Salivary pH, Cariogenic Bacteria, and Caries Status in One-Year-Old Children

Objectives: To compare the levels of salivary pH, mutans streptococci and lactobacilli of 1-year-old children without dental caries to those with non-cavitated caries and with cavitated caries.
Methods: Subjects were healthy 1-year-old children attending health centers for routine immunization in Khon Kaen, Thailand. Caries status was assessed by one dentist according to the World Health Organization criteria. Children were classified according to their caries status: caries-free children, children with non-cavitated caries lesions, and those with cavitated caries lesions. Unstimulated whole saliva was collected for the measurements of salivary pH (using a digital pocket pH meter), and for the levels of mutans streptococci and lactobacilli (by culture-based method on selective media). Demographic variables as well as mean dmfs were collected. Data were analyzed by descriptive statistics, Kruskal–Wallis test, and Mann–Whitney U test with Bonferroni adjustment. Critical value was established at 5%.
Results: Our study population (N=568) was on average 12.8 (SD=1.1) months of age and was evenly distributed by gender (50.2% female). While over half of the children were caries-free (58.3%), 200 (35.2%) had non-cavitated caries lesions (dmfs=4.2; SD=2.0) and 37 (6.5%) had cavitated lesions (dmfs=5.0; SD=3.5). Children in the caries-free group had the highest salivary pH and lowest lactobacilli levels, which were significantly different from both non-cavitated and cavitated caries groups (p<0.05). Moreover, they had significantly lower mutans streptococci level than those with non-cavitated caries (p=0.0001). There was no significant difference in the level of mutans streptococci between the caries-free and cavitated caries groups (p=0.65). Interestingly, there was no statistically significant difference in the levels of salivary pH, mutans streptococci, and lactobacilli between the groups with non-cavitated and cavitated caries (p>0.05).
Conclusions: Low salivary pH and high levels of mutans streptococci and of lactobacilli were associated with both non-cavitated and cavitated caries in one-year-old children.