Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, 510055, China.
Department of Oncology, Central Hospital of Xianning City, Tongji Xianning Hospital of Huazhong University of Science and Technology, Hubei, China.
Radiat Oncol. 2019 Jan 11;14(1):5. doi: 10.1186/s13014-019-1208-1.
Radiation caries is a complication of radiotherapy characterized by enamel erosion and dentin exposure. The mechanisms of characteristic radiation caries formation are not well-understood. The aim of this study was to evaluate the direct radiation-induced effects on dental hard tissue and investigate their role in the formation of radiation caries.
Sixty non-carious third molars were divided into three groups (n = 20), which would be exposed to 0 Gy, 30 Gy, and 60 Gy radiation, respectively. After radiation, microhardness and elastic modulus were measured at four depths by means of a Vickers microhardness tester and atomic force microscopy (AFM). The microstructure was observed by scanning electron microscopy (SEM). X-ray diffraction and Raman microspectroscopy were used to determine crystal properties and protein/mineral (2931/960 cm) ratios.
A statistically significant decrease in microhardness and elastic modulus values 50 μm from the dentino-enamel junction (DEJ) in enamel was revealed in the 30-Gy and 60-Gy groups. With the increasing dose, destruction of interprismatic substance and fissures at the DEJ-adjacent region were found. A greater reduction of crystallinity was revealed in enamel compared with dentin. Raman spectroscopic analysis showed a slight increase of the protein/mineral ratio for enamel following accumulated radiation, while the protein/mineral ratio for dentin was decreased.
Radiation could directly alter the mechanical properties, micro-morphology, crystal properties, and chemical composition of dental hard tissue. The early destruction of DEJ-adjacent enamel, combined with decreased crystallinity of enamel under radiation exposure, may be related to the formation of characteristic radiation caries.
放射性龋是放疗的一种并发症，其特征为釉质侵蚀和牙本质暴露。放射性龋特征性形成的机制尚不清楚。本研究旨在评估对牙体硬组织的直接辐射效应，并研究其在放射性龋形成中的作用。
将 60 颗非龋第三磨牙分为 3 组（n = 20），分别接受 0 Gy、30 Gy 和 60 Gy 照射。照射后，采用维氏显微硬度计和原子力显微镜（AFM）在 4 个深度测量显微硬度和弹性模量。扫描电子显微镜（SEM）观察微观结构。X 射线衍射和拉曼微光谱用于确定晶体性质和蛋白质/矿物质（2931/960 cm）比值。
在釉质牙本质交界处（DEJ）50 μm 深度处，30 Gy 和 60 Gy 组的釉质显微硬度和弹性模量值均有统计学显著降低。随着剂量的增加，在 DEJ 邻近区域可见柱间物质和裂隙的破坏。与牙本质相比，釉质的结晶度降低更为明显。拉曼光谱分析显示，随着累积辐射，釉质的蛋白质/矿物质比值略有增加，而牙本质的蛋白质/矿物质比值则降低。
辐射可直接改变牙体硬组织的力学性能、微观形态、晶体性质和化学成分。DEJ 邻近釉质的早期破坏，加上暴露于辐射下釉质结晶度降低，可能与特征性放射性龋的形成有关。
