Marginal bone loss in single implant-retained mandibular overdentures using two different healing protocols and two different types of attachments: A 2-year follow-up of a randomized controlled trial.

OBJECTIVES: "The objective of this randomized control trial is to compare the marginal bone loss (MBL) in single implant-retained mandibular overdentures (SIRMO) retained by two different types of attachments using two healing protocols after a 2-year follow-up. MATERIALS & METHODS: SIRMOs were constructed for eighty completely edentulous patients. The latters were randomized based on the healing protocol and the used attachments into 4 equal groups: Submerged healing with ball attachment (BS), submerged with CM-LOC attachment (CS), non-submerged with ball attachment (BN), and non-submerged with CM-LOC (CN). Standardized peri-apical radiographs at baseline, 12 and 24 months were recorded to measure MBL. Comparisons for numerical data were performed using either Mann Whitney-U or Kruskal Wallis tests. Binary and categorical data were compared using chi square test. Significance level was set at p < .05. RESULTS: During the healing period, 6 implants failed, and 4 drop-outs were recorded. At the second year, 27/34 ball groups and 28/36 CM-LOC groups were recalled, no significant difference between B (0.28 ± 0.44) and C (0.38 ± 0.46) favoring B group (p = .3), and N (0.27 ± 0.39) and S (0.43 ± 0.51) favoring N group (P = .6). MBL revealed no significant difference neither between B and C groups nor between N and S groups. CONCLUSION: Both attachments showed physiologically accepted limits of MBL, favoring the non-submerged healing protocol after a 2-year follow-up period. CLINICAL RELEVANCE: Submerged (S) and Non-submerged (N) protocols could be used for a SIMOR, favoring the N protocol after a 2-year follow-up. TRIAL REGISTRATION NUMBER: PACTR20183003085193.