Long-term survival data from a clinical trial on resin-bonded bridges

Objectives: A clinical trial, involving 203 resin-bonded bridges (RBBs) was undertaken to investigate the influence of retainer-type and luting material on the survival of these restorations. Methods: For this evaluation, 157 patients were available (14% of the original sample was lost to follow-up or excluded from the study following the stopping criteria). Fifty per cent of the patients were questioned concerning the fate of the RBBs and 59% of questioned patients were examined clinically. The patients that were seen for examination were representatives of the experimental groups. The findings from the clinical examination were compared with the data obtained from the questionnaire. Missing data were censored at the date of the last available information. Kaplan-Meier estimates were calculated to assess the survivals at the endpoints and compared using Coxʹs proportional hazards procedure. Results: A significant difference was found between perforated (P-type) and etched (E-type) RBBs (P = 0.05) for original bonded restorations but not when rebonded RBBs were taken into account. The results of the survival analysis were: anterior P-type, 49 ± 7% after 10.5 years; anterior E-type, 57 ± 7% after 10.5 years; posterior P-type, 18 ± 11% after 6.8 years; posterior E-type, 37 ± 13% after 10.2 years. Survivals of RBBs that were rebonded once during the evaluation period were 62 ± 9% (11.0 years) for anterior RBBs and 51 ± 11% (10.2 years) for posterior RBBs. Conclusions: The factor location (anterior versus posterior) was, as in previous analyses, highly significant. Differences in survival between cementation materials were not significant.