Thumbsucking is a natural reflex for babies, but as kids get older, it can affect teeth alignment and proper growth of the mouth. If your child still sucks his thumb by the time his permanent front teeth are ready to come in, help him kick the habit by praising him for not sucking, rather than scolding him when he does. Remind him not to suck by putting a bandage or sock on his hand at night. Ask your pediatrician to prescribe a bitter medication to coat the thumb.

 

Source:
“Thumb sucking,” http://www.ada.org/2977.aspx?currentTab=1 Updated May 04, 2010.