Effect of highly concentrated bleaching gels on enamel microhardness and superficial morphology, and the recovery action of four remineralizing agents

Abstract

Abstract Background: Dental bleaching is a common clinical practice. The aim of this study is to investigate the efect of 35% hydrogen peroxide (HP) bleaching gel on the morphology and microhardness of enamel, and to analyze the efect of four remineralizing agents. Methods: One hundred blocks were prepared. The enamel surfaces were bleached with 35% HP in one session. The specimens were divided into four remineralization treatment groups (n=25). G1: Tooth Mousse, G2: Remin-Pro, G3: Colgate Pro-Relif, G4: Mirafuor. The remineralizing protocol was applied 3 min per day for one week. Vickers micro‑ hardness (HV) measurements and SEM observations were performed at baseline, after bleaching, and after remineral‑ izing treatment in all groups. Statistical analyses were performed using the paired t-test and ANOVA. Results: After bleaching, SEM showed an increase of irregularities on the surface of the samples. Enamel microhard‑ ness decreased a mean of 47.7 HV, equivalent to a mean decrease of 18.3% (p<0.05). After remineralization, the HV increased in all groups between 16 and 33% (p<0.01), recovering the initial microhardness of enamel samples. SEM images revealed a higher quantity of superfcial mineral deposits in groups 1 and 2 compared to the rest of the groups. Conclusions: The application of remineralizing products generates a signifcant increase in enamel microhardness. Tooth Mousse-treated samples showed a greater microhardness recovery, followed by Remin Pro. The superfcial morphology of the samples refects the results obtained in the HV tests. Keywords: Enamel microhardness, Enamel morphology, Remineralization, Hydrogen peroxide, Dental bleaching