It’s normal for children to suck their thumbs, their fingers or a pacifier. Most children give up this habit on their own by age 4, with no harm done to their teeth. If your child still has a sucking habit after age 4, tell your dentist. Your dentist can watch carefully for any problems as the teeth develop. In most children there is no reason to worry about a sucking habit until around age 6, when the permanent front teeth come in.
Dr Costa Saridakis, your Milnerton dentist.