Differences in periodontal disease-associated microorganisms of subgingival plaque in prepubertal, pubertal and postpubertal children.

It is generally accepted that normal prepubertal children do not develop periodontitis, and that the severity of gingivitis in prepubertal children is usually less than that observed in children after puberty. One possible explanation is that the bacteria associated with periodontal diseases cannot become established in great numbers prior to puberty. Studies by Kornman and Loesche and others suggest that levels of black pigmented Bacteroides, especially B. intermedius, increase with increased levels of gonadotrophic hormones in pregnant women. Delaney and Kornman have found that there is a similar increase in levels of black pigmented Bacteroides with puberty. The present study involved cultural and microscopic characterization of the subgingival plaque flora of prepubertal, circumpubertal and postpubertal children with similar Silness and Löe plaque index scores. Puberty was confirmed through examination of wrist radiographs. Populations of black pigmented Bacteroides were very low in prepubescent children and were much higher in circumpubertal and postpubertal children. However, B. intermedius predominated only in circumpubertal plaques. Levels of total motile bacteria increased at each age level, but levels of spirochetes above 2% were observed only in the postpubertal group. These results support those of previous investigators who postulated a relationship between hormone levels and black pigmented Bacteroides levels in subgingival plaque and suggest that differences in the subgingival environment profoundly influence the proportions of suspected periodontopathic species in plaque.