Parent guide · Babies to school-age children
Thumb Sucking and Pacifiers: When Do They Affect Your Child’s Teeth?
Thumb sucking and pacifiers are normal in babies and toddlers, and most children stop on their own. If a strong habit continues past about age 4, or after permanent teeth arrive, it can push the front teeth forward or cause an open bite. Dr. Sally Chaekyung Lee, our orthodontist at Yonsei Baro in Seoul, can check your child’s bite.
Sucking habits at a glance
| Age | What it usually means |
|---|---|
| Babies and toddlers | Normal and soothing; no action needed |
| Around 2–4 | Many children stop on their own; gentle encouragement can help |
| Past about 4, or once permanent front teeth arrive | A frequent or intense habit can start to affect the bite; consider a dental or orthodontic check |
| Any age | Mention it at check-ups; never shame or punish |
Why do children suck their thumbs or pacifiers?
Sucking is a natural reflex. Babies suck to feed, and many also suck their thumb, fingers or a pacifier (dummy) to calm themselves, fall asleep or cope with tiredness, boredom or worry. In the first few years it is nothing to worry about.
Most children give up the habit gradually between about 2 and 4, as they find other ways to self-soothe.
When can sucking habits affect the teeth and bite?
The effect depends on how often, how long and how hard a child sucks. A child who rests a thumb in their mouth briefly at bedtime is unlikely to have problems; a child who sucks vigorously for hours each day and night is more likely to. Concerns grow when a strong habit continues past about age 4, or after the permanent front teeth begin arriving around 6.
Possible effects include:
- Open bite: the upper and lower front teeth don’t meet when the back teeth are together, leaving a gap the shape of the thumb (see open bite ).
- Protruding upper front teeth: the thumb pushes the upper teeth forward and the lower teeth back (see protruding front teeth ).
- Crossbite: the cheeks press inwards during sucking, which can narrow the upper jaw so the back teeth bite inside the lower teeth (see crossbite ).
- Tongue habits: a long-standing open bite often goes with a tongue that pushes forward when swallowing.
If the habit stops early, mild changes in baby teeth often improve on their own. Changes that persist into the permanent teeth are less likely to correct themselves.
Gentle ways to help your child stop
Pressure and punishment usually backfire, because the habit is a comfort.
- Notice the triggers. Tiredness, screens, car journeys and bedtime are common. Offer a comfort toy, a squeeze ball or a hand to hold instead.
- Praise, don’t scold. Notice and praise the times your child isn’t sucking, rather than pointing out when they are.
- Use a sticker or calendar chart for days or nights without the habit, with a small non-food reward after a run of successes.
- Gentle night-time reminders, such as a soft cotton glove or sock over the hand, can help a child who sucks only while asleep, if they agree to it.
- Pacifiers: many families reduce use to sleep only, then stop.
- Pick a calm time, not during a move, a new sibling or a new school.
Avoid bitter-tasting nail products and other deterrents unless your child’s dentist or doctor advises them. Never dip a pacifier in honey, syrup or sugar, which can cause decay; honey should not be given to babies under 12 months.
When should you see a dentist or orthodontist?
- your child still sucks frequently at about age 4, or as permanent front teeth arrive;
- you notice a gap between the front teeth when your child bites, or upper front teeth sticking out;
- speech, swallowing or lip closure seems affected;
- your child would like help to stop.
Our pediatric dentist can review habits at routine check-ups . For a closer look at the bite, an orthodontic check is recommended by about age 7 anyway; see when should my child see an orthodontist .
How can an orthodontist help?
Dr. Sally Chaekyung Lee will examine your child’s teeth, bite, jaw width, lips and tongue posture, and explain whether any changes are likely to settle once the habit stops. For a persistent habit, or where the bite has already been affected, she may discuss a habit or functional appliance , a small device that acts as a gentle reminder and can help guide tongue position. Any appliance is only recommended after an examination, and only when your child is ready to cooperate.
Dr. Lee explains every option herself, in English. For an overview of children’s treatment, see kids’ orthodontics .
Thumb sucking and pacifier FAQs
Is a pacifier better or worse than thumb sucking for teeth?
Both can affect the bite if used often and for a long time. A pacifier has one practical advantage: you can gradually limit and remove it, whereas a thumb is always available. Whichever your child uses, the effects on the teeth depend mainly on how often, how long and how intensely they suck, and on the age the habit stops.
Will my child's teeth go back to normal once they stop?
Often, yes, if the habit stops while the baby teeth are still in place. Mild open bites and slightly forward front teeth frequently improve over months as the lips and tongue settle. If changes persist after the permanent teeth arrive, or the jaw has narrowed, an orthodontic assessment can tell you whether treatment would help.
At what age should my child stop sucking their thumb?
Many children stop by themselves between about 2 and 4. Dentists generally encourage stopping by around age 4, and certainly before the permanent front teeth come in, at about 6. If a strong habit continues beyond this, mention it at your child’s next check-up so the bite can be monitored.
Is a thumb-sucking appliance uncomfortable?
Most children adapt within a few days, although speech and eating can feel a little different at first. Habit appliances are designed as reminders, not punishments, and are only used after an examination, when other approaches haven’t worked and your child is willing. Dr. Lee will explain what to expect and how long it is likely to be needed.
Medically reviewed by Dr. Sally Chaekyung Lee, DDS, PhD
Board-certified orthodontist (Korea Ministry of Health and Welfare) · Adjunct Professor of Orthodontics, Yonsei University · Last updated October 2026
This page is general information, not a diagnosis. Treatment results and duration vary from person to person. Orthodontic treatment can cause temporary discomfort and, in some cases, root shortening, gum recession or tooth decay if oral hygiene is poor; teeth can relapse if retainers are not worn as instructed.
Worried about a sucking habit?
Book a check and Dr. Lee will explain, in English, whether your child’s bite has been affected. Isu Station Exit 2 · Open until 9 PM Mon & Thu · Saturdays 9 AM–2 PM.