The composition of subgingival microflora in two groups of children with and without primary dentition alveolar bone loss.

The is study examined the relationships between the microbial composition of the subgingival plaque, contact loss caused by caries and alveolar bone loss (ABL) in primary molars. The study included 10 children with contact loss in at least two sites, one with ABL and one without ABL, and 10 children without ABL with sites with or without contact loss. The microbial composition of subgingival plaque was examined by dark-field microscopy and by cultures of total anaerobic bacteria, Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg). Dark-field microscopy confirmed that spirochetes and motile rods may be part of the indigenous flora of the oral cavity. More spirochetes and motile rods were observed in sites with ABL than in control sites in the same subject and control subjects without ABL. Lower numbers of cocci were seen in sites with ABL than in sites in children without ABL, but a significant difference was not observed between sites with ABL and healthy sites within the same subjects. No significant differences in the dark-field values were evident in sites without ABL, with or without contact loss. Aa and Pg were found in children and sites with or without ABL. In sites with Aa, larger proportions of spirochetes, lower values of cocci, and more colonies of Pg were evident. No significant differences in anaerobic bacteria were evident between sites with or without contact loss or with or without ABL. ABL in the primary dentition was found to be related to the microbial composition of the subgingival plaque, but not related to contact loss per se.