Physical activity, BMI and oral health behaviour among adolescents: Finnish School Health Promotion Study

BACKGROUND: To assess associations between oral health behaviour and physical activity and related factors among adolescents. METHODS: The study population (n = 76 529) consisted of a representative sample of 16- to 18-year-old Finnish adolescents (boys: 37 211, girls: 39 318). An anonymous, confidential and voluntary classroom-administered questionnaire included questions about tooth brushing frequency, physical activity, BMI and eating habits. Moderate-to-vigorous physical activity (MVPA) was used to assess the adolescents' physical activity. The chi-square test and multiple binary logistic regression were used for statistical analyses. Adjusted odds ratios (OR) and their 95% confidence intervals (CI) were calculated for MVPA, BMI, breakfast, smoking and socioeconomic factors as parents' education and school type. RESULTS: The prevalence of twice daily tooth brushing was highest among adolescents reporting 4 hours or more of MVPA (51-77%). Obese and smoking adolescents exercised less often than normal weighted and non-smokers. Girls brushed their teeth twice daily significantly more often than boys (P < 0.001), and high-school students brushed their teeth significantly more often than vocational school students (P < 0.001). Logistic regression models showed that obesity (OR = 2.14, 95% CI 1.92-2.37) and irregular breakfast eating (OR = 2.35, 95% CI 2.19-2.52) among boys, and obesity (OR = 2.81, 95% CI 2.48-3.17), physical inactivity (OR = 1.89, 95% CI 1.78-2.00) and irregular breakfast eating (OR = 1.91, 95% CI 1.79-2.04) among girls were strong predictors for poor tooth brushing. CONCLUSIONS: Physically active adolescents had better oral health behaviour than less active adolescents. Obesity and smoking were associated with infrequent tooth brushing.