The influence of initial mucosal thickness on crestal bone change in similar macrogeometrical implants: a prospective randomized clinical trial

Objective: The objective of this study was to evaluate crestal bone changes around bone- and tissue-level implants related to initial mucosal thickness. Materials and methods: Patients received at least 2 implants: one with the prosthetic abutment connection at the crestal bone level (MC) and one with the prosthetic abutment connection at 2.5 mm supra crestal (LC). Flap thickness measurements were taken using a periodontal probe after raising the buccal flap. Patients were divided into 2 groups according to the mucosal thickness-Group A (thickness, ≤2 mm) and Group B (thickness, >2 mm). Results: Our study included 33 patients and 78 implants. Each patient received at least 1 implant of each type: Group A (MC), 17 implants, with a mean bone change of -0.6 ± 0.5 mm; Group B (MC), 20 with a mean bone change of -0.2 ± 0.4 mm; Group A (LC), 15 with a mean bone change of -0.1 ± 0.5 mm; and Group B (LC), 22 with a mean bone change of -0.2 ± 0.4 mm. A paired-samples t-test for groups A (MC) and B (MC) yielded a statistically significant difference (P = 0.003); there was no statistically significant difference for groups A (LC) and B (LC) (P = 0.518). Conclusion: If the initial mucosal thickness surrounding bone-level implants is more than 2 mm, there is significantly less crestal bone change compared with bone-level implants placed in initial mucosal thicknesses of 2 mm or less. This difference is not statistically significant when tissue-level implants are used and the implant-abutment connection is 2.5 mm above the crestal bone level