口腔の健康と歯の管理

概要

Comparison of Evaluating The Ratio of Cariogenic Bacteria in Plaque and Saliva Samples

Hiroya Gotouda, Noriko Shinozaki-Kuwahara, Chieko Taguchi, Hiroyasu Endo, Mitsuhiro Ohta, Michiharu Shimosaka, Ryo Tamamura, Kensuke Matsune, Yoshiharu Kono, Hiroyuki Okada, Tomoko Kurita-Ochiai, Takanori Ito

Background: This study aimed to conduct a comparative analysis for evaluating the ratio of cariogenic bacteria in plaque and saliva samples as a preliminary study for developing a simple culture kit for caries-risk assessment. Materials and Methods: Stimulated saliva and plaque samples using sterile toothbrushes were obtained from adult volunteers. The ratio of Streptococcus mutans (S. mutans, Sm) to total streptococci (TS) (Sm/TS ratio) was determined by counting the number of colonies by the culture method. Results: The number of S. mutans, Sm/TS ratio (%), and plaque Sm%/saliva Sm% were significantly higher in plaque than in saliva. Moreover, there was a positive correlation between the number of S. mutans in plaque and saliva as well as between the Sm/TS ratios (%) in plaque and saliva. Conclusion: Although distinct positive correlations were observed between S. mutans levels in plaque and saliva, some subjects showed dissimilarities. The use of plaque samples, in which bacteria are detected at higher levels, is preferred because S. mutans levels were higher in plaque than in saliva, both in terms of the number of S. mutans and Sm/TS ratio. Moreover, the plaque to saliva ratios (plaque/saliva) in all subjects demonstrated better outcomes for the Sm/TS ratio than for the number of S. mutans, suggesting that plaque samples are more suitable than saliva samples for caries-risk assessment.