Thumb sucking is one of the most common habits of children. The habit starts early in life. About 9 in 10 newborns show some form of hand sucking by 2 hours after birth.
Thumb sucking is normal in infants and young children. It should cause no permanent problems if it stops by age 5. It's also generally harmless for babies to use pacifiers.
Most children stop thumb sucking on their own between the ages of 2 and 4. There is no reason to be concerned until the front teeth start erupting or breaking through the surface. At this point, some problems may occur, including bite problems, or protruding front teeth. The intensity of the thumb sucking is a factor in determining if problems might develop. If your child is an aggressive thumb sucker and damage is being done to the baby (primary) teeth, see your child’s dentist. Other problems that may occur with thumb sucking are sore thumbs, infections, and calluses on the thumb.
Experts believe that pacifier may actually be better than thumb sucking for the following reasons:
Pacifiers are softer and cause less damage to the teeth.
The plastic rim on the pacifier eases some of the tension placed on the teeth.
Pacifiers can be cleaned.
Talk with your child's healthcare provider or dentist if you are concerned with your child's thumb sucking.