放射疗法对乳牙釉质硬度和微观形态的影响
Effects of radiotherapy on microhardness and micromorphology of deciduous tooth enamel

目的 研究放射疗法对乳牙硬组织结构的影响。方法 随机选取40个健康且新鲜拔除的滞留乳磨牙，沿近远中方向将牙齿切成颊舌两半，选择40个半切片用于实验。实验采用自身对照原则，照射之前采用显微硬度计对牙釉质进行初始硬度测试。之后分次完成40 Gy照射，2 Gy/次，1次/d，5 d/周，连续4周。每照射10 Gy后，采用显微硬度计对实验标本进行阶段硬度测试，所有照射剂量完成后采用显微硬度计观察乳牙牙釉质的显微硬度，扫描电子显微镜观察微观形态的变化。结果 乳牙牙釉质的显微硬度随着照射剂量的增加而降低。扫描电子显微镜观察结果显示：照射过的牙釉质比未经过照射的牙釉质在所有位置上都表现出明显的微观表面形态改变。随着照射剂量的增加，表面形态发生渐进性破坏，表现为非晶体外观。结论 随着照射剂量的增加，乳牙硬组织显微硬度降低，牙釉质的表面形态发生渐进破坏。
： Objective To investigate the effects of radiation therapy on hard tissue structure of deciduous teeth. Methods Forty healthy and freshly extracted or exfoliated human deciduous molar teeth mesiodistally sectioned to yield buccal and lingual hemisections and forty vestibular sections were selected for enamel experiment following the principle of selfcontrol. Enamel initial hardness was measured by microhardness tester prior to irradiation. Then a total of 40 Gy of irradiation was performed with 2 Gy/time, 1 time/d, 5 times/week for 4 weeks. The enamel hardness was measured after each 10 Gy of irradiation. The microhardness of deciduous teeth was observed by microhardness tester after irradiation and micromorphological changes were observed by scanning electron microscopy (SEM). Results The microhardness of deciduous teeth enamel decreased with radiation dose. SEM results showed that significant micromorphological changes in enamel surface were seen in all regions of irradiated enamel compared with nonirradiated enamel. With the increase in irradiation dose, surface morphology exhibited a progressive destruction, which appeared an amorphous appearance. Conclusion The microhardness of hard tissue of deciduous teeth decreases with radiation dose. Surface morphology of enamel exhibits a progressive destruction