Nd:YAGレーザーによるHLLTがヒト歯肉上皮細胞に与える影響について

抄録

Purpose: High reactive level laser therapy （HLLT） is often used in surgical treatment. The present study investigated the effect of HLLT on human epithelial cells in vitro.
Methods: Epithelial cells were obtained and isolated from human normal gingiva （n＝5）. The cells were identified by cytokeratin clone AE1/AE3 immunofluorescence staining. Subsequently, the cells were irradiated using a Nd:YAG laser at a distance of 5mm. Three laser irradiation conditions were used: ①no irradiation （control group） ②100mJ, 30pps, 10seconds and ③200mJ, 30pps, 10seconds. Cell growth was measured at 1, 2 and 3 days post-irradiation using an improved MTT method. Cell migration was assayed at 0, 1, 5, and 7 days post-irradiation. For the analysis of cell migration, we compared the results of a scratch assay between the control and irradiation groups at each time point. Morphological analysis was also preformed using phase-contrast microscopy and scanning electron microscopy （SEM）.
Results: Cell growth was significantly higher in 100mJ, 30pps, 10seconds group than in the control group （P＜0.001）. In contrast, it was significantly lower in 200mJ, 30pps, 10seconds group than in the control group （P＜0.001）. In comparison to the control group, cell migration tended to be higher in 100mJ, 30pps, 10seconds group, and was significantly lower in 200mJ, 30pps, 10seconds group （P＜0.001） compared with control group. No morphological changes were detected among the groups by phase-contrast microscopy. However, SEM showed that number of microvilli on the cell surface was increased in 100mJ, 30pps, 10seconds group, while the cell shape appeared squashed in 200mJ, 30pps, 10seconds group.
Conclusion: Results of the morphological assay, cell growth assay, and migration assay showed the effectiveness of low level laser therapy （LLLT） in the 100mJ, 30pps, 10seconds group, whereas the effect of HLLT was shown in the 200mJ, 30pps, 10seconds groups.