[kgp genotypes of Porphyromonas gingivalis in subgingival plaque in puberty gingivitis]

To assess the prevalence of specific kgp genotypes in puberty gingivitis and investigate their possible association with disease severity.

Subgingival plaque samples were collected from 72 pubertal children aged from 14 to 17 years, which were divided into two groups, gingivitis group and healthy (control) group. Clinical parameters were recorded beforehand. PCR technique was used to amplify the region encoding the catalytic domain of gingipain K (KGP). The PCR products were digested with restriction enzymes Mse I.

The kgp-A genotype was digested in fragments of 102 bp, 288 bp and 402 bp, and kgp-B genotype was unrestricted with 792 bp. Virulent strain P. gingivalis W83 was manifested by kgp-A genotype while a virulent strain P. gingivalis ATCC 33277 was manifested by kgp-B genotype. All P. gingivalis positive subjects were subgingivally colonized by only one kgp genotype. The prevalence of kgp-A genotype in puberty gingivitis group and gingival healthy group was 79.0% and 22.2% respectively. The distribution differences of genotypes between the two groups were statistically different (P = 0.028). There was no statistically significant difference in the clinical parameters between pubertal subjects harboring P. gingivalis of kgp-A genotype and kgp-B genotype (P > 0.05).

Most subjects with puberty gingivitis were harbored by the same kgp genotype as that of virulent strain P. gingivalis W83. It may be necessary to continue to monitor individuals who are positive for P. gingivalis of kgp-A genotype since their risk of developing periodontal diseases may be increased in the future.