不同龋敏感者变异链球菌临床分离株的致龋特性

Cariogenecity of Streptococcus mutans isolated from children with different caries susceptibility

目的探讨不同龋敏感者变异链球菌临床分离株的生物膜形成和产酸能力。方法牙菌斑组织取自60例学龄前儿童,根据乳牙龋失补牙面(dmfs)指数分为无龋组(dmfs=0)和高龋组(dmfs>8)(n=30)。运用死菌/活菌荧光染色技术结合激光共聚焦扫描显微镜观察分析,计算菌斑组织中变异链球菌分离株的生物膜厚度和细菌密度;酸度计测定培养48 h后的pH值;比较不同龋敏感组变异链球菌的生物膜形成和产酸能力。结果高龋组变异链球菌临床分离株的生物膜厚度和细菌分布密度显著高于无龋组(P<0.05)。初始pH值>5.5时,高龋组和无龋组pH值改变无显著性差异;pH=5.0时,高龋组pH值改变明显大于无龋组(P<0.05)。结论高龋组变异链球菌临床分离株的高致龋力与其较强的生物膜形成能力和产酸能力密切相关。

Objective To investigate the ability of biofilm formation and acidogenicity of Streptococcus mutans isolated from children with different caries susceptibility. Methods Dental plaques were obtained from 60 Chinese pre-school children, 30 in caries-free group （ dmfs = 0） and 30 in caries-susceptive group （ dmfs 〉 8）. Confocal laser scanning microscopy and vital/dead fluorescent staining technique were combined to calculate the biofilm thickness and bacterial density. The terminal pH values were measured after culture for 48 h. The ability of biofilm formation and acidogenicity of different caries-susceptibility groups were compared. Results The biofilm thickness and bacterial density in caries-susceptive group were significantly higher than those in caries-free group （ P 〈 0.05）. There was no significant difference in the changes of pH values between the caries-free and caries-susceptive groups at initial pH 〉 5.5, while the change of pH values was significantly higher in the caries-susceptive group than the caries-free group at the initial pH = 5.0 （ P 〈 0.05）. Conclusion The high cariogenecity of Streptococcus mutans isolated from caries-susceptive children is closely related to the high ability of biofilm formation and aciduricity.