Tongue thrust is a swallowing pattern in which the tongue pushes forward against or between the teeth instead of pressing up against the roof of the mouth. It’s essentially an infantile swallow that persists past the age when a mature swallow pattern should have taken over. Between 40% and 80% of children ages 4 to 6 show some degree of tongue thrusting, but by ages 12 to 15 that number drops to roughly 3% to 25%, meaning most kids outgrow it naturally. When they don’t, it can affect tooth alignment, speech, and facial development.
How a Normal Swallow Differs From Tongue Thrust
In a mature swallow, the tip of the tongue rests high on the palate just behind the upper front teeth. The lips stay relaxed, the cheeks stay still, and the tongue drives food backward without pressing outward on the teeth at all. You do this thousands of times a day, every time you swallow saliva, water, or food.
With tongue thrust, the tongue drops forward or sideways and presses against the front teeth or slips between the upper and lower teeth. The lips and cheeks often have to contract to compensate and create a seal. Over months and years, that repetitive forward pressure can gradually shift the teeth and reshape the bite.
Types of Tongue Thrust
Clinicians generally describe three patterns:
- Simple tongue thrust: The tongue pushes forward to seal a gap, usually an open bite caused by a habit like thumb sucking. The problem is limited to the front teeth.
- Complex tongue thrust: The tongue pushes outward more broadly, and there’s a wider open bite that isn’t limited to the front. This pattern is most common in mouth breathers and children with chronic nasal congestion or allergies.
- Retained infantile swallow: The baby-like swallowing reflex simply never transitions to a mature pattern, even after the permanent teeth come in.
What Causes It
There’s rarely a single cause. Tongue thrust usually develops from a combination of structural and behavioral factors that reinforce each other over time.
Prolonged thumb sucking is one of the most recognized triggers. It can push the upper front teeth forward and weaken the lip seal needed for normal swallowing. Once that gap exists between the upper and lower teeth, the tongue naturally moves forward to close it during swallowing, which reinforces the open bite further.
Chronic mouth breathing is another major contributor. Children who breathe through their mouths because of enlarged tonsils, nasal allergies, or frequent upper respiratory infections tend to hold their tongues low and forward. Over time this resting posture becomes habitual. Anything that makes nasal breathing difficult, from seasonal allergies to a deviated septum, can set the stage.
Less commonly, an unusually large tongue (a condition called macroglossia) or structural differences in the jaw can physically force the tongue into a forward position. Low muscle tone in the face and tongue, sometimes seen in certain developmental conditions, also makes it harder for a child to develop the coordinated swallow pattern that keeps the tongue pressed to the palate.
Effects on Teeth and Bite
The most visible dental consequence is an anterior open bite, where the front teeth don’t meet when the back teeth are closed together. In severe cases, that gap can reach 6 millimeters or more. The upper front teeth may also flare outward, and the overall bite relationship can shift into a misalignment where the lower jaw sits too far back relative to the upper jaw.
What makes this especially frustrating for orthodontic patients is that tongue thrust can undo the results of braces or aligners. Research published in the Korean Journal of Orthodontics found a significant link between abnormal tongue function and retention failure after orthodontic treatment, in both the upper and lower jaws. Roughly 26% to 27% of patients whose retainers failed had abnormal tongue function. The repeated forward pressure of the tongue can create what orthodontists call “jiggling forces” on the front teeth, gradually nudging them back toward their old positions. If the swallowing pattern isn’t addressed alongside the orthodontic work, the teeth are more likely to shift after braces come off.
Effects on Speech
Tongue thrust commonly produces a frontal lisp. Because the tongue pushes forward against or between the teeth during speech, sounds that require the tongue to stay behind the teeth get distorted. The “s” and “z” sounds are most often affected, though “sh,” “ch,” and “j” can also be impacted. A child or adult with this pattern may sound like they’re placing their tongue tip right at the edge of their front teeth when they talk, because that’s exactly what’s happening.
How It’s Identified
Tongue thrust is typically spotted by a dentist, orthodontist, or speech-language pathologist. The assessment is straightforward: the practitioner watches how you swallow, noting where the tongue goes and whether the lips and cheeks contract excessively. They’ll also look at your bite, check for an open bite or flared front teeth, and ask about habits like thumb sucking, mouth breathing, and snoring. In children, it’s common for a dentist to notice the dental effects first and then refer to a specialist for a full evaluation of the swallowing pattern.
Treatment Options
Treatment depends on the type and severity, but the two main approaches are muscle retraining and dental appliances.
Myofunctional Therapy
This is essentially physical therapy for the tongue, lips, and facial muscles. A trained therapist (usually a speech-language pathologist or a myofunctional therapist) guides you through exercises designed to teach the tongue to rest on the palate and stay there during swallowing. The exercises build strength and muscle memory so the correct swallow pattern eventually becomes automatic. Sessions typically happen weekly, with daily home practice between visits. Programs often run for several months, and consistency with the home exercises matters more than anything else.
Dental Appliances
For children whose tongue thrust is tied to a habit like thumb sucking, an orthodontist may place a small appliance behind the upper front teeth. A tongue crib, for example, uses a series of small bars that physically block the tongue from pushing forward. These appliances work as a reminder and a barrier while the child learns a new swallowing pattern. They’re often used alongside myofunctional therapy rather than as a standalone fix.
When tongue thrust has already caused significant bite problems, orthodontic treatment (braces or aligners) addresses the tooth alignment while the therapy or appliance works on the underlying habit. Tackling both at the same time gives the best chance of a stable result. Without correcting the swallow pattern, orthodontic results are harder to maintain long term.
Adults With Tongue Thrust
Tongue thrust isn’t just a childhood issue. Adults who never outgrew the pattern or who developed it due to chronic allergies, jaw changes, or other factors can still be treated. Myofunctional therapy works for adults, though retraining a swallowing pattern you’ve had for decades requires more patience and practice. Adults often seek help after noticing their teeth shifting despite wearing retainers, or after a dentist flags the connection between their bite issues and their swallowing pattern. Speech improvements tend to follow once the tongue learns to stay behind the teeth consistently.