口腔の健康と歯の管理

概要

Association between Dental Caries in Adults and Evaluation of Streptococcus Sobrinus in Plaque Samples

Hiroya Gotouda, Noriko Shinozaki-Kuwahara, Chieko Taguchi, Mitsuhiro Ohta, Michiharu Shimosaka, Koichi Hiratsuka, Takanori Ito, Tomoko Kurita-Ochiai, Nobuhiro Hanada, Ikuo Nasu

Objective: Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus) are known to play major roles in the development of dental caries. Several studies have demonstrated the superior cariogenic potential of S. sobrinus. To date, no simple assay (kit) has been developed for detecting S. sobrinus using plaque samples for caries risk assessment. Additionally, the association between the level of S. sobrinus and dental caries (caries risk) in adults is somewhat unclear. This study aimed to evaluate the association between S. sobrinus and dental caries in adults based on the number and proportion of cariogenic bacteria in toothbrush plaque samples by culture methods to obtain basic data to develop clinical and chairside culture assay for caries risk assessment. Design: Brushing-plaque samples were obtained from 225 healthy adult volunteers. Risk levels were categorized based on S. mutans /total streptococci (Sm/TS) and S. sobrinus/TS (Ss/TS) ratios. The presence of decayed, missing, and filled teeth (DMFT) was analyzed as a measure of caries history. Results: DMFT in the detectable S. mutans group, non-detectable S. mutans group, detectable S. sobrinus group, and non-detectable S. sobrinus group were 8.11 ± 5.84, 4.93 ± 5.09, 10.63 ± 5.09, and 7.16 ± 5.81, respectively. DMFT for Ss/TS ratios in the high-risk, medium-risk, and low-risk groups were significantly different. DMFT were the highest in the groups that exhibited significantly higher Ss/TS ratio than Sm/TS ratio. Conclusions: The results of this study suggested a relationship between S. sobrinus levels and dental caries in adult subjects using plaque samples. Furthermore, the findings of this study showed that the quantity of S. sobrinus in dental plaque was more strongly associated with the severity of dental caries than the quantity of S. mutans and indicated that evaluation of the Ss/TS ratio was more useful than the total number of S. sobrinus.