Abstract
A cohort study was carried out to analyze the factors affecting dental caries incidence in 2.5-year-old children. The subjects were 71 infants and their mothers living in a town in Iwate prefecture. Infants had a dental examination and a plaque sample was removed for microbiological examination at 1 year, 1.5 years, and 2.5 years. Prior to the examination, mothers had completed a questionnaire containing questions about daily habits of dietary behavior and oral hygiene for their children, and surveys were recovered on the day of examination. To determine the mothers' experience of dental caries and the level of mutans streptococci, they underwent dental examinations and saliva was collected. The results were as follows : The dental caries prevalence rate was 21.1% and dft score was 0.93±2.50 at 2.5 years old. Logistic regression analysis was used to identify the specific nursing habits related to the incidence of dental caries. The results showed that intake of sugar-containing drinks with a feeding bottle, sharing of dishes and chop sticks with caretakers, and daily toothbrushing by caretakers at 1 year old, as well as intake of sugar-containing drinks with a feeding bottle and daily toothbrushing by caretakers at 1.5 years old were significantly correlated with the development of dental caries. The relationships between the age at mutans streptococci colonization and incidence of dental caries in infants were as follows : Compared with infants in whom mutans streptococci was first detected at 2.5 years old, infants in whom mutans streptococci was detected at 1 year old had a significantly higher incidence of dental caries. Furthermore, with respect to the relationship between early detection of mutans streptococci and nursing habits, the intake of sugar-containing drinks with a feeding bottle was a significant factor. From the results of this investigation, it is considered that the early colonization of mutans streptococci in infants is one cause of the development of dental caries and the presence of sucrose in the oral cavity may affect the early colonization of mutans streptococci in infants.
