Prevalence of five biofilm-related oral streptococci species from plaque

To examine the prevalence of five oral streptococci species of severe early childhood caries (S-ECC) and caries-free (CF) groups.

Supra gingival plaque samples were obtainedfrom 198 Thai children with ages ranging from one to six years old Eighty-seven subjects had no caries (dmft=0), and 111 had S-ECC. After DNA extraction, S. mutans, S. sobrinus, S. sanguinis, S. oralis, and S. gordonii were identified by standard PCR using species-specific primers. Statistical analysis determined the differences among prevalence rates of each species using Pearson chi-square test. The relationship among dmft score, age, sex and caries status within each group was analyzed by logistical regression (p < or = 0.05).

Sex was not correlated with any of the species detected in both groups (mean age =3.09, mean +/- SD of dmft = 11.04 +/- 7.89). S. mutans was found at greatest prevalence in both groups followed by S. oralis. S. gordonii was detected at a high prevalence, but S. sobrinus and S. sanguinis were lower in S-ECC when compared with those from the CF group.

S. mutans was associated significantly with S-ECC (p < or = 0.05). Caries prevalence was highest (56.5%) in subjects infected by S. mutans alone. S. sanguinis prevalence was higher in the CF group, but not statiscally different. Infection with MS did not show higher caries prevalence.