Effect of ozone and 10% sodium ascorbate on human dentin microhardness

: Several strategies have been tried out for the control and antimicrobial treatment of carious lesions such as the direct application of ozone. However, the the oxidation process after the use of ozone facilitates the permanence of residual oxygen, which can negatively influence the use of adhesive systems. The application of 10% sodium ascorbate on the dentin surface can neutralize the effect of oxygen. However, the influence of these substances on the coronary dentin microhardness must be studied. Objective: This study aimed to evaluate the microhardness of human dentin after the application of gaseous ozone and sodium ascorbate. Material and methods: Nineteen third molars were sectioned in order to separate the occlusal surface from the roots leaving a 4 mm thick specimen which was further divided into its mesial and distal parts. The mesial parts were allocated to Group A which was subdivided into two groups: control group, in which the initial microhardness was measured, and an ozone group, in which the application of gaseous ozone was performed for 40 seconds followed by the measurement of the final microhardness. The distal parts were allocated to Group B, subdivided into two groups, a control group in which the initialmicrohardness was measured and an ozone + sodium ascorbate group in which the application of gaseous ozone was performed for 40 seconds and a solution of 10% sodium ascorbate for 10 minutes followed by measurement of the final microhardness. Results: The results showed that there was a statistically significant increase in dentin microhardness (p>0.05) in Group A (control and ozone) and in Group B (control and ozone + sodium ascorbate). However,there was no statistically significant increase in microhardness (p>0.05) between ozone in group A and ozone + sodium ascorbate in group B. Conclusion: The application of gaseous ozone increased the microhardness of human dentin and the application of sodium ascobate had no influence on the microhardness that has already been modified by gaseous ozone.