School-based oral health education increases caries inequalities.

OBJECTIVE: To evaluate the effect of one and half years of an oral health promotion program in primary schools. DESIGN: A cluster-randomized controlled trial. PARTICIPANTS: 740 students aged 9-12 years (48% female) recruited from the fifth grade of 18 different primary schools in West Pomerania, Germany. METHODS: General and oral health education was provided to the teachers in the intervention schools, which they conveyed to their students. No additional measures were conducted in the control schools. Medical and dental school examinations, as well as questionnaires for the students and their parents were conducted at baseline and follow-up. Data were analysed using Poisson regression models. RESULTS: A significant incident rate ratio between caries increment was found, with a 35% higher risk in the control group. However, parents' socioeconomic characteristics modified the effect of the program on their children, as high socio-economic status in the intervention group was associated with 94% reduction in the incidence risk ratio (p ⟨ 0.001). CONCLUSIONS: The program was effective in improving dental health among students with higher socio-economic status. No preventive effect could be found in low socio-economic status groups.