A teenager cannot physically shove their maxilla forward with muscle force alone. But clinical research confirms that the strength and tonicity of the elevator chewing muscles, the masseter and temporalis, heavily dictate the transverse growth of the maxilla and the upward rotation of the face during puberty.
Chewing helps, but only as a daily routine rather than a casual habit.
Why resistance matters, and why it isn't about hardness
In a young person, the right amount of chewing resistance, consistently applied through medium-hard gum, provides the mechanical stimulation needed to build masseter tone, which in turn supports a wider maxilla. But the jaw joints are still growing, so common sense in selecting the gum's density is crucial to avoid injury.
That matters more now than it used to. So many people today start from a higher baseline risk of jaw joint problems, because craniofacial dystrophy is widespread for cultural and environmental reasons. The muscle force of an average person today is likely well below the natural baseline.
Because of that lower starting point, increased loading does not mean crazy hard biting. In today's world it simply means more normal chewing.
Medium-hard gum, whether that's a denser and more voluminous standard gum or a thoughtfully calibrated hard gum, offers distinct advantages over both typical soft commercial gums and ultra-hard facial fitness gums.
Chewing gum in that range provides enough resistance to trigger mild masseter thickening and increase biting force, which encourages the bones to adapt. More importantly, it increases the endurance tonicity of the chewing muscles, so they retain the capacity to keep the mandible elevated effortlessly and maintain correct oral posture at rest, day and night.
On joint safety, that range creates a safe middle ground. Ultra-hard gums and rubber jawline training blocks put immense structural stress on a growing jaw and can widen the lower face sideways rather than producing a defined look. Medium resistance is far less likely to cause joint displacement or damage teeth.
Two mechanisms, not one
The mechanical forces from regular, sustained chewing signal the maxillary sutures to remain active, which assists in the development of a broader maxilla: a broader palate, more room for straight teeth, and more room at the floor of the nose.
During the early teenage years the facial skeleton is still highly adaptable. Strong, well-toned elevator muscles influence the maxilla through two biological mechanisms:
- Sustained masticatory load stimulates maxillary suture growth, which widens the palate.
- Upward mandibular rest posture promotes counter-clockwise rotation, which gives a shorter, more defined face.
The maxilla connects to the rest of the skull by fibrous joints called sutures, which don't fully fuse until late adolescence, and in some people much later. Stronger chewing muscles create high mechanical loading on the jaws. That tension signals the body to increase bone apposition at the sutures, resulting in a wider maxilla and a broader dental arch. The changes are not major, but where facial structure and airway are concerned, a gain of a few millimetres can matter.
Which way the face rotates
People with weak elevator muscles often show a clockwise growth pattern, where the lower jaw and the tongue muscles attached to it drop open at rest, causing the face to grow long and narrow. This is the long face pattern, sometimes called adenoid face.
Keeping the mandible held up securely at rest promotes the opposite: an anterior, counter-clockwise growth rotation. That pushes the midface to develop forward with real three-dimensional depth, rather than recessed and downward.
Picture a profile facing right. An anticlockwise uplift is what you want. The opposite is a face pulled downward by gravity because nothing is holding it up: no toned elevator muscles, no correct tongue posture, no closed lips at rest. That produces the long face look, with a set of subtle but damaging effects on breathing.
Why resting posture matters more than hard chewing
Toning the chewing muscles is only half the battle. The structural shape of a young face is determined by the resting position held 23 hours a day, not the 30 minutes spent chewing food.
If a teenager builds strong elevator muscles but still rests with an open mouth, the mandible hanging low, teeth apart and tongue sitting at the bottom of the mouth, the benefit is lost entirely. To actually guide maxillary growth, those toned muscles have to hold a closed-mouth posture subconsciously and almost effortlessly. That's what the tone is for.
Three steps to support jaw growth safely
- Maintain lip seal, tongue seal, and upward mandibular rest. Lips gently touching, teeth lightly in contact at rest. This guides the mandible into the correct position against the maxilla.
- Breathe through the nose, strictly. Many people don't realise they're partially mouth breathing, which happens whenever the lips are apart and the tongue is off the palate. Even partial mouth breathing undermines muscle tone and pulls the jaw down, in a cycle that feeds itself. Nasal breathing lets the tongue rest on the roof of the mouth, where it acts as a gentle but constant internal expander for the maxilla.
- Chew everything thoroughly, and choose food with more texture. Rather than rubber bite blocks, build tone by chewing unprocessed food properly, at least 20 times per bite, or by using denser, more voluminous gum.