Method: Fifty bovine teeth fragments were stained in a black tea solution and randomly divided in 10 groups (n=5) according to the bleaching agents: 10% carbamide peroxide (CP), 6% hydrogen peroxide (HP) with calcium, 20% HP with calcium; 35% HP with calcium, 35% HP; and gel temperatures (22ºC and 41ºC). Approximately 1ml of bleaching agent was deposited in eppendorf tubes and cooled to 22ºC or heated to 41ºC by a digital dry incubator (Astory, Italy). The samples were stored in artificial saliva during the experiment. The enamel and dentin color change was evaluated using a spectrophotometer (CM-700d, Konica Minolta, Japan) before and after staining and after each of the bleaching weeks, and data was expressed in CIE Lab System values. For the L* coordinate, data was analyzed by the Tukey-Krammer Test and ΔE values were submitted to ANOVA 2-ways and Tukey Tests (α=0.05).
Result: There were no statistical differences between the evaluated temperatures 22ºC and 41ºC. At 22ºC, the 20% HP with calcium showed the lowest reflectance means differing statistically from 10% CP and 6% HP with calcium on the enamel and dentin surfaces. At 41ºC, no statistical difference among bleaching agents was observed after three weeks of treatment.
Conclusion: The 20% hydrogen peroxide with calcium was less effective at room temperature on enamel and deep dentin. However, the temperature at 41ºC improved the efficacy of this bleaching agent.