Nd：YAG激光照射对根管壁的作用

目的：观察Nd:YAG激光对根管壁的作用。方法 选用25颗离体单根牙，随机分5组，对照组不做根管预备，常规组用K型根管锉扩大根管，激光3个组在常规根管预备后，激光工作条件为1．70W，20pps,分别照射15秒，30秒和60秒，并用扫描电镜观察。结果，激光照射15秒和30秒组根管壁呈熔融状态，去除了玷污层，牙本质小管封闭和半封闭，未见对牙体硬组织的损伤。激光60秒组对根管壁有过分熔融，形成裂而且不能完全封闭牙本质小管。结论 激光照射15秒和30秒能够清洁根管壁和封闭牙本质小管。

Effect of Nd:YAG laser irradiation on the wall of root-canal

Objective To study effects of Nd:YAG laser on the wall of root-canal.Methods Twenty-five single-root human teeth were divided into 5 groups randomly in vitro.Root canals of control group was not instrumented,but the conventional and three laser groups were instrumented and then three laser groups were irradiated 15s,30s and 60s respectively and observed by SEM.Results The wall of root canals was clean in the control,conventional group had smear layers.The wall of lased 15s or 30s were fused,removed smear layers and sealed dentin tubules.Laser's effects on middle and apical third root canals were pronouced than that of coronal third and had no damage.In the group of lased 60s the dentin tubles appeared cracking and some dentin tubles were opened.Conclusion The irradiation of laser (15s,30s) on the wall of root canals can seal tubules and clean wall of root canals.