Influence of particle size distribution of dental opacifier on the color of titanium opaque porcelain

ObjectiveTo investigate the effect of particle size distribution of opacifier tin dioxides (SnO2) on the color of dental opaque porcelain for pure titanium by spectrophotometer.MethodsSixteen groups of opaque porcelain powders were prepared by combining four grain size SnO2 with four pigments (no pigment, yellow, coral pink and grey). Five porcelain discs (13 mm diameter and 2 mm thickness) for each powder were fired. K/S ratios and L*a*b* values of specimens were obtained by a spectrophotometer. The maximum color differences (ΔEmax) caused by grain size of SnO2 in each pigment group were determined using the CIELAB and the CIEDE2000 formulas. The L*a*b* values in each pigment group were compared by MANOVA and the ΔEmax of different pigment groups were subjected to one way ANOVA.ResultsWith SnO2 grain size increasing, the L* values decreased, and both a* and b* became more chromatic consistently in each pigment group (p < 0.001). The ΔEmax in all pigmented groups were above the 50:50% perceptibility thresholds, with ΔEmax in yellow group greater than the acceptability thresholds. Significant difference was found in the ΔEmax of four pigment groups regardless of the color formula (p < 0.001).Conclusions15 wt% SnO2 with median particle size ranging from 0.85 μm to 20.75 μm caused significantly perceptible color differences in the pigmented titanium opaque porcelains used in this study.