Evaluation of the Effect of recasting Nickel-chromium Base Metal Alloy on the Metal-ceramic Bond Strength: An in vitro Study

The aim of this study was to evaluate the effect of recasting base metal alloy on the metal-ceramic bond strength. A total of 60 test samples were prepared from new and recast nickel-chromium alloy and divided into six groups. In group A0, test samples were prepared from 100% new alloy. Groups A1, A2, A3, A4, and A5 were prepared from 50% new alloy and 50% casting remnants (sprue and buttons) of the previous group by weight. All these samples were coated with ceramic (IPS d.SIGN and Ivoclar-Vivadent), and samples were then subjected to three-point bending test to evaluate metal-ceramic bond strength. The values were analyzed using one-way analysis of variance and Tukey's post hoc test. The mean bond strength of group A0 was higher than that of groups A1, A2, A3, A4, and A5. Metal-ceramic bond strength decreased significantly with multiple recastings. Bond strength between metal and ceramic is a crucial factor for the clinical performance of metal-ceramic restorations. Recasting of alloys may affect the metal oxide layer composition and thickness of metal-ceramic interface, and thereby the metal-ceramic bond.