Objective To 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. Methods Subgingival 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. Results Numbers of T. forsythensis and total bacteria（P
