钕激光、半导体激光对窝洞消毒产热及抑菌效果的体外实验

Heat production and bacteriostatic effect of neodymium laser and semiconductor laser on cavity disinfection:in-vitro study

背景:局部高效的窝洞消毒手段可最大限度地杀灭窝洞内残存的细菌,从而扼制龋病的再次发生和发展。激光作为一种新型技术手段,通过激光的热效应及生物刺激效应破坏细菌的细胞膜从而杀灭细菌。目的:评价钕激光(Nd:YAP、Nd:YAG)、半导体激光(Diode)窝洞消毒的安全性与有效性。方法:收集完好的前磨牙并制备体外牙窝洞模型,分别用Nd:YAP激光、810 nm半导体(Diode)激光、Nd:YAG激光处理样本,利用热电偶温度测量仪监测髓腔内温度变化,菌落计数观察变形链球菌和乳酸杆菌的生长情况。结果与结论:①同一种激光下,髓腔温度随照射功率的增大而升高;②功率相同时,不同激光窝洞消毒,髓腔温度均有所升高且温升值小于引起牙髓坏死的温度5.5℃,当功率为1.8,4.0 W时,Nd:YAP激光温度高于Nd:YAG激光和半导体激光组(P<0.05);③菌落计数显示,同种激光下,随激光功率增大,菌落数明显减少,与阴性对照组(生理盐水组)相比,差异有显著性意义(P<0.05);④1.8 W、3.0 W、4.0 W组与阳性对照组(5.25%NaClO溶液)相比差异无显著性意义(P>0.05);⑤综合安全性、有效性及最小功率原则,3种激光在窝洞消毒时可选择的最佳功率为1.8 W。

BACKGROUND:Local effective disinfection method can kill the bacteria to the maximum extent,so as to prevent the recurrence and development of caries.As a new technology,laser destroys the cell membrane of bacteria through its thermal and biological stimulation effects.OBJECTIVE:To evaluate the safety and effectiveness of cavity disinfection with neodymium laser(Nd:YAP,Nd:YAG)and semiconductor laser(Diode).METHODS:The intact premolars were collected and the isolated alveolar cavity model was prepared.Samples should be processed with Nd:YAP laser,810 nm semiconductor(Diode),and Nd:YAG laser,separately.The pulp temperature was monitored by thermocouple temperature measuring instrument.The growth of Streptococcus mutans and Lactobacillus was observed by colony counting.RESULTS AND CONCLUSION:(1)The pulp temperature increased with the increase of irradiation power.(2)At the same power,different laser disinfection,the temperature was increased and less than the pulp necrosis 5.5℃,when the power was 1.8 and 4.0 W.Nd:YAP laser temperature was higher than Nd:YAG laser and semiconductor laser group(P<0.05).(3)Colony count showed that with the same laser,the number of colonies decreased significantly with the increase of laser power;compared with the negative control group(normal saline group),the difference was statistically significant(P<0.05).(4)There was no statistical difference between 1.8 W,3.0 W,and 4.0 W groups and positive control group(5.25%NaClO solution)(P>0.05).(5)The results show that,based on the principles of safety,effectiveness and minimum power,the optimal power that can be selected for the three kinds of lasers in the disinfection of cavities is 1.8 W.