An analysis of multiple failures of resin-bonded bridges.

A clinical trial involving 203 resin-bonded bridges (RBBs) was undertaken to investigate the influence of several variables on the survival of these prostheses. This article presents the experiences with rebonded and replacement RBBs after failure of the originally bonded RBBs. A total of 62 dislodged and rebonded RBBs was included in this study and evaluated using Kaplan-Meier estimates. Rebonded RBBs that dislodged for a second time were replaced by another type of RBB ('replacement' RBBs, n = 32). The study revealed that rebonded RBBs were more susceptible to dislodgement than originally bonded RBBs. Fifty per cent survival was reached 2.1 years after rebonding. The sooner the first dislodgement occurred, the lower the retention rate of the rebonded RBB (PH-model, beta = 0.78, P = 0.02). Also some failure characteristics were evaluated. Failure characteristics (i.e. fracture site and partial versus complete dislodgement) of first and second dislodgement were not correlated (Chi-square, P values > 0.25). The survival of 'replacement' RBBs was significantly better than the survival of multiply failure RBBs (median survivals respectively 1.6 years and 1.0 year, P = 0.03). From the results of this study it may be concluded that the survival rates of rebonded and replacement RBBs were unacceptable.