Er：YAG激光切除牙根断面的扫描电镜观察

目的对Er：YAG激光切除的牙根断面进行扫描电镜研究,并通过对比超声金刚砂尖以及高速涡轮金刚砂车针切除牙根断面的不同表面状态,为Er：YAG激光应用于临床根尖切除术提供依据。方法将30颗上颌中切牙随机分为3组（Er：YAG激光切除组、超声金刚砂尖切除组、高速涡轮金刚砂车针切除组）,分别使用Er：YAG激光、超声金刚砂尖以及高速涡轮金刚砂车针在距离根尖3 mm处进行牙根切除。使用扫描电镜观察3组牙根断面残屑及玷污层、牙本质小管开放、裂隙以及器械切割痕迹情况。结果Er：YAG激光切除组和超声金刚砂尖切除组牙根断面有少量残屑、玷污层,并有牙本质小管开放;高速涡轮金刚砂车针切除组牙根断面有大量残屑及玷污层,没有牙本质小管开放。高速涡轮金刚砂车针切除组中能看到大量裂隙出现,超声金刚砂尖切除组中可见裂隙出现,而Er:YAG激光切除组中几乎没有裂隙出现。高速涡轮金刚砂车针切除组和超声金刚砂尖切除组牙根断面的表面粗糙并有明显切割痕迹,而Er：YAG激光切除组牙根表面没有切割痕迹,较为平滑。结论Er：YAG激光应用于根尖切除具有一定的优势,其牙根断面组织形态学方面的表现明显优于超声金刚砂尖和高速涡轮金刚砂车针。

Root resection by Er:YAG laser: a scanning electron microscope study

Objective To compare the difference of the surface of root resection by Er:YAG laser, ultrasonic or high-speed handpiece with scanning electron microscope（SEM）, and to evaluate the possibility of using Er:YAG laser on the root resection in clinical application. Methods Thirty maxillary central incisors were divided into three groups（Er:YAG laser group, ultrasonic group, high-speed handpiece group）, and the root resection were made at root tip 3 mm with Er:YAG laser, ultrasonic instrument or long needle diamond bur according to grouping. The surface of the root resection by SEM in the aspects of debris, smear layer, opened dentinal tubules, cracks and ablation characteristics were compared. Results The examination revealed that Er:YAG laser group and ultrasonic group had no or little debris and smear layer and with opened dentinal tubules. High-speed handpiece group had great amount of debris and smear layer and without opened dentinal tubules. Cracks were observed in ultrasonic group and highspeed handpiece group, no in Er:YAG laser group. There were ablation characteristics in ultrasonic group and highspeed handpiece group, but no in Er:YAG laser group. Conclusion From the morphological aspect, Er:YAG laser has much more advantage than ultrasonic instrument and diamond bur for the root resection.