Thumbsucking is a natural reflex for children. However, after the permanent teeth come in, sucking may cause problems with the proper growth of the mouth and alignment of the teeth. It can also cause changes in the roof of the mouth. Pacifiers can affect the teeth essentially the same way, but is often an easier habit to break. Some aggressive thumbsuckers may develop problems with their baby teeth.
Children usually stop sucking between the ages of two and four years old, or by the time the permanent front teeth are ready to erupt. If you notice changes in your children's primary teeth, or are concerned about your child's thumbsucking, consult your dentist.
Dr. James L. Johnson