Tongue thrusting is a swallowing pattern where the tongue pushes forward against or between the teeth instead of pressing up against the roof of the mouth. While this movement is completely normal in infants, it typically disappears as a child grows. When it persists into adulthood, it can gradually shift teeth out of alignment, affect speech, and undermine orthodontic work.
How a Normal Swallow Differs From Tongue Thrust
In a healthy, mature swallow, the tip of your tongue presses upward against the hard palate just behind your upper front teeth. Your lips stay relaxed, and your cheeks do very little work. The whole motion is compact and contained inside the mouth.
With tongue thrust, the pattern looks more like the way a newborn swallows. Instead of pressing upward, the tongue pushes forward, sometimes sliding between the upper and lower teeth or pressing firmly against the backs of the front teeth. This can happen every time you swallow (and the average person swallows between 500 and 2,000 times a day), during speech, or even when the mouth is completely at rest. Clinicians sometimes call this a “retained infantile swallow” because the adult never fully transitioned to the mature pattern.
Why It Matters: Pressure on Your Teeth
The tongue is strong, and even small, repeated forces add up over thousands of daily swallows. Research using wireless pressure sensors inside the mouth measured tongue force on the upper front teeth during swallowing. A normal swallow produced about 132 g/cm², while a tongue-thrust swallow hit roughly 201 g/cm², about 50% more force. That extra pressure, applied hundreds of times a day for years, is enough to gradually push teeth forward, create gaps, or reopen spaces that braces previously closed.
The most common dental consequence is an anterior open bite, where the upper and lower front teeth no longer meet when the mouth is closed. Tongue thrust can also contribute to an overjet (upper teeth that flare outward) and general misalignment. For adults who have already gone through orthodontic treatment, an unaddressed tongue thrust habit is one of the main reasons teeth drift back toward their old positions after braces come off.
Signs You Might Have It
Tongue thrust in adults often goes unnoticed for years because the forward movement of the tongue is subtle, and people rarely think about how they swallow. Some common signs include:
- Visible tongue movement: Your tongue pokes forward between your teeth when you swallow, speak, or rest.
- Open mouth posture: Your lips tend to stay slightly apart at rest, sometimes with the tongue visible or resting low in the mouth rather than on the palate.
- Speech changes: A lisp or difficulty pronouncing “s” and “z” sounds clearly, since these sounds require the tongue to stay behind the teeth.
- Teeth that keep shifting: Front teeth that gradually space out or move forward despite previous orthodontic correction.
- Noisy or messy swallowing: Swallowing that seems effortful, or food and liquid escaping forward during meals.
A dentist, orthodontist, or speech-language pathologist can confirm the diagnosis by watching how the tongue moves during swallowing and speech. They may also evaluate resting tongue position, lip seal, and breathing patterns, since mouth breathing and tongue thrust frequently occur together.
What Causes It in Adults
For many adults, tongue thrust is simply a childhood pattern that never went away. Prolonged thumb sucking, pacifier use, or bottle feeding past the toddler years can reinforce the forward swallowing pattern during a critical window of development, and without intervention, it becomes deeply habitual.
Other contributing factors include chronic nasal congestion or allergies (which force mouth breathing and a low tongue position), enlarged tonsils or adenoids, and a short or restricted lingual frenulum (the band of tissue under the tongue). Stress and anxiety can also play a role. Some adults develop or worsen a tongue thrust habit under tension, pressing the tongue against the teeth as a subconscious response. In rarer cases, neurological conditions that affect muscle coordination can produce a tongue thrust pattern that wasn’t present earlier in life.
Myofunctional Therapy: Retraining the Muscles
The primary treatment for adult tongue thrust is orofacial myofunctional therapy, a structured set of exercises that retrain the tongue, lips, and facial muscles to adopt a correct swallowing pattern and resting posture. Think of it as physical therapy for your mouth. A trained therapist (usually a speech-language pathologist or a myofunctional therapist) guides you through exercises that strengthen the tongue, teach it to rest against the palate, and build a new automatic swallowing pattern.
Typical exercises include pressing the tongue tip to a specific spot on the palate and holding it, practicing correct swallows with water, and strengthening the lip seal. Sessions are usually spaced out over several months, with daily home exercises between visits. Research on orofacial myofunctional therapy in adults has shown statistically significant improvements in tongue mobility, jaw function, pain reduction, and overall quality of life. In one study, participants’ self-reported pain scores dropped from a median of 7 out of 10 before therapy to 4 out of 10 afterward, and quality-of-life scores improved substantially.
The challenge for adults is that the habit has been reinforced for decades, so retraining takes consistent effort. Most therapy programs run somewhere between three and six months of active treatment, followed by a maintenance period where you continue exercises on your own to make sure the new pattern sticks. The goal is for the correct swallow to become fully automatic so you no longer have to think about it.
Dental Appliances That Help
When exercises alone aren’t enough, or when a physical reminder is needed during the retraining process, dentists can fit appliances inside the mouth. A tongue crib is a small metal framework attached to the upper molars that sits behind the front teeth, creating a physical barrier the tongue can’t push past. It’s effective because it makes the old thrusting motion uncomfortable or impossible, essentially forcing the tongue to find a new resting spot higher on the palate.
Another option is a tongue bead, a small acrylic sphere (about 3 mm across) mounted on a wire near the roof of the mouth. Rather than blocking the tongue, the bead serves as a target. It encourages you to roll the tongue up to the palate and keep it there, retraining position through tactile feedback. Some appliances combine both a crib and a bead for simultaneous habit-breaking and retraining. These devices are cemented in place and typically worn for several months.
How Tongue Thrust Connects to Orthodontic Relapse
If you’ve had braces or clear aligners and your teeth have shifted back, an unresolved tongue thrust could be the reason. Orthodontic treatment moves teeth into alignment, but it doesn’t change the muscular forces acting on those teeth after the hardware comes off. If the tongue continues pushing forward with 50% more pressure than a normal swallow, retainers can only do so much.
This is why many orthodontists now screen for tongue thrust before or during treatment and refer patients to myofunctional therapy alongside braces. Addressing the habit before or during orthodontic correction significantly improves the chances that your results will last. If you’re an adult considering a second round of orthodontic work, it’s worth asking your provider whether tongue posture and swallowing patterns should be evaluated first.