Children suck on things because suckling a food source is one of a baby’s natural instincts. Sucking makes them feel secure and content, and may induce drowsiness. Most children stop thumb sucking on their own between the ages of two and four.
However, some children continue sucking beyond the preschool years. If your child is still sucking when his or her permanent teeth start to erupt (at around 5-6 years old), it may be time to take action. Taking action will stop the suck and protect the roof of the mouth as well as teeth.