Methods: Ten premolars extracted for orthodontic purposes were divided buccolingually and then longitudinally into two parts, so that four specimens were obtained from each tooth. The specimens were randomly assigned to one of the four groups. The following bleaching agents were applied to the specimens: 10% carbamide peroxide, 35% hydrogen peroxide and 38% hydrogen peroxide. In the control group no agent was applied. The specimens were treated with an artificial caries solution (pH 4) for 4, 8, 12 and 16 days. Calcium concentration was determined by an atomic absorption spectrophotometer (AAS). Completely randomize block design according to ANOVA tests were performed on cumulative concentrations of calcium at days 4, 8, 12 and 16.
Results: At the end of the 16th day, Calcium ions released per mm2 were calculated cumulatively as follows: Control group: 18.35±4.00 µg/ml 35% hydrogen peroxide applied group: 25.15±4.99 µg/ml 38% hydrogen peroxide applied group: 27.52±5.22 µg/ml 10% carbamide peroxide applied group: 19.53±4.03 µg/ml The differences between the control group and the 35% HP and between the control group and 38% HP applied groups were statistically significant. Although demineralization differences were observed between the control group and the10% carbamide peroxide applied group, this difference was not significant.
Conclusions: It was concluded that 35% of hydrogen peroxide and 38% of hydrogen peroxide increased the incidence of caries. On the other side, 10% of carbamide peroxide in the home bleaching agent generally had no effect on enamel