Impact of Interproximal Features on Marginal Bone Level Changes of Autograft, Allograft, and Xenograft after Functional Loading: A Retrospective Study

Abstract

Aim: This study aims to investigate the marginal bone level changes (MBLCs) concerning interproximal features of posterior implant-supported single crowns using different bone grafts. Materials and Methods: This retrospective study included 27 patients requiring 46 dental implants using autograft, allograft, or xenograft between January 2007 and December 2016. MBLCs were assessed using digital periapical radiographs at 3 months (T1), 12–15 months (T2), and 21–24 months (T3) after prosthesis delivery. The influence of interproximal features, such as embrasure surface area, emergence angle, and horizontal distance to adjacent teeth/implants, was assessed. Secondarily, age, gender, diabetes and smoking, arch distribution, implant locations, implant characteristics, average gonial angle, antagonist type, clinical crown-to-fixture ratio, retention method, and nearby tooth/implant were considered. Wilcoxon signed-rank test, Mann–Whitney U tests, and Kruskal–Wallis tests were employed with statistical significance set at a P value of <0.05. Results: The results revealed that mean MBLCs at T3–T1 were similar (autograft 0.5 ± 0.47 mm, allograft 0.51 ± 0.35 mm, and xenograft 0.57 ± 0.42 mm). There were significant increases in MBLCs associated with EA ≤ 30° in autograft (P = 0.04), and HD ≤ 3 mm in allograft (P = 0.03). Mesial/distal MBLCs showed no significant differences, except in cases with HD ≤ 3 mm in the distal area of autograft (P = 0.03). Regarding secondary factors, significant differences in MBLCs emerged between autograft and xenograft in the molar area (P = 0.03), and between premolar and molar areas within the xenograft group (P = 0.01). Conclusion: This study concludes that interproximal features, EA ≤ 30° and HD ≤ 3 mm, markedly influenced MBLCs for specific types of bone grafts. Furthermore, MBLCs exhibited a direct relationship with the posterior placement of dental implants.