Dental implant failure and bone augmentation: A retrospective study.

Background: To retrospectively assess the failure rate of implants placed in augmented and non-augmented sites and to investigate whether the time of implant and bone placement are associated with the risk of implant failure in a university setting. Material and Methods: In this retrospective study, data were retrieved from the electronic patient database of the University of Minnesota School of Dentistry, USA to identify patients older than 18 years of age who received dental implant treatment. Patient characteristics and the adequacy of available bone were retrieved from the patients' dental records and analyzed. Performing sinus lift and/or alveolar ridge augmentation in stages or simultaneously with implant placement and the need for multiple bone regeneration procedures were recorded. Kaplan-Meier plots and Cox regression models were created to analyze the data. Results: Data from 553 implants were analyzed in the study. More than half of the implants were placed in the maxilla (56.8%) and posterior regions (74.3%). The overall survival rate was 96.9%. Sinus augmentation was performed in 19.5% of the cases, while in 12.1% of the included treatments an implant was placed simultaneously. Staged and simultaneous ridge augmentation occurred in 45.2% and 18.8% of the cases, respectively. Implants placed in an area following ( Conclusions: Within the limitations of this study, implants placed in tobacco users as well as in augmented maxillary sinuses, simultaneously or in stages, and in augmented ridges lead to higher implant failure rates.