Parents of children in the intervention group were asked to respond to a questionnaire at baseline and at the second follow-up, while parents in the control group were asked at examination at age five years. The questionnaire contained 30 structured items. The topics covered were socio-demographic and anamnestic items, items about parental oral health attitudes, oral health related behaviours, and oral health promotion.The anamnestic background variables were coded cyanotic (1), not cyanotic (0), heart failure (1) and heart failure not present (0), taking heart medication (1) and does not take heart medication (0), low birth weight <2500 g (1) and normal birth weight >2500 g (0).