The effect of coffee solution on tooth color during home bleaching applications.

Purpose: To quantify the change in color of human and bovine teeth exposed to a coffee solution during a 16% carbamide peroxide (16% CP) home application bleaching treatment using photoreflectance analysis.

Methods: 40 enamel slabs (4 x 4 x 2 mm) were obtained from seven unerupted third human molars and seven bovine incisors, which were allocated into four groups: G1: human control group whitened and not exposed to a coffee solution; G2: bovine control group whitened and not exposed to a coffee solution; G3: human teeth whitened and exposed to a coffee solution; G4: bovine teeth whitened and exposed to a coffee solution. The home bleaching procedure was performed using 16% CP gel applied in a 1 mm-thick layer on the tooth surface over a period of 6 hours per day, for 28 days. Tooth color was evaluated using photoreflectance analysis throughout the bleaching procedure at intervals of 7, 14, 21 and 28 days, and posttreatment at 7, 15 and 30 days. Results were statistically analyzed using ANOVA and Tukey-Kramer tests.

Results: After 28 days of bleaching treatment, no significant difference was detected between photoreflectance analysis of specimens exposed to coffee solution and specimens not exposed to coffee solution (P < 0.05). However, when the teeth were exposed to a coffee solution during home bleaching treatment, the whitening effect was observed to be less stable (P < 0.05). Bovine and human enamel substrates behaved similarly in terms of staining and bleaching effects, although they presented inherent differences in color (P < 0.05).