Application of Laser to Next Endodontics Prevented From Cracking

本研究的目的是探讨Er：YAG激光和超声根端洞制备后牙根断裂的动力学和根端洞制备后的抗断裂性。取离体前牙根，用牙胶侧向加压，切去根尖。分别用Er：YAG激光器、超声设备、最高功率超声设备和最低功率超声设备在根端制备了3mm深的空腔。制备后，用显微镜和微型CT观察有无骨折和形态学变化。然后在万能试验机上对根管内充填材料进行反向加载。最高功率超声组与Er：YAG激光组和最低功率水冷超声组相比，有显著性差异。在本实验条件下，Er：YAG激光水冷却预备根端窝洞引起的牙根折裂是最小的，而Er：YAG激光组和超声组的牙根折裂形态和阻力无显著性差异。

The purpose of this study was to investigate the kinetics of root fractures produced byroot-end cavity preparation and the fracture resistance following root-end cavitypreparation using Er:YAG laser and ultrasonics. Roots of extracted human anteriorteeth were prepared, laterally condensed with guttapercha, and the root-end wasresected. Root-end cavities of 3 mm in depth were prepared using Er:YAG laser withwater cooling , an ultrasonic device at the highest power setting with or without watercooling, or at the lowest power setting with water cooling. After the preparation,presence or absence of fracture and morphological change were observed with amicroscope and a micro CT. Then, obturation materials in the root canal werevertically loaded using a universal testing machine. There were significantly morefractures in the ultrasonic group at the highest power setting group compared to theEr:YAG laser group and the ultrasonic group at the lowest power setting with watercooling. Within the limitations of thisin vitro experiment, fractures caused by Er:YAGlaser irradiation under water cooling for root-end cavity preparation was minimal.However, there were no significant differences in the resistance and vertical rootfracture patterns between the Er:YAG laser group and the ultrasonic group.