[Series: Concise Research. Relationship between Family Composition and Children's Oral Health].

Caries is one of the most common chronic diseases in children. Despite advice and guidelines, caries prevalence is alarmingly high in the Netherlands. Research suggests that family factors, such as family composition, may play a role in children's oral health. This study focused on the relationship between family composition and oral health in five-year-old children in the Netherlands. The central research question is, To what extent do family size and birth position influence the oral health of 5-year-old children in the Netherlands? This specifically examined whether family expansion affects a child's oral health and to what extent there is a difference between the oral health of only children and children with siblings.