A Research On Optical Properties Of Opal Porcelains

Objective : To compare the opalescence , fluorescence , transparancy and masking effect of opal enamel porcelain of different codes and shades. Method: The color of specimens with 33±1mm in diameter and 1±0.1mm in thickness of four codes (Ceramco 3,Shofu Vintage,Noritake Luster porcelain,VMK 95) totaled 22 kinds of shades was measured according to CIEL~*a~*b~* by Color- Eye 7000A spectraphotometer. The difference of the opalescence, reflected fluorescence , translucent , masking effect parameters related to code and shade factors was compared by AVNOA and SNK-q test(α= 0.05). The correlation between OP and△a~*(△b~*), between△E~*ab and OP, between△ME~*ab and TP were analyzed(α= 0.05). Multiple linear regression between△ME~*ab and TP, OP was taken(α= 0.05). The color space charts , opalescence and reflected fluorescence spectra curve were plotted. X-ray diffraction was also performed for Ceramco 3 light, Shofu 58, VMK 95, Noritake LT1 opal porcelain and Shofu 58 incisal porcelain. Result : There existed statistical difference in OP and FL by code and shade factors (P<0.05). OP was positively correlated to△a~*(△b~*)and△E~*ab was also positively correlated to OP . TP and△ME~*a b were not statistically different related to codes, while they were different related to colors. The correlation between the masking effect and translucent parameter was negative. The X-ray diffraction pattern of several porcelains were strongly matched with the leucite crystal. All porcelains also contained an amorphous glass component and cristobalite, while Noritake LT1 had silicate hydrate. Conclusion : Opalescence and fluorescence varied by code and shade of opal enamel porcelain, which may be mixed appropriately by the technician to mimic the nature of enamel . The translucency and masking effect were different when related to color. Opal effect and translucency of the material can affect the masking effect.. All porcelains contained the leucite crystal, an amorphous glass component and cristobalite, while Noritake LT1 had silicate hydrate.