Alveolar bone response to tooth movement with or without selective decortication (corticotomy) and long term stability of the bone related changes
Date
2009
DOI
Authors
Baloul, Soulafa Susan
Version
OA Version
Citation
Abstract
Background & Purpose: Bone turnover in response to orthodontic tooth movement is regulated by osteoblastic and osteoclastic activity. Enhancing the rate of this process through surgical alveolar decortication has proven to be a successful method in clinical practice. The exact biological mechanisms underlying this technique however, are not well understood. We have hypothesized that corticotomy-induced osteoclastogenesis and bone remodeling underlie the orthodontic tooth movement where corticotomy enhances the rate of tooth movement by increasing bone remodeling compared to conventional tooth movement.
Materials & Methods: The study consisted of two parts: 1) Active tooth movement phase and 2) Follow-up phase. In part I, total of 114 Sprague-Dawley (CD Crl) rats were included and 3 treatment groups were defined: corticotomy alone (CORT); tooth-movement alone (TM); and “combined” therapy (CTM). Tooth-movement was performed on the first molar utilizing a 25-gram Sentalloy spring secured to a micro-screw palatal to the incisors. Time line included baseline observation where no procedures were performed and 3, 7, 14, 21, 28 and 42 days of active tooth movement. Nine animals were used at each time point. Half of the animals were used in Microcomputed Tomography (MicroCT), faxitron, and histology analyses and the rest were used for molecular biology studies (RNA isolation and Real Time PCR). For part II, 60 animals were included in two treatment groups: TM and CTM. Appliances were removed at 42 days and an additiona1 42-days of follow-up was observed. The time line in this phase included: 42, 49, 56, 63, and 84 days. Similar to part I, half of the animals were used in MicroCT, faxitron, and histoIogy analyses and the rest were used for molecular bioIogy studies (RNA isolation and Q-PCR). Faxitron analysis was performed to measure amount and rate of tooth movement. MicroCT was used for quantitative assessment of bone structure and mineral content. Histomorphometric analyses were utilized to measure amount of bone in the region of interest surrounding the 1st molar tooth in response to CORT, TM and CTM. To determine how alveolar decortication changes alveolar bone remodeling during orthodontic tooth movement on the cellular and molecular level, mRNA expression was quantitatively assessed across the remodeling by real-time PCR (Q-PCR). The osteoblastic and osteoclastic bone markers included: M-CSF, RANKL, OPG, Calcitonin R, TRACP 5b, Cathepsin K, OPN, BSP, and OCN. Statistical analysis was performed using Student’s t-test and ANOVA with LSD post-hoc test.
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Thesis (DScD) --Boston University, Goldman School of Dental Medicine, 2009 (Department of Periodontology and Oral Biology).
Includes bibliography: leaves 213-241.
Thesis (DScD) --Boston University, Goldman School of Dental Medicine, 2009 (Department of Periodontology and Oral Biology).
Includes bibliography: leaves 213-241.
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.