Objective: To study the acquisition of mutans streptococci (MS) and lactobacilli in relation to dental caries development in 3-24 month old Thai children.
Methods: Salivary samples were collected from 169 children using sterile wooden tongue depressors at the ages of 3, 9, 12, 18 and 24 months. The blades were pressed onto selective media for MS or lactobacilli. After incubation, the colony forming units of MS/lactobacilli were counted. Dental status was recorded from 9 months old using modified WHO criteria.
Results: The number of children with caries and number and severity of decayed teeth significantly increased with age. The presence of MS/lactobacilli was detectable at an early age and the cumulative prevalence of MS/lactobacilli increased with age. Children who were colonised early by MS or lactobacilli showed a higher number of decayed teeth than of those who were colonised later. The children with no MS/lactobacilli had significantly fewer decayed teeth and there was a significant correlation between MS/lactobacilli level and tooth decay.
Conclusions: This longitudinal study shows early colonisation of the mouths of Thai children by MS/lactobacilli and where there are persistently high levels of the bacterias increased risk of development of dental caries.