Effect of toothbrushing on the material loss, roughness, and color of intrinsically and extrinsically stained porcelain used in metal-ceramic restorations: an in vitro study.

PURPOSE: Because of abrasion by toothbrushing, dental materials in the oral cavity are subjected to substance loss to a different extent depending on the hardness of the material. This study investigated the color-change effect of substance loss and change of roughness resulting from toothbrushing of internally and externally stained metal ceramic.
MATERIALS AND METHODS: Metal-ceramic specimens 15 mm in diameter and 2 mm thick were made. Blue colorant suspension was applied over the enamel porcelain (enamel-stained), in the body porcelain (dentin-stained), and over the opaque porcelain (opaque-stained). One group was not stained. Each group was made up of seven samples. All specimens were brushed in an experimental device. Material loss, roughness measurements, and spectrophotometric evaluations were made before and after brushing. Overall color change, chroma change, and value change were calculated with the use of the CIE-LAB uniform color scale.
RESULTS: Significant substance loss as a result of brushing was observed. No significant differences between chroma changes, between value changes of different groups, or between overall color changes of dentin- and enamel-stained groups were found. The difference between overall color changes of opaque-dentin and opaque-enamel stained groups was statistically significant.
CONCLUSION: Staining should be done as deeply as possible to obtain durable color appearance.