Thumb Sucking and Teeth: What It Does and When to Step In

Sucking is a natural comfort habit and starts before birth. In the first few years it rarely causes lasting trouble. The effect on teeth depends on how often the child sucks, for how long each time and how hard.

Steady pressure from a thumb or fingers can tip the upper front teeth outward and the lower ones inward. This can leave a gap between the upper and lower front teeth when the back teeth are closed, called an open bite. It can also narrow the roof of the mouth, so that the upper and lower back teeth do not meet properly, and it can affect how the tongue rests and how some sounds are made.

Dummies or pacifiers can cause similar changes, though they are often easier to take away. Teeth that have moved because of milk tooth habits often correct themselves if the habit stops early.

Many children drop the habit between two and four years old. Around the age when the permanent front teeth begin to appear, usually about six, the habit starts to matter more because it can affect where those new teeth settle. Our guide on milk teeth falling age explains when that happens.

If a child is still sucking strongly past that age, or the front teeth already look pushed forward, it is worth having a dentist look. A paediatric dentist can check the bite and tell you whether the habit has caused changes that need attention.

Punishment, nagging and bitter-tasting paints tend to make children anxious and often make the habit worse. Calm, positive methods work better.

Praise the times the child is not sucking, and notice when the habit happens, which is often at tiredness, boredom or bedtime. Offer another comfort, such as a soft toy or a hand to hold, and give the child something to do with their hands. A sticker chart for nights or days without sucking works well for older children who want to stop.

If the habit persists, the dentist can talk to the child about it, which sometimes works better than a parent. In some cases a small fixed appliance that sits behind the upper front teeth is used for an older child who is willing to stop but cannot manage it alone. This is the dentist's decision after an examination.

In young children, often yes. Once the habit ends, milk teeth and the bite can shift back over some months. If it continues until permanent teeth are in, the changes are less likely to correct themselves and braces may later be advised. A look at children's first dental visit will help you know what to expect when you take your child to be checked.