Thumb sucking becomes a problem if they go on for a very long period of time. Most children stop these habits on their own, but if they are still sucking their thumbs or fingers past the age of three, they need to be stopped.
Yes thumb sucking can have effect on the teeth of children in future. Many toddlers suck thumbs as they find it comforting. In some babies the urge to suck the thumbs is much stronger than others. Children suck their thumbs when they are bored, tired or in need of comfort. But prolonged thumb sucking can cause a whole lot of problems in toddlers. It can cause malformations in teeth.
It is important to stop this habit before your child's permanent teeth appear as their new teeth and the contour of their jaw bones may be adversely affected. Thumb sucking that persists beyond the eruption of the permanent teeth can lead to problems with the normal growth and development of the mouth and tooth alignment. Thumb-sucking can result in your baby's upper front teeth being pushed forward and the lower teeth back.My niece was into this habit and she has severely deformed teeth.