Takahashi K, Kimura Y, Matsumoto K
Department of Endodontics, Showa University School of Dentistry, Tokyo, Japan.
J Clin Laser Med Surg. 1998 Jun;16(3):167-73. doi: 10.1089/clm.1998.16.167.
The purposes of this study were to examine the effects of CO2 laser emitted at 9.3 microns on human sound and carious dental hard tissue ablation with a stereoscope, scanning electron microscope (SEM), and energy dispersive X-ray spectrometer (SEM-EDX) and to identify possible applications of this laser in clinical treatment.
There has been no report of morphological changes or atomic analytical studies on carious hard tissues after laser irradiation with 9.3 microns CO2 laser.
Sixty extracted human teeth with no caries and sixty teeth with enamel or dentin caries were used for this study. All teeth were horizontally sectioned into slices (approximately 3 mm in thickness) and the samples were irradiated with CO2 laser using the following two parameters: a fluence of 78 J/cm2 and 5 pps for 2 sec. After laser irradiation, half of the samples were observed by stereoscopy and SEM and the other half were analyzed by SEM-EDX.
The lased sound enamel and dentin surfaces showed crater-like structures which had been produced by the high laser energy. On the other hand, some portions of carious hard tissues were evaported by the laser. A slight amount of carbonization was observed by stereoscopy. Calcium (Ca) and phosphorus (P) content of sound or carious hard tissues was increased significantly (p < 0.01) after laser irradiation, but the ratio of Ca to P after laser irradiation was significantly increased (p < 0.01) on sound hard tissue only.
These results suggest that the 9.3 microns CO2 laser may be useful for the prevention or removal of caries in clinical situations.
本研究旨在通过体视显微镜、扫描电子显微镜（SEM）和能量色散X射线光谱仪（SEM-EDX），研究9.3微米波长的二氧化碳激光对正常和龋损牙体硬组织的消融作用，并确定该激光在临床治疗中的潜在应用。
目前尚无关于9.3微米二氧化碳激光照射后龋损硬组织形态变化或原子分析研究的报道。
本研究使用60颗无龋的拔除恒牙和60颗患有釉质或牙本质龋的牙齿。所有牙齿均水平切成薄片（厚度约3毫米），并使用以下两个参数用二氧化碳激光照射样本：能量密度为78 J/cm2，频率为5 pps，照射2秒。激光照射后，一半样本通过体视显微镜和扫描电子显微镜观察，另一半通过扫描电子显微镜-能量色散X射线光谱仪进行分析。
激光照射后的正常釉质和牙本质表面呈现出由高激光能量产生的坑状结构。另一方面，龋损硬组织的一些部分被激光蒸发。通过体视显微镜观察到有轻微碳化现象。激光照射后，正常或龋损硬组织中的钙（Ca）和磷（P）含量显著增加（p < 0.01），但仅在正常硬组织中，激光照射后Ca与P的比值显著增加（p < 0.01）。
这些结果表明，9.3微米二氧化碳激光在临床情况下可能有助于预防或去除龋齿。
