ABSTRACT:Objective To observe the structural changes of dentin irradiated with Nd:YAG laser under dif-ferent parameters and the changes of calcium-phosphorus ration,and evaluate the optimal parameters of Nd:YAG laser in treating dentin hypersensitivity (DH).Methods The model of dentin hypersensitivity was established by acid etching method.Samples were irradiated with Nd:YAG laser under different parameters.The morphological alterations of the dentin surfaces and Ca-P ratio were examined with scanning electron microscopy (SEM)combined with energy dispersive X-ray microanalysis.Results Compared with those in the control group,dentinal tubules could be blocked partially or totally with no cracks in A-C (30 mj,5 Hz),(30 mj,10 Hz)and (50 mj,5 Hz)groups. Dentinal tubules could be entirely blocked but with cracks in D (50 mj,10 Hz)and E (80 mj,5 Hz)groups.Dentin was carbonized in F (80 mj,10 Hz)group.Compared with that in the control group,Ca-P ratio was decreased sig-nificantly (P <0.05).Conclusion The suitable energy parameter of Nd:YAG laser in treating dentin hypersensi-tivity is (30 mj,10 Hz)and (50 mj,5 Hz).%目的：利用不同参数 Nd：YAG 激光照射牙本质过敏样本,观察牙本质小管封闭程度,测量钙磷比值变化,得出Nd：YAG 激光治疗牙本质过敏症的最佳参数。方法用酸蚀法建立牙本质敏感模型,用不同参数的 Nd：YAG 激光照射样本,扫描电镜观察照射前后样本表面牙本质小管封闭程度及微观结构改变,X 线能谱分析表面钙磷比值变化。结果B~D 组(30 mj,5 Hz；30 mj,10 Hz；50 mj,5 Hz)3组牙本质小管部分或完全封闭且无裂纹出现,E~F (50 mj,10 Hz；80 mj,5 Hz)组牙本质虽完全熔融,但有裂纹出现,G(80 mj,10 Hz)组牙本质发生碳化；X 线能谱分析实验组比对照组钙磷比值降低,差异有统计学意义。结论对于牙本质过敏症的治疗,Nd：YAG 激光较为理想的参数为(30 mj,10 Hz)和(50 mj,5 Hz)。
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