Abstract:  To explore the microbial diversity and difference of supragingival plaque in children with different degrees of dental caries by 16S rDNA sequencing. Methods    The children aged 3 were selected as the research subjects. They were divided into carious group（dmft ≥ 5）and healthy group（dmft = 0），with 12 children in each group. The supragingival plaque was collected，and the 16S V4 region was sequenced and compared based on Ion S5TMXL platform of Thermo Fisher. Results    By comparing with SILVA132 database，14 phyla，21 classes，53 orders，93 families，150 genera and 159 species were annotated. Alpha diversity analysis indicated that the species richness and evenness of carious group were lower than those of healthy group. Beta diversity analysis showed that the sample community structure of carious group and healthy group was similar，and there was no significant separation between the two groups. The dominant phyla with relatively high abundance in both groups were Actinobacteria，Proteobacteria，Bacteroidetes，Fusobacteria，Firmicutes，and so on. The dominant genera with relatively high abundance were Actinomyces，Corynebacterium，Neisseria，Rothia，Streptococcus，Capnocytophaga，etc. The LEfSe analysis showed that there were some significantly abundant microflora in the carious group：Rothia，Haemophilus，Kingella，Rothia dentocariosa，Neisseria bacilliformis，etc.（P < 0.05）. Meanwhile，there were also some significantly abundant microflora in the healthy group：Fusobacteria，Leptotrichia，Leptotrichia_sp_oral_clone_IK040，Capnocytophaga granulosa （P < 0.05）. The relative abundance of Streptococcus mutans did not differ significantly between the two groups（P > 0.05）. Streptococcus sobrinus was detected only in carious group. In addition，there were currently unidentified microbial species with low abundance in both groups of samples. The PICRUSt analysis showed that the microbial substance and energy metabolism in the carious group were more abundant than that in the healthy group. Conclusion    The microbial community of supragingival plaque of deciduous teeth presents diversity，and there are significant differences in classification and functional levels among the children with different degrees of caries，which provides new data for the study of microbial factors of deciduous teeth caries.

Key words: children, dental caries, supragingival plaque, 16S rDNA sequencing, oral microbiome, metagenomics

摘要： 目的    用16S rDNA测序技术，探讨不同龋患程度儿童乳牙龈上菌斑微生物多样性及差异。方法    选择3岁龄儿童为研究对象，高龋组（dmft ≥ 5）和无龋组（dmft = 0）各12名，采集光滑面龈上菌斑，基于Ion S5TMXL平台（Thermo Fisher，美国）进行16S V4区域测序并对比分析。结果    通过与SILVA132数据库比对，可注释到14个菌门、21个菌纲、53个菌目、93个菌科、150个菌属、159个菌种。Alpha多样性分析提示高龋组物种丰富度和均匀度低于无龋组。Beta多样性分析显示高龋和无龋样本群落结构相似，组间无显著分离。两组中，优势菌门为放线菌门、变形菌门、厚壁菌门、拟杆菌门、梭杆菌门等；优势菌属为放线菌属、棒状杆菌属、奈瑟菌属、罗氏菌属、链球菌属、二氧化碳嗜纤维菌属等。LEfSe分析显示，高龋组显著丰富的微生物菌群有罗氏菌属、嗜血杆菌属、金氏菌属、龋齿罗氏菌、奈瑟杆菌等（P < 0.05）；无龋组显著丰富的微生物菌群有梭杆菌门、纤毛菌属、Leptotrichia_sp_oral_clone_IK040、颗粒二氧化碳嗜纤维菌等（P < 0.05）。变形链球菌的相对丰度在两组之间不存在显著差异（P > 0.05）。远缘链球菌仅在高龋组中被检出。此外，两组微生物样本中均存在低丰度的未曾定义新物种。PICRUSt分析显示，高龋组的微生物物质代谢与能量代谢等较无龋组更为丰富。结论    3岁儿童乳牙龈上菌斑微生物群落呈现多样性，不同龋患程度儿童口腔微生物群落在不同分类和功能水平上呈现显著差异，为乳牙龋的微生物因素研究提供了新数据。

关键词: 儿童, 龋病, 龈上菌斑, 16S rDNA测序, 口腔微生态, 宏基因组学