Microstructural changes in irradiated teeth revealed by swept-source optical coherence tomography

Radiation-induced caries is a late complication of radiotherapy for head and neck cancers. Although direct irradiation-induced changes in tooth structure may contribute to its development, these changes have not been fully characterized. This study evaluated irradiation-associated microstructural alterations and tissue density changes in human teeth using swept-source optical coherence tomography (SS-OCT). Eight extracted fully impacted human third molars were assigned to irradiated and non-irradiated groups (n = 4 each). The irradiated group received X-rays at a total dose of 70 Gy, a clinically relevant dose in definitive radiotherapy for head and neck cancer. A total of 64 SS-OCT cross-sectional images were obtained and analyzed, with 32 images from each group, including 16 from the coronal area on the occlusal side and 16 from the cervical area. Microcrack-like features were observed in 100% (16/16) of irradiated and 31.3% (5/16) of non-irradiated images in the coronal area on the occlusal side, and in 43.8% (7/16) and 0% (0/16) of images in the cervical area, respectively. Attenuation coefficients were significantly higher in irradiated enamel and dentin. These findings suggest that irradiation-induced microstructural changes in extracted human teeth in vitro may contribute to increased susceptibility to radiation-induced caries.