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 lut ing material on the survival of these restorations. Methods: For this evaluation, 157 patients were available (14% of the original sample wa s lost to follow-up or excluded from the study following the stopping criteria). Fifty per cent of the patients were questioned concerning t he fate of the RBBs and 59% of questioned patients were examined clini cally. The patients that were seen for examination were representative s of the experimental groups. The findings from the clinical examinati on were compared with the data obtained from the questionnaire. Missin g data were censored at the date of the last available information. Ka plan-Meier estimates were calculated to assess the survivals at the en dpoints and compared using Cox's proportional hazards procedure. Resul ts: 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 sur vival analysis were: anterior P-type, 49 +/- 7% after 10.5 years; ante rior 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. Surviv als 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) f or posterior RBBs. Conclusions: The factor location (anterior versus p osterior) was, as in previous analyses, highly significant. Difference s in survival between cementation materials were not significant. (C) Elsevier Science Ltd.