Oral Streptococcus mutans level in high caries risk infants

The objective of this study was to assess the level of Streptococcus mutans in the saliva and plaque of infants with a high caries risk.

A self-administered parental questionnaire was used to identify one-year-old infants with high caries risk and to collect demographic information, the parents' and infants' oral health related behaviors. Saliva and plaque samples were collected from the participating infants. The real-time polymerase chain reaction assays were used to detect the quantity of MS in infants' saliva and plaque. A clinical examination was conducted to record the caries experience and oral hygiene level of infants.

579 high caries risk infants were recruited. The mean MS count in saliva and plaque was 0.08 ± 0.48 (×10⁷) CFU/mL and 5.72 ± 91.93 (×10⁷) CFU, respectively. Only a few infants had high MS% (>0.03%) in total bacterial count in plaque (4.8%) or saliva (7.3%). The MS level in plaque was found to have a significantly positive association with the prevalence of infants with a white spot or cavitated lesion (P = 0.039), but not for the MS level in saliva. Infants from families with 2 or more children (P = 0.029) and those who had been fed 7 times or more per day (P = 0.020) had a higher likelihood of having a high MS level (MS% > 0.03%) in dental plaque.

MS level in plaque and saliva was generally low among infants. The MS level in plaque showed a clearer association with the onset of dental caries than the salivary MS level in young children.