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

ObjectiveThe objective of this study was to evaluate crestal bone changes around bone- and tissue-level implants related to initial mucosal thickness. Materials and methodsPatients 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 2.5mm 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 thicknessGroup A (thickness, <= 2mm) and Group B (thickness, >2mm). ResultsOur 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 +/- 0.5mm; Group B (MC), 20 with a mean bone change of -0.2 +/- 0.4mm; Group A (LC), 15 with a mean bone change of -0.1 +/- 0.5mm; and Group B (LC), 22 with a mean bone change of -0.2 +/- 0.4mm. 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). ConclusionIf the initial mucosal thickness surrounding bone-level implants is more than 2mm, there is significantly less crestal bone change compared with bone-level implants placed in initial mucosal thicknesses of 2mm or less. This difference is not statistically significant when tissue-level implants are used and the implant-abutment connection is 2.5mm above the crestal bone level.