Subgingival distribution of Campylobacter rectus and Tannerella forsythensis in healthy children with primary dentition

SummaryObjectiveIt is important to know how many subgingival plaque samples should be assayed from a child to ascertain infection with a periodontal pathogen. Plaque samples from several sites may fail to detect some important bacteria if only a limited number of gingival sites are sampled. The purpose of this study was to evaluate the detection of periodontal pathogens in a large number of subgingival sites in the same children in order to determine the number of samples necessary.MethodsTen children, aged 4–6 years, with complete primary dentition were enrolled in this study. Plaque samples from the mesio-buccal aspect of each erupted tooth were first collected by gently inserting a sterile paper point for 10 s. Purified genomic DNA from all plaque samples was prepared for polymerase chain reaction. The primers for species-specific 16S ribosomal RNA sequence were selected as the target sequence. Standard strains of Campylobacter rectus and Tannerella forsythensis (formerly Bacteroides forsythus) were used as control strains.ResultsAll subjects were found positive for C. rectus and T. forsythensis with the mean of positive sites at 17.6 ± 2.4 (range: 12–20 sites) for C. rectus and 9.3 ± 5.0 (range: 1–19) for T. forsythensis. The mean number of positive sites was 1.7 ± 0.8 for C. rectus and 6.5 ± 4.9 for T. forsythensis, with a confidence ratio of 95%.ConclusionsWe concluded that two or more random sites for C. rectus and seven or more random sites for T. forsythensis from children to detect those bacteria at 95% probability.