Yuanhong Li, Zhongcheng Li, Mengqi Luo, Daonan Shen, Shu Zhang, Shu Meng
State Key Laboratory of Oral Diseases, Dept. of Periodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2016 Dec 1;34(6):579-583. doi: 10.7518/hxkq.2016.06.006.
This study aimed to evaluate the effects of treatment with different powers of Nd: YAG laser irradiation on root surfaces and Streptococcus mutans (S. mutans) adhesion.
Extracted teeth because of severe periodontal disease were divided into the following four groups: control group, laser group 1, laser group 2, and laser group 3. After scaling and root planning, laser group 1, laser group 2, and laser group 3 were separately treated with Nd: YAG laser irradiation (4/6/8 W, 60 s); however, the control group did not receive the treatment. Scanning electron microscopy (SEM) was used to determine the morphology. S. mutans were cultured with root slices from each group. Colony forming unit per mL (CFU·mL⁻¹) was used to count and compare the amounts of bacteria adhesion among groups. SEM was used to observe the difference of bacteria adhesion to root surfaces between control group (scaling) and laser group 2 (6 W, 60 s), thereby indicating the different bacteria adhesions because of different treatments.
Morphology alterations indicated that root surfaces in control group contain obvious smear layer, debris, and biofilm; whereas the root surfaces in laser group contain more cracks with less smear layer and debris. The bacteria counting indicated that S. mutans adhesion to laser group was weaker than that of control group (P<0.05). No statistical significance among the laser groups (P>0.05) was observed. Morphology alterations also verified that S. mutans adhesion to laser group 2 (6 W, 60 s) was weaker than that of control group (scaling).
This study demonstrated that Nd: YAG laser irradiation treatment after scaling can reduce smear layer, debris, and biofilm on the root surfaces as compared with conventional scaling. The laser treatment reduces the adhesion of S. mutans as well. However, Nd: YAG laser irradiation can cause cracks on the root surfaces. In this experiment, the optimum laser power of 6 W can thoroughly remove the smear layer and debris, as well as relatively improve the control of thermal damagee.
本研究旨在评估不同功率的Nd:YAG激光照射治疗对牙根表面及变形链球菌（S. mutans）黏附的影响。
因重度牙周病拔除的牙齿分为以下四组：对照组、激光组1、激光组2和激光组3。在进行龈下刮治和根面平整后，激光组1、激光组2和激光组3分别接受Nd:YAG激光照射（4/6/8 W，60秒）；然而，对照组未接受该治疗。使用扫描电子显微镜（SEM）确定形态。将变形链球菌与每组的牙根切片共同培养。每毫升菌落形成单位（CFU·mL⁻¹）用于计数和比较各组间细菌黏附量。使用SEM观察对照组（刮治）和激光组2（6 W，60秒）之间细菌在牙根表面黏附的差异，从而表明不同治疗导致的细菌黏附差异。
形态学改变表明，对照组牙根表面含有明显的玷污层、碎屑和生物膜；而激光组牙根表面有更多裂纹，玷污层和碎屑较少。细菌计数表明，变形链球菌在激光组的黏附比对照组弱（P<0.05）。激光组之间未观察到统计学意义（P>0.05）。形态学改变也证实，变形链球菌在激光组2（6 W，60秒）的黏附比对照组（刮治）弱。
本研究表明，与传统刮治相比，刮治后进行Nd:YAG激光照射治疗可减少牙根表面的玷污层、碎屑和生物膜。激光治疗也可减少变形链球菌的黏附。然而，Nd:YAG激光照射可导致牙根表面出现裂纹。在本实验中，6 W的最佳激光功率可彻底去除玷污层和碎屑，并相对改善对热损伤的控制。
