Thumb sucking is a common childhood habit that can be difficult to break. It is so widespread, in fact, that some studies have estimated that as many as 90% of children between the ages of 2 and 4 suck their thumbs. Thumb sucking does not usually pose long-term problems, with most children growing out of the habit naturally. When this doesn’t occur, however, it is important to intervene so that the dental health of your child is not compromised in the long-term.

Why it happens

Children suck their thumbs primarily because it is calming and comforting. Some babies begin to do this before they are even born and are still in the womb. Babies have instinctive sucking reflexes and when objects (or thumbs) are placed in their mouth, sucking is their natural reaction. Because the act of sucking is soothing for babies, they may naturally develop a habit of thumb sucking and may resort to it if they are feeling anxious, tired, sick, bored, or when trying to adjust to new challenges, such as starting day care, for instance.

How long does it last?

Most children will gradually grow out of the habit without intervention during their toddler years. Sometimes a child will continue sucking his or her thumb beyond this age. It’s also important to remember that even though a child may appear to have grown out of the habit, he or she may revert back to it as a comfort if they experience negative emotions.

When to intervene

Usually thumb sucking is not a cause for concern until the child’s set of permanent teeth comes through, usually around age 5 – 6. After this point, thumb sucking may begin to impact the roof of the mouth (palate) or the alignment of the teeth. This is especially the case if the sucking is aggressive. At this point, it is important to intervene because otherwise the habit could cause long-term dental effects.

Long-term effects of thumb sucking

If a child continues to suck his or her thumb beyond the age of 5 – 6, some of the long-term effects can include:

  • The movement of teeth, which may result in alignment problems, causing either an overbite or an underbite
  • The jaw bone positioning changing which can cause a lisp
  • The palate becoming more sensitive or damaged

How to intervene

The best intervention methods to discourage thumb sucking in children older than 5 or 6 include:

  • Eliminating sources of stress which can lead to thumb sucking as a coping mechanism
  • Positive reinforcement for the exhibition of desirable behaviour that does not involve thumb sucking. Negative reinforcement may cause a stress reaction.
  • Distractions such as toys or games if the child begins sucking his or her thumb
  • Offering gentle reminders to stop