Initial implant position determines the magnitude of crestal bone remodeling

Background: The ability to predict the amount of bone remodeling around implants is important for a stable and predictable esthetic result. The purpose of this study was to investigate the amount of radiographic bone remodeling that occurs over time using a one-piece implant system. Methods: Twenty-seven patients receiving implants in the maxilla and 15 receiving implants in the mandible were included in the study. All implants were placed with a non-submerged surgical technique with varying locations of the rough-smooth border with respect to the alveolar crest. Clinical exams and radiographs were taken on the day of implant placement, at 6 months, and annually up to 5 years. Linear measurements from digitized radiographs were made from the implant shoulder to the first bone-to-implant contact at all time points. Results: A significant amount of bone remodeling compared to baseline occurred for all implants at the 6-month follow-up visit (1.10 mm), with the remaining time points showing virtually no change (0.1 mm). A relationship was found between the amount of bone remodeling and the location of the rough-smooth border with respect to the alveolar crest. Those implants with the rough-smooth border surgically placed below the crest had, on average, a greater amount of remodeling at 6 months (average 1.72 mm) than implants with the rough-smooth border placed at or near the crest (average 0.68 mm). In both situations, this remodeling: 1) occurred early (within 6 months), 2) reached a similar level, and 3) remained virtually unchanged up through 60 months (0.05 mm). Conclusions: A physiologic dimension appears to exist between the bone and the implant-crown interface around one-piece implants that is established early and maintained over time. These results are significant because they demonstrate in patients that the magnitude of initial bone remodeling around these one-piece dental implants is dependent on the positioning of the rough-smooth border of the implant in an apico-coronal dimension. Furthermore, the dimension, from the crown-implant interface to the first bone-to-implant contact, is consistent with the formation of a biologic width similar to that found around the natural dentition.