The effect of recasting on bond strength between porcelain and base-metal alloys.

Purpose: Long-term success of metal ceramic restorations depends on metal ceramic bond strength. The purpose of this study was to determine whether recasting of base-metal alloys has any effect on metal ceramic bond strength.

Materials And Methods: Super Cast and Verabond base-metal alloys were used to cast 260 wax patterns. The alloy specimens were equally divided into five groups and cast as: group A 0.0%, B 25%, C 50%, D 75%, and E 100% once-cast alloy. Each group was divided into two subgroups: the first group was cast with Super Cast and the second with Verabond. In each subgroup half of the cast alloys were veneered with Vita VMK 68 and the others with Ceramco 3.

Results: Recasting decreased bond strength (p < 0.006) when used for 50% once-cast alloy. Group E with 100% new Super Cast alloy veneered with Vita VMK 68 porcelain had the highest bond strength (30.75 ± 9.58 MPa), and group B including 25% new and 75% recast Super Cast alloy veneered with the same porcelain had the lowest bond strength (21.72 ± 5.19 MPa).

Conclusions: By adding over 50% once-cast alloy in base-metal alloys, metal-ceramic bond strength decreases significantly.