Radiotherapy alters the composition, structural and mechanical properties of root dentin in vitro.

Abstract

Post-radiation dental lesions affect mainly the cervical area of the tooth. Until now, there are quite few evidences regarding the effects of radiation exposure on root dentin breakdown. To better understand this effect, we used human root dentin specimens obtained from third molars from similarly aged individuals. Twenty specimens were analyzed by the surface hardness (SH), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) to evaluate the baseline properties of their root dentin. Other six human teeth were prepared and analyzed by scanning electron microscopy (SEM). Then the specimens were randomly distributed between two groups (n = 13 per group) and irradiated with a total dose of 55 or 70Gy in a linear accelerator. The percentage of EDX and surface hardness loss (%SHL) were determined based on measurements before and after irradiation. The specimens were also analyzed after irradiation by SEM and XRD. The Ca/P weight ratio was calculated. Based on SEM analysis, radiation exposure induced dehydration of the dentin. The Ca/P weight ratio decreased (p = 0.0045). The %SHL of specimens irradiated with 70Gy was higher than that of the 55-Gy group (p < 0.05), although even the lower dose induced root dentin breakdown. Overall, we can state that radiation exposure changes the composition and structure of human root dentin, which detrimentally affect its hardness. The changes reported herein might influence the selection of the dental materials and will bring new knowledge in this field to prevent radiation-related caries in root dentin.