ABSTRACT
<p><b>BACKGROUND</b>The bacterial composition of periapical lesions in deciduous teeth has not been well documented. This study was designed to explore the bacterial compositions, especially the dominant bacteria in periapical lesions using 16S rRNA sequencing.</p><p><b>METHODS</b>Tissue samples were collected from 11 periapical lesions in deciduous teeth with primary endodontic infections. DNA was extracted from each sample and analyzed using 16S rRNA cloning and sequencing for the identification of bacteria.</p><p><b>RESULTS</b>All DNA samples were positive for 16S rRNA gene PCR. One hundred and fifty-one phylotypes from 810 clones were identified to eight phyla, and each sample contained an average of 25.9 phylotypes. In addition, 59 phylotypes were detected in more than two samples, and Fusobacterium (F.) nucleatum (8/11), Dialister (D.) invisus (8/11), Campylobacter (C.) gracilis (7/11), Escherichia (E.) coli DH1 (6/11), Aggregatibacter (A.) segnis (6/11), and Streptococcus (S.) mitis (6/11) were the most prevalent species. Furthermore, 45 as-yet-uncultivated phylotypes were also identified.</p><p><b>CONCLUSIONS</b>Chronic periapical lesions in deciduous teeth contained polymicrobial infections. F. nucleatum, D. invisus, C. gracilis, E. coli DH1, A. segnis, and S. mitis were the most prevalent species detected by 16S rRNA sequencing.</p>