Effect of brushing with different toothpastes on irradiated enamel roughness and composition: an in vitro study

Objectives: To evaluate the effect of toothbrushing with different toothpastes on the roughness and mineral composition of irradiated and non-irradiated enamel. Methods: One hundred twenty bovine crowns were randomly divided into three irradiated and non-irradiated groups submitted to toothbrushing with Bianco Pro Clinical 1% TCP, Colgate Sensitive Pro-Relief, or Sensodyne Sensitivity & Gum (n = 20 per group). Irradiation was performed in fractionated doses, totaling 72 Gy. All specimens were brushed in a 30-day simulation cycle. Surface roughness (Ra-μm) and chemical composition were measured before and after toothbrushing. Data were analyzed using the two-way ANOVA followed by Tukey's test with a significance level of α=0.05. Results: Irradiated enamel exhibited greater roughness than non-irradiated, even before toothbrushing, and had higher levels of amide I and phosphate but lower carbonate content. After toothbrushing, roughness increased in the irradiated enamel, regardless of the toothpaste used. Post-brushing changes in enamel composition varied depending on the toothpaste. Sensodyne and Colgate caused greater reductions in amide I compared to Bianco. Irradiated enamel treated with Bianco showed increased carbonate content, while those brushed with Colgate exhibited higher phosphate V1-V3 levels. Conclusions: Irradiation increased enamel roughness, and toothbrushing further amplified this effect, with no significant differences observed among the evaluated toothpastes. Both irradiation and toothbrushing influenced the enamel's chemical composition, with changes varying based on the specific toothpaste used.