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

Objective: To investigate the effect of particle size distribution of opacifier tin dioxides (SnO(2)) on the color of dental opaque porcelain for pure titanium by spectrophotometer.

Methods: Sixteen groups of opaque porcelain powders were prepared by combining four grain size SnO(2) with four pigments (no pigment, yellow, coral pink and grey). Five porcelain discs (13 mm diameter and 2mm 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 (ΔE(max)) caused by grain size of SnO(2) 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 ΔE(max) of different pigment groups were subjected to one way ANOVA.

Results: With SnO(2) grain size increasing, the L* values decreased, and both a* and b* became more chromatic consistently in each pigment group (p<0.001). The ΔE(max) in all pigmented groups were above the 50:50% perceptibility thresholds, with ΔE(max) in yellow group greater than the acceptability thresholds. Significant difference was found in the ΔE(max) of four pigment groups regardless of the color formula (p<0.001).

Conclusions: 15 wt% SnO(2) 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.