University of Alberta The Twin Block Appliance

133 Pages·2001·9.93 MB·English

University of Alberta
The Twin Block Appliance - A cephalornetric analysis of vertical control
@
Dr. Colleen AM Adams
A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of
the requirements for the degree of Master of Science
in
Orthodontics
Department of Dentistry
Edmonton, Alberta
Fa112000
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Abstract
This study investigates the twin block appliance's abifïty to correct overbite. Lateral
cephaiometric radiographs at time-l and time-2 were scanned and digitized for patients
treated with the twin biock appliance and a control group. The twin block group was
divided based on dxerent treatments for the correction of overbite- The deep bite
treatment group expenenced overbite correction of4mm while the open bite treatment
group did not change significandy from the control group. Regression analysis identified
the most important variables in the overbite correction for the deep group as increased
lower face height of 2 S m q downward movement of pogonion and gnathion by 2.0mm,
restriction of mandibular hcisor eruption by 1.7ma nd proclination of the lower incisor
by 4.5 degrees. Cornparison of the two treatment groups showed that there was no
difference in the anteropostenor correction; both groups nnished treatment with ANB
angles of 4 degrees and ovej ets of 2.2mm.
Dedication
This thesis is dedicated to the memory of my grandfathers. Their curïosity and academic
interest has been an inspiration for the whole family and they are felt with me in all things
chailenging. A speciai thank-you to my parents and to my husband for al1 their
unquestioning encouragement and support.
Table of Contents
Chapter
1. Introduction
1- 1R esearch fr oblem
1.2 Functiond AppIiance History
1.3 Functional Appliance Research in Animals
1 -4 Functiond Appliance Clinical Investigations
1- 5 Twin Block Clinical Investigations
1.6 Discussion of Vertical Facial Pattern
1- 7 Research Recommendations
1- 8 Statement of Objectives
1- 9R eferences
2. Pilot Study 1 Scanned Radiographs using Custom Cephalometric Analysis
2.1 Introduction 29
2.2 Materials and Methods 29
2.3 Redts 34
2.4 Discussion 38
2.5 References 41
3. Pilot Study for Mandibular Superimposition
3 - 1 Introduction
3 -2 Materials and Methods
3-3 Results
3 -4 Discussion
3.5 References
-
4. Paper 1 A Cephalometric Analysis of Twin Block Treatment of Overbite
4-1 Introduction 50
4.2 Material and Methods 5 1
4-3 Results 63
4-4 Discussion 75
4.5 Appendicies 82
4.6 References 88
-
5. Paper 2 Investigation of Treatment Effects for Bite Opening and Non Bite
Opening Twin Block Treatment Regimes
5.1 Introduction 90
5.2 Materials and Methods 91
5.3 Results 101
5.4 Discussion 110
5.5 References 114
6. General Discussion
6-2 Discussion
6.2Major Conclusions
6.3L imitations
6-4Future Studies
6.5References
List of Tables
Table Page
2.1 Cephalometric Landmark Identification Definitions 30
2.2 Distances Definitions for Landmark Distances and Calculated 30
Measurements
Angular Measurement Defhitions 33
Mean Errors and Maxïmurn Error in Distance and Angular Measurements 3 5
Reliability Analysis for Distance Measurements 37
The Reliability of Angular Measurements 37
Superimpo sition Measurement Delinittions 45
Descriptives for the Standard Deviation of Superimposition 46
Measurements
Reliability Values for Sup erimposition Measuements 46
Growth liidicators Used to Select Control Subjects 53
Table 4.2 Cephaiometric Landmark Identification Definitions 54
Distances Definitions for Landmark Distances and Calculated 55
Measurements
Anguiar Measurement Definitions 58
Superimposition Definitions 61
Open Bite Treatment and Control Group Composition 63
Open Bite Treatment and Control Group 63
Composition for Gender
Deep Bite Treatment and Control Group Composition 64
Deep Bite and Deep Bite Control Groups Gender Composition 64
Dental Pretreatment T-tests Open Treatment Group Versus Control 65
Statistically Significant Variables Only
Skeletal Pretreatment T-tests Open Treatment Group Versus Control 65
St atisticaily Significant Variables Only
Dental Pretreatment T-test Deep Treatment Group Versus Control 65
Statistically Significant Variables Ody
Skeletai Pretreatment T-tests Deep Treatment Gromp Versus Control
Statistically Significant Variables Oniy
Open bite Change in Overbite Compared to Control
Deep bite Change in Overbite Compared to Control
T-tests of Dental Measurement Changes over Treartment
(Observation) Time for Open Bite Group
T-tests for Skeletal Measurement Changes over Treatment
(Observation) Time for Open Bite Group
T-tests of Dental Measurement Changes over Treatment
(Obsemation) Time for Deep Bite Group
T-tests for Skeletal Measurement Changes over Treatment
(Observation) Thef or Deep Bite Group
Regression Model for Dental Factors on the Change in Overbite
Model of Regression of Skeletai Factors on the Change in Overbite
Combined Mode1 of Dental and Skeletal Factors im Regression on the
Change in Overbite
Cephalometric Landmark Identification Definitions
Distances Defuiitions for Landmark Distances and Calculated
Measurements
Anguiar Measurement Definitions
Superimposition Measurement Dehitions
Group Composition Characteristics
Group Composition for Gender
T-tests of Pretreatment Skeletal Measurements
T-tests of Pretreatment Dent al Measurements
Skeletal Measurements Changes with Treatment
Dental Measurements Changes with Treatment
Mandibular Superimposition Changes with Treatrnent
List of Figures
Figure Page
2.1 Distance Measurements 32
Angular Measurements
Mandibular Superimposition
Treatment to increase the vertical dimension
Distance Measurernents
Angular Measurements
Mandibular Superimposition Measurements
Treatment to increase the vertical dimension
Distance Measurements
Angular Measure ment s
Superimposition Measurement Definitions