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

To determine the clinical effectiveness of a community milk fluoridation programme.

Parallel arm 5-year cohort study, with final cross-sectional comparisons between groups.

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.

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.

Dental caries experience of primary, and permanent teeth.

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.

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.