Prevalence of Streptococcus mutans and Lactobacillus fermentum and their association with caries and dietary habits in preschool Thai children

Abstract

To detect the prevalence of Streptococcus mutans and Lactobacillus fermentum in plaque obtained from severe early childhood caries (S-ECC) and caries-free (CF) groups and to assess any association between their prevalence, feeding habits and oral hygiene practices within each group. Sixty-four supra-gingival plaque samples were collected from S-ECC and CF groups (CF=30, S-ECC=34). All participants were asked about feeding habits and oral hygiene care behaviour by direct questionnaire. After DNA extraction, S. mutans and L. fermentum were amplified using standard PCR. Nested PCR was performed as a second identification method for S. mutans. Mean age in CF and S-ECC was 2.29±0.42 and 2.49±0.41years, respectively. Mean dmft in S-ECC was 4.51±0.72. By standard PCR, no S. mutans was detected in CF group, while 10% was detected in S-ECC group. By nested PCR, S. mutans was detected for 48 and 50% in CF and S-ECC, respectively. L. fermentum was detected for 16 and 40% in CF and S-ECC, respectively. Nested PCR gave a higher detection frequency than standard PCR but not significant (p≤0.05). The prevalence of S. mutans was not different between the two groups, while the prevalence of L. fermentum was significantly associated with S-ECC (p≤0.05).