Trypsin‐Like Activity in Subgingival Plaque

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Abstract
Taxonomic screening of subgingival plaque organisms with various enzyme assays have shown that Treponema denticela, Bacteroides gingivalis and an unspeciated Capnocytophaga species possess a trypsin-like enzyme (TLE) that can be detected by the hydrolysis of N-benzoyl-DL-arginine-2-naphthylamide (BANA). As these organisms can be considered to be periodontopathic, it was of interest to determine whether this BANA hydrolyzing enzyme could be detected directly in subgingival plaque samples. Subgingival plaque samples were collected from single sites of known pocket depth, and after dispersal by vortexing, aliquots were incubated overnight with BANA and were counted microscopically. The color reactions were developed with fast garnet, read by the eye and classified as positive (red to red-orange), negative (yellow) and questionable. In the BANA-positive plaques, the spirochetes averaged 43% of the microscopic count, whereas in the BANA negative plaques the spirochetes averaged 8% of the microscopic count. The average pocket depth of BANApositive plaques was 6.7 mm, whereas the average pocket depth of BANA-negative plaques was 4.5 mm. When both of these parameters were combined, the presence of a positive BANA reaction was usually indicative of subgingival plaques containing >34% spirochetes removed from sites that had probing depths of 7 mm or more. Seventy-one per cent of the plaques removed from untreated periodontal patients were BANA-positive, while only 8% of the plaques removed from successfully treated patients seen at maintenance recall visits were BANA-positive. These data indicate that the ability of subgingival plaque to hydrolyze BANA is a reliable marker for the presence of high proportions of spirochetes in the plaque sample and possibly could be used clinically to identify those sites and/or individuals who might require treatment to reduce this spirochetal overgrowth.