dr. ramesh g.c.-dissertation

Rajiv Gandhi University of Health Sciences, Karnataka, Bangalore.

CEPHALOMETRIC EVALUATION OF OVERBITE AND VERTICAL CHANGES FOLLOWING FIRST PREMOLAR EXTRACTION IN HIGH

ANGLE CASES – A RETROSPECTIVE STUDY

By

Dr. RAMESH G.C.

Dissertation Submitted to theRajiv Gandhi University of Health Sciences, Karnataka, Bangalore.

In Partial fulfillmentof the requirements for the degree of

MASTER OF DENTAL SURGERY

In Speciality of

ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS

Under the Guidance of

Dr. ARUNKUMAR G.Associate Professor

Department of Orthodontics and Dentofacial OrthopedicsCollege of Dental Sciences,

Davangere.

2006- 2009

II

ACKNOWLEDGEMENT

This Dissertation represents the assistance and efforts of many individuals, the

contributions of whom I acknowledge and to whom I give my thanks.

I bow my head to the supreme force THE ALMIGHTY, driving me to my

destinations, I thank them for having blessed me with his choicest blessings and

opening the doors of opportunity to this adobe of knowledge and having blessed me

with most loving family and teachers.

Words are inadequate to express my indebtedness and infinite respect for my

“Guru” and Guide, DR ARUN KUMAR G. Associate Professor, Department of

Orthodontics, College of Dental Sciences, Davangere. His unfailing willingness to

render help and loving guidance, coupled with his rich knowledge and keen interest

have been a constant source of inspiration and backbone of this study. Lucky are the

few who are privileged to work under him and imbibe priceless insights into life. I

find myself deeply indebted to him for teaching me the true values of life, imbibing in

me his virtues of hard work, truthfulness and love towards fellow human beings.

It is with utmost sincerity that I thank my beloved Professor and Head,

Dr.G Shivaprakash. A mere word of thanks is not sufficient to express his solid

support, inspiration and unswerving guidance, during my post graduation and in the

preparation of this dissertation. As his post graduate student, I have not only

inculcated knowledge in the art and science of orthodontics but also other human

qualities of life. His discipline, principles, scientific approach and logical explanation

to this art of orthodontics shall always be my guiding star.

V

It is with utmost sincerity that I thank my beloved former Professor and Head,

Dr.Anmol S.Kalha. A mere word of thanks is not sufficient to express his solid

support, inspiration and unswerving guidance, during my post graduation and in the

preparation of this dissertation. To be his post graduate student definitely gives me

immense pleasure and honour.

The unflinching support and guidance I received from all the faculty members

during my post-graduate course leaves me with an overwhelming sense of profound

humbleness.

Let me at this juncture, pen down my deepest appreciation towards my

teachers, Dr.(Mrs) Mala Ram Manohar, Professor, Dr. Naveen Shamnur,

Associate Professor, Dr.Prabhuraj, Associate Professor, Dr.Umashankar, Reader,

Dr. Shashi Kumar, Asst. Professor, Dr. Anvar Latif, Asst. Professor, College of

Dental Sciences, Davangere for being my wheel of support and encouragement over

the last three years. It is with sincerest gratitude that I thank Dr. Litesh Singla &

Dr. Thomas, Assistant Professors, for giving valuable insights during the study and

during my post graduation course.

At this juncture my deepest gratitude goes to Sri. Shamanur

Shivashankarappa (Hon. Secretary), and Dr.V.V. Subba Reddy (Principal), for

providing me the kind of atmosphere, fully equipped with the near latest technologies.

This acknowledgement would be incomplete if I fail to mention

my Father Sri. CHANNAVEERAPPA, Mother Smt. GIRIJA, Brother in-laws,

DR A.R HANUMANTHAPPA and A.G NATRAJ GOWDA, and Sisters

Smt. SUDHA and Smt. REKHA and my Family Members. It is their love, prayers,

VI

many sacrifices and encouragement both morally and emotionally made it possible to

me what I am today.

It would be unfair on my part if I do not mention my batch mates,

Dr.Aravind, Dr. Naveen, Dr. Murtuza, Dr. Ankush and Dr. Divya, without them

this dissertation would have not been successful.

I would like to thank all my friends and especially juniors for their whole

hearted support in completion of my post graduate course.

With out the help of Mr. Sangam, our esteemed biostatistician, my work

would have gone unappreciated.

I also thank Mr.Surendra, Dyna Computers for organizing and neatly typing

this manuscript and Aruna Printers, for their services rendered.

A special word of thanks to the non teaching staff, especially sister Jesline,

Jagdish, Santosh and Neelappa, Geetha and Manjula for the help rendered

whenever required from them.

Place : Davangere.

Date : Dr. RAMESH G.C

VII

LIST OF ABBREVIATIONS USED

ANS Anterior nasal spine

BL1 Bodily movement of the mandibular incisors

FH Frankfort horizontal

Gn Gnathion

Go Gonion

HS Highly significant

I PM first premolar

II PM Second premolar

L1 Mandibular Central Incisor

L6 Mandibular first molar

LAFH Lower anterior face height

MNSK Mandibular skeletal change

MPA Mandibular plane angle

MXSK Maxillary skeletal change

N Nasion

NS Not significant

OP Occlusal plane

PEA Pre adjusted edgewise appliance

PFH Posterior face height

Pogv Pogonion vertical

S Sella

S Significant

Sv Sella vertical

TAFH Total anterior face height

TL1 Tipping movement of the mandibular incisors

TU1 Tipping movement of the maxillary incisors

U1 Maxillary Central Incisor

U6 Maxillary first molar

UAFH Upper anterior face height

ABSTRACT

VIII

Back ground & objectives : Orthodontists generally agree that non-extraction

treatment is associated with downward and backward rotation of the mandible and an

increase in the LAFH. They also agree that extraction line of treatment is associated

with upward and forward rotation of the mandible and decrease in the LAFH. The

intent of this cephalometric investigation was to examine the popular hypothesis,

(wedge hypothesis) that the vertical dimension collapses after first bicuspid

extraction. The present study was undertaken to evaluate the cephalometric overbite

and vertical changes following first premolar extraction in high angle cases.

Methods : A total of 25 adult patients having high mandibular plane angle i.e. Gogn –

SN more than or equal to 32 degrees having class I molar and canine relation were

included. Pre and post treatment lateral cephalograms were measured and compared

to analyze the cephalometric changes.

Results : There was a significant increase in the MPA. There was no significant

change in the pre and post treatment overbite, total anterior face height, lower anterior

face height and posterior face height.

Interpretation & Conclusion : The study concluded that, There was no increase in

the vertical facial dimension and overbite and no clinically significant increase in the

mandibular plane angle. However it should be interpreted with caution, given the

small sample size. The facial complex does increase in size with growth, but

mandibular plane while moving inferiorly, remain essentially parallel to its

pretreatment position, due to residual growth and treatment.

Key words: I premolar extraction; High angle; Wedge hypothesis; Lateral

cephalograms; Adult.

IX

TABLE OF CONTENTS

PAGE NO.

1. INTRODUCTION 01

2. OBJECTIVES 03

3. REVIEW OF LITERATURE 04

4. METHODOLOGY 24

5. RESULTS 38

6. DISCUSSION 44

7. CONCLUSION 50

8. SUMMARY 51

9. BIBLIOGRAPHY 52

10. ANNEXURES 58

X

LIST OF TABLES

SL.NO. TITLE PAGE NO.

Table 1DEFINITION OF CEPHALOMETRIC LANDMARKS AND MEASUREMENTS USED IN THE STUDY

25

Table 2 PRE AND POST TREATMENT COMPARISON OF ANGULAR MEASUREMENTS 39

Table 3 PRE AND POST TREATMENT COMPARISON OF LINEAR MEASUREMENTS 40

Table 4 PRE AND POST TREATMENT COMPARISON OF OVERBITE MEASUREMENTS 41

XI

LIST OF FIGURES


Fig. 1 ARMAMENTARIUM USED FOR TRACING RADIOGRAPHS 26

Fig. 2 OVERBITE MEASUREMENTS USED IN THE STUDY 28

Fig. 3 ANGULAR MEASUREMENTS USED IN THE STUDY 29

Fig. 4 LINEAR MEASUREMENT USED IN THE STUDY 30

Fig. 5 LAND MARKS USED TO EVALUATE MOLAR CHANGES 31

Fig. 6 PRE – TREATMENT EXTRA ORAL PHOTOGRAPHS 33

Fig. 7 PRE – TREATMENT INTRA ORAL PHOTOGRAPHS 33

Fig. 8 PRE – TREATMENT LATERAL CEPHALOGRAM 34

Fig. 9 MID – TREATMENT INTRA ORAL PHOTOGRAPHS 35

Fig. 10 POST – TREATMENT EXTRA ORAL PHOTOGRAPHS 36

Fig. 11 POST – TREATMENT INTRA ORAL PHOTOGRAPHS 36

Fig. 12 POST – TREATMENT LATERAL CEPHALOGRAM 37

XII

LIST OF GRAPHS


Graph I PRE – POST SIGNIFICANT ANGULAR MEASUREMENTS 42

Graph II PRE – POST INSIGNIFICANT ANGULAR MEASUREMENTS 42

Graph III PRE – POST INSIGNIFICANT LINEAR MEASUREMENTS 42

Graph IV PRE – POST ANTERIOR TOOTH MOVEMENTS 43

Graph V PRE – POST MOLAR MOVEMENTS 43

XIII

ANNEXURES


Master Chart 1 PRE – POST ANGULAR CEPHALOMETRIC MEASUREMENTS 57

Master Chart 2 PRE – POST LINEAR CEPHALOMETRIC MEASUREMENTS 58

Master Chart 3 PRE – POST OVERBITE CEPHALOMETRIC MEASUREMENTS 59

XIV

Introduction

INTRODUCTION

The extraction of permanent teeth has been a controversial topic throughout

Orthodontic history, beginning with the great extraction debate between Angle and

Calvin case1and continuing through Johnston’s comparison of extraction and non-

extraction outcomes in borderline cases.2 The “no extractions under any

circumstances”, Angle forces had been defeated by “extractions when necessary”,

Case forces on the strength of argument supported by the overwhelming

preponderance of countervailing scientific and clinical evidence.3

Schudy4-6 described facial types as “hypodivergent and hyperdivergent” and

recommended a nonextraction approach in treatment of hypodivergent facial types

and an extraction in hyperdivergent facial types “to close down the bite”. Sassouni

and Nanda7 concurred with this treatment sophy. Although it is difficult to argue

against extraction and non-extraction treatment, extraction of permanent teeth is still a

valuable arrow in the orthodontists quiver of options.1

The primary reason for extraction of permanent teeth are to correct the

discrepancy between tooth size and arch length to reduce bimaxillary protrusion. The

first clinical concern i.e. lack of contact between the anterior teeth, or openbite,

several authors have suggested that removing of permanent teeth from posterior

buccal segment with subsequent protraction to close the spaces corrects the open bite

by anti-clockwise rotation of mandible. This rationale for extraction is referred to as

“wedge hypothesis”.8

What role of extraction play in the cause or cure of TMJ disorders has been

actively debated in the dental literature. First premolar extractions are considered by

many to be an etiologic factor in TMJ disorders. These persons believe that extraction

1

Introduction

of premolars permits the posterior teeth to move forward resulting in a decrease in the

vertical dimension of occlusion. The mandible is then allowed to overclose, and the

muscles of mastication become foreshortened, as a result TMJ problems are likely to

occur. Although this theory is popular, no controlled study has published results

supporting this hypothesis. Another theory that has been proposed is that first

premolar extractions lead to over-retraction of anterior teeth, particularly the

maxillary anteriors. This over relocation of anterior teeth is thought to displace the

mandible and the condyle posteriorly resulting in TMJ disorders.9

Some disagreement exists concerning the effect of bicuspid extractions on the

vertical dimension. It has been suggested that orthodontic forward movement of the

posterior teeth after bicuspid extractions leads to a reduction in vertical dimension and

overclosure of the musculature. This is said to cause muscles to work inefficiently

and to result in pain and fatigue.10 Several authors suggests that it requires special

effort in addition to bicuspid extractions, to reduce the vertical dimension in high

mandibular plane angle (MPA) Grasis Pearson showed a mean decrease of 3.9o in

MPA following first bicuspid extraction, with vertical chin cups used before and

during orthodontic treatment.11

2

Objectives

OBJECTIVES

“The objective of the study is to evaluate vertical changes following first

premolar extraction in high angle cases”.

3

Review of Literature

REVIEW OF LITERATURE

An attempt has been made to analyze tooth movements occurring in cases

treated by the removal of four second and four first premolars. Also, to outline

primarily the indications for the use of second premolar extractions. There does not

appear to be any dominating evidence from which conclusions can be drawn;

however, a few generalizations may be permitted.

1. There seems to be an indication for mesial movement of molar teeth in certain

extraction cases if commonly accepted objectives are to be met consistently.

2. More mesial movement of molars (maintaining good inclinations) may be

accomplished through second bicuspid extraction than first bicuspid extraction

when that is the objective and the appliance is designed accordingly.

3. When arch length discrepancy is 7.5 millimeters or less and there is no

indication for incisor retraction, it may be advisable to consider second rather

than first premolars if extractions are to be performed.

4. There apparently is variability that exists in mesial movement and mesial drift

of molars in different individuals. Some factors involved may be:

a. Stage of dental development.

b. Number of unerupted molars.

c. Occlusion.

d. Degree of arch crowding.

e. Muscle balance.

Authors suggest, once extraction has been decided upon a further analysis as

to which teeth to remove should be considered, instead of accepting some may believe

to the only choice, namely, first premolars.12

4


A study was conducted to evaluate overjet and overbite after orthodontic

treatment. Pretreatment, posttreatment and postretention study models from fifty-

three orthodontically treated cases were examined at the State of New York

Department of Health, Bureau of Dental Health. Overbite and overjet data were

assembled, statistically analyzed, and tabulated for each of the different classes of

malocclusion leading to the following conclusions:

1. When total overbite correction and relapse were examined, the sample as a

whole showed continued posttreatment decrease in overbite. Both Class I and

Class III malocclusions exhibited this same pattern while Class II, Division 1

and Division 2 malocclusions showed, respectively, 30 per cent and 16 per

cent posttreatment increases in overbite.

2. The total overjet relapse in Class I cases was five per cent and in Class II,

Division 1 cases it was ten per cent. The whole sample showed a post-

treatment relapse in overjet of eight per cent.

3. The average relapse of those cases that did relapse was, at all times, less than

2.0 mm in all parameters measured.

4. The ability to predict relapse potential needs to be assessed further according

to more refined classifications of malocclusion, the types of treatment and the

characteristics of the patient.13

A study was carried out by utilizing standard diagnostic procedures in an

office, decisions were made on a number of extraction cases, selecting four first

premolars or four second premolars as the preferable teeth to remove. An effort was

made to determine whether there were some objective variables which were

significantly different for first premolar extraction cases and second premolar

5


extraction cases. 43 patients were studied with an average age of 12 years, (range 8.3-

22.8 years) which includes 23 girls and 20 boys. Various measurements were used to

evaluate the changes in hard and soft tissue changes.

Authors concluded that, for the cephalometric indices used in this study and

the tooth-arch size discrepancy, there were no parameters which were significantly

different. When soft-tissue measurements were included however, and a discriminant

computer analysis completed, it was discovered that the nose tip, the chin, the

mandibular plane and the relation of the lips to the E-line were statistically significant

in determining whether the case was a first or second premolar extraction case. The

combination of lips to E-line and lower left central to APg (angle only) was helpful in

classifying second premolar cases. It must be emphasized that these parameters were

for the results of this sample only. Further, this entire study assumed that the

diagnostician has already decided that the case being evaluated is indeed a case

requiring sacrifice of dental units in both maxillary and mandibular arches, and that

the extraction site should be in the premolar area. In applying these formulae to a

specific patient they may serve as an aid to their diagnosis. The additional utilization

of the nose length, chin length and mandibular plane angle all used singly, help to

identify where the patient varies from the above standard formula, when the formula

does not seem clinically applicable.14

A study conducted by means of corrected tomography, the positions of the

condyles in patients who had undergone four-premolar extraction treatment (20

edgewise and 7 Begg) were compared with the condylar positions of patients who had

not yet received orthodontic treatment. No significant between-group differences in

condylar position were noted. In addition, the relationship between bite depth and

condylar position was examined and no significant correlation was found. Thus, as

6


performed in this study, authors concluded that condylar position was unrelated to

extraction treatment and to bite depth.15

A cephalometric study investigates that the changes in the facial skeleton and

dento-alveolar structures which occur during orthodontic treatment of class II division

I malocclusion by extraction of four first premolars followed by fixed appliances. The

Begg and edgewise appliances are compared, and both are contrasted with a group of

untreated class II div I subjects. The main effects of treatment were in the dento-

alveolar structures, the change in the in the overall facial pattern small and largely due

to extrusion of molars during overbite reduction. Molar extrusion tended to interrupt

forward growth rotation of the mandible, temporarily making it more backwards in

direction and increasing lower anterior face height. An increase in the posterior lower

face height was also noted in the edgewise group. Whilst SNA, and therefore ANB,

reduced significantly during treatment, this was probably the result of palatal root

torque to the upper incisors. The Begg appliance was more successful than edgewise

in this respect.16

In a study, the effect of overjet and overbite correction in non-extraction and

extraction therapy in a class II malocclusion treated with edgewise appliance was

compared. The subjects were 20 children treated without extraction and 20 children

treated with extraction of four first premolars. During the post-treatment period

relapse of overjet and overbite occurred in both groups, however there was a

beneficial net effect of overjet and overbite correction in both groups with no

significant difference between the two groups. A study showed that mandibular

intercanine width space conditions in the lower jaw and mandibular incisor position

were important factors in treatment planning.17

7


The orthodontist has been both accused of causing and complimented for

curing temporomandibular dysfunction. To better understand the origins of these

conflicting opinions, a review of the orthodontic and temporomandibular joint

journals was performed for articles published since 1966. A total of 91 publications

that discussed the relationship between orthodontics and temporomandibular disorders

was found, and these articles were divided in three categories: viewpoint publications,

case reports, and sample studies. Among the areas scrutinized in each category was

the method that has led to the diversity of viewpoints. From this analysis, the

following conclusions were drawn: (1) viewpoint publications and case reports were

excessively represented in comparison with the number of sample studies; (2)

viewpoint publications and case reports described a wide variety of conflicting

opinions on the relationship between orthodontics and temporomandibular disorders;

(3) unlike sample studies, viewpoint publications and case reports have little or no

value in assessment of the relationship between orthodontics and temporomandibular

disorders; (4) sample studies indicate that orthodontic treatment is not responsible for

creating temporomandibular disorders, regardless of the orthodontic technique; and

(5) sample studies indicate that orthodontic treatment is not specific or necessary to

cure signs and symptoms of temporomandibular dysfunction.4

A study was conducted to evaluate the condylar position following maxillary

first premolars extraction. Condylar position in 17 patients whose Class II treatment

(14 with edgewise appliances and 3 with Begg appliances) included extraction of the

maxillary first premolars and in 17 control patients was compared by means of

corrected tomography. The condyles in both groups were in an anterior position, and

there were no statistical differences between the groups. In addition, no statistical

correlation was found when the posttreatment bite depth, interincisal angle, and

8


maxillary incisor inclination were correlated with condylar position. Thus, as

determined in this study, condylar position was unrelated to treatment, bite depth,

interincisal angle, and maxillary incisor inclination.19

It has been argued by a vocal coterie of disaffected dentists that premolar

extraction, incisor retraction, and "backward-pulling" mechanics conspire to

"distalize" the condyles and, pari passu, to produce craniomandibular dysfunction. 42

"edgewise" patients with Class II, Division 1 malocclusions, treated in conjunction

with the extraction of two maxillary first premolars. Regional and anterior cranial-

base cephalometric superimpositions were used to quantify the individual components

of the molar and overjet corrections, to measure both at the chin and condyles the

mandibular displacement seen during treatment, and to examine the extent to which

this displacement is related to the correction of maxillary incisor protrusion. Although

the present patients underwent marked upper incisor retraction (on average, about 5

mm), lip retraction was much less pronounced, and 70% of the sample showed a net

forward displacement of mandibular basal bone. Significantly, changes in condylar

position were not correlated with incisor retraction, as the "functional orthodontists"

would have it, but rather with the changes in the buccal occlusion and the growth of

the maxilla. Thus, 30% of the patients who showed evidence of distal displacement

were generally nongrowing patients who underwent more than average anchorage loss

in the mandible and less than average loss in the maxilla. Regardless of the direction

of basal displacement, however, condylar remodeling apparently served to stabilize

the spatial position of surface landmarks (e.g., condylion), an observation that

underscores the faulty of using any type of serial radiograph to assess changes in

condylar position in the growing, unimplanted patient.20

9


A study was carried out evaluate the orthodontic risk factors for temporo-

mandibular disorders. There is Concern about claims that premolar extractions may

put patients at risk for temporomandibular disorders (TMD). They have reported first

findings from a longitudinal study of orthodontic patients begun in 1983. By using the

methods of Helkimo, TMD data before initiation of orthodontic treatment, between 0

and 12 months after debanding, and 12 to 24 months after debanding. Analyses

related Helkimo scores with premolar extractions in 65 patients for whom orthodontic

treatment had been completed. Twenty-six patients were treated without premolar

extractions, 25 had four premolars extracted, and 14 had two upper premolars

extracted. Tests for significance of differences between mean Helkimo scores were

conducted for the nonextraction group compared with the extraction groups, and

between pretreatment and posttreatment Helkimo scores for each group. Results

included: (1) no significant intergroup differences between mean pretreatment or

posttreatment scores, and (2) small but statistically significant (p < 0.05) differences

(in the direction of improvement) between mean pretreatment and posttreatment

scores for both the nonextraction group and for the four premolar extraction group.21

Authors conducted a study to evaluate the effects of extraction and

nonextraction orthodontic treatment mechanics on patients with dolichofacial and

brachyfacial growth patterns between one and two standard deviations were studied.

Groups underwent treatment of either nonextraction or extraction of four premolars

with the appropriate mechanics for the facial type. Changes in the facial axis and

correlation between maxillary molar movement and facial axis change were

measured. A positive correlation was found between the amount of anteroposterior

movement of the upper molar and change in the facial axis in brachyfacial and

dolichofacial patients undergoing nonextraction treatment. A weak correlation was

10


found in the extraction treatment groups. No statistically significant difference was

found in the facial axis change among any of the groups studied, regardless of facial

type or plan of treatment. There were indications of a more severe opening of the

facial axis (Ba-Na plane to constructed gnathion) with greater degrees of maxillary

molar distal movement in both facial patterns studied.22

A study was carried out evaluate the effects of extraction versus non-

extraction orthodontic treatment on the growth of lower anterior face height. The

effect of Orthodontic treatment on the lower anterior face height (ANS – Me) is of

fundamental importance to Orthodontist. However, the choice between the two

methods of treatment, extraction versus non-extraction, is not clear cut. It is believed

that the extraction method decreases ANS – Me, whereas non- extraction method

results in increase in ANS-Me. This study examined both the methods on 174 subjects

which were equally divided into class I and class II malocclusions. In addition to

growth and treatment duration, other factors like the effects of treatment choice and

treatment mechanics were considered. The results showed that non-extraction

treatment in class I and class II subjects is associated with significant increase in

lower anterior face height. However extraction treatment is not associated with any

significant change in ANS-Me.23

A long term study was done to compare the outcomes in clear cut extraction

and non-extraction class II patients. Discriminant analysis was used to assess the

anatomical basis of the extraction/nonextraction decision in 238 former Saint Louis

University Class II edgewise patients. The resulting discriminant scores (based on six

measures of protrusion and crowding) were used to divide this parent sample into

three prognostic subgroups: clear-cut extraction, clear-cut nonextraction, and a

borderline stratum containing both extraction and nonextraction patients. The "clear-

11


cut" patients—those at the tails of the distribution—were then contacted and asked to

return for follow-up records (cephalograms, models, clinical examination); in the end,

62 (33 extraction and 29 nonextraction) were recalled. The average post-treatment

interval was about 15 years. Premolar extraction produced a significantly greater

reduction in hard-and soft-tissue protrusion. During the post-treatment period,

however, both groups underwent essentially the same change: decreased profile

convexity and a pattern of dental change/relapse that was correlated with antero-

posterior mandibular displacement. Because of their greater initial crowding and

protrusion, the various effects summed to make the extraction patients significantly

more protrusive at recall. Both treatment produced mesial mandibular displacement,

extraction significantly greater than non-extraction, however at recall both groups did

not differ with respect to the signs and symptoms of dysfunction. Authors concluded

that, this study fail to support the common influential belief that premolar extraction

frequently causes “dished in” profiles, “distalized” mandibles, and ultimately

craniomandibular dysfunction.24

A study was conducted to evaluate the effects of first bicuspid extractions on

facial height in high angle cases. Mesial molar movement is expected in first bicuspid

extraction cases and accounts for the belief that facial height should decrease. This

study examined 16 boys and 21 girls, with an average age of 11 years 10 months, at

the outset of treatment. Results showed that 3.2 mm of upper molar extrusion and 2.2

mm of lower molar extrusion. As much as 1.9 mm of vertical movement of molar and

1.6 mm of that mandibular molar can be attributed to growth. This study indicate that

the occlusal movement of the posterior teeth tends to keep the occlusal movement of

the posterior teeth tends to keep pace with the increase in anterior face height, thus

maintaining the MPA and nullifying the bite closing effect of posterior protraction.

12


The facial complex does increase in size with growth, but the Gogn plane, while

moving inferiorly, remains essentially parallel to its pretreatment position, due to both

the growth and treatment.10

A study was conducted to determine the vertical changes following first

premolar extraction. Orthodontic treatment involving the extraction of first premolars

has been implicated in the dental literature as an etiologic factor in the development of

TMJ disorders. Authors have proposed that the extraction of first premolars causes a

decrease in the vertical dimension of occlusion. The purpose of this study was to

investigate the validity of this claim. Records of 45 class I, non-extraction cases and

38 class I, first premolar extraction cases were obtained. The pre-treatment and post-

treatment cephalograms were digitized, and several cephalometric variables were

examined to evaluate the vertical changes occurring as a result of orthodontic

treatment. Statistical analysis of the data revealed no significant differences between

the vertical changes occurring in the extraction and non-extraction groups. On

average, orthodontic treatment in both groups produced an increase in the

cephalometric vertical dimensions that were examined.9

Extraction has been a controversial subject for as long as the specialty of

orthodontics has existed. Some authors believe that the extraction of premolars leads

to temporomandibular disorders. This occurs, they say, because the vertical dimension

collapses. Concomitantly, over-retraction and retroclination of the incisors cause the

facial profile to flatten, bring about premature anterior contacts, and distally displace

the mandible and mandibular condyle. Numerous correlation studies in the dental

literature do not support this contention. There appears to be no higher incidence of

temporomandibular disorders in patients treated with the extraction of premolars than

in nontreated patients or those treated without extractions. Analysis of premolar

13


extraction cases reveals that there is no collapse of the vertical dimension; on the

contrary, the vertical dimension is either maintained or slightly opened. Similarly,

there is no evidence that premolar extraction causes undesirable flattening of the

facial profile. The facial profile established during treatment is primarily the result of

diagnosis and treatment mechanics. Excessive anterior interferences resulting in

possible posterior condyle displacement are the result of treatment mechanics. When

arches are leveled properly and space closure and overjet reduction are adequately

controlled, there is no reason that such interferences should occur. Thus study reveals

little support for the claim that premolar extraction treatment leads to

temporomandibular disorders.25

A study was done to evaluate the effects of different growth pattern and

treatment type factors on craniofacial structures in cases treated with different fixed

mechanics and premolar extractions. A total of 41 cases with a mean chronologic age

of 14 years 7 months and skeletal age of 14 years 6 months was included in the study.

These cases were treated with fixed edgewise mechanics and with extraction of four

first premolars. The growth pattern factor was assessed in two levels as

mesiodivergent and hyperdivergent, and the treatment factor was assessed as with and

without headgear. The results in the assessment of differences between the two types

of growth patterns at the end of treatment, the changes in N-ANS and N-Me were

found to be statistically significant. Interaction was found to be non-significant for all

measurements. It was observed that treatment with fixed appliances and premolar

extractions does not change significantly the growth pattern.26

The study was conducted by authors to evaluate the vertical changes

occurring in Class I patients treated orthodontically with first premolar extraction and

to compare these changes with those occurring in Class I patients treated

14


orthodontically without extractions. Records of 40 Class I nonextraction cases (24

girls, 16 boys) and 40 Class I maxillary and mandibular first premolar extraction cases

(23 girls, 17 boys) were obtained. The pretreatment and posttreatment cephalograms

were digitized, and 6 linear and 8 angular cephalometric measurements were selected

to evaluate vertical changes. Evaluation of the treatment results of the extraction and

nonextraction cases showed that the vertical changes occurring after the extraction of

maxillary and mandibular first premolars were not different than those occurring in

the nonextraction cases. Authors concluded that this study disproves the hypothesis

that the extraction of premolars leads to a loss of vertical dimension which in turn

leads to TMJ disorders.27

Authors conducted a cephalometric study to evaluate an early nonextraction

treatment approach for patients with severe vertical skeletal dysplasia and maxillary

transverse constriction. Thirty-eight patients, 8.2 years (± 1.2 years) of age, were

treated for 1.3 years (± 0.3 years) with lip seal exercises, a bonded palatal expander

appliance, and a banded lower Crozat/lip bumper. The bonded palatal expander

functioned as a posterior bite-block and was fixed in place throughout treatment.

Patients with poor masticatory muscle force (79%) wore a high-pull chincup 12 to 14

hours per day. A control group was matched for age, sex, and mandibular plane angle.

Treatment changes for chincup and other patients were not significantly different.

Overall, treatment significantly enhanced condylar growth, altered it to a more

anterosuperior direction, and produced "true" forward mandibular rotation 27 times

greater than control values. Posterior facial height increased significantly more in

patients than in controls, and the maxillary molars showed relative intrusion. In

treated patients, articular angle increased, gonial angle decreased, and the chin moved

anteriorly twice as much as in controls. Treatment also led to increased overbite and

15


decreased overjet. Maxillary and mandibular expansion did not cause the mandibular

plane angle to increase. The 16 patients with openbite malocciusions exhibited a 2.7

mm increase in overbite and inhibition of growth in anterior lower facial height. The

aggregate of individual changes demonstrates a net improvement, indicating this

treatment approach may be suited for hyperdivergent patients with skeletal

discrepancies in all 3 planes of space.28

A study was carried out to evaluate the vertical facial changes in adult

orthodontic patients and to evaluate the stability of these changes. Thirty three

patients (8 males and 25 females) were examined. The patients had been treated fixed

edgewise appliance mechanics and exhibited atleast 1.0º of clockwise rotation of the

mandible during treatment. Mandibular rotation was determined by the angular

change in the Y-axis to the Frankfort horizontal plane. Twelve angular and 14 linear

skeletal and dental measurements and three skeletal ratios were derived from

pretreatment (T1), posttreatment (T2), and postretention (T3) cephalometric

radiographs. Twenty-five percent of the opening rotation of the mandible recovered

during the posttreatment period., resulting in a significant overall rotation that was

maintained. Both treatment and posttreatment changes in the Y-axis angle. Stepwise

regression analysis of pretreatment variables and treatment changes failed to predict

the behavior of the Y-axis angle change.29

A study was carried out to evaluate the effects of orthodontic treatment on the

soft tissue facial profile of patients with long and short facial types. Orthodontic

treatment records of 99 white long-faced and short-faced patients were analyzed to

determine the effects of edgewise orthodontic treatment over an average period of

2.16 ± 0.32 years. The average ages at the initiation and conclusion of treatment were

13.40 ± > 40 years and 15.61 ± 0.29 years, respectively. A significant finding in this

16


study was the large variability in set tissue response to tooth movement. This

variability was due to a wide dispersion of individual results between upper and lower

lip change to maxillary and mandibular incisor movement anteriorly or posteriorly.

Because of this soft tissue variability among individuals, definite differences between

the long-faced and short-faced types could not be identified, nor was it possible to

establish definite ratios for change in lip response to incisor movements.30

The study was conducted using lateral cephalometric radiographs taken before

and after treatment. fifteen patients who had an anterior open bite (AOB) only were

treated with first premolar extractions (Group E4). Seventeen patients with an AOB

extending to the posterior teeth were grouped according to the extractions: extraction

of second premolars (Group E5) and first molar (Group E6). Cephalometric data were

analysed according to the 'two factor experiment with a repeated measure on one

factor' model. The treatment group factor had three levels, E4, E5, and E6, and the

time factor two levels, pre- and post-treatment. The differences between the pre- and

post-treatment periods were statistically significant for all the cephalometric variables

(P< 0.001, P< 0.0001), except for ANS-Me/ Na-Me, The time and group interaction

were found to be statistically significant for the variables where the time factor is

important, such as SN-GoGn angle, SGn-NBa angle, ANS-Me dimension, Na Me

dimension, forward movement of the maxillary and mandibular molars, and the

distance to the mandibular plane of the lower molars. The severity of vertical

dysplasia did not change in group E4. Generally, however, within the appropriate

indications, extraction of the second premolars or the first molars led to a closing

rotation of the mandible in subjects with a skeletal AOB extending to the posterior

teeth.31

17


A study was carried out to evaluate the effects of bilateral upper premolar

extraction on mandibular growth. Twenty-six subjects (8 males and 18 females) in

maximum pubertal growth with an angle class II molar relationship, normal to mild

overjet increase, mild or lower arch length discrepancy and no severe skeletal

discrepancy were divided into two groups equal in number and gender, as extraction

and control groups. The median chronological age was 11.2 years in the extraction

group 12.6 years in controls. The subjects were observed for a median period 1.1

years in the extraction group after bilateral extraction of the upper premolars and 1.2

years in the controls until termination of pubertal growth (DP3u) without any

orthodontic treatment. Twenty nine linear and angular measurements were made on

52 lateral cephalograms and hand-wrist radiographs taken before and after the study

period. The increase in SNB measured on the total superimposition was significantly

greater in the controls than in the extraction group. In addition, anterior mandibular

counterclockwise rotation was significantly in the control group. Thus, it might be

suggested that bilateral upper premolar extractions might affect the mandibular

rotation tendency.32

A study was conducted to evaluate the effects on vertical dimension following

first or second premolar extraction. Objective of the study is, mesial movement of the

molars to reduce the “wedge effect” and decrease facial vertical dimension valid. This

study compares the mesial movement of Molars and changes in the FVD between P1

and P2 groups in class I malocclusion with hyperdivergent facial pattern. 27 cases

(P1-group1) with maxillary and mandibular first premolar extraction and 27 cases

(P2-group 2) with second premolar extractions were compared. Results showed that

group 2 showed more mesial movement of the maxillary and mandibular molars and

less retraction of maxillary and mandibular incisors than group 1. Both the groups

18


showed increased anterior facial height, but there were no statistically significant

differences in angular and proportional measurements between pre and post treatment.

There were no significant differences in the amount of FVD between group 1 and 2

except in the maxillomandibular plane angle and SN to palatal plane angle. These

results suggest that there is no decrease in FVD regardless of the maxillary and

mandibular first or second premolar extraction. Therefore authors conclude, the

hypothesis that second premolar extraction in hyperdivergent facial types will result

in mesial molar movement and decrease FVD by reducing “wedge effect” is invalid.33

A retrospective, longitudinal, cephalometric study was carried out to

investigate the influence of extraction and non-extraction orthodontic treatment on the

facial height of Japanese – Brazilians with class I and class II division I malocclusion.

Sample included 59 mesocephalic patients distributed into 4 groups. Group 1: class I

patients treated with 4 first premolar extractions, Group 2: class I patients treated with

non-extraction. Group 3: class II division I patients treated with 4 first premolar

extractions, Group 4: class II division I patients treated with non-extraction. The

overall initial mean age of the groups was 12.14 years, and all cases were treated with

standard edgewise appliances for a mean period of 2.49 years. The pre-treatment and

post-treatment stage comparison and the intergroup comparison of the treatment

changes were conducted between extraction and non-extraction groups in the class I

and class II malocclusions. Results showed that changes in the absolute magnitude of

posterior and anterior facial heights and in the ratios of lower posterior facial heights/

lower anterior face height and lower anterior face height/total anterior face height

were similar in extraction and non-extraction treatment in both class I and class II

malocclusions. Authors concluded that facial height were similar between extraction

and non-extraction treatment in both class I and class II malocclusios34

19


A study was carried out to evaluate the outcome of standard edgewise

orthodontic treatment with extraction of 4 first molars (6xT group) or Tweed

edgewise treatment with extraction of 4 first premolars (4xT group). A cephalometric

analysis that isolated tipping and bodily movements of the maxillary and mandibular

incisors and measured vertical changes in the anterior region of the maxilla and

mandible used. Thirty subjects treated 10 practioners comprised the 6xT group,

whereas 31 subjects treated in the case western university orthodontic clinic were

used in the 4xT group. Control groups (6xC) and 4xC) were selected from untreated

subjects enrolled in the Bolton-Brush growth study and were matched on age and

gender. Data were collected before (T1) and after (T2) treatment. Results showed no

statistically significant changes between 6xT and 6xC for any of the variables studied.

An increase in overbite of 2.1 mm in the 6xT group was small but clinically

significant changes in both tipping and extrusion of maxillary and mandibular

incisors. In the 4xT group, statistically and clinically significant changes were

observed for intrusion of the maxillary and mandibular incisors, resulting in a 4.1 mm

decrease in overbite. Importantly, both the 6xT and 4xT groups showed no increase in

mandibular vertical height during treatment. Authors concluded that both treatment

strategies showed good control of vertical mandibular growth. Bodily intrusion of

the anterior teeth was the main contributor to correction of deep overbite in the Tweed

edgewise sample.1

A study was conducted to evaluate the vertical changes in class II division 1

malocclusion after premolar extractions. 26 cases each in two groups with 16 boys

and 10 girls, group 1 treated with mandibular first premolar extractions (age: 13.2 ±

1.5years) and group 2 treated with mandibular second premolar extraction. The two

groups were matched by sex, age, (with in six months) and facial divergence

20


measured by maxillary-mandibular plane angle and ratio of posterior face height to

total anterior face height. Results showed, second premolar extraction was associated

with more mesial movement of the mandibular molars, but there was no significant

difference in vertical facial growth between the two groups. There was no significant

change in mandibular plane angle and MM angle in both the groups. Authors

concluded that this study do not support the hypothesis, that mandibular premolar

extraction is associated with mandibular overclosure or reduction in the vertical

dimension, or both, in subjects with class II division I malocclusion.35

Authors conducted a cephalometric study was to investigate vertical

dentoalveolar compensation in untreated adults with excessive (long-face) and

deficient (short-face) lower anterior face heights. Vertical and sagittal base

relationships, vertical dentoalveolar dimension in the anterior region of the jaws,

incisor inclination, overbite, and overjet were assessed in 112 short-face and 95 long-

face subjects. The contribution of skeletal and dentoalveolar components to achieve a

normal overbite was assessed by means of regression analysis. For the 2 most

important independent variables of the regression equation, the values were calculated

that would render an overbite of 2 mm. It was subsequently investigated whether the

calculated value fell within the range of the sample. The results showed that, in long-

face subjects, overbite was mainly related to lower anterior face height; in short-face

subjects, it was mainly related to mandibular anterior alveolar and basal heights.

Dentoalveolar compensation occurred in both groups mainly by adaptations in

mandibular incisor alveolar and basal heights. Molar height was unrelated to overbite.

Cutoff values for achieving a positive overbite were calculated for lower face height

and mandibular incisor alveolar and basal heights. Authors concluded that, the lower

face height mainly determines the overbite in long-face subjects, while in short-face

21


subjects, lower dentoalveolar morphology influences overbite. Lower dentoalveolar

compensation can maintain a normal overbite in long-face subjects to a limited

extent.36

A study was carried out by authors to determine, if appliance induced increase

in the in the heights of upper and lower molars in girls with class II division I

malocclusion, and the consequential increase the height of the face are maintained.

Ten angles and ten linear measurements were measured on lateral cephalograms of 11

year old girls (8.5-14 years) with treated (N =9) and untreated (N=8) class II division

I malocclusion. The intervals between initial and recall records were, on average, 12

years (7.6-15.5 years) for the girls in the treatment group, and 8 years (4-13 years) for

the girls untreated/control group. In the treatment group 8 girls were treated with

Begg appliance and class II elastics. Results showed that upper and lower molar

heights in both the groups increased significantly, between the initial and recall visits.

There were no significant differences between the molar heights in the groups at the

start or recall visits. AFH also increased significantly in both groups between initial

and recall visits. At recall, AFH in the treatment group was significantly greater than

AFH in the control group. This finding is attributed to similar sized differences

between the groups at the start, to the longer period between the initial and longer

period in the treatment group and to lesser variation in the both groups at recall. In

both groups, posterior face height increased significantly between the initial and recall

stages. At the conclusion of the study there were no statistically significant

differences between the treated and control groups in either overjet or the inclination

of upper incisors. Relapse of upper incisors in the treatment group and retroclination

of upper incisors in the control group reduced the initial differences between the

groups. These changes are attributed to altered lip posture and increased lip pressure

22


in adolescence. At recall, angles SNA and SNB were significantly smaller in the

treatment group. Authors concluded that heights of the upper and lower molars and

the face increased in both groups. Orthodontic treatment effect have no lasting effect

on either the height of the face or the heights of the molars in girls with class II

division I malocclusion.37

There is disagreement concerning the effect of premolar extractions on the

dentofacial vertical dimension. It has been suggested that orthodontic forward

movement of the posterior teeth after first premolar extraction leads to reduction in

vertical dimension. The purpose of this study was to examine cephalometrically the

dentofacial vertical changes in Class I Indian subjects treated with and without

extractions. The extraction group included 31 normodivergent patients (26 female, 5

male; pretreatment age, 17.19 ± 3.89 years) with maxillary and mandibular first

premolar extractions. The nonextraction group included 29 patients (18 female. 11

male; pretreatment age, 18.48 to 3.61 years). A coordinate system with the Frankfort

horizontal plane and a mandibular fiduciary line was used for the cephalometric

calibration. To determine vertical dimension changes due to treatment and to compare

differences between the 2 groups, paired and unpaired t tests were performed,

respectively. Results showed that both groups had increases in linear vertical

dimensions (P <0.05), but the change was comparatively greater in the extraction

group (P <0.05). Mesial movement of the maxillary and mandibular posterior teeth

was coincidental with the extrusion to such an extent that it increased the vertical

dimension, although the mandibular plane angle remained unchanged during

treatment. Authors concluded that extraction of teeth only to increase the overbite or

decrease the mandibular plane angle might not be justified.38

23

Methodology

METHODOLOGY

Materials and Method :

The present retrospective study was designed to evaluate the overbite and

vertical changes following first premolar extraction in high angle cases, who have

been orthodontically treated with pre-adjusted Edgewise appliances (0.022 slot, MBT)

in the Department of Orthodontics and Dentofacial Orthopaedics, College of Dental

Sciences, Davangere.

Sample Size :

Twenty five adult patients were randomly selected from the pool of completed

cases with pre and post treatment records in the Department of Orthodontics and

Dentofacial Orthopedics. All 25 cases were treated with consistent biomechanical

principles, transpalatal arch / Nance palatal arch were used for anchorage. Sample

included 12 boys, of age ranging from 17.3 years to 21.6 years (Average 18.9 years)

and 13 girls of age ranging from 17.1 years to 20.6 years (Average 18.6 years).

Sample Selection :

The sample eligible for the study was selected on the basis of the following

criteria.

Inclusion Criteria :

Cases having high mandibular plane angle, that is GoGn-Sn greater than or

equal to 32o (Steiners analysis).

Cases treated with PEA with all first bicuspids extractions

Cases having Class I molar relation bilaterally.

Exclusion Criteria :

Cases with Class II and Class III molar relationship.

24

Methodology

Cases treated with surgical orthodontics.

Armamentarium Used in the Study (Fig.1):

0.3 mm pencil

0.3mm lead acetate tracing sheets

Set of proctractors

X – ray View box

Eraser

TABLE – 1 : DEFINITIONS OF CEPHALOMETRIC LANDMARKS

MXSK The distance between the intersection of the vertical horizontal reference liens to ANS.

BU1 The distance between ANS and CRU1.

TL1 The distance between CRU1 and IEU1.

BL1 The distance between CRLI and IEL1

MNSK Distance between CRLI and Me.

MPA It is the angle formed between Gogn - SN

UAFH It is the linear distance from N to ANS.

TAFH It is the linear distance t from N to Me

LAFH It is the linear distance from ANS to Me

PFH It is the linear distance from S to Go

Sv Perpendicular to FH plane from sella

Pogv Perpendicular to FH plane from pogonion

Gogn – FH It is the angular measurement between Gogn – FH

Gogn – PP It is the angular measurement between Gogn – PP

Go - OP It is the angular measurement between Gogn – OP

SN - PP It is the angular measurement between SN – PP

SN - OP It is the angular measurement between SN – OP

25

Methodology

26

Methodology

The analysis compares radiographs with judicial horizontal and vertical

reference lines, at the T1 tracing horizontal drawn parallel to the FH and a

perpendicular line was drawn to establish the vertical reference used. The T2 tracing

was superimposed on the T1 tracing by using cranial base landmarks and both the

horizontal and vertical fudicial lines were carried through the T2 tracing. Six

landmarks, Anterior Nasal Spine (ANS), Centre of Rotation of the maxillary and

mandibular central incisors (CRU1 and CRL1), incisal edges of the maxillary and

mandibular central incisors (IEUI) and (IELI) and menton (Me) were identified on

each cephalogram and projected on to the vertical reference line, keeping the

landmark location parallel to the horizontal reference line. This procedure resulted in

six linear variables.

1) Maxillary skeletal change (MXSK): - The distance between the intersection

of the vertical horizontal reference lines to ANS.

2) Bodily movement of the maxillary incisors (BU1): - the distance between

ANS and CRU1.

3) Tipping movement of the maxillary incisors (TU1): – the distance between

CRU1 and IEU1.

4) Tipping movement of the mandibular incisors (TL1): – the distance

between CRLI and IEL1.

5) Bodily movement of the mandibular incisors (BL1): – distance between

CRLI and Me.

6) Mandibular skeletal change (MNSK): - the distance between ANS and Me

projected onto the vertical reference line.

27

Methodology

Fig. 2 : Schematic Diagram showing Overbite changes

The net change in these variables were used to compute changes in the

dependent variables – ‘overbite’ by using the following equation.1

AOB = ∆ MNSK + ∆ BUI + ∆ TUI + ∆ BLI + ∆ TLI

Where ∆ - Net change

Tracing 2 minus tracing 1, gives the post treatment changes in overbite.

Following, angular and linear measurements were selected to evaluate

vertical dimensional changes.7

28

Methodology

Angular Measurements :

1) Go Gn to SN

2) Go Gn to FH

3) Go Gn to PP

4) Go Gn to Occlusal plane

5) SN to PP

6) SN to FH

7) U1 to SN

8) L1 to Go Gn

9) IMPA

10) Y-Axis

Po Or

S

Cd

AANS

Me

N

PgGn

Go

Fig. 3 : Schematic diagram showing angular land marks used in the study

29

Methodology

Linear Measurements :

1) UAFH – N to ANS

2) Post FH – Se to Go

3) AFH – N to ANS

4) LAFH – ANS to Me

5) Anteroposterior face height ratio = X 100 = _ _ _ %

6) Sv – U6

7) Pog – L6

8) FH – U6

9) FH – L6

Fig. 4 : Schematic diagram showing linear land marks used in the study

Po Or

S

Cd

Me

ANSA

Go

N

30

Fig. 5 : Schematic diagram showing land marks used to evaluate molar changes in the study

Po Or

S

Cd

AANS

Me

N

PgGn

Go

STATISTICAL ANALYSIS :

Results are expressed as mean SD paired t-test was used to analyse post-

treatment changes in cephalometric evaluation.

The results were also ascertained by non-parameteric Wilcoxon’s test

whenever the measurements were presumed to be non-normally distributed. All the

analysis were done using SPSS Software (Version 13), USA.

P-value of 0.05 or less was considered for statistical significance.

Formulae Used for Analysis:

∑ xi Mean, x = ------- i = 1, 2… n

n

∑ (xi – x)2 Standard deviation, SD = -------------

n – 1

SD

Standard Error, SE = ---------

Mean of the differences Paired t test, t = ------------------------------------------- Standard error of the differences

= -------------

sd /

Wilcoxon’s Signed Rank Test (Alternative to Paired t-test)

Pre-post differences are found for each case and ranks are assigned to the

differences. Sum of the negative and positive ranks are found separately.

Least of these two sums (-ve +ve) is compared with table value for

significance.

Results

RESULTS

There was statistically significant change in the MPA (Gogn-SN) but the mean

difference in the change -0.5 mm (Table I) suggests that the change is clinically

insignificant.

There was statistically significant change in the U1 to SN, L1 to Gogn, BUI

and BLI (Table II and Table IV) suggesting that, the extraction space was closed by

retraction of the anteriors. The mean change in the U1 to SN and LI to Gogn is 10.8

and 7.9 degrees respectively. The mean change in the BU1 and BL1 is -2.4 and 2.3

mm respectively.

There was significant change in the sella vertical to mesiobuccal cusp tip of

maxillary first molar and pogonion vertical to mesiobuccal cusp tip of mandibular

first molar (Table IV) suggests that there was mesial movement of the upper and

lower molars. The average mesial movements of maxillary and mandibular molars is -

2.3 and -2.2 respectively.

There was a statistically significant change in the FH plane to mesiobuccal

cusp tip of maxillary first molar and FH plane to mesiobuccal cusp tip of mandibular

first molar, suggesting that there was extrusion of molars in maxillary by -2.2 mm and

in mandible by 1.2 mm.

There was a slight changes in the certain parameters shown in the Table II III

V IV. Although there was a slight change, the difference in the changes were very

less and statistically insignificant.

Results

TABLE – II

PRE AND POST TREATMENT ANGULAR MEASUREMENTS

Parameters Pre Post Difference t-Value p-Value

Gogn-SNMean 33.8 34.3 -0.5

2.3 0.03, SSD 1.2 1.3 1

Gogn-FHMean 27.04 27.04 0

0 1.00, NSSD 2 1.1 2.4

Gogn-PPMean 25.4 25.7 -0.3

-1.77 0.09, NSSD 1.6 1.1 0.8

Gogn-OPMean 16 16.04 0.04

-1 0.92, NSSD 0.9 1.6 2.1

SN-PPMean 10 10.3 -0.3

-1.16 0.26, NSSD 1.1 1.4 1.2

SN-FHMean 9.8 9.8 0

0 1.00, NSSD 0.8 0.9 0.7

UI-SNMean 116.8 105.9 10.8

29.08 <0.001, HSSD 2.3 1.2 1.9

LI-GognMean 102 94 7.9

26.94 <0.001, HSSD 3 2.5 1.5

U-GonialMean 53.6 53.6 0

-0.44 0.66, NSSD 1 1 0.5

L-GonialMean 76.2 76.3 -0.04

-0.09 0.93, NSSD 1.9 2 2.3

Y-ANSMean 67.2 67.4 -0.2

-1.04 0.31, NSSD 1.3 1.6 1

Results

TABLE – III

PRE AND POST TREATMENT VALUES OF LINEAR MEASUREMENTS

Parameters Pre Post Difference t-value p-value

N-MeMean 125.1 126 -0.12

0.37 0.72, NSSD 3.1 2.8 1.6

N-ANSMean 52 52.1 -0.1

-0.62 0.54, NSSD 1.6 1.5 0.6

ANS-MeMean 70.1 71.1 -0.04

-0.17 0.87, NSSD 3.6 3.3 1.2

Se-GoMean 72.4 72.2 0.2

1.41 0.17, NSSD 3.3 3.3 0.7

APF Ht Ratio

Mean 59.64 59.71 0.020.2 0.84, NS

SD 0.6 0.8 0.6

Results

TABLE – IV

OVERBITE AND VERTICAL CHANGES OF DENTITION

Parameters Pre Post Difference t-value p-value

MXSISMean 23.4 23.9 -0.5

-1.81 0.08, NSSD 1.7 1.6 1.3

BU1Mean 16.15 18.9 -2.4

-11.52 <0.001, HSSD 1 1 1

TU1Mean 19.4 20.6 -1.2

-5.79 <0.05, SSD 1.1 1.1 1

BL1Mean 25.7 23.4 2.3

7.77 <0.001, HSSD 1.7 1.1 1.5

TL1Mean 13.6 12.6 1.1

4.22 <0.05, SSD 1.2 1.1 1.3

MNS1sMean 73.9 73.8 0.1

0.25 0.80, NSSD 1.2 1.2 1.6

OBMean 150.5 150.2 0.2

0.79 0.44, NSSD 2.4 1.8 1.5

Sv-U6Mean 40 42.3 -2.3

-25.2 <0.05, SSD 0.9 0.9 0.5

Pog-L6Mean -20 -17.8 -2.2

-19.58 <0.05, SSD 1 1 0.6

FH-U6Mean 46.4 48.6 -2.2

-24.39 <0.05, SSD 1.7 1.5 0.5

FH-L6Mean 47.5 46.3 1.2

4.77 <0.05, SSD 1.6 1.6 1.3

Results

Graph I : Pre-Post Significant Angular Measurements

0

20

40

60

80

100

120

Deg

rees

Gogn-SN U1-SN L1-GognAngular Parameters

Pre Post

Graph – II : Pre-Post Insignificant Angular Measurements

0

10

20

30

40

50

60

70

80

Deg

rees

Gogn-FH Gogn-PP Gogn-OP U.Gonial L.GonialAngular Parameters

Pre Post

Graph III : Pre-Post Insignificant Linear Measurements

0

20

40

60

80

100

120

140

160

mm

N-Me ANS-Me Se-Go OBLinear Parameters

Pre Post

Results

Graph IV : Pre-Post Anterior Tooth Movement

0

5

10

15

20

25

30m

m

BU1 TU1 BL1 TL1Linear Parameters

Pre Post

Graph V : Pre-Post Molar Movements

-20

-10

0

10

20

30

40

50

mm

SV-U6 Pog-L6 FH-U6 FH-L6Linear Parameter

Pre Post

Discussion

DISCUSSION

For evaluation of treatment results it is important to consider facial types.

Long faced individuals exhibit long anterior face height, excessive backward rotation

of the mandible, and high MPA.39,40 Similarly short anterior face height, excessive

forward rotation of the mandible and low mandibular plane angle has been reported

for short faced individuals.40,41

Schudy advocated extraction of teeth “to close the bite”, in hyperdivergent

facial type.4-6 Sassouni and Nanda concurred with a such a treatment phylosophys.7

Orthodontists generally agree that non-extraction treatment is associated with

downward and backward rotation of the mandible and an increase in the LAFH. They

also agree that extraction line of treatment is associated with upward and forward

rotation of the mandible and decrease in the LAFH.23

Previously published literatures9,10,23,27 showed that there is no significant

changes in the vertical facial dimension following first premolar extraction treatment.

The present study aimed to study the comparison of overbite and vertical facial

changes following first premolar extraction in high angle adult patients.

Twenty five adult patients having high mandibular plane angle i.e. GoGn-SN

greater than or equal to 32o were compared with pre and post treatment cephalometric

results. Pre and post treatment lateral cephalograms of all the adult 25 patients were

taken, obtained with patient positioned in the natural head position42,43 and evaluated

for pre and post treatment overbite and vertical facial dimensions. Frankfort

horizontal plane (porion to orbitale) was taken as a horizontal reference plane and a

perpendicular to this FH plane gives a judicial vertical plane, which was used to

evaluate the overbite changes.1

Discussion

To evaluate the mandibular plane angle, Gogn - SN plane was used, as given

by the Steiner’s analysis.44 N-Me and ANS-Me were used as landmarks and evaluate

the AFH and LAFH respectively. As Se point is stable, vertical line drawn

perpendicular to FH from sella was used to evaluate the mesial movement of

maxillary first molar and Pog vertical was drawn from Pog perpendicular to FH in

order to overcome the errors by mandibular rotation. Perpendicular line was drawn

from FH to mesiobuccal cusps of the maxillary and mandibular first molars to analyze

the extrusion of molars after treatment.38

The absolute measurements of vertical face height, the ratio of AFH / PFH,

MPA and incisor vertical heights did not show significant difference between the pre

and post treatment changes, following first premolar extraction in high angle cases.

This suggests that the treatment approach following first premolar extraction in high

angle cases does not affect the vertical proportions of the face.

Results in this study suggests that, there were no statistically significant

difference in the amount of change in the variables for TAFH and LAFH. This is

because of the extrusion of molars, which would compensate for the mesial migration

of the molars which would accounts for anchorage loss.

Kocadereli27 and Staggers9 showed that there was no statistically significant

difference in vertical dimension changes between first premolar extraction and non-

extraction groups, and orthodontic treatment produced increase in the cephalometric

vertical dimensions in both extraction and non-extraction groups. Chua et al23

examined the effects of extraction and non extraction on LAFH and reported a

significant increase in the non-extraction group and no significant change in the

Discussion

extraction group. Cusimano, McLaughlin et al10 found no difference in facial height

of hyperdivergent patients with first premolar extraction treatment.

Garlington and Logan studied vertical changes in high mandibular plane cases

following enucleation of second premolars and observed significant change in the

lower anterior face height due to forward rotation of the mandible, but there were no

significant changes in the total anterior face height. This suggests that there were

compensatory changes in the maxillary vertical growth.45 This study corroborates our

study, could be due to enucleation of second premolar might reduce the arch length

resulting skeletal changes, Whereas in this study there was no significant skeletal

changes, rather more of dental changes have occurred.

Baumrind45 reported that the mean increase in anterior lateral face height was

significantly greater in the Class II extraction subgroup than in Class II non extraction

group This does not agree with our results, probably due lack of class II mechanics as

the samples included in the study were Class I molar and canine relation. Kim et al33

tested the occlusal wedge hypothesis by comparing the mesial molar movement and

the changes in vertical dimension between first premolar and second premolar

extraction groups and concluded that there was no decrease in facial vertical

dimension regardless of maxillary and mandibular first premolar and second premolar

extraction.

The present study did not show the significant changes in AFH and PFH. This

is due to, though there is mesial movement of the molars and tend to reduce the bite,

extrusion of the molars tend to increase the downward and backward rotation of the

mandible and maintain the vertical reduction of the facial height. Our results goes in

favour of Hayasaki et al34 reported that the changes in the absolute magnitude of

anterior and posterior facial heights between extraction and non-extraction treatments

Discussion

in both Class I and Class II malocclusion patients. Their results conclude that facial

growth pattern in the vertical and anteroposterior position of the maxillary and

mandibular molars, in the absolute magnitude of anterior and posterior face heights, in

the ratios of lower posterior face height/lower anterior face height lower anterior face

height/total anterior face height are similar between extraction and non extraction

treatment, either in class I or class II malocclusions.

Al-Nimri35 compared the changes in facial vertical dimension in patients with

Class II division I malocclusion after extraction of either the mandibular first

premolar or second premolar. The forward movement of the mandibular molars was

greater in second pre molar extraction group and this is attributed to the larger

residual space in the lower arch after alignment in this group and difference in the

distribution of the anchorage values in the lower arch with in extraction group and

concluded that the mandibular premolar extraction, whether first or second was not

associated with mandibular over closure or reduction in facial vertical dimension,

despite more forward movement of the mandibular molars in second premolar

extraction group.

The analysis of the variables at pre-treatment and post-treatment in table III

suggests that there was some extrusion of maxillary and mandibular molars, which

were statistically significant. This could have been consequent to the

mechanotherapy9,10,46 or residual growth.33 Growth is nearly complete at 14 years in

girls and at 16 years in boys.38 The average age of the sample was 17.39 3.99 years.

So we can mention little about the influence of residual growth as it is limited at these

ages. The present study suggests that some residual growth as well as treatment

mechanics took place. This finding is similar to the studies of Kim et al 33 and Harris

et al47 with subject in the late teens.

Discussion

The maxillary and mandibular molars showed mesial movement in relation to

‘S’ vertical and Peg vertical respectively, which were statistically significant (Table

III). This movement may be consequent to mechanotherapy or residual growth. This

finding is similar to the studies of Gardner et al,48 West and McNamara49 in late teens

and Gesimano et al,10 Gardner et al48 reported that the horizontal distance of the

maxillary first molar measured in relation to pterygomaxillary vertical, continued to

increase mesial movement on an average of 2.6 mm from post treatment at the age of

16.6 years to the first recall examination at the age of 21.6 years.48 West and

McNamara reported the same with the molars in males and females with mean ages of

17 years 2 months and 17 years 6 months, respectively, erupted and moved mesially

during adulthood.49 In addition to this, the normal mesial displacement of the

maxillary and mandibular molars, mesial movement in the extraction group might be

allowed, depending on the severity of the anterior discrepancies.9,50

Mandibular plane angle showed statistically significant increase from pre-

treatment to post-treatment (Table 1). This is due to the extrusion of molars in both

maxilla and mandible. It could also be due to of residual growth as as explained

earlier. Another criteria for sample selection was high mandibular plane angle,

suggests that vertical jaw pattern. This finding supports the study done by Mc

Laughlin, Cusimano et al on effects of first premolar extraction on facial heights in

high angle cases. where as a study38 done by Arunachalam and Ashima Valiathan on

cephalometric assessment of dentofacial vertical changes in class I subjects

corroborates our findings. But the difference in the changes from pre-treatment (-0.5)

to post-treatment (1.0) is negligible. So we can say that though it is statistically

significant, it is clinically insignificant. This statistical change may be due to small

sample size.

Discussion

Overbite did not show any significant changes in this study. Probably due to

more of bodily movement of the incisors.

There was a statistically highly significant change in the U1-SN, L1-GoGn

(Table II) and BUI and BLI (Table 3) suggests that the most of the extraction space

was closed by upper and lower anterior retraction.

There was significant change in the tipping movement of upper and lower

anteriors (TUI and TLI) (Table III) suggesting that there was bite closure by tipping

movement of anteriors both in maxilla and mandible. There was no significant

changes in the pre and post treatment comparison of maxillary and mandibular

skeletal measurements (Table III) rather relative positions of the maxillary and

mandibular incisors were affected by treatment. These results goes in favor with the

study done by Mark G. Hans et al.1

There was a slight changes in the certain parameters shown in the Table I, II

and III. Although there was a slight change, the difference in the changes were very

less and statistically insignificant. This could be probably due to limitations of the

study which could be due to small sample size. Another limitation of the study is we

could not analyze in depth the response differences of different patients. For example,

in our study nine patients showed vertical reduction, but statistical evaluation masked

these findings. So it is better to assess an in-depth evaluation of vertical dimension

changes in each stage of treatment of the samples, and treatment results should be

contemplated with concomitant evaluation of the biomechanics of the

temporomandibular joint, since they do not function as simple hinges. So further

studies are required on the biological response to treatment effects as well as

compensatory mechanisms, particularly affecting vertical dimensions.

Conclusion

CONCLUSION

The intent of this investigation was to examine the popular “wedge

hypothesis” that the vertical dimension collapses following first bicuspid extraction

line of orthodontic treatment.

The results of this study leads to the following conclusion,

1. There was no linear change in the vertical facial dimension

2. There was no significant increase in the overbite

3. There was no clinically significant increase in the mandibular plane

angle

This study indicate that occlusal movement of the posterior teeth tend to keep

pace with the increase in anterior face height, thus maintaining the mandibular plane

angle and nullifying the bite closing effect of posterior protraction. The facial

complex does increase in size with growth, but Gogn – SN plane while moving

inferiorly, remain essentially parallel to its pretreatment position, due to residual

growth and treatment mechanics.

Summary

SUMMARY

The stimulus for this investigation was assertion that extraction treatment is

tantamount to reduction in facial vertical dimension and subsequent increase in depth

of the bite. In clinical practice most of the orthodontists believed the theory that

reducing tooth mass will lead to bite closure by accelerating the normal forward

growth rotation of the mandible. Such rotation, would, in theory, reduce the anterior

facial height and carry the chin forward. Most of the previous literature showed that

there was no significant change in the facial vertical dimensions following extraction

line of treatment.

The present study was designed to evaluate cephalometric overbite and

vertical height changes following first bicuspid extraction in high angle cases. i.e.

Gogn – SN ≥ 32 degrees.

A total of 25 adult patients having high mandibular plane angle (GoGn-SN ≥

32o) treated in the Department of Orthodontics, College of Dental Sciences,

Davangere, with all first bicuspid extraction over a period of 18 to 24 months, using

consistent biomechanical principles. In order to evaluate the overbite changes all pre

and post cephalograms were traced and measured in relation to the vertical fuducial

line drawn perpendicular to FH plane. Similarly various linear and angular

measurements were measured to evaluate the facial vertical dimensions.

Results showed that extraction line of treatment with all first bicuspids did

not show significant changes in overbite and vertical facial height after treatment.

There was a slight increase in the mandibular plane angle, but it was clinically

insignificant. However it should be interpreted with caution, given the small sample

size. The results in this study concludes that there is no vertical reduction in the facial

height following first bicuspid extraction, thus extraction of teeth solely to increase

the overbite or decrease the mandibular plane angle might not be justified.

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Annexures

MASTER CHART - 1 : PRE – POST ANGULAR CEPHALOMETRIC MEASUREMENTS (IN DEGREES)

Sl.No. Name A

ge(Y

rs)

Sex

Gogn - SN Gogn - FH Gogn - PP Gogn-OP SN-PP SN - FH U1 - SN L1 - Gogn U.Gonial L.Gonial Y - Axis

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

1 Veeranna 21 M 35 34 26 25 29 28 17 13 8 11 9 9 115 105 105 96 54 55 75 75 69 702 Manjunath M G 20 M 36 36 26 26 27 27 16 15 9 8 9 9 118 106 103 94 54 55 75 78 70 683 Santosh 19 M 34 34 27 27 26 26 16 16 9 9 8 8 114 106 101 93 52 52 72 73 67 684 Nabi 18.6 M 33 34 27 29 25 25 15 16 10 12 10 9 112 104 100 92 52 52 76 77 66 665 Lokesh 18 M 33 34 27 28 25 26 17 14 10 11 10 10 115 105 104 95 52 52 76 76 67 676 Pradeep 17.6 M 33 33 26 26 25 25 15 17 11 11 9 9 114 106 101 93 53 54 76 78 67 687 Basavalingappa 20 M 35 36 28 28 26 26 15 18 11 12 10 11 118 105 103 95 55 54 78 80 68 698 Pradeep 20 M 33 35 27 28 24 26 16 17 10 10 10 10 120 107 106 98 53 53 75 77 67 689 Sanketh 18 M 32 33 26 27 24 24 17 17 11 10 11 11 118 106 99 90 54 54 76 73 65 6510 Girish U T 21 M 34 33 27 27 24 25 16 17 11 10 10 10 120 108 104 97 55 55 79 75 67 6511 Praveen G M 18 M 32 33 26 27 24 24 17 17 10 9 10 10 117 107 98 90 54 54 76 75 66 6612 Basavaraj 20 F 35 36 26 26 26 26 15 14 8 7 10 9 119 107 103 95 54 54 78 78 69 6913 Tabussam 19 F 35 35 27 28 24 25 16 17 10 10 11 10 116 104 92 90 53 53 75 77 67 6814 Swathi 21 F 34 33 27 27 24 25 16 17 11 10 10 10 120 108 104 97 55 55 79 76 66 6715 Yasmeen 18.6 F 36 36 28 27 27 26 15 16 9 9 9 8 114 106 101 93 52 52 72 78 67 6816 Gowri 19 F 34 34 26 26 25 25 15 17 11 11 9 9 114 107 101 95 53 53 78 78 68 6817 Roopa 20 F 34 37 28 29 26 27 15 18 11 12 10 11 118 105 103 95 55 54 78 80 68 6918 Reena 21 F 34 33 36 25 29 28 17 13 8 11 9 11 115 105 105 96 54 54 75 75 69 7019 Sharada 20 F 32 33 26 27 24 24 17 17 11 11 11 10 118 106 99 90 54 54 76 73 65 6520 Ashwini 18 F 33 35 27 28 25 26 17 14 10 11 10 10 115 105 104 96 53 53 75 75 67 6721 Shobha 19 F 35 36 26 27 28 27 15 15 9 8 9 9 118 106 103 94 54 54 78 78 68 6822 Bhagya 19 F 33 33 26 26 25 26 15 18 11 12 10 11 118 105 103 95 53 53 77 77 67 6823 Vineeta 20 F 33 34 27 27 24 25 16 17 11 10 10 10 120 108 104 97 55 55 79 76 67 6524 Deepa 19.6 F 33 34 27 28 25 26 17 14 10 11 10 10 115 105 104 95 52 52 76 76 67 6725 Halamma 20 F 34 33 26 27 24 24 17 17 11 12 11 11 118 106 99 90 54 54 76 73 65 65

Annexures

MASTER CHART – 2 : PRE – POST LINEAR CEPHALOMETRIC MEASUREMENTS (IN MM)

Sl.No. Name Age

(Yrs) Sex

N – Me Se – Go N – ANS ANS-Me APF ht Rt SV - U6 Pog-L6 FH - U6 FH - L6

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

PRE

POST

1 Veeranna 21 M 129 128 78 78 55 55 74 73 60.4 60.9 40 42 -20 -18 47 49 48 472 Manjunath M G 20 M 128 130 78 79 55 55 75 73 60.7 60.1 41 43 -21 -19 46 48.5 47 45.53 Santosh 19 M 127 128 77 76 54 55 73 73 59.9 60.3 39 42 -19 -16 49 52 50 484 Nabi 18.6 M 125 127 76 75 54 53 73 74 60.8 59.1 40 43 -20.5 -17.5 47 48.5 48 475 Lokesh 18 M 124 124 74 73 51 51 73 75 59.6 59.4 40 42 -20 -18 48 50 49 476 Pradeep 17.6 M 124 124 72 72 53 53 71 71 58.6 58.1 39 42 -19 -16 48 50 50 487 Basavalingappa 20 M 127 125 75 73 54 54 73 71 59.1 59 39 41 -19 -17 46 48.5 47 458 Pradeep 20 M 128 127 76 77 52 52 76 75 59.3 60 39 42 -20 -17 48 49.5 49 47.59 Sanketh 18 M 124 123 73 72 51 51 74 73 58.8 58.5 40 42 -19 -18 45 48 46 4810 Girish U T 21 M 125 123 74 74 52 52 73 71 59.2 60.1 40 42 -20 -18 46 48 47 4911 Praveen G M 18 M 120 121 73 73 50 50 70 71 60.5 61 41 43 -21 -19 44 46.5 45 4712 Basavaraj 20 F 119 120 72 72 52 52 67 68 59.6 60.3 40 42 -20 -18 43 46 47 45.513 Tabussam 19 F 118 118 68 68 50 51 66 67 59.3 59.3 39 41 -19 -17 47 49 48 46.514 Swathi 21 F 129 128 71 72 52 53 67 68 60 60.1 41 43 -21 -19 46 48 47 45.515 Yasmeen 18.6 F 130 128 73 73 54 52 68 69 60.1 60.1 41 43 -21 -19 48 49.5 49 47.516 Gowri 19 F 127 128 70 70 51 51 67 67 59.4 59.9 40 42 -21 -19 49 51 50 4817 Roopa 20 F 128 125 72 72 52 52 67 68 58.6 58 40 42 -20 -18 47 49 48 46.518 Reena 21 F 127 124 71 71 52 52 66 66 59.3 59 41 43.5 -21 -18.5 44 46.5 45 4319 Sharada 20 F 124 124 69 69 53 53 65 65 60.1 60.3 42 45 -22 -19 45 47 46 4520 Ashwini 18 F 125 127 68 68 50 50 66 66 60 60.3 39 41 -19 -17 44 46.5 45 4421 Shobha 19 F 127 126 69 69 50 51 68 68 60.3 60.3 39 42 -19 16 44 47 45 4322 Bhagya 19 F 128 127 66 66 50 50 67 68 59.9 59.1 39 42 -18 -17 46 48.5 47 4523 Vineeta 20 F 124 126 67 67 52 53 66 65 59.1 59.4 40 42 -20 -18 48 50 49 4724 Deepa 19.6 F 124 126 74 73 51 51 73 75 59.6 59.4 40 42 -20 -18 47 49.5 48 4625 Halamma 20 F 124 123 73 72 51 51 74 73 58.8 58.5 41 43 -21 -19 47 49 48 46.5

Annexures

MASTER CHART – 3 : PRE – POST OVERBITE CEPHALOMETRIC MEASUREMENTS

Sl.No. Name Age

(Yrs) Sex MXSK BU1 TU1 BL1 TL1 MNSK OBPRE POST PRE POST PRE POST PRE POST PRE POST PRE POST PRE POST

1 Veeranna 21 M 17 19 15 17 19 20 28 23 13 12 72 74 147 1472 Manjunath M G 20 M 22 21 17 19 18 20 27 23 1 12 74 75 151 1523 Santosh 19 M 24 25.5 17 19 22 21 25 23 15 13 75 76 155 1544 Nabi 18.6 M 23 25 17 19 20.5 21 26 24 15 14 72 74 152 1515 Lokesh 18 M 24 25 15 18 19 21 26 23 15 14 76 74 153 1516 Pradeep 17.6 M 23 24 16 18 18 20 27.5 24 14 12 75 74 152 1507 Basavalingappa 20 M 25 26 16 20 20 22 26 23.5 13 12 74 75 151 1528 Pradeep 20 M 25 24 17 20 20 22 25 23 14 12 73 74 150 1529 Sanketh 18 M 25 24 18 21 20 22 26 24 14 12 74 72 152 152

10 Girish U T 21 M 25 23 16 19 19 21 27 24 15 13 74 73 153 15211 Praveen G M 18 M 24 23 17 20 19 21 25 24 13 12 73 72 147 14912 Basavaraj 20 F 24 25 15 19 19 21 25 22 12 11 73 74 146 14813 Tabussam 19 F 23 24 16 18 18 20 27 24 14 12 75 74 152 15014 Swathi 21 F 24 25 15 18 19 20 23 25 11 12 73 73 148 14915 Yasmeen 18.6 F 22 24 16 19 19.5 19 25.5 23 14 13 72 74 148.5 14816 Gowri 19 F 24 22 17 19 19 21 26 24 15 12 73 72 151 14917 Roopa 20 F 24 26 16 19 21 22 22.5 24 11 13 75 73 146.5 14918 Reena 21 F 25 24 17 20 20 21 24 22 13 11 74 72 149 14819 Sharada 20 F 23 24 16 18 21 22 24 22 15 14 75 76 152 15220 Ashwini 18 F 24 25 19 17 20 19 22 20 13 15 76 74 151 15021 Shobha 19 F 23 24 16 19 17 19 27 23 14 15 73 74 148.5 15022 Bhagya 19 F 22 23 17 19 19 18 29 26 14 11 17.3 76 149.5 14723 Vineeta 20 F 22 23 17.5 20 18.5 20 27 24 14 12 74 75 151 15224 Deepa 19.6 F 24 25 15.5 18 19 21 26 23 15 14 76 74 153.5 15125 Halamma 20 F 25 24 18 21 20 22 26 24 13 12 74 72 152 152

dr. ramesh g.c.-dissertation

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