Diagnostic Utility of Specific Microbiological Markers for Periodontal Diseases

S pecific detection of marker organisms Porphyromonas gingivalis, Prevotella intermedia , and Actinobacillus actinomycetemcomitans with an immunoassay provided 2 types of useful information directly into private clinical practice: 1) persistence of P. gingivalis in patients undergoing regular treatment allowed rapid identification of pockets requiring further treatment without waiting for measurable progression of lesions and 2) presence of A. actinomycetemcomitans in adults at any stage of diagnosis or treatment identified patients who may prove to have difficult‐to‐manage periodontitis. We made these findings in 253 patients (234 in specialist periodontal practices [F‐ME 55; MHM 179] and 19 in general dental practice [EWM]). The search for useful diagnostic markers overlaps only partly with the search for periodontal pathogens. The P. gingivalis marker and the A. actinomycetemcomitans marker identify 2 different patterns of infection that appear to reflect 2 different underlying problems. Demonstration of pocket‐dependent infection with P. gingivalis in treated patients provides an outcome marker for sites not converting to marker‐negative sites at detection levels of the immunoassay. This information facilitates selection of sites and patients requiring adjustment of treatment regimens. Detection of A. actinomycetemcomitans in adult patients is significantly associated with periodontitis characterized as refractory. Positive identification of A. actinomycetemcomitans with the immunoassay supports clinical decision‐making by drawing attention to adult patients who require closer monitoring and intensive persistent treatment. Successful application of immunoassay detection of microbiological markers is based on continuous patient monitoring to support clinical decisions; it does not replace careful clinical judgment. J Periodontol 1998;69:1373–1381 .