Er:YAG激光对犬根尖周组织影响的组织学评价

Histological evaluations on periapical tissues after irradiation by erbium-doped yttrium aluminum garnet laser in Labradors dogs

目的 :以Er:YAG激光(erbium-doped yttrium aluminum garnet laser)对人离体牙根管峡区内的粪肠球菌、大肠杆菌杀菌效果所得的适当能量参数范围为依据,拉布拉多犬作为动物模型,观察不同功率对犬牙根尖周组织的影响,评估不同能量参数的Er:YAG激光在根管消毒中的安全性。方法:将10只成年健康拉布拉多犬的200个根管分为5组,除对照组仅用生理盐水冲洗外,其余4组分别用Er:YAG激光1.5、2.0、2.5、3.0 W功率照射,每次照射30 s,间隔10 s,共2次,尔后用生理盐水冲洗。10只犬分别于即刻、2 d、2周、1个月、2个月处死,制作根尖周组织病理切片并进行组织学评估。采用SPSS 13.0软件包对数据进行统计学分析。结果:在所有观察时间段内,对照组、1.5 W和2.0 W激光组未观察到根尖吸收,2.5 W组部分切片观察到轻微炎症反应,3.0 W组部分切片观察到管壁部分吸收、根尖周中度到重度炎症反应。统计学分析表明,在所有时段,对照组与1.5、2.0 W组无显著差异(P>0.05),与2.5 W组(2 d时段除外)无显著差异(P>0.05),与3.0 W组差异显著(P<0.05)。结论:在根管消毒中,如果Er:YAG激光功率选择适当,在达到消毒效果的前提下,对根尖周组织的热损伤可以降至最低。

PURPOSE： To investigate the thermal effects on periapical tissues of Labrador dogs after intra-canal irradiation by erbium-doped yttrium aluminum garnet （Er：YAG） laser at different powers based on the antibacterial experiment of Enterococcus faecalis and Escherichia coli in root canals with an isthmus, to assess the histological changes, and to prove the safety for clinical applications. METHODS： Two hundred root canals of 10 healthy adult Labradors dogs were selected and divided into 5 groups. Excepted one as control group, root canals in other 4 groups were irradiated by Er： YAG laser with 1.5, 2.0, 2.5, 3.0 W for 30 s. Ten Labradors dogs were sac6ficed at 0 （immediately after irradiation）, 2 days, 2 weeks, 1 and 2 months. After preparation of pathological specimen, histological changes after laser irradiation in periapical tissues were evaluated and scores of inflammation were graded. Statistical analysis was performed using SPSS 13.0 software package. RESULTS： No significant difference was observed at the apical area between 1.5, 2.0, 2.5 W and control groups at most periods （P〉0.05）, whereas significant difference was observed between 3.0 W and other groups for all periods （P〈0.05）. CONCLUSIONS： These results suggest that if proper output powers （2.0-2.5 W） of laser irradiation are chosen, disinfection in root canals can be finished successfully and thermal effects on the periapical tissues can be minimized.