Many children who suck their thumb go on to have normal teeth. Whether thumb sucking causes a problem depends on the child’s growth development, how often they suck their thumb, the angle of their thumb in the mouth, and how hard they suck. 

Problems caused by thumb sucking can include: 

the child’s upper jaw being pushed out further from their face 

upper front teeth being pushed upwards and out, commonly called an ‘overbite’ 

tipped back lower front teeth 

a gap between the child’s upper and lower teeth 

not being able to bite the front teeth together 

the palate (roof of the mouth) becoming pushed up and narrow 

speech being affected, such as forming a lisp 

the tongue not being in a normal position in the mouth 

Many children who suck their thumb go on to have normal teeth. Whether thumb sucking causes a problem depends on the child’s growth development, how often they suck their thumb, the angle of their thumb in the mouth, and how hard they suck. 

Problems caused by thumb sucking can include: 

the child’s upper jaw being pushed out further from their face 

upper front teeth being pushed upwards and out, commonly called an ‘overbite’ 

tipped back lower front teeth 

a gap between the child’s upper and lower teeth 

not being able to bite the front teeth together 

the palate (roof of the mouth) becoming pushed up and narrow 

speech being affected, such as forming a lisp 

the tongue not being in a normal position in the mouth 

How to stop your child sucking their thumb 

Remember, most children will stop sucking their thumb by themselves by the time they are 4 years old. Others will stop when they get to school and find out that other children there are not sucking their thumb. 

Positive reinforcement is the best way to help your child to stop thumb sucking, as well as support, encouragement and reminders. Noticing when they haven’t been sucking their thumb, and pointing out how ‘grown up’ they are, is a way to be positive. It also becomes easier when the child realizes that they want to stop sucking their thumb. 

Here are some strategies for helping your child to stop thumb sucking: 

Gently remind your child regularly to take their thumb out of their mouth, and when they do, offer hugs and praise. You may also like to create a private signal if you are with other people, to prevent your child being embarrassed about the reminder. 

Record their thumb sucking on a calendar, with rewards or stickers when they reduce or stop the behavior. 

At night, dress your child in a large pyjama top with the arm ends sewn up, or use gloves, mittens or a thumb guard as a barrier. 

Look for what is triggering the thumb sucking. For example, if stress or fear causes your child to put their thumb in their mouth, help them reduce this fear in other ways, such as with a hug or comforting words. You could also give them a soft toy they can squeeze. 

Thumb sucking is a habit which may take some time to stop, so try to be patient and positive while helping your child. Encourage them to want to stop themselves and don’t nag them in a negative way, as this can make the habit worse. 

If the habit continues after they start school, you may like to discuss it with your child’s dentist or orthodontist. It’s best to wait until this age because your child needs to be old enough to understand, and accept responsibility to break the habit. 

Thumb sucking isn’t usually a concern until a child’s permanent teeth come in. At this point, thumb sucking might begin to affect the roof of the mouth (palate) or how the teeth line up. The risk of dental problems is related to how often, how long and how intensely your child sucks on his or her thumb. 

Although some experts recommend addressing sucking habits before age 3, the American Academy of Pediatrics says treatment is usually limited to children who continue thumb sucking after turning 5.