Yasuda Yoshiyuki, Kawamorita Toru, Yamaguchi Hiroyasu, Saito Takashi
Division of Clinical Cariology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
Photomed Laser Surg. 2010 Oct;28 Suppl 2:S75-8. doi: 10.1089/pho.2009.2554. Epub 2010 Aug 25.
The purpose of this study was to evaluate the bactericidal efficacy of Nd:YAG and Er:YAG laser in the experimentally infected curved root canals.
Previous studies revealed that laser systems have a significant bactericidal effect in both human and bovine infected straight root canals.
Sixty extracted single-rooted teeth with single root canals were selected and then instrumented with endodontic files to a size 60 (K-type file). The degree of root curvature was determined according to modified Schneider's method. Each of the specimens was incubated in a sterile centrifuge tube with 1 mL of the Enterococcus faecalis suspension at 37°C for 2 weeks under aerobic conditions. After laser irradiation at each of the two settings, 50 mJ, 10 pps (0.5 W) or 100 mJ, 10 pps (1.0 W), the number of E. faecalis in each root canal was examined.
In the straight root canals, the Er:YAG laser showed higher bactericidal effects by 6.4-10.8% than did the Nd:YAG laser. Conversely, the bactericidal effect of Er:YAG laser in the curved root canals was higher by 1.5-3.1% than was that with the Nd:YAG laser. The bactericidal effect of the Er:YAG laser in the curved root canal is significantly lower than that in the straight root canal (p < 0.05).
These results suggest that further development in the endodontic laser tip and technique is required to ensure its success in curved root canals sterilization.
本研究旨在评估钕钇铝石榴石（Nd:YAG）激光和铒钇铝石榴石（Er:YAG）激光对实验性感染的弯曲根管的杀菌效果。
先前的研究表明，激光系统在人类和牛感染的直根管中均具有显著的杀菌作用。
选取60颗单根管的离体单根牙，然后用根管锉预备至60号（K型锉）。根据改良的施奈德方法确定牙根弯曲程度。将每个标本置于无菌离心管中，与1 mL粪肠球菌悬液在37℃有氧条件下孵育2周。在两种设置下进行激光照射后，即50 mJ、10脉冲/秒（0.5 W）或100 mJ、10脉冲/秒（1.0 W），检测每个根管中的粪肠球菌数量。
在直根管中，Er:YAG激光的杀菌效果比Nd:YAG激光高6.4%-10.8%。相反，Er:YAG激光在弯曲根管中的杀菌效果比Nd:YAG激光高1.5%-3.1%。Er:YAG激光在弯曲根管中的杀菌效果明显低于直根管（p<0.05）。
这些结果表明，为确保牙髓激光头和技术在弯曲根管消毒中取得成功，需要进一步改进。
