Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

School of Dentistry

Department

Orthodontics

Committee Chair

Timothy Tremont

Committee Co-Chair

Richard Jurevic

Committee Member

Chris Martin

Committee Member

Peter Ngan

Abstract

Background and Objectives: Correct tooth position in all planes of space while respecting the boundaries of the underlying bone has been proposed as a necessary hallmark to providing a foundation of stability for the teeth as well as the supporting periodontium. The aim of this study was to determine 1) If teeth centeredness over basal bone improves when teeth are more upright or approach WALA Ridge norms 2) If teeth centeredness in alveolar bone improves when teeth are more upright or approach WALA Ridge norms 3) If the WALA ridge is located at or near the estimated center of resistance of molar and premolar teeth. Methods: 34 pre-treatment CBCT and mandibular cast samples of patients ages 12-18 were randomly selected and analyzed. WALA ridge cast measurements were transferred to CBCT images. The centeredness of the teeth within bone was then quantified. The WALA Ridge location was measured and compared to the center of resistance location. Results: 1) No statistical significance was found across the board for centeredness of teeth over basal bone when they are more upright or approach WALA Ridge norms. 2) No statistical significance was found across the board for centeredness of teeth in alveolar bone when they are more upright or approach WALA Ridge norms. 3)Statistical significance (p-value <.05) was found for the center of resistance and WALA Ridge being located at or near each other for all mandibular posterior teeth. 4) Statistical significance (p-value <.05) was found for posterior teeth center of resistance being centered in the alveolar bone regardless of the long axis inclination or WALA Ridge norms. Conclusion: 1) More upright posterior teeth based on long axis inclination or teeth more closely related to the WALA ridge landmark are not more centered over basal bone. 2) More upright posterior teeth based on long axis inclination or teeth more closely related to the WALA ridge landmark are not more centered in alveolar bone. 3) The WALA Ridge soft tissue landmark is located at or near the center of resistance for all posterior teeth. 4) The center of resistance of all posterior teeth can most often be found in the center of the alveolar bone regardless of inclination.

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