The Impact of Recasting on the Bond Strength of Metal Ceramic Restorations

The objective of this study is to evaluate the effect of recasting of Nickel Chromium (Ni-Cr) alloy on the bond strength of metal-ceramic restoration.

Forty-five samples fabricated from one Ni-Cr alloy were divided into three groups. Group 1 consisted of 100% fresh alloy; Group 2 consisted of 50% fresh alloy mixed with 50% alloy taken from sprue and button remnants of group 1 and group 3 consisted of 50% new alloy mixed with 50% alloy taken from sprue and button remnants of group 2. All samples were then bonded to a ceramic material. The bond strength of the Metal-Ceramic was then assessed using a 3-point bending test. The failure mode was investigated under a stereomicroscope and confirmed under scanning electron microscopy (SEM).

Group 1 (100% fresh alloy) showed the highest bond strength amongst the other groups, while the lowest was recorded for group 3 (50% fresh alloy with 50% cast twice alloy). According to the International Organization for Standardization (ISO), the bond strength of fresh alloy and the group casted once attained the required level.

The outcome of this study indicates that the use of 100% fresh Ni-Cr base metal alloy yields the highest bond strength of metal ceramic restoration.