Purpose: This retrospective study compared the long-term outcomes of dental implants according to type of connection and surface.
Materials and Methods: Multiunit restorations were classified as follows: an external connection with a turned surface, an external connection with an anodized surface, or an internal connection with a fluoride-modified surface. Patients who were followed up for longer than 7 years after implant loading were included in the study. Cumulative implant survival rates and the amounts of marginal bone loss were calculated by reviewing dental records and radiographs. Only implants that survived until the last follow-up visit were included in the analysis of marginal bone loss. Statistical analyses were performed to detect between-group differences at the significance level of .05.
Results: Sixty-nine patients with 261 bone-level implants were included. The average follow-up duration was 15.2 years in the external turned group, 10.6 years in the external anodized group, and 9.9 years in the internal fluoride-modified group. There was no significant between-group difference in the cumulative survival rate (P = .439) despite eight implant failures (six in the external turned group and two in the internal fluoride-modified group). The mean (SD) marginal bone loss values at the last follow-up were 0.47 mm (0.67), 0.87 mm (1.07), and 0.23 mm (0.58) in the external turned, external anodized, and internal fluoride-modified groups, respectively. After adjusting for follow-up duration, there was significantly less marginal bone loss in the external turned group than in the external anodized group (P < .001) and in the internal fluoride-modified group than in the external anodized group (P < .001). No significant difference in marginal bone loss was found between the external turned and internal fluoride-modified groups (P = .44).
Conclusion: The implant-abutment connection structure is an important contributor to the maintenance of the level of marginal bone surrounding the implant. Implant surface characteristics are another contributor to marginal bone resorption.