Establishment of treatment that activates oral mesenchymal cells using dental LASER.

目的：采用逆转录-聚合酶链式反应(RT-PCR)和免疫组织化学方法观察CO2激光照射磨牙尖部后的牙髓反应。用CO2激光照射上颌第一磨牙牙尖区，总能量为4J(密度：203.84 J/cm2)。结果：CO2激光照射后，牙髓侧温度升高22.5℃。激光照射后6、12和24小时(48小时)，肿瘤坏死因子α和IL-1的mRNAs表达均显著高于对照组(P<0.05)。组织学观察，激光照射后即刻牙髓组织轻度变性，CO_2激光照射后即刻髓角内可见HSP-70阳性细胞。激光照射后即刻和5d，在成牙本质细胞亚层可见VEGF阳性细胞。激光照射后5d，在牙髓深层细胞中可检测到Nestin的表达。结论：低能量激光通过牙本质照射牙髓组织，可诱导炎症和病理细胞因子途径修复受损牙髓组织。

Aim : The purpose of this study was to investigate pulp responses after CO_2 laser irradiation of the cusp of molar teeth using RT-PCR and immunohistochemical methods.Methods : Adult male Sprague-Dawley rats, weighing about 200 g each, were used in this study. A CO_2 laser was used to irradiate the cusp region of the upper first molar with a total energy of 4 J (Density ; 203.84 J/cm^2). The temperature change in the pulp was measured using a super fine sheath thermocouple.Results : The temperature at the pulp side after the CO_2 laser irradiation increased 22.5℃. The expression of both TNFa and IL-1 mRNAs was significantly higher at 6, 12 and 24 hr (but not at 48 hr) after the laser irradiation compared to the control group (p<0.05). Histologically, a slight degeneration of the pulp tissue was observed immediately after the laser irradiation, and HSP-70 positive cells were observed in the pulp horn immediately after the CO_2 laser irradiation. Cells positive for VEGF were seen in the sub-odontoblast layer immediately and 5 days after the laser irradiation. At 5 days after the laser irradiation, the expression of Nestin was recognized in the deeper pulp cells. NFP-positive nerve fibers had disappeared in the pulp horn by 5 days after the laser irradiation.Conclusions : These results suggest that a low energy of laser irradiation such as used in the clinic to the pulp tissue through the dentin induces the inflammatory and pathological cytokine pathways to repair the damaged pulp tissue.