Early Implant Failures in Edentulous Patients: A Multivariable Regression Analysis of 4615 Consecutively Treated Jaws. A Retrospective Study.

PURPOSE: To study the incidence of early implant failures in edentulous jaws and to describe the effects of some patient- and implant-related factors on the risk for early implant failures.

MATERIALS AND METHODS: The study retrospectively analyzed 4615 edentulous jaws (4067 patients), consecutively treated with dental implants at one referral clinic from 1986 to 2013. Implant failures that occurred from implant surgery up to the first recall examination 1 year after prosthesis insertion were recorded and defined as early implant failures. All removed implants were included as failures. Features of the study group and early implant failure rates were reported. A multivariable logistic regression model was used for analyzing possible associations between clinical factors, and the risk for early implant failures. Implant surfaces were categorized by means of roughness: turned (Sa 0.5-1.0 μm) and moderately rough (Sa 1.0-2.0 μm).

RESULTS: Three hundred twenty-seven patients (344 jaws) were lost to follow-up. Early implant failures occurred in 8.6% of the jaws. In the maxilla there was a significantly higher incidence of early failures compared to the mandible both with turned implants, OR 5.93 (95% CI 4.21; 8.36), and moderately rough implants, OR 2.52 (95% CI 1.19; 5.34). The impact of implant surface roughness was significant in the maxilla with higher incidence of early failures with turned implants, OR 3.51 (95% CI 2.27; 5.42). There was a significant interaction between implant surface and jaw type on early failures (p = 0.034). Older age was associated with lower risk for early implant failures, OR 0.9 (95%CI 0.82; 0.99). In total, 63% of the jaws with failure could proceed with the prosthetic treatment without further implant insertions. Twenty-six percent of the early failures occurred after prosthesis insertion and 59% of those could maintain the same prosthesis after implant loss with or without adjustments.

CONCLUSIONS: Changing the implant surface from turned to moderately rough decreased the incidence of early implant failures significantly in the maxilla, but not in the mandible. Older age at implant insertion was associated with lower risk for early implant failures in edentulous patients.