Ishizaki Nelson Tatsunari, Matsumoto Koukichi, Kimura Yuichi, Wang Xiaogu, Kinoshita Jun-Ichiro, Okano Sheila Mayumi, Jayawardena Jayanetti Asiri
Department of Endodontics, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan.
Photomed Laser Surg. 2004 Aug;22(4):291-7. doi: 10.1089/pho.2004.22.291.
This study was performed to investigate the temperature rises on root surfaces and morphological changes on root canal walls of extracted human teeth after irradiation by erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr:YSGG) laser and to evaluate the efficiency in removing smear layer and debris from the prepared root canal walls in vitro.
No report on Er, Cr:YSGG laser effects under various conditions and specific tips for endodontic treatments has been reported.
Sixty extracted human teeth with single and straight root were used in this study. The teeth were prepared at 1 mm short of the apical foramen by a conventional technique using K-files. Fifty-four specimens were irradiated by Er, Cr:YSGG laser at the output powers of 2 W, 3 W, and 5 W for 7 sec with three fiber tips (200, 320, and 400 microm diameters). Temperature changes were recorded thermographically. All teeth were examined by light microscopy or scanning electron microscopy (SEM).
Thermographic study showed that the average temperature rises on root surfaces were less than 8 degrees C. Observation by light microscopy revealed the ablation at the apical stop, and that by SEM indicated that laser irradiation at 5 W using a fiber tip with 400 microm diameter was efficient for removing smear layer and debris without carbonization or melting.
The results of this study suggested that the temperature rises during Er, Cr:YSGG laser irradiation at the parameters used in this study are minimal to cause the damage on periodontal and bone tissues. Moreover, it was suggested that it is efficient to remove smear layer and debris without causing any carbonization and melting.
本研究旨在调查铒铬：钇钪镓石榴石（Er, Cr:YSGG）激光照射后离体人牙根管壁的温度升高及根管壁的形态变化，并在体外评估其从预备后的根管壁去除玷污层和碎屑的效率。
尚无关于各种条件下Er, Cr:YSGG激光效应及牙髓治疗特定技巧的报道。
本研究使用60颗单根直的离体人牙。采用K锉常规技术在距根尖孔1 mm处进行预备。54个样本分别用三种直径（200、320和400微米）的光纤头，以2 W、3 W和5 W的输出功率，照射7秒。用热成像仪记录温度变化。所有牙齿均通过光学显微镜或扫描电子显微镜（SEM）检查。
热成像研究表明，牙根表面的平均温度升高低于8℃。光学显微镜观察显示根尖止点处有消融，扫描电子显微镜观察表明，使用直径400微米的光纤头、5 W功率的激光照射能有效去除玷污层和碎屑，且无碳化或熔化现象。
本研究结果表明，在本研究中使用的参数下，Er, Cr:YSGG激光照射期间的温度升高极小，不会对牙周和骨组织造成损伤。此外，表明其能有效去除玷污层和碎屑，且不会引起任何碳化和熔化。
