The Survival of Ultrashort Locking-Taper Implants

Purpose: To evaluate the performance of 5-mm-long implants. Materials and Methods: A retrospective cohort study was conducted between January 2008 and December 2009. The sample was composed of patients who had received at least one 5-mm-wide, hydroxyapatite-coated Bicon implant. The outcome variable was implant failure. Descriptive statistics and univariate and multivariate Cox proportional hazards regression models, adjusted for multiple implants in the same patient, were utilized to identify predictors of dental implant failure. Results: Two hundred ninety-one subjects who received 410 locking-taper implants were followed for an average of 20 months. Of these, 211 were ultrashort implants (57 were 5 × 5.0 mm and 154 were 5 × 6.0 mm) and 199 were short implants (5 × 8.0 mm). Three hundred twenty-two implants (93.4%) were restored with single crowns. There was a higher proportion of ultrashort single-tooth implants (94.6%) as compared to short single-tooth implants (92.2%). Nine implants failed, for a cumulative survival rate of 97.5%. Of the failed implants, five were ultrashort (all 5 × 6.0 mm) and four were short. No failures were documented for 5- × 5.0-mm ultrashort implants. There was no statistically significant difference (P = .68) in the Kaplan-Meier survival rates of ultrashort implants (97.6%) and short implants (95.2%). After adjusting for other covariates in a multivariate model, implant length was not associated with implant failure (P = .49). Conclusions: The survival of ultrashort (5- and 6-mm) implants was comparable to that of short (8-mm) implants. Keywords: dental implants, implant length, retrospective cohort study, short implants, single-tooth implants