Elucidation of mechanism of stimulating to hard tissue fomation ability by laser iradiation in dental pulp and its application

采用体外培养的人牙髓细胞(HDP细胞)，观察低功率激光照射对牙髓硬组织形成能力和钙化细胞外基质代谢能力的影响。在本研究中，HDP细胞取自年轻患者正畸治疗过程中拔除的第三磨牙。使用Ga-Al-As半导体激光器(松下公司，日本东京，型号：Panalas-1000)，其连续波长为830 nm，最大功率输出为600 mW。照射10min所对应的总能量为3.65J/cm2。HDP细胞在融合前仅照射5~10min一次。照射后5周，照射组和未照射组细胞均出现骨结节。照射5min和10min的细胞骨结节形成数明显多于未照射的细胞。低功率激光照射后，细胞内碱性磷酸酶(ALP)活性降低，骨钙素生成增加。研究了干酪乳杆菌提取的肽聚糖对HDP细胞产生IL-6的影响。该肽聚糖以时间和剂量依赖的方式刺激IL-6的产生。IL-6处理组HDP细胞纤溶酶原激活剂活性显著高于未处理组，且呈时间和剂量依赖性。照射后的HDP细胞产生IL-6的能力明显低于未照射的HDP细胞。提示激光照射可抑制细胞外基质的破坏，增强硬组织的形成能力。

We examined the effect of low power laser irradiation on ability of hard tissue formation and metabolism of extracellular matrix involved calcification, using cultured human dental pulp cells (HDP cells). In this study, HDP cells were obtained from the third molars which were extracted form young patients in the course of orthodontic treatment. A Ga-Al-As diode laser (Matsushita, Inc., Tokyo, Japan, model : Panalas-1000), which has a continuous wavelength of 830 nm and maximal power output of 600 mw, was used. The total energy, corresponding to 10 min exposure, was 3.65 J/cm2.The HDP cells were irradiated, just before the cells were confluent, for 5 or 10 min only once. The bone nodule of both cells irradiated and non-irradiated was found at 5 weeks ago after irradiation. The number of bone nodule formation of cells irradiated for 5 and 10 min were significantly increased compared with non-irradiated. The activity of alkaline phosphatase (ALP) was decreased and the production of osteocalcin was increasedWe examined the effect of low power laser irradiation on metabolism of extracellular matrix. The effects of peptidoglycan extracted from Lactobacillus casei on the production of IL-6 in HDP cells were examined. The peptidoglycan stimulated IL-6 production in a time- and dose-depend manner. IL-6 treatment induced significantly high plasminogen activator activity in the HDP cells in a time- and dose-dependent manner compared with non-treated control. The production of IL-6 from HDP cells treated with LPS and irradiated were decreased compared with HDP cells treated with LPS and non-irradiated. Our findings were suggested that the destruct of extracellular matrix were inhibited and ability of hard tissue formation was enhanced by laser irradiation.