Characterization of Mechanical Properties of Six Noble Dental Casting Alloys

The constant development of new dental alloys for the market forces researchers to evaluate their mechanical properties for clinical suitability. Objective: To determine the mechanical properties of six representative noble casting alloys marketed by Ivoclar Vivadent: five ceramic alloys [Aquarius XH (Au-Pt-Pd), Brite Gold XH (Au-Pt), Capricorn 15 (Pd-Ag-Au), d.Sign 59 (Pd-Ag), and d.Sign 91 (Au-Pd)] and one alloy for all-metal restorations [Maxigold KF (Au-Ag-Pd)]. Methods: Using torch melting, specimens meeting the dimensional requirements in ISO Standards 9693 and 1562 were prepared by standard dental laboratory casting procedures, and the five ceramic alloys were subjected to heat treatment simulating the porcelain firing cycles. Six specimens for each alloy were loaded in tension to failure at a crosshead speed of 2 mm/min. Values of 0.1% and 0.2% yield strength (YS), ultimate tensile strength (UTS), elastic modulus, and percentage elongation were obtained. Statistical comparisons were made using ANOVA and the Ryan-Einot-Gabriel-Welsch multiple range test (α = 0.05). Results: Statistically significant differences were found among the six alloys for all mechanical properties. The d.Sign 91 alloy had the highest elastic modulus (136 GPa), 0.1% YS (548 MPa) and 0.2% YS (570 MPa). Brite Gold XH had the lowest UTS (518 MPa), elastic modulus (90 GPa), 0.1% YS (409 MPa) and 0.2% YS (427 MPa). The lowest percentage elongation (4 %) was observed for Maxigold KF, and the highest percentage elongation was observed for d.Sign 59 (15 %). The highest UTS (782 MPa) was observed for d.Sign 59. No statistically significant difference was found between d.Sign 91 and Capricorn 15 for any of the mechanical properties. Conclusions: The mechanical properties of these gold and palladium alloys differ widely. Clinical alloy selection should be based upon the type of restoration and mechanical property requirements in vivo. Supported by NIDCR Grant DE10147 and Ivoclar Vivadent.