Periodontopathic bacterial colonization in plaques of children

Abstract

Although 'red complex species' [Porphyromonas gingivalis (Pg), Treponema denticola (Td) and Tannerella forsythensis (Tf)] and Aggregatibacter actinomycetemcomitans (Aa) are the major pathogens in adults of chronic and aggressive periodontitis, respectively, it is also evident that the putative periodontopathic bacteria can be detected in the plaques from periodontally healthy children. To elucidate the relationship to the colonization of mutans streptococci (MS) and the maternal transmission, in this study, the periodontal pathogens were detected in the plaque samples from 327 periodontally healthy children, and compared to 239 mothers' plaques. After oral examination, plaque samples were collected and the bacterial DNA was purified. The periodontal pathogens and MS were detected by the species-specific PCRs. The results indicated a positive correlation between MS colonization and the caries score (dmf/DMF) in the children. Among the periodontopathic bacteria, Aa was most frequently detected in both the children and mothers, followed by Tf, and the percentages of Aa- and Tf-positive subjects increased with age. Pg was detected in 13.1% of children's and 23.0% of mothers' plaques, whereas Td was not found in the children and was detected in only 7/239 mothers. The statistical analysis revealed no significant correlation between MS and periodontal-bacterial colonizations. Further, the mother-and-child pair-based analysis indicated that the concordance in colonization was observed in 50 out of 93 Tf-positive children and in 17 out of 43 Pg-positive children. Thus, the present findings strongly suggested that some periodontal pathogens including Aa, Tf and Pg, but not Td, can colonize in children's plaques without relation to MS colonization. It was also suggested that the vertical (maternal) transmission, especially of 'red complex species' rarely occurs.