Impact of implant diameter on bone level changes around platform switched implants: preliminary results of 18 months follow-up a prospective randomized match-paired controlled trial

Objective This prospective randomized match-paired controlled trial aimed to evaluate the impact of implant platform diameter on marginal bone level around implants restored according to the platform switching (PS) concept. Material and methods A total of 24 implants were examined in 12 patients. All patients received two adjacent implants inserted at the crestal level: 4.3 similar to mm (control group) and 4.8 similar to mm (test group) in diameter. Mesio-distal implant position was randomly performed. According to the PS concept, for restoration, a 3.8 and 4.3 similar to mm diameter abutment was used, respectively in the control and test groups, resulting, in both groups, with 0.25 similar to mm of implant/abutment mismatching. Implant restorations were splinted. Eighteen months after final restoration, periapical standardized digital radiographs were taken to evaluate marginal bone level alterations after loading. The Wilcoxon Signed-Rank Test was selected to identify differences between groups. Results At the last follow-up, control implants exhibited a mean bone loss value of 1.10 similar to mm (SD: 0.47 similar to mm); the test group showed a mean value of 1.09 similar to mm (SD: 0.08 similar to mm). No statistically significant differences were found between test and control groups. Conclusions Within the limits of this study, the present results suggest that bone resorption is mostly related to biologic (biologic width re-establishment) rather than to biomechanical factors (implant platform diameter). Furthermore long-term studies with a wider sample size are needed to confirm the platform diameter influence on hard tissue response around implants restored according to the PS concept.