Thumb sucking, tongue thrusting, lip biting: habits that affect children's teeth

Sucking a thumb or a dummy is a natural reflex that helps young children calm down and fall asleep. In a very young child it is nothing to worry about. Problems only arise when the habit goes on long enough and often enough to put pressure on growing teeth and jaws. This article helps parents tell when to leave it alone, when to have a child checked, and how to help a child give up a habit without turning it into a battle.

In short: • Thumb-sucking and dummies are a natural reflex in young children; they only become a concern when the habit is long, frequent and still there when the adult front teeth start coming in. • A lasting habit can push the upper front teeth forward, cause an open bite or narrow the upper arch. • Praise, spotting when the child tends to suck and letting them share the decision usually work better than scolding. • If your child is around 4 or 5 and hasn't stopped, or the teeth have already changed, have them checked so the dentist can judge whether an appliance would help.

Why can a small habit affect the teeth?

Teeth sit in a balance between the lips and cheeks on the outside and the tongue on the inside. A child's jaw bone is still soft and growing. When an extra force is applied regularly, for hours each day, such as a thumb pressing on the front teeth or the tongue pushing forward with every swallow, that balance is upset and the teeth and bone gradually change with it.

How much depends on three things: how many hours a day, how strong the pressure is, and until what age the habit lasts.

Common habits

Thumb and dummy sucking

Many children stop by themselves between about two and four. If the habit continues when the permanent front teeth start coming through, it may lead to:

• Upper front teeth tipping forward and lower front teeth tipping back.
• Front teeth that do not meet when biting (an anterior open bite).
• A narrower upper arch, which can lead to a crossbite at the back.

Tongue thrust when swallowing

Normally, when we swallow, the tip of the tongue presses against the palate just behind the upper front teeth. In some children the tongue pushes between the teeth instead. Tongue thrusting often goes with an open bite or mouth breathing, or is left over from thumb sucking. Parents may notice a child lisping on certain sounds, or the tongue showing between the teeth when swallowing.

Lip sucking and lip biting

A child who often sucks or bites the lower lip may push the upper front teeth forward and the lower ones back, making protrusion more noticeable.

Nail biting and pen chewing

These habits affect the bite less, but can chip enamel, injure the gums and bring germs into the mouth.

When should parents have a child checked?

• Your child still sucks a thumb or uses a dummy regularly at around four or five or older.
• The upper front teeth stick out, or there is a gap between the upper and lower teeth when your child bites.
• Your child often sleeps with the mouth open or breathes through the mouth.
• The tongue shows between the teeth when talking or swallowing, or some sounds are unclear.
• You have tried several ways and your child still cannot stop.

At the visit, the orthodontist assesses how far the habit has affected the teeth, and tells you whether your child just needs to stop the habit or needs an appliance to help.

Helping your child stop: gentle but persistent

Habits are often tied to feelings: tiredness, boredom, worry. Scolding or slapping a hand usually makes children suck in secret more. A few things parents can try:

• Talk to your child in a way they understand, for example "your thumb is pushing your teeth out".
• Praise the times your child does not suck, rather than only reminding them when they do. A sticker chart for each successful day works for many children. Stars work for brushing too: the "Brush with Asa" game in the Zalo Mini App of Asahii Dental Clinic times a full two minutes and gives a star when the child finishes.
• Notice when your child sucks: watching TV, before sleep, when anxious. Give their hands something else to do, such as hugging a soft toy or squeezing a soft ball.
• Wean off the dummy gradually, using it fewer times a day before stopping at night.
• Let your child decide part of it, for example choosing the start date or the reward.

Do not put bitter or spicy substances on your child's fingers without asking the dentist first, as they can irritate the skin and make the child more stressed.

Tip from Dr. Chu Thuy Trinh: Don't scold a child for thumb sucking. Praising the moments they forget, and giving their hands something else to do, usually works better than constant reminders.

When an appliance can help

If the habit has already affected the teeth, or an older child still cannot stop, the orthodontist may consider:

• A tongue crib or reminder appliance that stops the thumb or tongue from going back to its old position.
• Oral muscle exercises to train the correct tongue position at rest and when swallowing.
• An expander if the upper arch has already become narrow.

At Asahii, tongue cribs and expanders are part of the growth-guidance appliances for children led by Dr. Chu Thuy Trinh; the doctor explains why an appliance is (or is not yet) needed before the parents decide.

An appliance is only a tool. A parent's support and the child's own wish to stop remain the most important part. When a habit is given up early, some mild problems in young children may gradually improve; the orthodontist will monitor the rest and treat it if needed. Photographs taken at each visit are kept in the records, so you can see how the front teeth change after your child stops. See also Early orthodontic treatment for children.

When to bring your child in straight away

• Front teeth clearly sticking out, or unusually loose.
• A finger that is swollen, cracked or infected from constant sucking.
• Loud snoring, ongoing mouth breathing, tiredness during the day.

Every child's habit affects them differently, and only an examination can tell whether your child needs monitoring or extra help. See our orthodontics and braces page or book a visit for your child by hotline 0928 888 121, Zalo or the Mini App.