Dental implant failure and factors associated with treatment outcome: A retrospective study

PURPOSE: The purpose of the present study was to retrospectively 1) investigate the association between implant-, patient- and bone-related parameters with the risk of implant failure; 2) analyze the survival rates of dental implants placed in a university clinical setting.

METHODS: Data were retrieved from patient charts from the University of Minnesota School of Dentistry to identify patients older than 18 years of age who received dental implant treatment by faculty, residents or students in the university dental clinics. Implant-, patient- and bone-related parameters such as implant system, length, diameter, jaw, region, installation protocol, gender, smoking, medical history, history of periodontal disease, self-reported oral parafunctions, type of bone, and operator were manually retrieved and analyzed.

RESULTS: Five hundred and fifty-three implants were randomly selected from a total of 4,424. Of these 553 implants, 440 (79.6%) were associated with a >10 mm length, 371 (67.1%) with a >4 mm diameter and 431 (77.9%) had replaced a single tooth. Submerged healing mode was followed in 363 (65.6%) of the implants with the mean healing time being 3.2 months. History of periodontal disease was identified in 294 (53.2%) of these cases. A total of 17 implants failed after a mean time of 6.29 ± 6.75 months, resulting in an overall survival rate of 96.9%. Based on a univariate analysis, implant system, operator, time between extraction and implant surgery, time between bone grafting and implant placement, tobacco use as well as clenching and grinding were considered potential implant failure predictors and were further included in the multivariate logistic regression analysis. Tobacco use (p < 0.001) was significantly associated with implant failure.

CONCLUSION: Within the limitations of this retrospective randomly selected university-treated sample tobacco use increased the risk for implant failure. Failure occurred in 17 implants representing a 3.1% failure rate.