Detection of Porphyromonas gingivalis from saliva by PCR by using a simple sample-processing method.

Simple sample-processing methods for PCR detection of Porphyromonas gingivalis, a major pathogen causing adult periodontitis, from saliva were studied. The ability to detect P. gingivalis from 118 salivary samples by PCR after boiling and Chelex 100 processing was compared with bacterial culture. P. gingivalis was detected three times more often by PCR than by culture. Chelex 100 processing of saliva proved to be effective in preventing PCR inhibition and was applied to determine the occurrence of P. gingivalis in saliva samples from 263 Finnish subjects between 5 and 80 years of age. The occurrence of P. gingivalis increased with age, and it was detected by PCR in the saliva of 5.0% of subjects between 5 and 10 years of age, 13.8% of subjects between 11 and 20 years of age, 13.4% of subjects between 21 and 30 years of age, and 63.3% of subjects between 31 and 80 years of age. The results indicate that P. gingivalis is a rare finding in saliva from periodontally healthy children and young adults but a frequent one in saliva from adult periodontitis patients.