Evaluation of bleaching agents effect on artificially stained pulpless teeth

Objectives: the aim of this study was to evaluate in vitro the effectiveness of three associations of bleaching agents on artificially stained pulpless teeth. Methods: forty-eight recently extracted intact human premolars were stained by immersing them in human blood, and divided into four groups. All teeth were endodontically treated and 3mm of zinc phosphate cement was placed at the cementoenamel junction. The teeth were divided into one control group and three test groups (n=12): C) control group, without bleaching agent, A1) sodium perborate with water, A2) sodium perborate with 10% carbamide peroxide, A3) sodium perborate with 35% carbamide peroxide. On days 7 and 14, each pulp chamber was refilled with fresh bleaching paste. Color coordinates L* (lightness), a* (redness), and b* (yellowness) of CIELAB color system were measured and assessed with the aid of a dental spectrophotometer (EasyShade, Vita). The color difference (ΔE*ab)between baseline and subsequent measurements was calculated. Results: data were submitted to ANOVA for repeated measures, Tukey's and Dunnett's tests at the 0.05 level. Tukey's test showed that A1 (10,58±4,83ΔE*ab) was statistically different from A2 (19,57±4,72ΔE*ab) and A3 (17,58±3,33ΔE*ab) and there was no significant difference between A2 and A3. At the end of 7 days, A1 was different from A2, and A2 had the best bleaching effect. At the end of 14 and 21 days, both groups A2 and A3 were better than A1. The group A1 had its best result after 21 days. Both groups A2 and A3 had their bleaching effect at days 14 and 21 statistically different from day 7. Dunnett's test showed statistically differences among the control group and the experimental groups at all periods (p<0.05). Conclusion: sodium perborate mixed with carbamide peroxide (10% or 35%) was more effective than mixed with water.