Open or submerged healing of implants with platform switching: a randomized, controlled clinical trial

Enkling N, Johren P, Klimberg T, Mericske-Stern R, Jervoe-Storm P-M, Bayer S, Gulden N, Jepsen S. Open or submerged healing of implants with platform switching: a randomized, controlled clinical trial. J Clin Periodontol 2011; 38: 374–384. doi: 10.1111/j.1600-051X.2010.01683.x Abstract Aim: The temporal pattern of bone-level alterations in conventionally restored implants is dependent upon healing mode (open or submerged). This study examined the influence of healing on marginal bone levels at implants with a medium–rough surface including the implant collar and a clearance-fit implant–abutment connection restored according to a platform-switching concept. Material and Methods: Two implants were placed in the posterior mandible of 21 test subjects, randomly assigned to open (OH) or submerged (SH) healing. Standardized radiographs were obtained after implant surgery, before re-entry, after crown mounting, 1 and 2 years after implant surgery, and evaluated for implant–bone-level alterations (ΔIBL). Bacterial samples of the implants' inner cavities were analysed by cultivation. Statistics: Brunner–Langer Model, equivalence testings by Wilcoxon's (equivalence range ±0.4 mm). Results: After 2 years, ΔIBL were −0.47±0.46 mm (OH) and −0.54±0.38 mm (SH). At the 1-year follow-up, all implants were contaminated with bacteria. ΔIBL (p<0.001) and the amount of bacterial contamination (p<0.001) significantly depended on time, but not on healing mode. ΔIBL of OH and SH were equivalent at all time points (all p0.044). Conclusions: Platform-switched implants showed very limited peri-implant bone-level alterations. The healing-mode neither affected the total amount nor the temporal patterns of ΔIBL. Thus, the results for the tested implants with a non-rigid implant–abutment connection were similar to results reported previously for implants with a rigid implant–abutment connection.