A Study of Subgingival Plaque Formation

The purpose of this study was to investigate the mode of subgingival plaque formation and its association with various microflora in the thoroughly debrided periodontal pocket by scanning electronmicroscopy. Eleven Periodontally involved teeth with an avarage pocket depth of 6 mm, were selected. Experimental surfaces were thoroughly debrided by flap operation at the baseline. Mechanical plaque control with toothbrush was maintained for 6 weeks after the operation. Then the teeth were extracted and examined by Scanning electronmicroscopy. The following results were obtained: Subgingival plaque was formed as the continuation from supragingival plaque. No isolated plaque were recognized in the subgingival area. Average distance of formed subgingival plaque from gingival margin was 0.35 mm at bucco-proximal site, 0.67mm mid-proximally and 0.65mm lingua-proximally. The microflora of the plaque composed of coccoids and rods predominantly, but spirochetes were seldom observed. The present study suggests that supragingival plaque is intimately ralated in the formation of subgingival plaque.