Abstract
Many studies have shown that removal of supra-gingival plaque by toothbrushing prevents periodontal disease. However few observations have been reported about the effect of toothbrushing on more harmful subgingival plaque.
The purpose of the present study was to evaluate;
1. the extent of subgingival plaque removal by toothbrushing
2. the effect of toothbrushing (Bass method) on the composition of subgingival microbial flora using darkfield microscope and scanning electron microscope (SEM).
[Materials & Methods]
Exp. 1; Thirty-two teeth with periodontal disease were extracted, after careful toothbrushing by the operator. They were stained and the distance of the non staining area from the gingival margin to the coronal border at subgingival zone was estimated.
Exp. 2; Fourteen proximal surfaces of seven anterior teeth with periodontal disease were selected. The teeth were covered with metal inlays, one side of the inlay was made as “overhanging” to keep that side off from toothbrushing, which was termed as “non-brushing site”. The other side of the inlay was made flatter to facilitate toothbrushing and was termed as “brushing site”.
Darkfield microscope and scanning electron microscope were used to compare the subgingival microbial flora at “brushing site” and “non-brushing site”.
[Results]
Exp. 1; Subgingival plaque was removed as far as 2.22mm below the gingival margin on the average by toothbrushing, irrespective of the degree of GI and probing depth.
Exp. 2;
Darkfield assessment; On “brushing site” the percentage of spirochetes decreased significantly from 42.3% to 25.1%, while coccoid cells increased significantly from 24.7% to 48.0% after brushing.
Observation by SEM; On “non-brushing site”, mature subgingival plaque was observed, which was in accordance with previous studies. On the other hand, on “brushing site”, two types of plaque adhesion were observed. One type of plaque adhesion was similar to that on “non-brushing site”. In the other, little plaque was observed on the root surface from gingival margin about 2mm below, and in the deeper area plaque was spread on the surface.
The experiment indicated that toothbrushing removes a part of subgingival plaque and the composition of subgingival microbial flora is affected by toothbrushing.
