Abstract:We studied the distribution and proportion of oral streptococci isolated from dental plaque and saliva of healthy adults and from subgingival plaque and fluid of gingival pocket of periodontitis patients to clarify the relation betweeen oral streptococci and periodontitis. α一hemolytic sreptococci were isolated from all materials of the healthy adults and the periodontitis patients. The isolation rate ofβ一hemolytic streptococci from dental plaque of the healthy adults was 20%, and the

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... olation rates of subgingival plaque and fluid of gingival pocket of the periodontitis patients were 25%and 65%, respectively. The isolation rate of non−hemolytic streptococci from dental plaque of the healthy adults was 35%and the isolation rates of subgingival plaque and subgingival fluid of periodontitis patients were 65%and 60%, respectively. The 670 strains of these isolated oral streptococci on the basis of hemolysis were identified as S. Sαη9泌s,S.90γ40励, S. o鋤S, S.砿づS, S. Sα1勿α酩S, S.勿鋤ηS, S. sobη ημS, S.α㎎仇OSμS, S.伽θ帷伽S and S. coηs ¢1↓αωs through biochemical tests. The species which were identified by the biochemical tests, agree to the species identified by DNA−DNA hybridization. Eight of these strains were not identified by the biochemical tests, but were identified as S. sαηg磁s, S.7η仇s and S. goπ》oη商by DNA−DNA hybridization. The isolation rates of S. goπ》om , S.α㎎仇osμs, S.仇彪ηηα抗6s and S. coηs花〃ατμs from periodontitis patients were higher than those from healthy adults. These results suggest that those bacteria may be associated with periodontitis.