Gholami Gholam Ali, Fekrazad Reza, Esmaiel-Nejad Azadeh, Kalhori Katayoun A M
Dental Faculty of Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Photomed Laser Surg. 2011 Feb;29(2):115-21. doi: 10.1089/pho.2009.2628.
Dentin hypersensitivity (DH) is one of the most frequent problems causing patients' complaints following stimulation of cervically exposed dentin. Studies have shown that different lasers have various occluding effects on dentinal tubules. This study is aimed at evaluating the occluding effects of Er;Cr:YSGG (P:0.25W,F:20Hz,Pd:140μS), Nd:YAG (P:1W,F:20Hz), CO(2) (P:1W, Pd:50μs), and 810-nm diode (P:2 W, Pd:30ms) lasers on dentinal tubules.
Fifteen human third molars were collected and ground-sectioned vertically on the buccal and lingual surfaces to yield two dentin disks of 2-mm thickness. Then, four sites for laser irradiation and one control site were marked in the cervical areas of the dentin disks. Before laser application, specimens were exposed to a 14% EDTA solution to expose dentinal tubules and were then evaluated by scanning electron microscopy (SEM). The tubules' entrance diameters were determined by "scale-bar" software (Phillips Scale-Bar, Phillips, Amsterdam, The Netherlands), which is specifically designed for SEM. The mean diameters for the tubules were then estimated for each site and analyzed statistically.
The mean dentinal tubule entrance diameters for Er;Cr:YSGG, 810-nm diode, CO(2), and Nd:YAG, were 1.73, 3.27, 2.10, and 1.64 microns, respectively, compared with 3.52 microns before laser irradiation. Overall, the furthest reduction in mean tubule diameter resulted from the Nd: YAG laser (53%). However, tubular diameter reduction in all laser groups (p<0.05) was found to be statistically significant. In all laser groups, melting of the peritubular dentin was the dominant observed phenomenon.
Our results indicate that Nd: YAG, Er; Cr: YSGG, and CO(2) lasers, through their ability to melt peritubular dentin, can occlude dentinal tubules partially or totally, and therefore reduce patients' hypersensitivity symptoms. The 810-nm diode laser sealed tubules to a far lesser degree, with negligible effects on desensitization.
牙本质过敏症（DH）是颈部暴露牙本质受到刺激后引起患者主诉的最常见问题之一。研究表明，不同的激光对牙本质小管有不同的封闭作用。本研究旨在评估铒铬钇钪镓石榴石激光（P：0.25W，F：20Hz，脉宽：140μS）、钕钇铝石榴石激光（P：1W，F：20Hz）、二氧化碳激光（P：1W，脉宽：50μS）和810纳米二极管激光（P：2W，脉宽：30ms）对牙本质小管的封闭作用。
收集15颗人类第三磨牙，在颊面和舌面垂直磨切成厚度为2毫米的两个牙本质盘。然后，在牙本质盘的颈部区域标记四个激光照射部位和一个对照部位。在激光照射前，将标本暴露于14%的乙二胺四乙酸（EDTA）溶液中以暴露牙本质小管，然后通过扫描电子显微镜（SEM）进行评估。牙本质小管的入口直径通过专门为SEM设计的“比例尺”软件（飞利浦比例尺，飞利浦，荷兰阿姆斯特丹）测定。然后估计每个部位牙本质小管的平均直径并进行统计学分析。
铒铬钇钪镓石榴石激光、810纳米二极管激光、二氧化碳激光和钕钇铝石榴石激光照射后牙本质小管入口的平均直径分别为1.73微米、3.27微米、2.10微米和1.64微米，而激光照射前为3.52微米。总体而言，钕钇铝石榴石激光导致牙本质小管平均直径减小的幅度最大（53%）。然而，所有激光组的牙本质小管直径减小均具有统计学意义（p<0.05）。在所有激光组中，观察到的主要现象是管周牙本质的熔化。
我们的结果表明，钕钇铝石榴石激光、铒铬钇钪镓石榴石激光和二氧化碳激光通过其熔化管周牙本质的能力，可以部分或完全封闭牙本质小管，从而减轻患者的过敏症状。810纳米二极管激光对牙本质小管的封闭程度要小得多，对脱敏的效果可忽略不计。
