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

Objective: It 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 fait 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. Methods: Ten 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 at[ plaque samples was prepared for potymerase 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. Results: All 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%. Conclusions: We 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. (c) 2005 Elsevier Ltd. All rights reserved.