光动力疗法对牙菌斑生物膜内致龋菌的影响及作用机制的研究

Study on the Influence and Mechanism of Photodynamic Therapy on the Cariogenic Bacteria in Dental Plaque Biofilms

目的:探讨以血卟啉单甲醚(hematoporphyrin monomethylether,HMME)为光敏剂的光动力疗法(photo-dynamic therapy,PDT)对牙菌斑生物膜内致龋菌的杀灭作用及机制。方法:以变形链球菌、血链球菌、嗜酸性乳杆菌和粘性放线菌为实验菌株,建立牙菌斑生物膜模型。实验分为4组:HMME-PDT组、HMME-PDT加叠氮钠组、西吡氯铵处理组、生理盐水处理组。平板菌落计数观察牙菌斑内致龋菌的活力,并测定不同处理前后pH的变化值(⊿pH)观察其对致龋菌产酸能力的影响。结果:与生理盐水组相比,HMME-PDT组和西吡氯铵组牙菌斑内致龋菌的数量(CFU/mL)显著下降(P<0.05),其杀菌率分别为94.92%和51.86%;而HMME-PDT加叠氮钠组牙菌斑内致龋菌数量无显著性差异,杀菌率仅为9.47%。⊿pH值测定结果显示,在一定时间范围内(0～24h),与生理盐水组相比,HMME-PDT组牙菌斑内致龋菌的产酸能力显著下降。结论:PDT可有效杀灭菌斑生物膜内的致龋菌,并抑制其产酸,同时单线态氧在PDT杀菌过程中起着极其重要的作用。

Objective： To study the killing effects and mechanism of photodynamic therapy using hematoporphyrin monomethylether as photosensitizer on the cariogenic bacteria in dental plaque biofilms. Methods： S. mutans, S. sangius, L. acidophilus, A. viscosus had been chosen as the experimental bacteria to establish dental plaque biofilms model. Divide them into four groups ： HMME-- PDT group, HMME-PDT＋ sodium azide group, cetylpyridinium chloride group, normal saline group. The influence of the cariogenic bacteria in plaque biofilms was observed accord- ing to plate counting of bacteria method. Z1 pH reflect the acid production of eariogenic bacteria of the different treatments. Results： Compared to normal saline group, HMME-PDT and cetylpyridinium chloride rnade the number of cariogenic bacteria （CFU/mL） in plaque biofilms significantly reduced（P〈0.05）, with the bactericidal rate 94.92% and 51. 860/oo separately. The number of cariogenic bacteria in plaque biofilms of HMME ＋sodium azide group was not significant different, with the bactericidal rate only 9. 47%. pH of the records showed that, HMME-PDT group could prevent the acid production of cariogenic bacteria in plaque biofilms in a certain time range （0-24h）. Conclusion： PDT is an effective method in eliminating cariogenic bacteria of dental plaque biofilms and inhibiting the acid production,while singlet oxygen plays an important role in the sterile process of PDT.