Abrasive challenge effects on enamel and dentin from irradiated human teeth: an in vitro study

This study aimed to evaluate the effects of radiotherapy (RT) and chemoradiotherapy (CRT) on the wear and surface roughness of in vitro irradiated human enamel and dentin subjected to abrasive challenge. Enamel and dentin specimens (n = 42) were prepared from teeth donated by healthy patients and those with head and neck cancer who had received radiotherapy (RT) or chemoradiotherapy (CRT). The specimens were categorized into three groups: control, RT, and CRT (n = 14 per group for both enamel and dentin). These samples were subjected to an in vitro abrasive experiment using a brushing machine, followed by wear and surface roughness assessments with a confocal laser scanning microscope conducted before and after the abrasive challenge, considering both exposed and non-exposed areas. Statistical analysis used Shapiro-Wilk tests for normality, Wilcoxon tests for comparing two means, and Kruskal-Wallis tests. A significance level of 5% was adopted. In enamel specimens, wear profile values ​​of CRT and RT groups were not different from the control (p > 0.05). The RT group presents lower step values than the CRT and control groups (p < 0.001). No significant difference in final surface roughness was observed in all groups (p > 0.05). In dentin specimens, no significant difference in wear profile and step was observed in all groups (p > 0.05). However, CRT and RT groups present higher values in final surface roughness (p < 0.001). The exposure to ionizing radiation (associated or not to chemotherapy) influenced the surface roughness of dentin and the wear (step) of enamel after the in vitro abrasive challenge.Trial registration: Ethical procedures were approved by the FORP/USP Research Ethics Committee (CAAE: 61308416.4.0000.5419), and Hospital do Câncer de Barretos/Fundação Pio XII (CAAE: 61308416.4.3001.5437).