Dental caries situation of Hong Kong kindergarten children

Objective: The main objective of this study was to describe the dental caries situation of kindergarten children in Hong Kong. Material and Methods: The survey target population was Chinese children attending kindergartens in Hong Kong. The sample frame was kindergartens with an enrolment of 70 children or more located on Hong Kong Island. Through stratified (by enrolment size) simple random sampling, 12 kindergartens were selected and recruited. All children attending grades 1 and 2, aged 3 to 5 years, in the kindergartens were invited. Children with parental consent were clinically examined in the kindergarten by one of two calibrated examiners using a disposable mouth-mirror attached to an intraoral LED light. Diagnostic criteria for dental caries followed those recommended by the World Health Organization. A probe with a 0.5 mm ball tip was used to confirm presence of a caries cavity if necessary. A questionnaire on the child's demographic background and oral health related behaviours was completed by the parents. Results: A total of 1,513 children were invited and 1,343 were finally examination, response rate was 88.8%. Their mean age was 52 months (SD=7) and 51.5% were boys. Around one-third (35.3%) of the children had experienced caries. The mean dmft score was 1.5, increasing from 1.2 at age 3 to 2.0 at age 5 (ANOVA, p=0.016). Active decay (dt) accounted for 90% of the dmft score. Higher dmft scores were found in children who were born outside Hong Kong or came from lower socio-economic classes (lower parental education level and lower family income). Children who had poorer dietary or toothbrushing habits also had more dental caries. Conclusion: Prevalence of dental caries among Chinese kindergarten children in Hong Kong was not high but the severity of caries varied by the socio-economic background of parents, and their dietary and toothbrushing habits.