Cumulative Success Rate of Short and Ultrashort Implants Supporting Single Crowns in the Posterior Maxilla: A 3-Year Retrospective Study

Aim. To determine cumulative success rate (CSR) of short and ultrashort implants in the posterior maxilla restored with single crowns. Patients and Methods. We performed a retrospective study in 65 patients with 139 implants. 46 were ultrashort and 93 short. Implants were placed with a staged approach and restored with single crowns. Success rate, clinical and radiographic outcomes, and crown-to-implant ratio (CIR) were assessed after three years. Statistical analysis was performed by descriptive and inferential statistics. A log-binomial regression model where the main outcome was implant success was achieved. Coefficients and 95% confidence intervals were reported. Analyses were performed with Stata 13.2 for Windows. Results. 61.54% of patients were female and mean overall age was 51.9 +/- 11.08 years old. Overall CSR was 97.1% (95% CI: 92.4-98.9): 97.9 and 95.1% for short and ultrashort, respectively (p value: 0.33). Four implants failed. Covariates were not associated with CSR (p value > 0.05). Regression model showed coefficients correlated with implant success for ultrashort implants (0.87) and most of covariates but none were statistically significant (p values > 0.05). Conclusions. Our results suggest that short and ultrashort implants may be successfully placed and restored with single crowns in the resorbed maxillary molar region.