Tooth Enamel Properties And Morphology After Microabrasion: An In Situ Study

Aim: This study evaluated the effect of saliva on enamel after microabrasion with different microabrasive compounds under in situ conditions.Methods: Enamel/dentin blocks (16 mm(2)) from bovine incisors were divided into nine groups (n = 19): one control group ( no treatment), four groups treated with microabrasion using 35% phosphoric acid (H3PO4) + pumice, and the last four groups treated with microabrasion using 6.6% hydrochloric acid (HCl) + silica. The treated groups were subdivided according to the in situ regimen: without salivary exposure, 1 h, 24 h, or 7 days of saliva exposure. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were tested. Scanning electron microscopy (SEM) was used to evaluate enamel morphology. Microhardness data were tested by analysis of variance, and Tukey's and Dunnett's tests (alpha = 0.05).Results: The SMH analysis revealed that all the microabrasion-treated groups presented significantly-reduced SMH values when compared to the control group (P < 0.05). Treatment with HCl + silica was more prone to the effect of saliva than H3PO4 + pumice, even for CSMH analysis, once the superficial layers reached the same microhardness of that of the control group ( P > 0.05). These results were confirmed by SEM, which demonstrated the mineral recovery effect over time.Conclusion: Saliva was effective in promoting the rehardening of enamel after microabrasion, mainly for the surfaces treated with HCl + silica.