Family Dentistry |4 min read

Thumb-Sucking and Overbites

Avatar for Vicki Fidler by Vicki Fidler

Seattle Dentist image of thumb sucking

Many parents are concerned about their child’s thumb-sucking, finger-sucking or pacifier use. They may wonder if it is harmful, at what age it should stop. Thumb-sucking is a common habit among many children. It is common with children under two and is associated with the need to seek food. In some infants it can signal fatigue, sleep, hunger, teething and shyness. Sucking is one of an infant’s natural reflexes. They begin to suck on their thumbs or other fingers while they are in the womb. Infants and young children may suck on thumbs, other fingers, pacifiers or other objects. It makes them feel secure and happy, and it helps them learn about their world. Thirty percent of preschool children continue the habit.

A strong thumb-sucking habit by a child beyond the age of five can alter the jaw line and cause misalignment of teeth, termed “malocclusion”. This can result in what is sometimes referred to as ‘bucked teeth’ or an overbite, where the front teeth are not closed when the back teeth are clenched. While most of this damage is caused to the child’s baby teeth, there is a chance that it will affect the permanent teeth as well – especially if the child continues sucking their thumb after the age of six.

The intensity of thumb-sucking is a factor which determines whether or not dental problems may occur.  Children who rest their thumbs passively in their mouths are less likely to experience difficulty than those who vigorously suck their thumb. When an active thumb-sucker removes his or her thumb from the mouth, a popping sound often is heard. Some aggressive thumb-suckers may cause problems with their primary (baby) teeth.

Thumb-Sucking After Age 2 Can Lead to Overbite

Children who sucked their thumb by the age of 4 to 5 were more likely to:

* develop protruding front teeth
* an irregular bite
* affect the development of the jaw
* influence the placement
of developing teeth

The study of 372 children found that nearly 6% of those who stopped sucking before they turned 1 had an irregular bite in the molar area, or in the back of the mouth. In comparison, the problem was noted among 13% of children who stopped between 2 to 3 years and in 20% of those who continued to suck fingers or a pacifier after the age of 4.

Helping Your Child Break the Habit


Pacifiers can affect the teeth in essentially the same way as does sucking thumbs. However, pacifier use often is an easier habit to break. Most children stop sucking their thumbs or other fingers on their own between the ages of 2 and 4 years. The behavior lessens gradually during this period, as children spend more of their waking hours exploring their surroundings. Peer pressure also causes many school-aged children to stop placing their fingers in their mouths. If a child does not stop on his or her own, parents should discourage the habit after age 4 years.



  • Instead of scolding the child for thumb sucking, offer praise for not doing so.
  • Children often suck their fingers when feeling insecure. Focus on correcting the cause of the anxiety and comfort the child.
  • Reward the child when he or she avoids thumb-sucking during a difficult period, such as being separated from family members.
  • The family dentist also can encourage the child to stop sucking his or her thumb and explain what could happen to the teeth if it continues the habit.


Research has shown thumb-sucking to be more detrimental to the development of teeth than using a pacifier. Parents are encouraged to prevent their child from developing a finger or thumb-sucking habit, even if that means encouraging a pacifier habit for a while. The reason for this is that when the child is 2 to 3 years old the pacifier can be thrown away and the habit stopped. Since it’s very difficult to stop a finger or thumb habit, it’s best to avoid them. Early dental visits should provide parents with needed guidance to help their children cease such habits by 36 months of age or younger. Seattle
Dr. Vicki Fidler follows the American Dental Association’s recommendations to have your baby’s first dental exam at 1 year of age. Fidler on the Tooth
SOURCES:Journal of the American Dental Association, Dr. John Warren 2001;132:1685-1693.ADA:

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