To investigate the longitudinal association between obesity and dental caries among adolescents.

The present cohort study was conducted among a random sample of 12-year-old adolescents in Hong Kong. Two rounds of follow-up were performed when the participants were aged 15 and 18 years. A total of 668 participants were included at age 12 years, and 282 of them completed all 3 phases of data collection. Body mass index, waist circumference, waist-to-hip (WHR) ratio, waist-to-height ratio, and triceps skinfold thickness were measured as indices of obesity. Dental caries were assessed by the number of decayed, missing, and filled permanent teeth (DMFT).

The percentage of underweight adolescents increased significantly from 6.0% to 23.8% during the observation period (P < .001). Body mass index, waist circumference, waist-to-hip ratio, and waist-to-height ratio were related to frequency of tooth brushing at age 15 and 18 years. The prevalence of dental caries was 25.5%, 53.2%, and 62.1% at 12, 15 and 18 years, respectively. At age 18 years, mean DMFT of participants whose WHR at age 15 years was below the median value was 0.707 times (ie, 29.3%) lower than the DMFT of those whose WHR was above the median (P = .028). Participants with greater DMFT at age 15 demonstrated significantly increased probability of having WHR above the median (OR 1.135; 95% CI 1.01-1.28; P = .041) at age 18 years.

There is longitudinal association between central obesity and dental caries experience among adolescents aged 15-18 years.