Dental Implants Placed in Patients with Mechanical Risk Factors: A Long-term Follow-up Retrospective Study

OBJECTIVES Risk factors in oral implantology are defined as local or systemic conditions that increase failure rates. The purpose of this paper is to evaluate the long-term survival rate of dental implants placed in patients presenting mechanical risk factors. MATERIALS AND METHODS This retrospective study was conducted only with patients presenting at least one of the following risk factors were included: Bruxism; crown-to-implant (C/I) ratio <0.8; abutment angulation. The overall implant survival was estimated using Kaplan-Meier analyses. Risk factors for implant failure were identified using the Cox proportional hazard regression models. RESULTS Eighty-nine eligible patients were enrolled in this study: They were both male (n = 56, 62.92%) and female (n = 33, 37.08%), with an average age of 53.24 (23-76 years), with 227 dental implants inserted. The mean follow-up was 13.6 years (range: 10-16 years). The overall 10-year Kaplan-Meier survival estimate with associated 95% confidence intervals was 86.34% (82.8, 87.1). Bruxism was the only variable that showed a statistically significant association with implant failure (P < 0.05) and a hazard ratio of 2.9, while both Crown to-implant and abutment angulations reported lower values of failure (P > 0.05). CONCLUSIONS Within the limitations of this study, can be concluded that data suggested an evident relationship between bruxism and dental implant failure but further studies, with a larger sample and a different design are required to assess this relationship.