Date of Award

2011

Degree Type

Thesis

Degree Name

Master of Clinical Dentistry

Program

Orthodontics

Supervisor

Dr. Antonios H. Mamandras

Abstract

Introduction: Degenerative joint disease (DJD) or condylar resorption (CR) is mildly prevalent in a pre-orthodontic population and theoretically could contribute to jaw pain and skeletal relapse following orthodontic treatment.

Purpose: To determine whether craniofacial form, dental characteristics or particular orthodontic treatment modalities are related to bony condylar degeneration.

Materials and methods: 174 subjects were divided into three groups based on the grade of condylar resorption. 1) moderate-severe condylar resorption, 2) mild condylar resorption and 3) no condylar resorption (as diagnosed from panoramic radiographs). Lateral cephalometric radiographs were traced at initial presentation (Tl) and treatment factors were recorded. Groups were compared for differences in skeletal, dental and modalities of orthodontic treatment. Bony condylar change over time was also measured and compared between those with a history of orthognathic surgery and those without.

Results: Cephalometric findings of statistical significance among those with moderate- severe condylar resorption included increased vertical skeletal measurements (increased Y-axis, SN-PP, SN-OP, SN-MP, UFH, MPA, gonial angle, decreased P-AFH% and facial axis), increased overjet, decreased Ll-MP, increased NLA, decreased SNA, SNB and maxillomandibular differential when compared to the other groups. Treatment modalities of statistical significance included a history of orthognathic surgery (three­ fold relative risk) and increased treatment time.

Conclusions: Results from this study indicate that risk factors for condylar resorption include a dolichofacial type with increased overjet, extended treatment length and orthognathic surgery.

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