Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance

Abstract

Purpose: The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. Methods: CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanal- ysis (EPMA) of the joined interfaces were also performed. Results: The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Conclusions: Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechan- ical properties instead of conventional high-gold alloys.