Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Av Pará 1720, Block 4L, room A32, Campus Umuarama, Uberlândia, Minas Gerais, 38405-320, Brazil.
Laboratory of New Nanostructured and Functional Materials, Institute of Physics, Federal University of Alagoas, Av Lourival Melo Mota S/N, Campus A. C. Simões, Maceió, Alagoas, 57072-970, Brazil.
Clin Oral Investig. 2019 Aug;23(8):3351-3358. doi: 10.1007/s00784-018-2758-6. Epub 2018 Dec 4.
To evaluate the effect of in vivo radiotherapy on the chemical properties of human dentine by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis.
Chemical composition was evaluated comparing control and irradiated group (n = 8). Irradiated teeth were obtained from radiotherapy patients subjected to fractionated X-ray radiation of 1.8 Gy daily totaling 72 Gy. The teeth were sectioned according to the type of dentine (crown or root dentine), obtaining 3-mm dentine cervical slices. The analyzed parameters by FTIR and Raman spectroscopies were mineral/matrix ratio (M:M), carbonate/mineral ratio (C:M), amide I/amide III ratio, and amide I/CH ratio. Raman also calculated the phosphate and carbonate crystallinity.
FTIR revealed that M:M had a decrease in both factors (p = 0.008; p = 0.043, respectively) and root dentine showed a lower C:M in the irradiated group (p = 0.003). Raman revealed a higher phosphate crystallinity and a lower carbonate crystallinity in crown dentine of irradiated group (p = 0.021; p = 0.039). For amide I/amide III, the irradiated showed a lower ratio when compared to the control group (FTIR p = 0.002; Raman p = 0.017). For amide I/CH, the root dentine showed a higher ratio than the crown dentine in both methods (p < 0.001).
Radiotherapy altered the chemical composition of human dentine. The exchange of phosphate-carbonate ions in the hydroxyapatite and higher concentration of organic components was found after radiotherapy.
The increased risk of radiation-related caries in patients undergoing head and neck radiotherapy is due not only to salivary, dietary, and microbiological changes but also to changes in tooth chemical composition.
通过傅里叶变换红外光谱（FTIR）和拉曼分析评估体内放射治疗对人牙本质化学性质的影响。
通过比较对照组和照射组（n=8）来评估化学成分。照射牙齿来自接受 1.8 Gy 每日分割 X 射线照射共 72 Gy 的放射治疗患者。根据牙本质类型（牙冠或牙根牙本质）将牙齿切成 3mm 的牙本质颈段切片。FTIR 和拉曼光谱分析的参数有矿质/基质比（M:M）、碳酸盐/矿质比（C:M）、酰胺 I/酰胺 III 比和酰胺 I/CH 比。拉曼还计算了磷酸盐和碳酸盐结晶度。
FTIR 显示两种因素的 M:M 均降低（p=0.008；p=0.043），照射组的根牙本质 C:M 较低（p=0.003）。拉曼显示照射组牙冠牙本质的磷酸盐结晶度较高，碳酸盐结晶度较低（p=0.021；p=0.039）。对于酰胺 I/酰胺 III，与对照组相比，照射组的比值较低（FTIR p=0.002；Raman p=0.017）。对于酰胺 I/CH，两种方法中根牙本质的比值均高于牙冠牙本质（p<0.001）。
放射治疗改变了人牙本质的化学成分。在羟基磷灰石中发现了磷酸盐-碳酸盐离子的交换，并且在放射治疗后有机成分的浓度增加。
接受头颈部放射治疗的患者发生放射性龋齿的风险增加不仅与唾液、饮食和微生物变化有关，还与牙齿化学成分的变化有关。
