Determination of the infection rate of dental caries-causing bacteria in adolescents by a real-time PCR test method

Abstract

The aim of this study was to investigate the infection rates of bacteria associated with dental caries among children and adolescents in Korea. Methods: Oral examinations were conducted in 146 students. The numbers of bacteria associated with dental caries, such as Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus casei, in the subjects' oral cavity were counted by real-time PCR, and infection rates for those bacteria were additionally investigated. Results: The infection rate of Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, and Lactobacillus casei was 99.3% (145/146), 63.0% (92/146), 1.4% (2/146), and 25.3% (37/146), respectively. The amounts of Streptococcus sobrinus and Lactobacillus casei did not differ with the participants' age. However, the number of Streptococcus mutans was 537.6 for primary school students, 5698.2 for middle school students, and 19037.5 for high school students. The mean number of oral bacteria increased with age (P<0.05). The mean bacterial numbers of the infected subjects indicated significant differences in the numbers of Streptococcus mitis and Streptococcus mutans (P<0.05). Conclusions: The infection rates of Streptococcus mitis and Streptococcus mutans were distinct in children and adolescents. Efforts to control the bacteria associated with dental caries are needed to prevent dental caries.