Dental caries status and its associated factors among 5-year-old Hong Kong children: a cross-sectional study

BACKGROUND: This study investigated dental caries status and its associated factors among 5-year-old children in Hong Kong. METHOD: This cross-sectional survey was conducted in 2016. It comprised a questionnaire survey and a clinical examination. Kindergarten children aged 5 were recruited using a multistage sampling method. Parents of the participating children were asked about their children’s demographic information, sugary snacking behaviours, and oral health–related behaviours and about their own oral health knowledge. One trained dentist performed oral examinations on the children. Caries experience was measured using the dmft index. The relationships between the dmft scores and background information, sugary snacking behaviours, oral health–related behaviours and parental dental knowledge were studied using a zero-inflated negative binomial (ZINB) regression analysis. RESULTS: A total of 570 children were invited to participate, and 501 completed the oral examination (response rate: 88%). The prevalence of dental caries was 55%, and the mean dmft score was 2.7 ± 3.7. Decayed teeth (dt) constituted 93% of caries experience. ZINB analysis found that children who visited a dentist, who were taken care of primarily by grandparents and whose parental dental knowledge levels were moderate had higher dmft scores. Children who ate sugary snacks more than twice daily, had irregular dental attendance and lived in low-income families had a significantly higher chance of having dental caries. CONCLUSIONS: Dental caries was prevalent among 5-year-old Hong Kong children, and most of the decayed teeth were untreated. The caries prevalence of the children was related to their frequency of sugary snack intake, dental attendance and socio-economic background. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12903-017-0413-2) contains supplementary material, which is available to authorized users.