Influence of Cervical Crown Contour on Marginal Bone Loss Around Platform-Switched Bone-Level Implants: A 5-Year Cross-Sectional Study.

PURPOSE:To evaluate the influence of the cervical crown contour on marginal bone loss and soft tissue health around platform-switched, posteriorly placed, two-piece implants. MATERIALS AND METHODS:A dataset from two previously conducted studies was used. Patients with single two-piece, platform-switched implants in between two natural teeth or adjacent to one natural tooth were included. Clinical parameters and standardized periapical radiographs from 1 month and 5 years after final crown placement were assessed. A new measurement method was developed to analyze geometric values of the cervical crown contour. Inter- and intraexaminer reliability were assessed. Emergence angles were measured at 1, 2, and 3 mm above the implant shoulder. Linear correlations between variables were determined by calculating Pearson correlation coefficients. RESULTS:A total of 64 patients with 67 posterior implants met the inclusion criteria. At 1, 2, and 3 mm above the implant shoulder, mean emergence angles at the mesial implant sites were 0.5 ± 2.8, 12.8 ± 12.8, and 18.0 ± 11.3 degrees, respectively. At the distal sites, the corresponding values were 2.8 ± 8.3, 16.2 ±16.6, and 18.7 ± 13.8 degrees, respectively. Mean marginal bone loss between 1 month and the 5-year evaluations was 0.14 ± 0.34 mm at the mesial aspect and 0.26 ± 0.47 at the distal aspect of implants. No correlation with peri-implant bone loss or soft tissue health could be found. No implants showed signs of peri-implantitis. CONCLUSION:The cervical crown contour at platform-switched, posteriorly placed, two-piece implants showed no correlation with peri-implant marginal bone loss or soft tissue health up to 5 years after implant placement.