Objectives: The primary objective of this study was to evaluate the effect of an innovative double-layer, single-application desensitizing/whitening technique of potassium nitrate (PN) and hydrogen peroxide (HP) diffusion at different time points. Methods and Materials: Specimens were prepared from extracted caries-free human molars (n=90). Teeth were randomly assigned into four groups: Group A (HP CTRL) treated with 25% HP for 45 minutes, group B (PN CTRL) received a single-layer treatment of 5% PN for 45 minutes, group C received the double-layer treatment of 5% PN and 25% HP for 45 minutes, and group D received a 3% PN incorporated in a 40% HP gel for 45 minutes. PN and HP concentrations were measured at 5, 15, 30, and 45 minutes using standard chemical kits. Group comparisons were made using a repeated measures analysis of variance (ANOVA) test. Pairwise tests for differences in diffusion were done, using the Tukey adjustment of p values for multiple comparisons. A significance level of 5% was used.

Results: Group A showed no significant difference in HP diffusion rates between the 5- and 15- minute, 15- and 30-minute, or 30- and 45-minute time points; group D showed a similar trend; however, group C differed significantly at the 5-and 15-minute time points (p=0.0004), at the 15-and 30-minute time points (p=0.0026), and the 30- and 45-minute time points (p=0.0014). For PN diffusion, groups B and C had significantly different levels at the 15-, 30-, and 45-minute time points (p=0.0005, p=0.0002, and p<0.0001, respectively); and at the 15-, 30-, and 45-minute time points, groups D and C had significantly different PN diffusion (p=0.0327, p=0.0004, and p< 0.0001, respectively). Group C had significantly different PN diffusion at the 5- and 15-minute time points (p=0.0004), the 15- and 30-minute time points (p=0.0026), and at the 30- and 45-minute time points (p=0.0014).

Conclusion: The double-layer technique showed superior diffusion of PN into the pulp chamber and did not affect the diffusion of HP when compared to other techniques. The double-layer technique may be suggested as an alternative tooth-whitening treatment to minimize tooth sensitivity.

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