Influence of a die spacer on the fit and load to failure of cantilever resin-bonded fixed dental prostheses.

Purpose: To evaluate the effect of die spacer thickness on the fit and load to failure of cantilever resin-bonded fixed dental prostheses (RBFDPs).

Methods: Two identical maxillary RBFDPs with a retainer on the canine were designed to replace a lateral incisor. One design involved a closely fitting retainer with no die spacer (NDS), and the other included an 80-µm die spacer (DS). A total of 10 RBFDPs were produced for each group by selective laser melting. To simulate a natural canine abutment, lithium disilicate abutments were fabricated digitally. After bonding the RBFDP with an adhesive resin luting agent, the marginal fit was measured, and the specimens were then loaded until failure of the luting agent.

Results: The mean marginal fit in the NDS and DS groups was 79.1 µm and 75.7 µm, respectively, and the corresponding mean maximum load to failure was 272.8 N and 254.7 N, respectively. The inter-group differences in these values were not significant.

Conclusion: The inclusion of a RBFDP die spacer had no effect on the marginal fit and maximum load to failure. In addition, the die spacer had no significant effect on the pattern of resin luting agent failure.