Breastfeeding Duration and Posterior Crossbite in Children

This systematic review and meta-analysis focused on a specific, measurable bite problem: posterior crossbite, where the upper back teeth sit inside the lower ones instead of outside them. The authors gathered 31 studies examining how breastfeeding related to this and other malocclusions in young children.

The headline figure is striking. Children who were not breastfed had nearly four times the odds of a posterior crossbite. Because the included studies were graded moderate-to-high quality and the finding appeared in both baby teeth and the mixed-dentition stage that follows, the result is hard to dismiss as noise.

This matters because a posterior crossbite is one of the clearest early signs that the upper jaw hasn't grown wide enough — the same narrowing that crowds teeth and pinches the nasal airway above it. Tying it back to feeding in infancy shows how far upstream these structural problems begin, and how much is potentially shaped before a child ever sees a dentist.