冷光美白对釉质表面细菌生物膜形成的影响

目的:研究Beyond冷光美白对牙釉质表面主要致龋菌生物膜形成的影响。方法:制备4 mm×4 mm×1 mm的釉质片20片,随机分为冷光美白组、美白剂组、冷光照射组和对照组4组,每组5片。冷光美白组用Beyond美白凝胶（主要成分为H₂O₂）+冷光照射美白3次,每次12 min;美白剂组只在釉质片表面涂布美白凝胶美白3次,每次12 min;冷光照射组仅用冷光灯照射釉质片3次,每次12 min;对照组不做任何处理。在人工口腔模型内,将上述4组釉质片置于变形链球菌、黏性放线菌、具核梭杆菌混合菌液中培养36 h,用激光共聚焦显微镜(confocal laser scanning microscopy, CLSM）观察所形成的混合细菌生物膜,采用SAS8.2软件包对所得数据进行Kruskal-Wallis秩和检验。结果:CLSM扫描可见冷光美白组、美白剂组、冷光照射组的生物膜较对照组生物膜稀疏,生物膜厚度均显著小于对照组（P<0.05）;冷光美白组、美白剂组、冷光照射组之间生物膜厚度差异无显著性（P>0.05）;与对照组相比,冷光美白组、美白剂组、冷光照射组釉质表面生物膜中活菌百分比显著降低（P<0.001）。结论:冷光美白可抑制釉质表面混合细菌生物膜的形成,破坏生物膜的结构,降低混合细菌生物膜中活菌的数量。

The efficacy of cold-light tooth bleaching on the formation of bacteria biofilm on the enamel surfaces

PURPOSE: To evaluate the efficacy of Beyond cold-light tooth bleaching on the formation of main cariogenic bacteria biofilm on enamel surfaces. METHODS: Twenty enamel discs with the size of 4 mm×4 mm×1 mm in size, were made .The enamel discs were divided into 4 groups randomly: cold-light bleaching group, bleaching gel group, cold-light group and control group. Five discs were in each group. Cold-light bleaching group was whitened 3 times with bleaching gel and cold-light, and 12 min per session. Bleaching gel was smeared on the surface of enamel in bleaching gel group for 3 times and 12 min per session. Enamel discs of cold-light group were treated with cold-light for 12 min and 3 sessions. Control group was treated without any processing. The 4 groups were incubated in mixed bacteria liquid, including Streptococcus mutans(SM), Actinomyces viscosus (Av) and Fusobacterium nucleatum (Fn), within the artificial oral cavity model. After 36 h, the samples were observed under confocal laser scanning microscopy(CLSM). The data was analyzed with SAS8.2 software package. RESULTS: The biofilms in 3 experimental groups were sparser than the control group under CLSM, and the thickness significantly decreased after treatment (P<0.05), while no significant difference was found among 3 experimental groups (P>0.05).Compared with the control group, the percentage of vital bacteria in biofilm of the experimental groups decreased significantly after treatment (P<0.001). CONCLUSIONS: Cold-light tooth bleaching can inhibit the formation of mixed bacteria biofilm, damage the structure of biofilm and reduce the number of vital bacteria.