Fibronectin-degrading activity in human crevicular fluid, gingival explants culture medium and bacterial plaques.

125I-fibronectin was incubated with extracts having presumably a proteolytic activity. Plaque from children without gingivitis, plaque from adults with chronic periodontitis, human gingival fluid and pooled culture media of human gingival explants were studied. Proteolysis was usually faster with plaque from patients with adult periodontitis than with plaque from children without gingivitis and the inhibition tests showed that several enzymes were implicated in the process. For the culture medium of gingival explants, the electrophoretic profile of the digestion products of fibronectin was different and showed a decreased activity. Nevertheless the gingival fluid gave a very similar degradation to bacterial plaque. The sulcular content was able to assume enzymatic activity capable of destroying fibronectin. These sulcular activities could be important for bacterial colonisation of sulcular surfaces and perhaps also for fibronectin destruction of periodontal tissues.