3D Assessment of Anterior Alveolar Bone Remodeling in Orthodontic Cases Using Extra-Alveolar Reference

Objective: To explore alveolar cortical positional change in response to tooth movement in extraction and non-extraction orthodontic cases, using CBCT and stable extra-alveolar references. Materials and Methods: CBCT of 25 extraction (EXT) and 25 non-extraction (NonEXT) orthodontic cases were recruited from the University of Illinois Chicago, Case Western Reserve University, and an Illinois private practice. The pre-treatment (T1) and post-treatment (T2) CBCT were imported into Dolphin Imaging 3D, and oriented uniformly. Sagittal and axial CBCT cross-sections were traced using software-generated guides. The displacement of teeth and cortices were automatically measured using the palatal plane (PP) and the line perpendicular to PP and passing Sella as reference. Intra- and inter-group differences between T1 and T2 were analyzed. 3 extractions and 3 non-extraction subjects were also superimposed 3-dimensionally using Geomagic Control X for qualitative analysis of cortical remodeling. Results: EXT showed incisor retraction, while NonEXT exhibited statistically significant incisor anterior tipping. In EXT, both the labial and palatal cortices resorbed. NonEXT showed labial cortex anterior modeling, and statistically significant palatal cortex resorption. In both groups, statistically significant decrease in total and palatal alveolar widths, increase in labial widths, and palatal dehiscence were observed. Comparatively, EXT showed significantly more incisal total and palatal width decrease and palatal vertical bone loss. Conclusion: palatal cortical remodeling was shown to follow anterior tooth movement, but the palatal cortical response to incisor retraction and labial cortical remodeling in general remained inconclusive. Narrowing of the alveolar housing and palatal dehiscence were observed regardless of extraction following orthodontic treatment.