From six months to age three, your child may have sore gums when teeth erupt. Many babies like a clean cold teething ring, cool spoon or cold wet washcloth. This type of sucking is completely normal for babies and young children. It provides, a sense of security. For young babies, it's a way to first learn and make contact with the world around them.
Babies begin to suck on their fingers or thumbs even before they are born.
Most children stop sucking on thumbs, pacifiers or other objects on their own between two and four years of age. No harm is done to their teeth or jaws. However, some children repeatedly suck on a finger, pacifier or other object over long periods of time. However this can become a problem if the child is in the process of loosing the front bay or primary teeth, since the pressure exerted by the finger or pacifier can cause the upper permanent teeth to stick out, the lower permanent teeth to be pushed in, or cause a separation between the upper and lower permanent teeth, producing what dentist call an anterior open bite. Most children stop sucking habits on their own, but some children need the help of their parents and their pediatric dentist.