Abstract:

Objective To measure the translucency parameter（TP）, masking effect（ME）, and contrast ratio（CR） of opal porcelain of Ceramco, Shofu, Noritake, and Vita, and to compare the correlations among the three transmission parameters, in order to provide reference for selecting opal porcelain correctly. Methods The color of specimens was measured according to CIE L*a*b* under different background and reflectance mode with a Color- Eye 7000A spectrophotometer. The color difference, TP, and ME value were calculated. Within 400- 750 nm spectra, the ratio of light reflectance was measured, and CR was also calculated. The data was compared by ANOVA and SNK- q test （α=0.05）. The correlation and multiple linear regression between TP, CR, and ME were analyzed（α=0.05）. Results There were statistical difference with different shade of the same brands （P<0.05）. The correlations between ME and TP, TP and CR, ME and CR were existed（P<0.05）. TP was correlated not only with ME but also with CR based on multiple regression analysis（P<0.05）. The partial correlation coefficients were statistically significant（P<0.05）. CR was the main devotion to translucency parameter on multiple regressions. Conclusion It is recommended to select opal porcelains based on transmission parameters. CR value has an inner significance of opaque property of opal porcelain and can express opacity property of opal porcelain more appropriately than ME.

Key words: opal porcelains, spectrophotometer, translucency parameter, contrast ratio, masking effect