Background: Little information is available on periodontopathic bacterial infection in childhood. We assessed the prevalence by age of 10 putative periodontopathic microorganisms in periodontally healthy children using a polymerase chain reaction (PCR) assay.
Methods: Plaque samples were collected from the buccal-mesial sulcus of the first molar or second primary molar in the right upper quadrant of 144 children (2 to 13 years old, 12 subjects from each year of age) who showed negligible periodontal inflammation. Using species-specific primers of Porphyromonas gingivalis, Bacteroides forsythus, Prevotella intermedia, Prevotella nigrescens, Campylobacter rectus, Eikenella corrodens, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea, Capnocytophaga sputigena, and Treponema denticola, PCR amplification was performed with bacterial genomic DNA from plaque samples.
Results: The results indicated that C. rectus, E. corrodens, A. actinomycetemcomitans, C. ochracea, and C. sputigena were found in about 50% of the plaque samples from all age groups, while B. forsythus and P. intermedia were detected less frequently, and P. gingivalis and T. denticola were not found. In contrast, the percentage of P. nigrescens-positive subjects increased with age in primary dentition, and reached about 50% at 7 years of age and older. Subject-based analyses suggested that the number of bacterial species in the plaque samples increased gradually with age until 5 years old, and then reached a plateau after the mixed dentition period.
Conclusions: The colonization of many putative periodontopathic microorganisms can occur quite early in childhood without clinical signs of periodontal disease. However, colonization by P. gingivalis and T. denticola was not detected in periodontally healthy children.