Concentration and Frequency of Tea Exposure and Color During Bleaching

Objectives: Determine the influence of tea concentration and frequency of exposure on the color change of teeth during dental bleaching
Methods: Eighty bovine incisors were thoroughly cleaned with pumice slurry and distributed randomly in 10 groups. Nine experimental groups were treated with 10% carbamide peroxide (Opalescence® PF®) for 14 days and were exposed to a combination of one tea concentration (2gr/50ml, 2gr/500ml or 2gr/1,000ml water) and one frequency of exposure (1,3 and 6 times a day). A control group remained untreated. VITA Easyshade® spectrophotometer was used to register color at baseline, 5, 10 and 14 days; L*, C*, H*coordinates were measured and ΔE were calculated. Results were analyzed with Kruskal-Wallis, ANOVA and Tukey’s Test, with a significance level of 95%.
Results: No significant differences in ΔE between experimental groups were observed at 5, 10 and 14 days (p=0.37, 0.25, 0.79), although significant differences were observed in color change within all groups when compared to their baseline and to the control group at 5, 10 and 14 days. Color change for all groups through the bleaching and tea exposure process was clinically significant (ΔE≥3.7). Significant changes (p≤0.05) between experimental and control group were observed in color change when color dimensions ΔL*, ΔC*, ΔH* were analyzed separately. Value (ΔL) and Chroma (ΔC) changes were more affected than Hue (ΔH); the differences were more significant as tea concentration and frequency of exposure to tea increased.

Conclusions: No significant differences were found in ΔE between experimental groups, but there were significant differences in ΔE for all groups when compared to their baseline and control group. Those differences were clinically significant. Value and Chroma were mainly affected by tea; the magnitude of color change and its statistical significance was related to tea concentration and frequency of exposure.