OBJECTIVETo compare the number of the Tannerella forsythensis (T. forsythensis), total bacteria, and proportion of T. forsythensis in subgingival specimens in diseased sites of chronic periodontitis patients and in healthy sites of periodontally healthy subjects, and clarify the relationship between bacterial load and periodontal status.

METHODSSubgingival plaque samples from 61 chronic periodontitis patients and 12 healthy controls (positive for T. forsythensis by conventional PCR) were analyzed with TaqMan real-time polymerase chain reaction assay for T. forsythensis and total bacteria. Quantification was performed with species-specific primer/probe, universal primer/ probe and serial dilution of plasmid standards.

RESULTSNumbers of T. forsythensis and total bacteria(P<0.001) , the proportion of T. forsythensis in subgingival specimens (P<0.05) were significant higher in diseased sites of chronic periodontitis patients than in healthy sites of healthy subjects. In addition, a significant correlation was found between the number of bacteria and various probing depth (P<0.001). There was no significantly difference between the proportion of T. forsythensis in subgingival plaque and probing depth.

CONCLUSIONNumber of T. forsythensis are closely associated with periodontal status, and demonstrate the broad potential of real-time polymerase chain reaction application on periodontology.