Effect of Desensitizing Agent on Enamel Microhardness: In vitro Study

Aims: Investigate possible changes in the microhardness of tooth enamel associated with the use of ozonized sunflower oil during the whitening procedure.

Study Design: In vitro study.

Place and Duration of Study: Department of Dentistry of the State University of Western Paraná - UNIOESTE between January 2023 and December 2023.

Methodology: 30 healthy bovine incisor crowns were stored in 0.01% thymol solution (4ºC/30 days). Blocks measuring 4x4x2.5mm were made. With the exception of the buccal side, all sides were waterproofed and stored in artificial saliva and phosphate buffer. The specimens were divided into 3 groups (n=10) - CT (control), NP + H2O2 (desensitizing agent based on potassium nitrate and 35% hydrogen peroxide) and OL + H2O2 (ozonized sunflower oil and 35% hydrogen peroxide). The desensitizing agents were applied before the whitening gel. Color was recorded before and after the whitening procedure. Knoop surface microhardness was measured at 7, 14 and 21 days. The data obtained was submitted to Shapiro Wilk statistical analysis, Friedman ANOVA (p<0.05), Durbin-Conover (p<0.05) and Kruskal-Wallis ANOVA (p<0.05).

Results: In the intra-group analysis, the groups tested showed a statistical difference in enamel surface hardness, except for the OL + H2O2 group, before bleaching (234

+ 95) and after bleaching (200 + 99). In the inter-group analysis, there was a significant statistical difference between the groups in the periods of 14 and 21 days after bleaching and no significant change in the period before and immediately after bleaching. In the analysis of color saturation, statistical changes were observed in the bleached groups.

Conclusion: Ozonated sunflower oil did not influence the microhardness values of the enamel surface, confirming its safety as a desensitizing agent during treatment.