Hossain M, Nakamura Y, Kimura Y, Ito M, Yamada Y, Matsumoto K
Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan.
J Clin Laser Med Surg. 1999 Oct;17(5):223-6. doi: 10.1089/clm.1999.17.223.
This investigation was performed to evaluate the effect of CO2 laser irradiation on the acquired acid resistance of dental hard tissues to artificial caries-like formation and the ultrastructure of lased areas was morphologically investigated in vitro.
In recent years, many studies have been carried out to evaluate the effect of the CO2 laser on the enhanced resistance to artificial caries formation of enamel. However, a limited number of papers concerning its effect on dentin have been published.
A CO2 laser of 10.6 microns wavelength was used to irradiate human enamel and dentin samples from 20 extracted human molar teeth, and samples were subjected to 2 microliters of 0.1 M lactic acid solution (pH 4.8) for 24 h at 36 degrees C. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometry and the morphological changes were investigated by scanning electron microscopy (SEM).
The lowest mean Ca2+ ppm was recorded in the samples irradiated at 3 W, followed by 2 W, 1 W, and unlased samples. SEM observation showed that the lased areas were melting with solidification of the smear layer. Even after acid demineralization, the lased surfaces were almost unchanged.
The results of this study suggested that CO2 laser irradiation could sufficiently melt and solidify the enamel and dentin surfaces and thus enhance resistance to artificial caries-like formation.
本研究旨在评估二氧化碳激光照射对牙硬组织获得性抗人工龋样形成的影响，并在体外对激光照射区域的超微结构进行形态学研究。
近年来，已经进行了许多研究来评估二氧化碳激光对牙釉质增强抗人工龋形成能力的影响。然而，关于其对牙本质影响的论文数量有限。
使用波长为10.6微米的二氧化碳激光照射从20颗拔除的人类磨牙获取的牙釉质和牙本质样本，样本在36℃下接受2微升0.1M乳酸溶液（pH 4.8）处理24小时。通过原子吸收分光光度法测定每种溶液中溶解的钙离子（Ca2+）的百万分率（ppm），并通过扫描电子显微镜（SEM）研究形态变化。
在3W照射的样本中记录到最低的平均Ca2+ ppm，其次是2W、1W和未照射的样本。SEM观察表明，激光照射区域正在熔化，同时涂片层凝固。即使经过酸脱矿后，激光照射表面几乎没有变化。
本研究结果表明，二氧化碳激光照射可以充分熔化并凝固牙釉质和牙本质表面，从而增强对人工龋样形成的抵抗力。
