Detection of 6 periodontal bacteria in dental plaque samples from Japanese children

We analyzed the distribution of 6 periodontal bacteria (Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia, Eikenella corrodens, Actinobacillus actinomycetemcomitans and Capnocytophaga sputigena) in dental plaque materials from 227 children (3–6 years old). The plaque materials were collected from all erupted teeth sites using a sterile toothbrush. Chromosomal DNA was extracted from each plaque sample, followed by a polymerase chain reaction with species-specific sets of primers. Standard strains of 6 bacteria were used as controls. Total detection rate of P. gingivalis, P. nigrescens, P. intermedia, E. corrodens, A. actinomycetemcomitans and C. sputigena were 5.3%, 47.1%, 8.4%, 83.7%, 83.3% and 81.1%, respectively. E. corrodens, C. sputigena and A. actinomycetemcomitans were very frequently detected at all ages. On the other hand, P. gingivalis and P. intermedia were detected less frequently. Detection rate of P. nigrescens, E. corrodens and C. sputigena increased with age. The average detection number for each age group increased with age (2.63, 2.98, 3.43 and 3.45 for age 3, 4, 5 and 6, respectively). The number of bacterial species in the plaque materials increased with age as well. Our results indicate that P. nigrescens, E. corrodens, A. actinomycetemcomitans and C. sputigena are established quite early in childhood, these bacteria increase with age in the oral cavity.