Bone Remodeling Under Screw-Fixed Chin Implants in Patients With Microgenia: A Cross-Sectional Study

Abstract

The use of alloplastic chin implants has been associated with a risk of bone resorption. The aims of this study were to evaluate, in patients with microgenia, the association between chin implants and bone resorption and identify the associated risk factors for such resorption. The sample consisted of 51 patients with microgenia: 17 with chin implants (group A, placed over the course of a 15-year period [2002-2017]) and 34 without implants (group B). Cone-beam computed tomography was used to evaluate bone erosion in different areas of the chin. The patients were evaluated, and their medical records were reviewed to identify risk factors. A chi-square or Fisher exact test and the Mann-Whitney test were used to compare groups; resorption sites were compared with Friedman test. Linear regression models were used to evaluate associations between potential risk factors and resorption. Bone resorption was higher in group A than in group B (mean ± SD: 0.98 ± 0.63 mm vs 0.03 ± 0.12 mm; P < .0001). Symphyseal buccal cortical bone in group A was thinner (1.66 ± 0.34 mm) than it was in group B (2.07 ± 0.45 mm), P < .001. Group A showed appositional bone growth and no cortical bone perforation. The mean of the amount of bone resorption of chin implant patients compared with that of those without implants was, on average, 0.99 mm greater (95% confidence interval: 0.64-1.35; P < .001). Although statistically significant differences in bone resorption were observed between groups, these differences were not clinically significant. Thinning of symphyseal buccal cortical bone without perforation and appositional bone growth occurred in chin implant patients, suggesting bone remodeling. Our results suggest that bone that is in contact with chin implants remodels and remains stable throughout the years, instead of undergoing progressive resorption.