Diederik Hentenaar

128 Chapter 6 ABSTRACT Aim The aim of the present cohort study was 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. 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 peri-apical radiographs taken at 1 month and 5 years after final crown placement were assessed. A new measurement method was developed to analyse geometric values of the cervical crown contour. The inter and intra-examiner reliability was assessed. Emergence angles were measured at 1, 2 and 3 mm above implant shoulder. The linear correlation between variables was determined by calculating the Pearson correlation coefficient. Results A total of 64 patients with 67 posteriorly 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 corresponding values were 2.8±8.3, 16.2±16.6 and 18.7±13.8 degrees. Mean marginal bone loss between 1 month and 5 years evaluation was 0.14±0.34mm at the mesial and 0.26±0.47 at the distal aspect of the implants. No correlation with peri-implant bone loss and 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 and soft-tissue health up to 5 year after implant placement.