Abstracts Biological Sciences

Morphological Changes in Alveolar Bone Following Orthodontic Space Closure

by Ninette Hacopian

Introduction: Changes occurring in anterior alveolar bone following orthodontic tooth movement are controversial. Some research has shown that orthodontic tooth movement results in the adaptation of cortical bone; others have shown that it results in dehiscence and fenestrations. Purpose: The purpose of this study was to evaluate the alveolar bone changes around maxillary anterior teeth following orthodontic space closure. Materials and Methods: Cone beam computed tomograms (CBCTs) of non-growing patients who received orthodontic treatment with bilateral maxillary premolar extraction were evaluated. Only patients with at least 5 degrees of changes in maxillary incisor (U1) to palatal plane angle were included in the study. Before (T1) and after (T2) orthodontic treatment CBCTs were reconstructed with the anterior cranial base segmented. The original T1 and T2 volumes and the segmented anterior cranial base volumes were superimposed using voxel based registration method. The superimposed sagittal images of right and left maxillary incisor were evaluated for alveolar bone changes. The distances from labial and palatal crest to CEJ were measured to evaluate vertical bone changes. Labial and palatal bone thicknesses at 3, 6, 9, 12 mm from CEJ as well as the angles formed between palatal plane with labial and palatal alveolar plates were measured to evaluate the changes in the morphology of the maxillary alveolar process. A paired T-Test was used to compare the means of T1 and T2 measurements at the significance level of α = 0.05. Results: Twenty-six (7 male and 19 female) patients with a mean age of 22.1 years with a total of 49 maxillary central incisors were evaluated. The crestal alveolar bone showed statistically significant resorption both in the labial (p = .038) and palatal (p < .001) aspects. Significant losses in palatal bone thickness were observed at the 3, 6, and 9 mm from the CEJ (p < .05). Small gains in labial bone thickness were observed but they were not significant (p > .05). Conclusion: Alveolar process modeling in the maxillary anterior teeth occurs in response to retraction during space closure. The most adversely affected area is the palatal crest, which might lead to periodontal consequences. Advisors/Committee Members: Viecilli, Rodrigo, Caruso, Joseph M., Rungcharassaeng, Kitichai.