Methods: Consecutively treated 296 patients who received 721 rough surface dental implants at Okayama University Hospital from February 1990 and March 2007 were included in this retrospective cohort study. Early and late implant failure were estimated by inspecting clinical record as an outcome. Age, gender, tobacco use, number of remaining teeth, implant length, diameter, position of implantation (maxilla/mandible or anterior/posterior), with or without bone augmentation, opposing teeth condition and super-structure type (fixed or removable) were estimated as predictors. We estimated the risk factors for early and late implant failure by a logistic regression analysis and a Poisson regression model with GEEs with an intention-to-treat regime, respectively.
Results: Early failure rate was 1.5%, and 10- year cumulative survival rate was 94.0%. The risk factor for early failure was tobacco use (OR=10.67, p<0.01), and late failures were the super-structure type (removable)(relative ratio [RR]=29.88, p<0.01) and tobacco use (RR=2.95, p=0.02).
Conclusion: Tobacco use was identified as the risk factor for early and late implant failure and super-structure type (removable) was also indicated as the risk factor for late implant failure in this study.