Abstract
Metal ceramic restorations with high-gold alloys have been used for crowns and fixed dental prostheses (FDPs). Today, however, high-gold alloys have been largely replaced by cobalt-chromium alloy (Co-Cr alloy) for the FDP framework of the implant superstructure, due to the low cost and favorable mechanical properties such as high strength, high modulus of elasticity as well as high corrosion resistance. When fabricating the superstructure, it is necessary to use high-fusing gold solder for joining the Co-Cr alloy framework to the gold cylinder. However, the strength of solder joints between Co-Cr alloy and high-fusing gold solder has not been fully clarified. This study aimed to evaluate the tensile bond strengths of Co-Cr alloys that were joined with high-fusing gold solder in comparison with conventional gold alloys joined with high-fusing gold solder. In addition, scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joint interface were performed.
The tensile bond strengths of Co-Cr alloy joined with high-fusing gold solder were more than 600 MPa, and were significantly larger than those of metal-ceramic gold alloys joined with high-fusing gold solder. The cohesive fracture pattern in solder was observed in the fractured surface of all specimens by SEM observation. EPMA analyses revealed that the elements of the gold solder had diffused into the Co-Cr alloy, leading to firm bonding between the alloy and solder.
These results indicated that the joining technique of Co-Cr alloy using a high-fusing gold solder is promising for fabricating implant superstructures.
