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

Abstract Background: The objective of this study was to evaluate wear and surface roughness of in vivo irradiated human enamel and dentin after abrasive challenge. Methods: Using teeth donated by healthy patients or with head and neck cancer who received radiotherapy (RT) or chemoradiotherapy (CRT), 42 enamel and dentin specimens were made, divided into three groups: control, RT and CRT (n = 14 in each group, both for enamel and dentin). The specimens were submitted to an in vitro experimental abrasive using a brushing machine and wear and surface roughness were evaluated. Results: In enamel specimens, wear profile values of CRT and RT groups were not different from control ( p -value >0.05). The RT group presents lower step values than CRT and control groups ( p -value <0.001). No significant difference in final surface roughness was observed in all groups ( p -value >0.05). In dentin specimens, no significant difference in wear profile and step was observed in all groups ( p -value >0.05). However, CRT and RT groups present higher values in final surface roughness ( p -value <0.001). Conclusion: 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). Clinical relevance: Considering probable effects of ionizing radiation on teeth structure, understanding the behaviour of enamel and dentin under physiological processes is important to prevent and treat adverse oral side effects related to radiotherapy.