Interoperative Research Center in Dental and Medical Sciences, Faculty of Dentistry, Universidad de Valparaíso, Valparaíso, Chile.
Nanobio-Corrosion Laboratory, Institute of Chemistry, Faculty of Sciences, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
Int J Radiat Biol. 2020 Jul;96(7):910-918. doi: 10.1080/09553002.2020.1741718. Epub 2020 Mar 26.
The main goal of this study was to evaluate the impact of different ionizing radiation doses on the mineral (carbonate/phosphate ratio, crystallinity index [CI]) and organic (amide III/phosphate, amide I sub-band ratios) structures, as well as the microhardness, of enamel and dentin, along with their influence on the bonding strength stability of the etch-and-rinse (ER) and self-etch (SE) dental adhesive strategies. Enamel and dentin human tissue specimens were irradiated (with 0, 20, 40, and 70 Gy radiation doses, respectively) and sectioned to perform an attenuated total reflection-Fourier transform IR spectroscopy assay (ATR-FTIR) and the Vickers microhardness (VHN) test to conduct a biochemical and biomechanical evaluation of the tissues. Regarding the adhesive properties, restored enamel and dentin specimens exposed to the same radiation doses were submitted to microshear bond strength (μSBS) tests for enamel in immediate time (IM) and to microtensile bond strength (μTBS) tests after for IM and 12-month (12 M) period of time, Mann-Whitney U tests were implemented, using the ATR-FTIR data for significant differences (α < 0.05), and three- and two-way analyses of variance, along with post-testing, were performed on the μTBS and μSBS data (MPa), respectively (Tukey post hoc test at α = 0.05). The ATR-FTIR results showed a significant decrease ( < .05) in the amide III/phosphate ratio after 20 Gy for the enamel and after 40 Gy for the dentin. The CI was significantly reduced for both tissues after a dose of 70 Gy ( < .05). All radiation doses significantly decreased microhardness values, relative to the respective enamel and dentin controls ( < .05). In both tissues and adhesive strategies, the decrease in bond strength was influenced by ionizing radiation starting from 40 Gy. The ER strategy showed high percentages of enamel cohesive failure. In general, ER in both tissues showed greater and more stable bond strength than SE against increased radiation doses and long term. It is possible to conclude that structural alterations of enamel and dentin are generated by all radiation doses, decreasing the microhardness of dental hard tissues and influencing bond strength over time, starting at 40 Gy radiation dose. The etch-and-rinse strategy demonstrates better adhesive performance but generates cohesive fractures in the enamel.
本研究的主要目的是评估不同电离辐射剂量对牙釉质和牙本质的矿物质（碳酸盐/磷酸盐比例、结晶度指数[CI]）和有机成分（酰胺 III/磷酸盐、酰胺 I 亚带比）结构的影响，以及对牙釉质和牙本质的显微硬度的影响，并研究其对自酸蚀（SE）和酸蚀-冲洗（ER）两种牙本质黏接策略黏接强度稳定性的影响。采用 0、20、40 和 70Gy 剂量的电离辐射分别辐照牙釉质和牙本质组织样本，进行衰减全反射傅里叶变换红外光谱（ATR-FTIR）分析和维氏显微硬度（VHN）测试，对组织进行生物化学和生物力学评估。对于黏接性能，将暴露于相同辐射剂量的牙釉质和牙本质样本进行即刻（IM）微剪切黏接强度（μSBS）测试和 IM 及 12 个月（12M）后微拉伸黏接强度（μTBS）测试。采用曼-惠特尼 U 检验，对 ATR-FTIR 数据进行显著性差异分析（α<0.05），并对 μTBS 和 μSBS 数据（MPa）分别进行三因素和两因素方差分析，以及 Tukey 事后检验（α=0.05）。ATR-FTIR 结果显示，牙釉质在 20Gy 后和牙本质在 40Gy 后，酰胺 III/磷酸盐比值显著降低（<0.05）。牙本质在 70Gy 后 CI 显著降低（<0.05）。所有辐射剂量均显著降低了牙釉质和牙本质的显微硬度值（<0.05）。在两种组织和黏接策略中，从 40Gy 开始，黏接强度的降低受电离辐射的影响。ER 策略显示出较高比例的牙釉质内聚性破坏。总体而言，ER 在两种组织中的黏接强度均高于 SE，且随着辐射剂量的增加和时间的延长，黏接强度更稳定。综上所述，所有辐射剂量都会导致牙釉质和牙本质的结构发生改变，降低牙本质硬度，并影响黏接强度，40Gy 辐射剂量即可产生影响。酸蚀-冲洗策略显示出更好的黏接性能，但会导致牙釉质内聚性断裂。
