Dose-Dependent Effects of Simulated Clinical Radiotherapy on the Structure and Properties of Root Dentine

Head and neck radiotherapy (HNRT) can expose teeth to moderate radiation doses, yet the effects on root dentine under clinically relevant conditions remain unclear. This in vitro study compared dentine subjected to 0, 30, or 50 Gy IMRT. Palatal roots from 35 maxillary molars were allocated to non-irradiated, 30 Gy (oropharyngeal simulation), or 50 Gy (maxillary simulation). Flexural strength, Vickers microhardness, and Raman spectroscopy were assessed, while SEM was qualitatively evaluated. Mechanical and chemical properties did not differ among groups (p > 0.05). SEM, however, revealed dose-dependent microstructural changes: fissures and partial tubule obliteration at 30 Gy, and more frequent cracks and complete obliteration at 50 Gy. Under these in vitro simulated conditions, radiotherapy doses preserved bulk properties despite structural alterations. These findings should be interpreted within the limitations of the model, as interactions among experimental factors may influence how microstructural changes affect dentine mechanics.