Does Mewing Actually Expand the Palate?

No published study has demonstrated that mewing, the practice of pressing the tongue flat against the roof of the mouth, can widen an adult’s palate. The palatal bones are joined by a suture that progressively fuses with age, and the light force a tongue generates is a fraction of what clinical devices use to achieve measurable expansion. That said, the idea is not built on pure fantasy: there is real science linking tongue posture and breathing patterns to how the jaws develop during childhood, and understanding what that science actually says helps separate the plausible from the wishful.

What Mewing Promises

The technique is named after John Mew and his son Mike Mew, British dentists who developed an approach they call “orthotropics.” The core instruction is simple: rest the entire tongue against the palate, keep your lips sealed, and breathe through your nose. Proponents claim that maintaining this posture over months or years will widen the upper jaw, improve facial symmetry, sharpen the jawline, and even change the position of the cheekbones. Online communities share before-and-after photos that appear dramatic, though they rarely control for lighting, camera angle, weight change, or normal growth in teenagers who are still developing.

The promise rests on a reasonable-sounding chain of logic: the tongue exerts force on the palate, force on bone causes remodeling, and therefore habitual tongue pressure should reshape the maxilla over time. Each link in that chain needs scrutiny, because the devil is in the biology.

The Bone That Has to Move

Your upper jaw is not one solid piece. The palate is formed by two maxillary bones that meet in the middle at the midpalatal suture. In a young child, this suture is wide open, held together by fibrous tissue that allows the two halves to drift apart relatively easily. As you age, the suture knits together with increasingly complex interlocking fingers of bone and eventually fuses into solid tissue.

Researchers have classified this fusion into five stages. In the earliest stage, the suture appears as a straight, high-density line with little interdigitation. In the middle stages, the line becomes scalloped and begins separating into two parallel lines with small gaps. By the later stages, fusion is complete in the back of the palate and progresses forward through the maxilla.

1PubMed Central. Midpalatal suture maturation: Classification method for individual assessment before rapid maxillary expansion

A cross-sectional study of people aged 10 to 25 found that the most common maturation stage was already substantially fused, with about 38% of subjects at stage D and another 20% at stage E. Only about 40% of the sample still had an unfused suture.

2PubMed Central. Midpalatal Suture Maturation Stage in 10- to 25-Year-Olds Using Cone-Beam Computed Tomography—A Cross-Sectional Study

Microscopic analysis has confirmed that sutural width and volume decrease after about age 20, with the rate of bone filling the suture increasing beyond that age.

3PubMed. Age-related changes in the midpalatal suture: Comparison between CBCT staging and bone micromorphology

This matters because any claim about expanding the palate is fundamentally a claim about separating two bones at this suture. A young child’s suture is loose enough that moderate forces can do it. An adult’s fused suture resists separation the way a healed fracture resists re-breaking. No amount of tongue posture changes that basic anatomy.

What It Actually Takes to Expand a Palate

Orthodontists and oral surgeons have been expanding palates for over a century, and the forces involved put the mewing claim in perspective. In children, a rapid palatal expander (RPE) is a metal appliance cemented to the upper teeth that delivers heavy mechanical force directly to the palatal bones, typically activated by turning a screw one or two quarter-turns per day. Even in growing children, this device needs to generate several pounds of continuous force to split the suture apart. A meta-analysis of RPE studies in children found measurable increases in internasal distance, the space between the cheekbones, and airway volume after treatment.

4PubMed Central. The effect of rapid maxillary expansion in children: a meta-analysis

In growing children, RPE produces real skeletal change. One study using cone-beam CT scans showed that the maxillary arch width increased by about 2.4 mm and intermolar width by about 2.9 mm after expansion.

5Oral and Maxillofacial Surgery Cases. Dental and skeletal changes on cone-beam computed tomography after rapid maxillary expansion using rapid palatal expander for the growing children

But even with these heavy-duty appliances, the expansion is not purely skeletal. A CT-based study found that actual bone separation accounted for only about 55% of the total measured expansion at the premolars and just 38% at the first molars. The rest came from the teeth tipping outward in their sockets, not the bones themselves moving apart.

6PubMed. Skeletal effects to the maxilla after rapid maxillary expansion assessed with cone-beam computed tomography

For adults whose sutures have fused, conventional RPE usually cannot split the bone and instead just tips the teeth. The modern solution is MARPE, which stands for miniscrew-assisted rapid palatal expansion. Tiny screws are drilled directly into the palatal bone so that the expansion force bypasses the teeth and acts on the skeleton itself. A systematic review found MARPE had a mean success rate of about 94%, with roughly half the total expansion coming from true skeletal widening and the rest from dental tipping.

7PubMed Central. Long-term efficacy and stability of miniscrew-assisted rapid palatal expansion in mid to late adolescents and adults: a systematic review and meta-analysis

One consecutive-patient study found successful non-surgical expansion in adults aged 18 to 49, achieving an average of about 5.4 mm of anterior expansion, though complications increased with age and the mean age of those who failed was significantly higher than those who succeeded.

8PubMed Central. Success and complication rate of miniscrew assisted non-surgical palatal expansion in adults – a consecutive study using a novel force-controlled polycyclic activation protocol

The scale of these forces is the key point. These devices generate forces measured in pounds or even tens of pounds, applied continuously and directly to bone. Your tongue, pressed against the palate, generates a small fraction of that. Clinical measurements of tongue pressure during various exercises in healthy adults show forces that are trivial compared to what palatal expanders deliver.

9PubMed. Tongue Pressure Production and Submental Surface Electromyogram Activities During Tongue-Hold Swallow with Different Holding Positions and Tongue Length

Bone does remodel under sustained force, but there are thresholds. Below a certain level, bone simply absorbs the load without changing shape. The forces a resting tongue creates fall well below the threshold needed to separate a fused suture or meaningfully remodel the hard palate in an adult.

The One Setting Where Tongue Posture Seems to Matter

If the adult story is discouraging for mewing enthusiasts, the childhood story is more nuanced. In young children whose palatal sutures are still wide open, the cumulative effect of oral posture appears to influence how the jaws grow. A controlled pilot study of children aged 4 to 7 with mild oral habits (like thumb sucking or mouth breathing) found that 12 months of myofunctional training, essentially guided exercises to improve lip seal, tongue posture, and nasal breathing, produced significantly greater increases in arch width compared to controls. The intervention group gained about 3.4 mm of intercanine width versus about 1.9 mm in controls, and about 2.8 mm of intermolar width versus about 1.5 mm.

10Frontiers in Pediatrics. Influence of early myofunctional training on maxillary arch development in children aged 4–7 years with mild oral habits: a controlled pilot study

Those differences are real but modest, roughly a millimeter or two of additional widening over a full year. And they occurred in very young children whose bones are still growing rapidly and whose sutures are completely open. Extrapolating from four-year-olds to twenty-five-year-olds is not supported by any evidence. The biological window for this kind of postural influence appears to narrow significantly as facial growth slows and sutures mature.

Mouth Breathing and Narrow Jaws

The strongest scientific thread supporting the general philosophy behind mewing, if not the specific practice, is the well-documented relationship between chronic mouth breathing and underdeveloped dental arches. Children who breathe primarily through their mouths tend to develop narrower upper jaws, deeper palates, and higher rates of posterior crossbite. A systematic review and meta-analysis found that mouth-breathing children had significantly reduced upper intercanine width and intermolar width compared to nasal breathers, along with increased palatal depth and a substantially higher frequency of posterior crossbite.

11PubMed Central. Dental arch dimension and palatal morphology in children and adolescents with mouth breathing: a systematic review and meta-analysis

The mechanism connecting airway obstruction to facial development has been studied for decades. Children with enlarged adenoids or chronic nasal obstruction often present with a characteristic set of features: increased overjet, posterior crossbite, a high-arched palate, narrow dental arches, and altered facial proportions sometimes called “adenoid facies.”

12Frontiers in Public Health. Adenoid facies: a long-term vicious cycle of mouth breathing, adenoid hypertrophy, and atypical craniofacial development

When the mouth hangs open, the tongue drops away from the palate, and the normal outward pressure it would exert during growth is lost. At the same time, the cheeks push inward without opposition, and the altered muscle balance during swallowing adds further inward forces. Over years of growth, these small imbalances add up to measurable skeletal differences.

13PubMed Central. Association between oral habits, mouth breathing and malocclusion

This is the kernel of truth mewing advocates point to: if losing tongue-to-palate contact during growth leads to narrower jaws, restoring that contact should lead to wider jaws. For children who are actively growing and whose breathing obstruction is resolved, this logic has some clinical support. For adults whose growth is complete and whose sutures are fused, the logic breaks down because the biological substrate has fundamentally changed.

What Happens to Tongue Posture After Real Expansion

An interesting finding from orthodontic research is that the tongue naturally repositions itself after palatal expansion. A study measuring tongue-to-palate distances before and after rapid maxillary expansion found that the tongue moved significantly closer to the palate after treatment, and this new position remained stable during the follow-up period.

14PubMed Central. Stability of maxillary expansion and tongue posture

This suggests that tongue posture is partly a consequence of palatal shape, not just a cause of it. When the palate is narrow, the tongue has nowhere to go and drops down. When expansion creates space, the tongue fills it. This flips the mewing narrative on its head: rather than tongue posture driving palatal width, the relationship may run more strongly in the other direction, at least in adults. You might get better tongue posture by fixing the narrow palate first, rather than hoping tongue posture will fix the narrow palate on its own.

The Evolutionary Backstory

Mewing communities often invoke an evolutionary argument: our ancestors had wider jaws and better-aligned teeth because they chewed tougher, less processed food. This part of the claim has solid research behind it. Animal experiments have shown that subjects raised on cooked, soft food had roughly 10% less growth in the lower and posterior portions of the face compared to those raised on raw food, with chewing strain measured at nearly double in some areas when processing raw versus cooked diets.

15Journal of Human Evolution. Effects of food processing on masticatory strain and craniofacial growth in a retrognathic face

Studies of human skull morphology across the agricultural transition have confirmed that shifts toward softer diets are associated with changes in skull shape consistent with reduced mechanical loading. The effects were most pronounced in populations that adopted dairying, where dietary softness was greatest.

16PubMed Central. Changes in human skull morphology across the agricultural transition are consistent with softer diets in preindustrial farming groups

The evolutionary evidence supports the broader claim that mechanical loading during growth shapes the face. But “during growth” is doing a lot of work in that sentence. These skeletal differences develop across an entire childhood of different dietary habits, driven by the repeated high-strain forces of chewing, not by the gentle resting pressure of a tongue. And they describe population-level changes across generations and lifetimes, not the kind of personal transformation that a twenty-something can achieve by changing their tongue posture for six months.

Risks of Aggressive Tongue Posture

While passively resting your tongue on the roof of your mouth is unlikely to cause harm, actively pressing hard against the palate is a different story. Research on anterior bite opening in adults has identified sustained tongue pressure as one possible contributing factor. In a study of adults who developed an open bite (where the front teeth no longer meet), tongue pressure was listed among the potential causes, and the majority of participants reported symptoms like orofacial pain, headaches, and jaw joint clicking.

17PubMed Central. Anterior Bite Opening in Adulthood

The concern is not that gentle tongue contact will wreck your bite. Rather, some mewing practitioners describe pressing as hard as they can against the palate for hours at a time, sometimes developing jaw soreness, headaches, or changes in how their teeth meet. The tongue is strong enough to push teeth around, especially front teeth, even if it cannot move bone. Chronic forceful tongue thrusting is a recognized cause of orthodontic relapse and dental misalignment. Someone who mews aggressively might not get a wider palate but could get a worse bite.

Skeletal Expansion With Screws Versus Posture Without Them

MARPE has emerged as a genuinely exciting development for adults with narrow palates, and it is worth understanding how it contrasts with the mewing claim. The device uses four small titanium screws inserted into the palatal bone, with an expansion mechanism connecting them. Turning the screw generates enough force to gradually crack the midpalatal suture open, even in adults with significant fusion. Three-dimensional imaging confirms that this produces real skeletal change: the maxillary bones separate, the nasal cavity widens, and the dental arch expands.

18PubMed Central. Three-Dimensional Evaluation of Skeletal and Dental Effects of Treatment with Maxillary Skeletal Expansion

Even with screws anchored directly into bone, complications can occur. Age significantly increases the odds of problems, and some degree of relapse happens over time as the bone and teeth settle into new positions.

8PubMed Central. Success and complication rate of miniscrew assisted non-surgical palatal expansion in adults – a consecutive study using a novel force-controlled polycyclic activation protocol

Literature reviews describe MARPE as less invasive than surgical expansion and note benefits for breathing in people with obstructive sleep apnea, though challenges like asymmetrical expansion remain.

19SVOA Dentistry. The Success of Miniscrew-Assisted Rapid Palatal Expansion (MARPE) in Adult Orthodontics: A Literature Review

If you are an adult with a genuinely narrow palate causing dental crowding, crossbite, or breathing issues, evidence-based options exist. MARPE or surgically assisted expansion can produce measurable, verified skeletal change. Mewing cannot make the same claim. The gap between the two approaches is not one of degree but of kind: one delivers forces sufficient to overcome fused bone, the other delivers forces that bone barely registers.

Why Before-and-After Photos Seem Convincing

The mewing community thrives on photographic evidence, and it is worth understanding why those photos can look so compelling despite the absence of clinical data. Facial appearance changes substantially with body composition; losing even a modest amount of fat sharpens the jawline and makes cheekbones more visible. Posture changes also alter facial appearance on camera: holding your head upright with your chin slightly tucked (which mewing instructions typically encourage) pulls the skin taut under the jaw and makes the mandible look more defined. Lighting direction and camera lens focal length can reshape facial proportions dramatically in photos.

For teenagers, the most obvious confound is normal growth. Males in particular undergo significant facial development between ages 15 and 25, including forward growth of the chin, widening of the cheekbones, and thickening of the brow ridge. A teenage boy who starts mewing at 16 and takes a comparison photo at 20 has experienced four years of testosterone-driven facial maturation. Attributing those changes to tongue posture rather than puberty requires controlled evidence that does not exist.

None of this means every person sharing mewing photos is being dishonest. Many genuinely believe the practice helped them. But personal conviction is not evidence, and the human capacity for attributing changes to the wrong cause is enormous. Without standardized imaging, controlled groups, and blinded assessments, before-and-after photos tell you almost nothing about whether mewing caused the changes shown.