Nd:YAG激光对水门汀与牙本质剪切强度的影响

目的:评价脉冲Nd:YAG激光对水门汀与牙本质间剪切强度的影响,并观察激光照射前后的牙本质表面结构变化。方法:取人前磨牙30个,暴露牙本质粘接面形成60个测试样本,随机分为激光组和对照组。激光组以0.8W、10Hz脉冲Nd:YAG激光照射牙本质表面25sec,联合3种水门汀充填;对照组直接使用3种水门汀充填于牙本质表面,置于37℃生理盐水24h后,测试剪切强度,并进行统计学分析,在根管显微镜下观察断裂模式并分类。扫描电镜观察激光照射前后的牙本质表面形态。结果:聚羧酸锌组、玻璃离子组和树脂加强玻璃离子组在Nd:YAG激光照射前(后)的剪切强度分别为4.63±1.39(4.77±0.97)MPa、5.15±0.67(5.26±1.21)MPa和0.92±0.46(0.99±0.35)MPa,激光照射前后的差别均无统计学意义(P>0.05)。扫描电镜观察,0.8W、10Hz的Nd:YAG激光照射会使牙本质表面熔融,玷污层基本去除,大部分牙本质小管封闭,且在局部会出现裂纹。结论:Nd:YAG激光(0.8W、10Hz)处理牙本质,对聚羧酸锌和玻璃离子水门汀与牙本质间的粘接强度无影响。

Effect of Nd: YAG laser on the shear bond strength of cements to dentin

Objective： To evaluate the effect of Nd：YAG laser on the shear bond strength of cements to dentin,and observe the microscopic characteristic of the dentinal surface before and after using Nd：YAG laser.Methods： Thirty premolars were prepared to expose dentin and randomly divided into two groups： laser group and control group.The teeth in the laser group were processed with pulse Nd： YAG laser（0.8W,10Hz） for 25s,and filled with 3 cements respectively.The teeth in the control group were directly filled with 3 cements.After 24 hours under 37℃ water,the shear bond strengths of specimens were measured.Each fractured specimen was examined under dental microscope and all statistical analysis were performed.Finally the microscopic characteristic of the dentinal surfaces before and after using Nd： YAG laser were observed.Results： The shear bond strength of zinc polycarboxylate cement,glass ionomer cement and resin-modified glass ionomer cement before（after） using Nd： YAG laser were 4.63±1.39（4.77±0.97） MPa,5.15±0.67（5.26±1.21） MPa and 0.92±0.46（0.99±0.35）MPa respectively.There was no statistical difference in bond strength between two groups（P 0.05）.SEM observation：Nd： YAG laser could rough the dentinal surface,the smear layer was removed and the dentinal tubules were sealed or partly sealed.Conclusions： There was no influence on dentin bonding between zinc polycarboxylate cement and glass-ionomer cement after using Nd： YAG laser（0.8W,10Hz）.