What Are the Incidence and Factors Associated With Implant Fracture?

PURPOSE: Implant fracture is a serious complication, which leads to treatment failure. The purpose of this study is to estimate the incidence of implant fractures and identify factors associated with them. MATERIALS AND METHODS: In this retrospective cohort study, the sample was derived from 2 implant centers. The predictors were grouped into the following categories: demographic, location of implant, physical characteristic of implant, implant-abutment connection, type of prosthesis, type of retention, and outcome variable (time to implant fracture). The Kaplan-Meier test was used to estimate implant survival. A Cox regression model was applied to evaluate the time-to-event effect of variables on implant fracture. RESULTS: Of 18,700 implants, 37 (0.002%) had fractures. The 1- and 5-year risk of implant fracture was 0.38 per 1,000 and 1.46 per 1,000, respectively. Implant fractures more often occurred in the premolar and molar area (94.6%) than in the anterior of the jaws. The Pearson correlation test did not show any correlation between age, implant diameter, or implant length and time of fracture (P > .05). Analysis of the data by the log-rank test showed a significant difference for survival between cemented and screw-retained crowns (P = .001). The Cox regression model showed a hazard ratio of 0.23 for tapered implants versus cylindrical fixtures and for screw-retained crowns (hazard ratio, 296.54) versus cemented crowns. CONCLUSIONS: According to this study, conical implants and screw-retained prostheses may have lower survival rates due to implant fracture.