Objective: Oral hygiene must start at a young age. Childhood is the perfect time to start the conversion of knowledge into creative thinking and subsequent health care activity. This study aimed to assess the efficacy of oral hygiene instruction via an educational film for oral health promotion of elementary students.

  Methods: In this experimental, interventional, before and after study, data were collected using an author-designed questionnaire. The validity of the questionnaire was confirmed using face validity while its reliability was approved using Cronbach’s alpha statistics. The study population comprised of all four graders of an elementary school in district 14 of Tehran in 2012-2013. An educational package containing an educational film on oral hygiene suitable for children aged 10-12 years was prepared and a questionnaire was designed according to the educational content of the film. The questionnaires were filled by the students before and two weeks after watching the film. Data were analyzed using paired t-test at 0.05 level of significance.

  Results: Significant differences were noted in level of knowledge, attitude and function of students after the intervention compared to their baseline state. According to t-test, the mean knowledge, the mean attitude and the mean short-term performance scores after the intervention were 15.43 (0.9 increase) ( P<0.05) , 28.11 (9.35 increase) (P<0.001) and 26.79 (9.02 increase) (P<0.001) respectively.