IN VITRO COMPARISON OF VISUAL AND COMPUTER-AIDED PRE- AND POST-TOOTH SHADE DETERMINATION USING VARIOUS HOME BLEACHING PROCEDURES

Statement of problem. Due to inter- and intraexaminer differences, subjective evaluation of tooth color is deemed problematic. Purpose. The purpose of this study was to evaluate the efficacy of home bleaching products, and to compare visual and computer-aided tooth shade determinations when various agents were applied. Material and methods. Human incisors (n=288) were stained (red wine, black tea) and allocated to 8 groups (n=36). Paint-on varnish (VivaStyle Paint On; 6% carbamide peroxide, CP) was used either for 1 x 20 min/d (VSP1), 2 x 20 min/d (VSP2), or 2 x 5 min/d (VSP25). Paint-on lacquer (Colgate Simply White, CSW; 5.9% hydrogen peroxide, HP) was applied for 2 x 30 min/d. Moreover, bleaching was performed using trays (VivaStyle, VS; 10% CP; 1 x 60 min/d, and Odol-med3 Beauty Kur, OBK; sodium chlorite; 2 x 10 min/d) or whitening strips (blend-a-med Whitestrips, BWS; 5.9% HP; 2 x 30 min/d). Water was used as control (1 x 60 min/d). Tooth shades were determined blindly (Chromascop Complete) after staining and 24 hours after final bleaching (visual and computer-aided assessment). Change in shade was analyzed using nonparametric methods (Kruskal-Wallis) and post hoc tests (Tukey and Kramer) (alpha=.05). Results. Color changed significantly to lighter shades for all active agents. Analysis revealed significant differences among the control and all other groups, and among CSW/BWS versus VSP25/OBK, and VS versus OBK, for both evaluation methods. Additionally, significant differences were spectrophotometrically observed for VSP1/VSP2 versus BWS, and VSP2 versus OBK, with comparable reliabilities (0.995 at baseline; 0.994 after bleaching). Conclusions. Increased bleaching efficacy was observed with high peroxide concentrations; application time did not alter efficacy. Spectrophotometry was reproducible and objective. The 2 assessment methods matched 45.8% of the time. (J Prosthet Dent 2009;101:92-100)