Comparison of the bond compatibility of titanium and an NiCr alloy to dental porcelain

Abstract

Objectives: The aim of this study was to investigate the bond compatibility between porcelain and titanium, by using three-point bending, oxide adherence and thermal expansion tests, and to compare the results with those of a conventional NiCr alloy–porcelain system. Methods: The three-point bending test was used and the results were evaluated according to DIN draft 13927. Fractured surfaces of the metal and porcelain were examined macroscopically. The oxide adherence test was applied to titanium and NiCr alloy with appropriate oxidation degrees. After an oxide film was formed on the specimens, tensile strength test was applied. Oxide adherence strength values were set and fractured surfaces were examined macroscopically. In the thermal expansion test, thermal expansion curves and thermal expansion coefficients of titanium, NiCr alloy and tested porcelains were determined. Differences in thermal expansion values (Δα) in all metal–porcelain pairs were calculated to allow inferences to be made about residual stress levels. Results: The bending strengths of all groups were found to be within the acceptable standard levels. At the end of the oxide adherence test, the results indicated that the adherence of the formed oxides to the metals were at a desired level. As a result of the thermal expansion test, the titanium–porcelain and NiCr–porcelain systems showed compressive thermal stress. However, the titanium–porcelain pair exhibited large positive Δα values. This result is found to be above the proposed thermal compatibility. Conclusion: It was concluded that the bond compatibility between titanium and porcelain was comparable with the NiCr–porcelain system.