Introduction: Prosthetic abutments with reduced width in relation to the implant diameter (platform switching, PS) seems to have potential to reduce crestal bone loss around dental implants. There are limited studies comparing this concept with standard abutments in the same implant system. In accordance to this, the study aimed to evaluate crestal bone level of the same implants in a definite indication restored with PS and with standard abutments (SA). Materials and Methods: In a prospective randomized international multicenter study, 68 patients were provided with 163 implants (Camlog® Screw line) and restored with PS (n=83) as well as with SA (n=80) in the posterior mandible. Indications were: ≥2 adjacent missing teeth, natural tooth mesial to proximal implant site, full opposition dentition, implants placed at least 6 weeks post extraction and no bone augmentation. Primary objective was a comparison of changes in crestal bone levels (fig. 1) between the groups. We will report the first results of the implants after 1 and 2 years. Results: After a total follow-up of 2 years, in the PS group a mean bone gain of 0.15 mm was recorded between the time of prosthesis placement and 12-months post-loading and 0.22 mm after 24-months post-loading (fig. 2). In comparison, a bone loss of 0.09 mm and 0.27 mm was measured in the SA group for the one and two-years loading period. For both time points the difference is significant (p=0.005 and 0.004; fig. 3,4 and 5). The total implant survival was 98.2%, 3 implants were lost. Discussion: the PS concept seems to be suitable in order to limit crestal resorption and to preserve peri-implant bone levels. Schlagwörter: Dental Implant, Camlog, Platform Switch, Crestal Bone Resorption, peri-implant Bone Level