与窝沟龋有关的优势耐酸菌构成的分析

Predominant Aciduric Microflora Related to Fissure Caries of the First Permanent Molars

目的分析不同患龋状态窝沟中的优势耐酸菌构成,了解其在龋病发病中的作用。方法第一年轻恒磨牙窝沟新发早期龋儿童10名,2年无龋儿童10名。取新发龋窝沟处菌斑和同口正常第一恒磨牙窝沟菌斑及无龋儿童第一恒磨牙窝沟菌斑,用平皿培养法分析菌群构成;用最可能数法(MPN)分离优势耐酸菌;API 20 Strep试剂盒鉴定链球菌。结果变形链球菌是无龋组窝沟的优势耐酸菌,且中性条件下检出较多;血链球菌是新龋组正常窝沟和新龋窝沟处的优势耐酸菌;革兰阳性杆菌在酸性条件下占总检出菌比例(82%)显著高于中性条件下(61%)。结论菌斑生态构成非常复杂,在各个生态阶段,菌群组成不同。菌斑内局部pH值伴随菌群构成的变化推动着龋病过程。

Objective To investigate the aciduric bacteria in different stages of the fissure caries in order to determine potential roles of the microflom in the development of dental caries. Methods Plaque samples were taken from 10 incipient carious fissures of the first permanent molars. Plaque samples were also collected from sound fissures of the first permanent molars in 10 other subjects who kept caries free over the past 2 years and from the above 10 subjects. The predominant bacteria were isolated by using both the most probable method in media at pH7.0 and 5.2, and the conventional plating methods. Streptococcus spp. was identified by means of API 20 Strep commercial kit. Results S. mutans was the predominant aciduric bacteria in fissures of cariesfree children and mere frequently recovered at neutral pH. Whilst, S. sanguis was predominant at pH5.2 in sound and carious fissures of caries-active children. The proportion of Gram-positive rods at pH5.2 was 82%, significantly greater than that of 61% at pH7.0. Conclusion The ecology of plaque is complex and the composition of microflom at each stage of caries could be different. The composition of bacteria was consistent with the changes of local pH in the plaque.