Spectrophotometric analysis of the influence of metal substrate on the color of ceramic

Lee, Su Ok; Woo, Yi Hyung; Choi, Dae Gyun; Kwon, Keung Rok

Abstract

STATEMENT OF PROBLEM: Metal-ceramic restorations have been used extensively by dental clinicians for nearly 40 years. Strength an functional ability of metal-ceramic restorations are proved to be satisfying, However esthetics and biocompatibility of metal alloy which is used in metal-ceramic restoration is not ideal. Using pure gold as an alternative, have advantage of esthetics, biocompatibility over conventional metal alloy. But there had been little article which studied on the color effect of pure gold on final porcelain color. PURPOSE: The purpose of this study was to spectrophotometrically evaluate the difference between color of metal alloy(Au-Pt, Ni-Cr) and pure gold, during color masking procedure with opaque porcelain and to analyze the differences. MATERIAL AND METHODS: Three types of metal-base metal(Ni-Cr), high gold alloy(Au-Pt), pure gold(GES)-specimen were fabricated 1cm in diameter. Four steps were established-after finishing, after pre-coditioning, after application of first opaque porcelain(0.08mm in thickness), after application of second opaque porcelain(0.15mm in thickness)- and tested color with spectrophotometer every each steps and analyzed with CIEL* a* b* color order system. One-Way ANOVA test was used to find out if there were significant differences between groups tested and Shaffe multiple comparison was used to identify where the differences were. RESULTS: 1. After finishing and pre-conditioning, pure gold(GES) group showed most high values in L*, a*, b*. 2. After application of first opaque porcelain(0.08mm in thickness), after appllication of second opaque porcelain(0.15mm in thickness), pure gold(GES) group showed the least difference in L*, a*, b* values and the lowest .E value(.E=0.63). 3. After application of first opaque porcelain and after application of second opaque porcelain differences that were significant (P< 0.05) between groups were found only in a values. 4. Base metal alloy group showed the lowest a value in test after application of first opaque porcelain and the highest value in test after application of first opaque porcelain. CONCLUSION: Pure gold group and high gold group showed higher a values than base metal group when tested after 0.08mm thickness of opaque porcelain was applied and pure gold group showed much similar L*, a*, b* values between 0.08mm thickness and 0.15mm thickness of opaque porcelain. This meant that pure gold was more easily masked by opaque porcelain than the other two groups.