W.J. Loesche

The Role of Spirochetes in Periodontal Disease

The spirochetal accumulation in subgingival plaque appears to be a function of the clinical severity of periodontal disease. It is not known how many different spirochetal species colonize the plaque, but based upon size alone, there are small, intermediate-sized, and large spirochetes. Four species of small spirochetes are cultivable, and of these, T. denticola has been shown to possess proteolytic and keratinolytic enzymes as well as factors or mechanisms which suppress lymphocyte blastogenesis and inhibit fibroblast and polymorphonuclear leukocyte (PMNL) function. All of these attributes could contribute to periodontal tissue insult. Yet independent of these potential virulence mechanisms, the overgrowth of spirochetes can be clinically useful if simply interpreted as indicating the result of tissue damage. In this case, the spirochetes would be indicators of disease and could be easily monitored by microscopic examination of plaque, or possibly by the measurement of benzoyl-DL-arginine-2-naphthylamide (BANA) hydrolytic activity in the plaque.

Clinical and microbiological aspects of chemotherapeutic agents used according to the specific plaque hypothesis.

Certain forms of dental decay and periodontal disease appear to be due to specific bacterial infections following overgrowth of certain indigenous plaque bacteria, i.e., the specific plaque hypothesis. If so, then antimicrobial treatment based on a diagnosis of elevated levels or proportions of these organisms should be considered. Such treatment cannot be administered according to concepts of the non-specific plaque hypothesis. A treatment philosophy is presented which is based upon considerations long established in medical infections following overgrowth of certain indigenous plaque bacteria, i.e., the specific plaque hypo-microbial to the site of the infection for periods long enough to suppress or destroy the pathogenic agent. Examples of this treatment philosophy are given.

DNA Probe and Enzyme Analysis in Periodontal Diagnostics

Recent research in periodontology has indicated that a finite number of bacterial species are associated with periodontal disease. This has generated the hypothesis that periodontal disease is essentially an infection due to one or more of the putative periodontopathogens; i.e., the specific plaque hypothesis (SPH). This microbial specificity paradigm has already changed the way researchers and some clinicians view periodontal disease. The clinician must heed several cautions signs, however, if he is to use the SPH to provide treatment options that could enhance the delivery of care. There are several diagnostic technologies that can be used to detect and semi-quantitate those bacterial species that have been identified as periodontopathogens. This paper discusses diagnostic tests based upon the detection in plaque of DNA segments or enzyme activity(ies) that are unique for one or more of the suspected periodontopathogens. J Periodontol 1992; 63:1102- 1109.

Characteristics of Trypsin-like Activity in Subgingival Plaque Samples

Previous studies have demonstrated that the hydrolysis of the trypsin substrate N-benzoyl-DL-arginine-2-naphthylamide (BANA), by subgingival plaque obtained from a single site, correlates best with the numbers and proportions of spirochetes in plaque samples and may serve as an indicator of clinical disease. In this investigation, we determined whether the association between BANA hydrolysis and spirochetes could be obtained in pooled subgingival plaque samples. Concomitantly, the characteristics of this reaction in terms of substrate type and concentration, microbial numbers needed to give a positive reaction as assessed by microscopic counts, rapidity of hydrolysis, and the effect of pH and various additives on the plaque BANA hydrolytic activity have been studied in pooled plaque samples from patients who were periodontally healthy or diseased. In addition, it was determined whether BANA hydrolytic activity found in subgingival plaque reflected contributions from saliva and supragingival plaque. Results indicated that the assay can best be performed with 0.67 mmol/L BANA at pH 7.0. EDTA and CaCl2 gave a slight inhibition and DTT a slight enhancement of the BANA reaction by the pooled plaque suspensions. The majority of the reactions (85%) developed their full color after overnight incubation. BANA hydrolysis was not found in saliva and occurred with much greater frequency in subgingival plaque as opposed to supragingival plaque. Analysis of the data indicated that BANA hydrolysis by pooled subgingival plaque samples is a suitable test for the detection of spirochetes when two or three spirochetes per high microscopic field are present in the sample.

Correlation of the Hydrolysis of Benzoyl-Arginine Naphthylamide (BANA) by Plaque with Clinical Parameters and Subgingival Levels of Spirochetes in Periodontal Patients

Recent studies have shown that the extent of hydrolysis by plaque of the trypsin substrate, N-benzoyl-DL-arginine-2-naphthylamide (BANA), correlates with the numbers and proportions of spirochetes in subgingival plaque samples, and appears to be an indicator of clinical disease. In this study, BANA hydrolysis by subgingival plaque was evaluated in a blind manner for its ability to reflect both clinical parameters and subgingival levels of bacteria and spirochetes. Subgingival plaque samples were collected from periodontally healthy and diseased sites in 23 untreated periodontal patients and in 13 treated and maintained periodontal patients. In untreated patients, BANA hydrolysis was statistically associated with the total number of spirochetes and bacteria in the plaque sample, but in the treated patients BANA hydrolysis was statistically associated only with the spirochetes. Most BANA-positive reactions in both patient groups were from the sites which were clinically diseased and high in spirochetes. The majority of the negative reactions for BANA hydrolysis in both patient groups was among the sites which were periodontally healthy and low in spirochetes. Specificity and sensitivity of the test were above 80% for disease status in untreated patients. The predictive value of a positive and negative test was above 83%. Slightly lower sensitivity, specificity, and predictive values were found in the treated group. The BANA reaction appears to be an accurate and simple indicator of both clinical disease status and plaque levels of spirochetes in individual tooth sites in untreated and treated periodontal patients.

ADVANCES IN DIAGNOSIS AND DETECTION OF ORAL DISEASES

Medicine, particularly with respect to diagnostic decision-making, has seen remarkable advances in the last ten years. The art of diagnosis has become much more of a science. Basic science advances have moved from the laboratory into the hospital and radically changed the way a medical diagnosis is arrived at or confirmed. Dentistry, especially oral diagnosis, as yet has not been a significant part of this general medical advance. However, several examples demonstrate that this situation is starting to change. Oral conditions are beginning to be evaluated with greater precision and sophistication. This report reviews some recent advances in oral diagnostic research and suggests where they will carry dentistry over the next 25 years.