Crestal bone resorption around platform-switched dental implants with fine threaded neck after immediate and delayed loading

Bone resorption and peri-implantitis are some of the most important problems of dental implantology. The implant macrodesign might decrease initial bone loss. The aim of this longitudinal study was to investigate crestal bone loss around screw type, tapered implants showing a fine threaded neck and platform switching design. In 32 patients of a dental practice, 147 maxillary implants with a diameter of 3.7 mm and 4.2 mm were placed and loaded according to clinical criteria. Immediate loading was exclusively performed in 3.7 mm diameter implants when adequate splinting and implant stability could be guaranteed (n=50). The remaining implants were loaded delayed. The bone level change was measured mesially and distally of the implant shoulder using follow-up X-rays and calculated per year in a linear mixed model. Bone resorption was low in all groups (3.7 immediate: -0.06 mm/year; 3.7 delayed: -0.16 mm/year; 4.2 delayed: -0.09 mm/year) after a mean follow-up period of 1.6 years (0.5-3.2 years). Based on the results of this study, it can be concluded that this implant macrodesign showed negligible bone resorption for all loading times. Immediate loading seems to be a reliable treatment option in the maxilla when clinical criteria are considered.