光动力疗法对基牙预备体表面变形链球菌的抗菌作用

Antibacterial effect of photodynamic therapy on prepared tooth structure contaminated with Streptococcus mutans

目的通过检测抗菌率评价光动力疗法(PDT)对基牙预备体表面变形链球菌的抗菌作用。方法选取25颗单根离体正畸牙,按照金属烤瓷全冠修复要求进行牙体预备,在预备体咬合面接种变形链球菌。将预备体随机分组,分别进行以下处理:单独采用75%酒精处理;单独采用PDT处理;采用75%酒精及PDT联合处理。同时保留5颗未予以任何处理的基牙预备体作为对照。抗菌处理完成后收集所有基牙预备体咬合面的细菌进行菌培养并计算抗菌率。同时检测PDT处理前后基牙预备体的表面温度及硬度。结果单因素方差分析表明,单独采用PDT处理组与酒精+PDT处理组抗菌率分别为99.04%以及99.20%;而单独采用75%酒精处理组抗菌率仅为89.45%。经PDT处理后,预备体表面温度略有升高;而表面硬度未发生明显变化。结论PDT对基牙预备体表面的变形链球菌具有较好的抗菌作用,且不会导致预备体表面温度的过度增高,也不会造成其表面硬度的明显下降。

Objective To evaluate the efficiency of antibacterial PDT on Streptococcus mutans （ S. mutans） imported onto prepared tooth structure. Methods 25 single-root teeth removed for orthodontic reasons were used in this vitro study. They were prepared according to the requirement of crown restorations and contaminated intentionally by S. mutans. Sterilization of teeth was performed with the following treatments： 75% alcohol alone, PDT alone, the combination of 75% alcohol and PDT. 5 teeth were left untreated as control. All the teeth were then submitted to bacteria culture, and the antibacterial efficiency （Rn） were calculated. On the other hand, surface temperature and hardness of prepared tooth structure were tested before and after PDT, to examine the side-effects of this treatment. Results The one-way ANOVA test showed no significant statistical difference between antibacterial efficiency of PDT group （ Rn = 99.04% ） and combination treatment group （ Rn = 99.20% ）, while that of the alcohol group was significantly higher than the others （ Rn = 89.45% ）. Acceptable surface temperature increase of （5.8 ± 0.9） ℃ after PDT was measured, as well as insignificant surface hardness change （P 〉 0.05）. Conclusion PDT based on a photochemical mechanism has a reliable antibacterial effect on S pared tooth structure, and it will result in neither lethal increase of surface temperature nor decrease of surface hardness.