Influence of Transmucosal Area Morphology on Peri-Implant Bone Loss in Tissue-Level Implants.

PURPOSE: To analyze peri-implant bone loss around two types of tissue-level implants (convergent and divergent transmucosal morphology) placed in the same region of either the maxilla or mandible in a single surgical session. MATERIALS AND METHODS: This prospective study included 21 patients who each received two implants, one with a convergent transmucosal collar (n = 21) the other with a divergent collar (n = 21). Implants were placed in a single surgical session, by the same clinician, in the same clinical setting at the Prosthodontic and Occlusion Unit, University of Valencia (Spain). The implants (n = 42) were restored with splinted crowns screwed directly onto the prosthetic platforms. Bone loss analysis consisted of measurements taken from periapical radiographs 24 months after loading. Statistical analysis evaluated the homogeneity of the groups using Pearson's chisquare test; bone loss was compared with the Wilcoxon test. Statistical significance was set at 5% (alpha = .05), with a confidence interval of 95% and a power of 57%. RESULTS: Implants with convergent transmucosal morphology presented less mean peri-implant bone loss (0.29 +/- 0.34 mm) than those with divergent transmucosal morphology (0.60 +/- 0.63 mm), with a statistically significant difference between the two types of implants (P = .031). CONCLUSION: Less peri-implant bone loss occurs around supracrestal implants with convergent transmucosal morphology than divergent transmucosal morphology.