RESUMEN
The purpose of this study was to evaluate the long term tooth-brushing effect on the color change of specially treated IPS Empress porcelain surface. Staining technique with blue stain and liquid was used. The surfaces of the specimen were treated with 5% and 10% Hydrofluoric acid, 50mm and 250mm alumina sandblast, and then blue stain and liquid were used for external stain. After 29,200, 58,400, 87,600, 116,200 brushing strokes (equivalent to 2, 4, 6, 8 years each), color changes of the stained layer were measured with spectrophotometer(CM-3500d, MINOLTA, Thkyo, Japan). The result of this study was obtained as follows : 1. The color changes were great after 29,200 tooth brushing strokes in every group, but from 29,200 strokes to 116,800 strokes, there were no significant color changes in each group.(p>0.05) 2. The greatest color changes were observed in 5% HF treated group and the least color changes were observed in 50 micrometer aluminar sandblast treated group in every stroke(p0.05). According to these results, pretreatment of I.P.S. Empress porcelain with alumina sandblast improved the color of IPS Empress porcelain significantly on this condition, but long term follow-up will be needed.