 0.05. No significance was noted in the measurements of the first

and second evaluation.

The cephalometric data of the control, Class III cross bite groups were

presented as a mean ± SD. The results were inferred by analysis of variance

(ANOVA) using statistical software (SPSS version 23). P < 0.05 was considered

significant.

Table.1 and fig.1

No Landmarks Definition

1. 1/PP (°) The angle from the maxillary central Incisor’s axis to

the palatinal plane (ANS–PNS).

2. 1/MP (°) The angle from the mandibular central incisor’s axis

to the mandibular plane (Go – Me).

3. Mandibular incisor

dentoalveolar

height (L1–AH)

The perpendicular distance between the lower incisor

tip and mandibular plane.

4. Mandibular molar

dentoalveolar

height (L6–AH)

The perpendicular distance between the lower first

molar mesial cusp tip and mandibular plane.

5. Maxillary incisor

dentoalveolar

height (U1–AH)

The perpendicular distance from the upper incisor tip

to the palatal plane.

6. Maxillary molar

dentoalveolar

height (U6–AH)

The perpendicular distance from the upper first molar

mesial cusp tip to the palatal plane.

Methodology

19

7. Id–Id′ width The distance between the most anterosuperior (Id) and

most posterosuperior (Id′) points on the mandibular

alveolus.

8. B–B′ width The distance between the B and B′ (the lingual

projection of the B point at the lingual symphysis

border) points.

9. Symphysis

height

The distance from the midpoint of the anterior

alveolus to the Menton point. The symphysis ratio

was calculated by dividing the symphysis height by

the symphysis width.

10. Symphysis

width

The perpendicular distance from the pogonion to the

most convex point of the lingual curvature of the

symphysis.

11. Maxillary depth The distance from the deepest point on the palatal

bone curvature to the A point.

Figure 1. Dentoalveolar and Symphysis Parameters. 1: 1/PP, 2: 1/MP,

3:L1/AH, 4:L6/AH, 5:U1/AH, 6:U6/AH, 7:Id-Id' width, 8:B-B' width, 9:

Symphysis height, 10: Symphysis width, 11: maxillary depth.

Sample size Estimation

20

SAMPLE SIZE ESTIMATION

The formula for sample size determination for t test is

n=(Z*Z*SD*SD)/ME*ME

Z = z value for 85% power = 1.44

SD= SD of SNB = (3+3.6)/2 = 3.3 (table no 2)

ME= Margin of error = SD/(SQRT of N) = 3.3/ (SQRT32)=0.58

substituting the above we get the total sample size of

(1.44*1.44*3.3*3.3)/0.58*0.58 = 68.4 = 70

the minimum total sample size will be 70.

Results

21

RESULTS

Table 2 provide a summary of the skeletal characteristics of the Class III cross

bite and Class I control groups. The skeletal Class III cross bite group showed a larger

SNB, ANB and AO-BO measurements compared with the control group. The values

for the above parameters were significantly different between the control and class III

cross bite groups. Class I control group had a significantly lesser mandibular plane

angle than the Class III cross bite group (p <0.001).

Table 2: Intergroup comparison of skeletal parameters

Parameter Class III Class I Mean

Difference

P value

N Mean Std.

Deviation

N Mean Std.

Deviation

SNA (o) 30 82.033 5.1158 50 81.960 2.8569 0.073 0.935 NS

SNB (o) 30 85.700 4.4346 50 78.600 5.4210 7.1 <0.001**

ANB (o) 30 -3.667 2.7834 50 2.880 .9179 -6.54 <0.001**

AO-BO

(mm)

30 -7.733 4.1100 50 .680 .4712 -8.41 <0.001**

GO-GN-

SN(o)

30 26.800

4.5768 50 23.867 1.6288 -2.93 0.002*

NS- Not significant (p>0.05), *-Significant (p<0.05), **-Highly significant (p<0.001)

COMPARISON OF MAXILLARY PARAMETERS

Table 3 shows an increased maxillary incisor inclination in Class III cross bite

group (128.5 ± 8.3; Mean ± SD) compared to class I subjects (123.6 ± 7.7; Mean ±

SD) with a significant difference between the two groups (p<0.05). The maxillary

Results

22

incisal dento alveolar height has an insignificant difference between the two groups.

The maxillary molar dento alveolar height and maxillary depth were significantly

greater in the Class III cross bite group, than in the control group (p<0.001).

Table 3: Intergroup comparison of various maxillary parameters


Difference

P value

N Class

III

Std.

Deviation

N Class I Std.

Deviation

1/ PP(o) 30 128.533 8.3490 50 123.660 7.7739 4.87 0.010*

U1-

AH(mm)

30 26.333 4.9434 50 25.720 2.5638 .6133 0.467 NS

U6-

AH(mm)

30 23.900 3.0777 50 20.780 2.2704 3.1200 <0.001**

Max

Depth

(mm)

30 16.200 3.2206 50 12.460 2.4596 3.7400 <0.001**


COMPARISON OF MANDIBULAR PARAMETERS

Table 4 shows Mandibular incisal inclinations were significantly greater in

Class I control group than in Class III cross bite group (P<0.001**). Mandibular

insisal dento alveolar height and mandibular molar dento alveolar height were

significantly greater in the Class III cross bite group than in the Class I control group

(p<0.001).

Results

23

Table 4: Intergroup comparison of mandibular parameters


Difference

P value

N Class

III

Std.

Deviation

N Class I Std.

Deviation

1/MP(o) 30 92.533 8.5892 50 105.120 7.2016 -12.5867 <0.001**

L1-

AH(mm)

30 41.267 4.2906 50 36.840 2.7207 4.4267 0.001*

L6-

AH(mm)

30 31.733 3.7040 50 28.800 2.3561 2.9333 <0.001**

**-Highly significant (p<0.001)

COMPARISON OF SYMPHYSIS PARAMETERS

Table 5 shows symphysis height and width were significantly greater in Class

III cross bite group than in the control group, while symphysis ratio was similar in

both the groups.

Results

24

Table 5: Intergroup comparison of symphysis parameters


Difference

P value

N Class

III

Std.

Deviation

N Class I Std.

Deviation

Id-IdI

(mm)

30 6.600 .8137 50 5.900 .6776 .7000 <0.001**

B-BI

(mm)

30 8.367 1.0981 50 9.460 1.4316 -1.0933 0.001*

Sym Ht

(mm)

30 32.200 3.9339 50 28.920 2.2663 3.2800 <0.001**

Sym

Width

(mm)

30 13.800 1.7499 50 12.620 1.4270 1.1800 0.002*

Sym h/w 30 2.3567 .36073 50 2.2752 .28403 .08147 0.266 NS


Discussion

25

DISCUSSION

The mandibular bone is strongly influenced by the masticatory function.42-45

Maxillofacial region contains essentially membranous bone and is more susceptible to

environmental factors such as the stimulating influence of muscles and extra

functional forces.17,46

During the power stroke of mastication, the middle and lower third of the

labial aspect of the symphysis is predominantly sheared dorsoventrally, twisted and

bent according to the magnitude and position of the bite force.42-44

Therefore it was hypothesized that due to differences in the bite force direction

of mandibular incisors, the morphological characteristics of mandibular symphysis

and premaxillary alveolus can vary between normal Class I and Class III cross bite

brachyfacial subjects.

The results showed a significant increase in the maxillary incisal inclination,

depth and dento alveolar molar height in the Class III cross bite groups than in the

control groups. In the lower jaw the mandibular incisor showed a significant

retroclination in Class III cross bite group and the mandibular molar dento alveolar

height and incisal dento alveolar height was greater in the Class III cross bite group

than in the control group.

Maxillary incisal proclination and mandibular incisal retroclinaton in Class III

cross bite group probably resulted from a dento alveolar compensation, to Class III

skeletal discrepancies.

The maxillary alveolar process, mandibular condyle and alveolar process were

defined as major sites of bony additions.10

The Class III cross bite subjects in the

Discussion

26

present study showed an increased gonial angle compared to the control group. This

downward and backward rotation of the mandible is associated with excessive

extrusion of posterior maxillary and mandibular alveolar processes contributing to

vertical development. This also explains the increased lower anterior dental height in

Class III cross bite subjects. The increased depth of the maxillary alveolus in Class III

cross bite subjects could be possibly due to remodeling changes associated with

premaxillary alveolus as a part of dento alveolar compensations seen with Class III

skeletal patterns.

Karlsen10

stated that alveolar process growth demonstrated compliance with

mandibular rotation. He also stated that dentoalveolar mechanisms have great

potential for compensating for vertical skeletal deviations. Overdevelopment of the

anterior lower facial height was compensated by marked growth of the incisal heights

in both jaws. In his study evaluating low and high angles in patients 6-12 years of age,

he found great increases in the upper and lower incisor heights in the high angle cases.

As the mandible is displaced downward and forward, supraeruption of the incisors

fills the created space.6 Mandibular rotation also interacts with vertical growth, and

anterior or counterclockwise rotation might be expected to limit vertical change in the

anterior region.

Baumrind et al47

investigated the amount of modeling at the apices of the

mandibular and maxillary incisors and molars associated with remodeling changes in

the mandible from 8.5 to 15.5 years of age. They observed statistically significant

tooth displacements associated with surface remodeling in the maxilla at all

timepoints, whereas significant differences in the mandible were observed only in the

vertical direction in the incisors.

Discussion

27

Janson et al48

stated that the lower anterior dental height was significantly

different in each facial type. When we compared anterior alveolar heights in the

present study, we found that the upper and lower incisor heights were increased

slightly but significantly in the Class III cross bite group as seen in Karlsen’s10

study.

Clinicians classify the growth pattern of the mandible anteriorly or posteriorly

according to the symphysis shape and size.10

Symphysis ratio in particular was found

to be strongly related to the direction of mandibular growth4.

Noh et al49

found that a high symphysis ratio presented high correlations with

the hyperdivergent pattern and increased gonial angle. In contrast, Kim and Son50

found no statistically significant difference in symphysis ratio to mandibular plane

between forward and backward rotational growth patterns.

Morphological differences in the symphyseal region between Class III cross

bite and Class I normal occlusion were found in the present study. Symphyseal height

and width; Id–Id and B-B widths were significantly greater in Class III cross bite

subjects compared to Class I controls.

The findings of the present study indicate a large symphysis allows a greater

sagittal but also vertical mandibular tooth movements, particularly required during

decompensation of anterior dental segments during the phase of pre surgical

orthodontics.

Bone is a dynamic tissue that constantly undergoes remodeling, but it has been

reported that remodeling can remove or conserve the bone but not add to it. New bone

formation at the labial side after incisal movements could be expected in growing

patients but not in nongrowing patients.3 It is suggested that rapid tipping tooth

Discussion

28

movements contribute to bone dehiscence and root resorption.51

Sufficient alveolar

bone thickness in the lower incisor region is critical in the case of Class III skeletal

malocclusions requiring orthognathic surgery.

Studies have shown a narrow symphysis is detrimental in surgical treatment of

Class III malocclusions since the lower incisors would be limited in their antero

posterior tooth movements thus compromising on the antero posterior segments

during surgical intervention.

Hence a wider and thicker symphysis is accommodative of all incisal

movements in the labiolingual direction in Class III skeletal subjects requiring

camouflage treatment or orthognathic surgery. The clinical implications from the

above findings imply iatrogenic damage of orthodontic treatment like dehiscence,

fenestration and root resorption are minimal in brachyfacial skeletal Class III

malocclusions compared to hyperdivergent skeletal Class III malocclusions.

Conclusion

29

CONCLUSIONS

Maxillary incisor inclination, Max molar dento alveolar height and maxillary

depth were significantly greater in the Class III cross bite group than in the

Class I control group.

Mandibular incisal dento alveolar height and mandibular molar dento alveolar

height were significantly greater in the Class III cross bite group than in the

Class I control group.

Symphysis height and width were significantly greater in the Class III cross

bite group than in the Class I control group.

Summary

30

SUMMARY

The prevalence of class III malocclusion varies according to ethnicity. In

orthodontics, knowledge of mandibular growth is highly beneficial in diagnosis and

treatment planning and is critical in the development of balanced dentofacial

structures.

The symphysis is one of the most important regions of the craniofacial

complex for clinical orthodontists, and it serves as a primary reference for esthetic

considerations in the lower one-third of the face. Vertical and sagittal positions of the

mandibular incisors are important determinants in planning occlusal and skeletal

relations for orthodontic treatment and orthognathic surgical procedures.

The region of the mandibular symphysis is involved in delicate and limited

movements, not only in esthetics, but with regard to bone and tooth resorptions.

Therefore, knowledge of the adequate limits of tooth movement and establishment of

parameters for the thickness of the alveolar process in the mandibular symphysis

region may have a significant influence on the diagnosis, and consequently, the end

result of orthodontic treatment.

Therefore the present study focused on the morphological characteristics of

symphysis and alveolus in Adult skeletal class III malocclusions with cross bite and

compared them with normal occlusion in brachyfacial structural patterns.

In this study a total of 80 lateral cephalograms of adult patients over the age of

18years (50 of patients with skeletal class I malocclusions and 30 lateral

cephalograph of patients with skeletal class-ІІІ malocclusion were evaluated. The

Summary

31

cephalometric data of the control class I group and Class III cross bite groups were

presented.

Thus the study concluded that Maxillary incisor inclination, Max molar dento

alveolar height and maxillary depth were significantly greater in the Class III cross

bite group than in the Class I control group.

Mandibular incisal dento alveolar height and mandibular molar dento alveolar

height were significantly greater in the Class III cross bite group than in the Class I

control group. Symphysis height and width were significantly greater in the Class III

cross bite group than in the Class I control group.

Bibliography

32

BIBLIOGRAPHY

1. Mehboob B, Rasool G, Amin M, Characteristics of skeletal class III

malocclusion and its associated dento alveolar compensation, JKCD

December 2011, Vol. 2, No. 1.

2. Sassouni V. The Class II syndrome: Differential diagnosis and treatment.

Angle Orthod 1970;40:334-341.

3. Esenlik E, Sabuncuoglu F A. Alveolar and symphysis regions of patients with

skeletal class II division 1 anomalies with different vertical growth patterns.

European Journal of Dentistry 2012; 6.

4. Aki T, Nanda RS, Currier GF, Nanda SK. Assessment of the symphysis

morphology as a predictor of the direction of mandibular growth. Am J Orthod

1994;106:60-69.

5. Bjork A. Prediction of mandibular growth rotation. Am J Orthod 1969;55:585

599.

6. Isaacson JR, Isaacson RJ, Speidel TM, Worms FW. Extreme variation in

vertical facial growth and associated variation in skeletal and dental relations.

Angle Orthod 1971;41:219-229.

7. Buschang PH, Julien K, Sachdeva R, Demirjian A. Childhood pubertal

growth changes of the human symphysis. Angle Orthod 1992;62:203-210.

8. Enlow DH, Harris DB. A study of the postnatal growth of the human

mandible. Am J Orthod 1964;75:25-50.

9. Skieller V, Bjork A, Linde-Hansen T. Prediction of mandibular growth

rotation evaluated from a longitudinal sample. Am J Orthod 1984;86:359-370.

10. Karlsen AT. Craniofacial growth differences between low and high MP-SN

angle males: a longitudinal study. Angle Orthod 1995;65:341-350.

Bibliography

33

11. Perera PSG. Rotational growth and incisor compensation. Angle Orthod

1987;57:39-49.

12. Chung CJ, Jung S, Baik HS. Morphological characteristics of the symphyseal

region in adult skeletal Class III crossbite and openbite malocclusions. Angle

Orthod 2008;78:38-43.

13. Haskell BS. The human chin and its relationship to mandibular morphology.

Angle Orthod 1979;49:153-66.

14. Wehrbein H, Bauer W, Diedrich P. Mandibular incisors, alveolar bone, and

symphysis after orthodontic treatment. A retrospective study. Am J Orthod

Dentofacial Orthop 1996;110:239-46.

15. Beckmann SH, Kuitert RB, Prahl-Andersen B, Segner D, The RPS, Tuinzing

DB. Alveolar and skeletal dimensions associated with overbite. Am J Orthod

Dentofacial Orthop 1998;113:443-52.

16. Tanaka R, Suzuki H, Maeda H, Kobayashi K. Relationship between an

inclination of mandibular plane and a morphology of symphysis [in Japanese].

Nippon Kyosei Shika Gakkai Zasshi. 1989;48:7–20.

17. Kubota M, Nakano H, Sanjo I, Satoh K, Sanjo T, Kamegai T, Ishikawa F.

Maxillofacial morphology and masseter muscle thickness in adults. Eur J

Orthod. 1998;20:535–542.

18. Eroz UB, Ceylan I, Aydemir S. An investigation of mandibular morphology in

subjects with different vertical facial growth patterns. Aust Orthod J.

2000;16:16–22

19. Ceylan I, Eroz UB. The effects of overbite on the maxillary and mandibular

morphology. Angle Orthod. 2001;71:110–115.

Bibliography

34

20. Nojima K, Nakakawaji K, Sakamoto T, Isshiki Y. Relationships between

mandibular symphysis morphology and lower incisor inclination in skeletal

class III malocclusion requiring orthognathic surgery. Bull Tokyo Dent Coll.

1998;39:175–181.

21. Shimomoto Y, Iwasaki Y, Chung CY, Muramoto T, Soma K. Effects of

occlusal stimuli on alveolar/jaw bone formation. J Dent Res. 2007;86:47–51.

22. Garn SM, Lewis B, Vicinus JH. The inheritance of symphyseal size during

growth. Angle Orthod. 1963;33:222–231.

23. Handelman CS. The anterior alveolus: its importance in limiting orthodontic

treatment and its influence on the occurrence of iatrogenic sequelae. Angle

Orthod. 1996;66:95–110.

24. Proffit WR, Whilte RPJ, Sarver DM. Contemporary Treat ment of Dentofacial

Deformity. New York, NY: Elsevier Inc; 2003.

25. Mulie RM, Hoeve AT. The limitations of tooth movement within the

symphysis studied with laminagraphy and standardized occlusal films. J Clin

Orthod. 1976;10:882–893,886–889.

26. Schudy F F. Cant of the Occlusal Plane and Axial Inclinations of Teeth. Angle

Orthod 1963; 33( 2):69-82.

27. Robert J. Sci-Iuli-Iof, A.B, M.A. Robert W. Allen, Roland D. Walters and

Michael Dreskin. The Mandibular Dental Arch: Part 1, Lower Incisor

Position. Angle Orthod. 1974, ;47( 4): 280- 87.

28. Bibby R E. Incisor relationships in different skeletofacial patterns. Angle

Orthod: 1980; 50(1): 41-44.

29. Perera P S G. Rotational Growth and Incisor Compensation. Angle Orthod.

1987; 57(1):39-49.

Bibliography

35

30. Kilpeläinen P V J, Phillips C, Tulloch J F C. Anterior tooth position and

motivation for early treatment. Angle Orthod. 1993;63(3):171-174 .

31. McIntyre G T, Millett D T. Crown-root shape of the permanent maxillary

central incisor. Angle Orthod. 2003; 73(6):710-5.

32. Ochoa B K and Nanda R S. Comparison of maxillary and mandibular growth

.Am J Orthod Dentofacial Orthop. 2004;125:148-59.

33. Yamada C, ‘et al’, SpatiaRelationships between the Mandibular Central

Incisor and Associated Alveolar Bone in Adults with Mandibular

Prognathism. Angle Orthodontist 2007; 77( 5)

34. Kim Y, Park J U, Kook Y. Alveolar Bone Loss around Incisors in Surgical

Skeletal Class III Patients. Angle Orthod 2009; 79:676–682.

35. Gracco A, Lombardo L, Mancuso G, Gravina V, Siciliani G. Upper incisor

position and bony support in untreated patients as seen on CBCT. Angle

Orthod. 2009; 79(4):692-702.

36. Baysal A, Ucar F I, Buyuk S K, Ozer T , Uysal T . Alveolar bone thickness and

lower incisor position in skeletal Class I and Class II malocclusions assessed

with cone-beam computed tomography. Korean J Orthod 2013; 43(3):134-140

37. Krishna N, Shetty A, Girija MP, Nayak R. Changes in alveolar bone thickness

due to retraction of anterior teeth during orthodontic treatment: A

cephalometric and computed tomography comparative study. Indian J Dent

Res 2013; 24:736-41.

38. Nahás-Scocate A. C, De Siqueira Brandão A, Patel MP, Lipiec -Ximeneme,

Chilvarquer I, DoValle - Corottickm. Bone tissue amount related to upper

incisors inclination. Angle Orthod. 2014; 84(2):279-85.

Bibliography

36

39. Gutermanna C, Peltomakib T, Markicc M, Hanggia M, Schatzlec M ,

Signorellia L and Patcas R. The inclination of mandibular incisors revisited.

Angle Orthod.2014; 84:109-119.

40. Dayoub N S T et al. Assessment of Supporting Bone Thicknesses Related to

Lower Incisors -A CBCTStudy Int.J. PharmTech Res. 2015; 8(1):53-62.

41. Arriola-Guille´n L E, Flores-Mir C. Anterior maxillary dentoalveolar and

skeletal cephalometric factors involved in upper incisor crown exposure in

subjects with Class II and III skeletal open bite. Angle Orthod 2015; 85:72–79.

42. Hylander WL. In vivo bone strain in the mandible of Galago crassicaudatus.

Am J Phys Anthropol. 1977;46:309–326.

43. Hylander WL. Stress and strain in the mandibular symphysis of primates: a

test of competing hypotheses. Am J Phys Anthropol. 1984;64:1–46.

44. Korioth TW, Hannam AG. Deformation of the human mandible during

simulated tooth clenching. J Dent Res. 1994; 73:56–66.

45. Korioth TW, Hannam AG. Mandibular forces during simulated tooth

clenching. J Orofac Pain. 1994;8:178–189.

46. Dulkin J. Secondary cartilage: a misnomer? Am J Orthod. 1972;62:15–41.

47. Baumrind S, Bravo LA, Ben-Bassat Y, Curry S, Korn EL. Lower molar and

incisor displacement associated with mandibular remodeling. Angle Orthod

1997;67:93-102.

48. Janson GRP, Metaxas A, Woodside DG. Variation in maxillary and

mandibular molar incisor vertical dimension in 12-year old subjects with

excess, normal and short lower anterior face height. Am J Orthod

1994;106:409-418.

Bibliography

37

49. Noh SH, Lee KS, Park YK. A cephalometric study on correlation between

mandibular symphysis and craniofacial skeleton. Korean J Orthod

1997;27:119-127.

50. Kim SJ, Son WS. A study on the relationship of the mandibular symphysis

and anterior alveolar and skeletal morphology according to the rotational

growth pattern of mandible in skeletal Class III malocclusion Korean J Orthod

1999;29:303-315.

51. Diedrich P. Problems and risks in the movement of the mandibular anterior

teeth. Fortschr Kieferorthop 1995;56:148-156.

Consent Form

38

AL - BADAR

RURAL DENTAL COLLEGE & HOSPITAL, GULBARGA

CONSENT FORM

I ………………………………………. OPD No…...... undergoing Orthodontic

treatment in the Department of Orthodontics and Dentofacial Orthopedics, Al Badar

Rural Dental College and Hospital, have been explained about the research study, and

I hereby give my consent for taking my lateral cephalogram.

Signature of patient

Ethical Clearance

39

Proforma Prototype

40

PROFORMA PROTOTYPE

The skeletal Class III sample was selected in accordance with the

following inclusion criteria

Class III intermaxillary jaw base relationship (ANB below 0O, AO – BO ≤

-0.5mm)

Class III molar relationship, negative overjet, positive overbite and deep

vertical incisal overlap.

Brachyfacial pattern with low mandibular plane angle (angular value of

FMA < 20o and SN GO-GN < 29

o)

The skeletal Class I control group exhibited normal ANB angle, normal

overjet and acceptable occlusion.

Exclusion criteria

Patient with

1. Congenital anomalies and

Hypodontia are excluded from study.

Lateral cephalogram evaluation parameters;

Proforma Prototype

41

Dentoalveolar and Symphysis Parameters. 1: 1/PP, 2: 1/MP, 3:L1/AH, 4:L6/AH,

5:U1/AH, 6:U6/AH, 7:Id-Id' width, 8:B-B' width, 9: Symphysis height, 10:

Symphysis width, 11: maxillary depth.

Annexures

44

ANNEXURES

Digital Panoramic and Cephalometric Extra oral Imaging System

– Cephalostat (Kodak 8000C).

Annexures

45

The lateral cephalograms were taken with the head locked position.

Annexures

46

Annexures

47

Documents

ALVEOLAR AND SYMPHYSIS REGION CHARACTERISTICS OF …