He-Ne激光对正畸牙根吸收影响的组织形态学研究

 目的通过组织形态学观察He-Ne激光照射对实验性牙移动根吸收的影响与作用。方法选用Wistar大鼠建立根吸收的动物模型。利用HE和TRAP酶染色定量根吸收面积并进行破牙骨质细胞计数，对照射组与对照组大鼠牙移动过程中根吸收的严重程度进行分析比较。结果根吸收最早出现在加力4 d组，7 d时破牙骨质细胞开始增多，照射组细胞数低于对照组（P<0.05）；14 d时根表面破牙骨质细胞数达高峰，照射组细胞数明显低于对照组（P<0.01）；21 d时根吸收基本停止，照射组根吸收面积明显低于对照组（P<0.01），并在照射组观察到根吸收的修复现象。结论He-Ne激光的局部照射可有效地减少实验性牙移动根吸收的程度。

Effect of He-Ne laser irradiation on root resorption induced by orthodontical treatment

Objective To investigate the effect of low power laser irradiation on root resorption induced by heavy force during the experimental tooth movement.Methods Fifty-five Wistar rats were used in this study.The animals were divided into 11 groups of 5 animals each: 5 groups of animals as irradiated groups were exposed to low power laser irradiation for 15 minutes per day after orthodontic treatment,5 groups of animals as control groups did not receive low power laser irradiation,and 1 group of animals as blank control group was left untreated.An orthodontic appliance,consisting of a coil spring,connected the left first molar and the two incisors by ligature wire.90 g force was used in the experiment as heavy force.The animals were sacrificed on days 1,4,7,14,and 21.Tartrate resistant acid phosphatase(TRAP) staining and HE staining were used for observing root resorption and counting osteoclast cells.t-test was used for statistical analysis.Results The earliest root resorption was detected on day 4 in the circumference of necrotic hyalinized tissue.On day 7,the osteoclast-like cells close to cementum in control group outnumbered those in irradiated group(P<0.05),reaching the peak on day 14(P<0.01).On day 14,serious root loss deep into dentine could be often observed in the pressure side.After 21days,resorption stopped generally.The area of resorption in irradiated group was significantly smaller than in control group(P<0.01).Besides,the repair process of root resorption was detected on day 21 in the irradiated group.The cells involved in root resorption were mono-and multi-nucleated TRAP-positive cells.Conclusions Low power laser irradiation not only accelerates alveolar bone and periodontal tissue turn-over during tooth movement but also reduces root resorption effectively.