Long-term evaluation of the clinical effectiveness of community milk fluoridation in Bulgaria.

OBJECTIVE To determine the clinical effectiveness of a community milk fluoridation programme. BASIC RESEARCH DESIGN Parallel arm 5-year cohort study, with final cross-sectional comparisons between groups. PARTICIPANTS 3-year-olds in 8 Bulgarian cities/towns entered the cohort study with random samples (n = 1,782) recruited at baseline in 2004. After 5 years in 2009 sub-samples (about 30%) of these now aged 8 were randomly selected in intervention sites for follow-up examination (n = 454); 276 controls were examined at the age 8 years. For cross-sectional comparisons, in 2004, 284 3-year-olds from control cities were baseline examined for caries, then 276 children at the age 8 years in 2009. INTERVENTIONS In six intervention communities: 1,498 examined children received 0.5 mg F in 100 or 200 ml school milk or yogurt provided each school day; a further 180 received non-fluoridated milk. In two control communities, fluoride was not added to 284 children's school milk. MAIN OUTCOME MEASURES Dental caries experience of primary, and permanent teeth. RESULTS For primary teeth, caries increments were 46% (p < 0.001) and 30% (p < 0.01) lower in the fluoridated milk groups compared with non-fluoridated milk groups in the intervention and control communities, respectively. For permanent teeth those reductions were 61% and 53% (p < 0.001). The cross-sectional comparisons of 8-year-olds showed significant changes in dental caries experience over time; in children consuming fluoridated milk the level of dmfs fell by 43% (2004 and 2009) against 11% in the control group. Among children consuming fluoridated milk the DMFS fell 68% against rising 3% in the controls. CONCLUSIONS Fluoridated milk delivered daily in schools in Bulgaria resulted in substantially lower caries development compared with children in schools receiving milk without added fluoride. The nation-wide experiences from milk fluoridation indicate that such a public health scheme can be effective to the global fight against dental caries of children.