David C. Lee

Abstract

Introduction: Functional appliances have been efficiently used in the treatment of Class II malocclusions caused by retrognathic mandibles. Cone beam computed tomography has enabled us to make more accurate linear measurements by eliminating superimposition of other structures and to analyze skeletal anatomic detail in all three planes of space. This retrospective study evaluated the osseous changes in the temporomandibular joint (TMJ) and length of the mandible in skeletal Class II malocclusion patients treated with the fixed functional appliances and compared measurements with Class I malocclusion patients treated with orthodontic mechanics that did not alter skeletal relationships.

Materials and Methods: Twelve patients (10 male, 2 female; mean age, 15.1 years) who were treated with the fixed functional appliance therapy until Class I molar occlusion was achieved and had the pre-treatment (T1) and progress (T2) CBCT images available were included in the study as functional appliance group. The control group included twelve gender-and age-matched patients (10 male, 2 female; mean age 15.3 years) who completed treatment for Class I malocclusion with orthodontic mechanics without orthopedic effects and had the pre-treatment (T1) and post-treatment (T3) CBCT images available. Newtom NNT imaging software measurements of the TMJ and mandibular osseous changes were compared in each treatment modality. The glenoid fossa location was determined by measuring from the most superior point of the glenoid fossa (GF) to porion (Po) and pterygomaxillary fissure (PtM). The length of the mandible was measured from the superior point of the condyle (C) to gnathion (Gn)1 and from GF to Gn. Corrections achieved through dental changes were measured by comparing the incisor mandibular plane angle (IMP). The data at different time intervals and between groups were analyzed using paired and independent t-tests at the significance level of α=0.05 respectively.

Results: In the functional appliance group, GF-Gn, C-Gn and GF-Po at T2 were significantly greater than those at T1 (p < .05); IMP at T2 was significantly higher than T1 (p < .05); whereas no statistically significant difference in GF-PtM between T1 and T2 (p = .067). In the control group, Gf-Gn, C-Gn, and GF-Po at T3 were significantly greater than those at T1 (p < 0.05). However, there was no statistically significant difference between T1 and T3 of IMP (p = 0.078) or GF-PtM (p = 0.957). When comparing the changes achieved between experimental and control group, no statistically significant difference was found between any of the measurements (p > 0.05).

Conclusions: Evaluating three-dimensional cone-beam computed tomography allows for improved reliability over two-dimensional radiographs in landmark identification as well as linear and angular measurements. The results of this study seemed to validate the motion [sic] that functional appliance therapy corrects Class II malocclusion by increasing the length of the mandible, anterior repositioning of the glenoid fossa, and proclination of the mandibular incisors.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate Studies

First Advisor

Joseph Caruso

Second Advisor

Kitichai Rungcharassaeng

Third Advisor

Guy Taylor

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2009

Date (Title Page)

9-2009

Language

English

Library of Congress/MESH Subject Headings

Orthodontics, Corrective; Orthodontic Appliances, Functional; Temporomandibular Joint Disorders -- therapy; Bone and Bones -- radiography; Mandibular Condyle -- radiography; Mandible -- growth and development; Malocclusion, Angle Class II -- therapy; Cone-Beam Computed Tomography; Tomography, X-Ray; Cross-Sectional Studies; Analysis of Variance

Type

Thesis

Page Count

xi; 42

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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