To determine the prevalence of Mutans Streptococci (MS) colonization in children aged 3 to 5 years with early childhood caries in a Nigerian Southwestern city.
Method:
Five hundred and forty children were recruited into the study from 8 nursery schools after obtaining informed consents from the parents/guardians. These were examined for caries (dmft) in the schools by visual inspection with a sterile spatula under natural light. One hundred and twenty children were then systematically allocated into two groups: caries-free (dmft=0) and caries groups (dmft>0). Plaque samples were collected with wooden toothpicks and cultured for MS using Dentocult® SM strips at 370C for 48hrs. The presence of MS was confirmed by the detection of raised dark blue to light blue colonies on the inoculated strips. Inspection of the growth for raised colonies was done with a magnifying glass (x10). The result from each child was evaluated as following: Class 0: <10,000cfu/ml, Class 1: < 100,000cfu/ml, Class 2: 100,000-1000000cfu/ml, Class 3: >1000000cfu/ml.
Result: One hundred and twenty seven children (23.5%) were found to have caries. All the 120 children whose plaque samples were taken to culture MS had bacterial growth. About 67% of children with caries had >106 CFU/ml and lower scores (<106 CFU/ml) were seen more in those that are caries free (55.2%) (p=0.033, Chi square=4.566). When MS levels were compared with mean dmft, a statistically significant relationship was also observed (p=0.033, Mann Whitney U test= 2.13). Three year old children were observed to be 4.2 times less likely to develop caries (OR=0.237, CI=0.086-0.651) and children with MS colonization level >106cfu/ml being 3.6 times more likely to develop caries (OR=3.63, CI=1.414-9.34).
Conclusion: Mutans Streptococci prevalence was 100% among children studied and significantly higher levels of MS colonization (>106cfu/ml) were present in children with caries.