[Subgingival microflora in children of early childhood, school age and circumpuberty. The proportion and frequency of gram-negative bacteria in periodontally healthy and gingivitis groups].

The present study characterized the microbial profiles of the gingival sulci in children. Subgingival samples from 36 gingivitis lesions of 18 patients and 36 sites in 18 healthy persons were examined. The tested individuals were divided into three stages according to physiological maturation i.e. early childhood, school age, circumpuberty. Puberty was confirmed through examination of wrist radiographs. Using continuous anaerobic techniques, samples were dispersed, diluted and then inoculated on selective and nonselective media and cultured under the condition appropriate gaseous phase respectively. Isolates were identified microbiologically and counted. All values were evaluated statistically. The samples were simultaneously examined by dark-field microscopy. Changes in the proportions and the frequency of periodontophathic bacteria were distinct in different stages of physiological maturation. Black-pigmented Bacteroides species were commonly found in gingivitis lesions. Bacteroides intermedius was frequently detected in the subgingival samples from children with gingivitis. In all stages, the proportion of black-pigmented Bacteroides and B. intermedius in the gingivitis groups were found to be significantly higher than that of the healthy groups. Statistical analysis revealed that levels of B. intermedius increased in circumpuberty stage compared with the 2 younger stages. Black-pigmented Bacteroides and B. intermedius were closely related to GI, PlI in 3 stages. Bacteroides gingivalis was found only in two gingivitis sites of a circumpubertal child with gingivitis. Actinobacillus actinomycetemcomitans was detected in 4 out of 12 sites in the school age group, and in 6 out of 12 sites in the circumpuberty group with gingivitis respectively. In the circumpuberty group, the proportion of A. actinomycetemcomitans in the gingivitis group was significantly higher than that of the healthy group, and A. actinomycetemcomitans was closely related to GI, PlI, CI, PPD. Eikenella corrodens was found to be associated with gingivitis in the school age and circumpuberty groups. No correlation was found in the detection of Fusobacterium nucleatum in 3 stages. Microscopic examination showed that the proportion of rods, fusiforms, filaments, motile rods, spirochetes in the gingivitis groups was significantly higher than that of the healthy groups, while the proportion of cocci in gingivitis groups was significantly lower than that of the healthy groups in 3 stages. Spirochetes were closely related to GI, PlI, PPD in all stages.