Black‐pigmented Bacteroides and spirochetes in the subgingival microbiota of prepubertal schoolchildren

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Abstract
As part of an ongoing longitudinal study of the subgingival microbiota at the onset of – and during – puberty, the subgingival microbiota and clinical periodontal condition in prepubertal children were studied. Twenty‐two boys and 20 girls (age 11.4 ± 0.4) participated in the study. Using the criteria of secondary sex characteristics (Tanner index) and radiographic bone age, 15 boys and 16 girls were classified as clearly prepubertal. At the maxillary first molars, the Plaque Index (P1I) was assessed, subgingival samples were obtained and Gingival Index (GI) and Papillary Bleeding Index (PBI) were determined. Using continuous anaerobic techniques, samples were cultivated on selective and non‐selective media and were studied by darkfield microscopy. Special attention was focused on the occurrence of black‐pigmented Bacteroides (BPB) and spirochetes. In 75% of the children, BPB (> 104 colony forming units cfu) were detected. B. intermedius was the most commonly isolated BPB. At sites scoring P1I = 2 33%, at those scoring P1I= 1 22% and at sites scoring P1I = 0 none of the samples contained BPB > 106 cfu. Likewise, > 106 cfu of BPB were found in 40% of the sites with a PB1 of 3, in 35% of the sites with a FBI of 2, while none of the sites with a FBI of 0 or 1 contained these numbers of BPB. Similar observations were made for the proportions of spirochetes. The study confirmed that BPB and spirochetes are frequently found in prepubertal children and are correlated with the presence of supragingival plaque and the degree of gingivitis.