Objective: Early childhood caries (ECC) was prevalent in Hong Kong. Children with ECC risk should be identified early for prevention. This study aimed to identify common risk factors of ECC in Hong Kong 3-year-old children. Study design: Sample size calculation showed at least 6,321 of 3-year-old children should be invited in this study. A consent form and a questionnaire enquiring the children's oral health behaviours and social-economic background were distributed to their parents. Children with parental consent were examined by a trained dentist. Caries status was recorded in dmft index. Chi-square test and logistic regression analysis were performed to identify the risk factors of ECC. Results: A total of 5,167 children from the 6,331 children invited were examined. Among them, 1,130 children (22%) had ECC (dmft>0). Logistic regression analysis found age of starting tooth brushing, snack-intake frequency, dental visit experience, birthplace, family monthly income, primary caretaker, and mother's education level were factors associated with ECC of the children.
Conclusions: Children who started tooth brushing later, had higher snack-intake frequency, were not born in Hong Kong, and whose family monthly income was lower, mother's education level was lower, primary caretaker was not domestic helper, had a statistically significant higher chance of having ECC.