Influence of Platform-switching on Crestal Bone Changes at Non-submerged Straight and Inclined Implants Retaining Mandibular Overdentures

. AbstrAct The purpose of this clinical trial was to study the influence of platform-switching concept on crestal bone changes at non-submerged straight and inclined implants retaining mandibular overdentures. Eight patients received 2 implants one straight and the other inclined in the canine region of the mandible. Mandibular overdentures were retained using spheroflex abutment attachments, with reduced platform width in relation to the implant diameter. Standardized digital radiographs were obtained for evaluation of the crestal bone levels at the time of the installation of the final restoration and at a 2-year follow-up. Crestal bony levels were measured at the mesial and distal surfaces of each implant using digital image analysis. The mean crestal bone level changes from baseline to one and two years followup in both straight and inclined implants were 0.07, 0.15 and 0.18, 0.30 at the mesial side and 0.07, 0.17 and 0.13, 0.22 at the distal side, respectively. The concept of the platform-switching appears to limit crestal bone resorption in both straight and inclined implants and seems to preserve periimplant bone levels. However, a significant difference concerning the mesial periimplant bone height of the inclined implant compared to that of the straight one was still detected.