Parents often first spot it in a photo or while their child is eating: the back teeth close together, but a gap stays open between the top and bottom front teeth, and the tip of the tongue fills it. Dentists call that gap an anterior open bite. A forward tongue position is often part of the story, but it is not always the starting point, and working out what began the problem shapes what will help.
Cause, effect, or both
For years, the forward push of the tongue during swallowing was seen as the main force that opened the bite. Current thinking is more nuanced. Each swallow is brief, and many researchers now see the tongue's resting position, held for hours each day, as more influential on where the teeth settle than the swallow itself. In many children, a sucking habit or mouth breathing opens the bite first, and the tongue then moves forward into the gap to seal the mouth when swallowing. In that case, tongue thrust is partly an adaptation to the open bite rather than its original cause, and it may ease once the bite improves.
All babies swallow with the tongue forward. As teeth arrive and the mouth matures, most children shift to a swallow with the tongue lifted against the roof of the mouth, usually by early school age. When that shift is late, the reason is usually one or more of the following.
Habits and breathing that keep the tongue low and forward
Thumb, finger and dummy sucking. A long-standing sucking habit puts something between the front teeth for hours a day and holds the tongue low. It is one of the most common reasons for an open bite in young children. When the habit stops, the bite often improves or closes by itself, even in children older than four, although the research behind this is limited.
Mouth breathing. Enlarged tonsils or adenoids, allergies or a blocked nose can make nose breathing hard. To keep the airway open, the child rests with lips apart and the tongue down and forward. Snoring, a constantly open mouth, dark circles under the eyes and restless sleep can be clues.
Tongue-tie. A short or tight band under the tongue can make it hard to lift the tongue to the palate. This applies to a smaller number of children, and our article on tongue-tie explains how it is assessed.
Jaw growth pattern. Some children grow with a longer lower face and a tendency to an open bite regardless of habits. This skeletal pattern is harder to change and is a reason some cases need specialist orthodontic care.
What parents can look for at home
- The tongue showing between the front teeth when your child swallows, talks or is relaxed.
- A gap between upper and lower front teeth when they bite together on their back teeth.
- A lisp, or trouble with "s", "z" and "th" sounds.
- Lips that rarely close at rest, snoring or noisy breathing.
- A thumb, finger or dummy habit that has continued past about age three or four.
None of these on its own is a diagnosis, but two or more together are worth raising at your child's next dental visit.
Treatment usually works from the habit outwards
The first goal is to remove whatever is holding the tongue and teeth apart. That often means helping a child give up a sucking habit, with encouragement, reward charts and sometimes a reminder appliance. If mouth breathing is suspected, a GP, paediatrician or ear, nose and throat specialist may need to assess the airway. Dental treatment alone may have limited lasting success while the nose stays blocked.
Orofacial myofunctional therapy is a program of exercises for the tongue, lips and face that aims to retrain resting tongue posture and swallowing. It is usually provided by a speech pathologist with training in this area. It is widely used and can be helpful, particularly when speech is affected, although the quality of research on long-term bite changes is still limited. It tends to work best for motivated children and alongside other steps rather than on its own.
Habit appliances. A small fixed appliance, sometimes called a tongue crib or tongue guard, sits behind the upper front teeth. It acts as a reminder and physical barrier while a thumb habit or forward tongue position is being broken, and is commonly worn for several months.
Orthodontic treatment. If an open bite persists after the habit and breathing have been addressed, braces or aligners may be needed to close it. Open bites have a known tendency to reopen, so retainers matter and treatment works best once the habits behind it are under control. Lumi's general dentists provide orthodontic treatment with fixed braces and clear aligners, and children with more complex bites or skeletal growth patterns may be referred to a registered orthodontist. An early orthodontic assessment helps decide whether to act now or watch, and our guide to the first week with braces covers what comes later if braces are needed.
What parents ask about tongue thrust
Will my child grow out of it?
Many do, especially once a sucking habit stops in the early years. If the pattern is still obvious once the adult front teeth have come through, around ages six to eight, it is worth an assessment rather than waiting.
Is tongue thrust the same as tongue-tie?
No. Tongue thrust describes how the tongue moves during swallowing and rest. Tongue-tie is a physical restriction of the tongue. A tie can contribute, but most children with tongue thrust have a normally mobile tongue.
Can braces fix it without the exercises?
Braces can close the gap, but if the tongue posture or habit that caused it continues, the bite is more likely to open again. That is why habits and breathing are addressed first.
Booking a check for your child
If you have noticed a gap between your child's front teeth, a tongue that rests forward, or ongoing mouth breathing, our dentists and OHTs can check the bite and talk through who else might need to be involved. Eligible children may be covered under the Child Dental Benefits Schedule. See our current offers or read about general dental care for the whole family.
This article is general information only and is not a substitute for an individual dental or medical assessment.
