The Underdeveloped Jaw and Airway Epidemic, Part 2: Mouth Breathing

Mouth breathing is more than just a habit — it’s a root cause of many developmental concerns, especially when it begins early in life. Its impact on facial growth, airway development, sleep, and overall health is significant, and yet too often overlooked.

How Proper Tongue Posture Shapes the Face and Airway

In an ideal resting state, the mouth is closed, the lips are gently sealed, and the tongue is lightly suctioned to the roof of the mouth — the palate. This proper resting posture plays a crucial role in facial and airway development.

The tongue serves as a natural scaffolding system. It gently guides the maxilla (upper jaw) to grow outward and remain shallow in height. This creates a wide, supportive palate that provides enough room for the tongue to rest, for the teeth to align properly, and for the airway to remain open and functional.

Since the hard palate extends back to become the soft palate and the throat, its width directly affects the space available in the upper airway. And the other side of the hard palate forms the floor of the sinuses — meaning that healthy palate growth also supports healthy sinus development.

Proper tongue posture also encourages lip seal — and nasal breathing. When the tongue is resting where it should, it’s generally easier for the lips to stay closed. This keeps us breathing through our nose, which is how air is naturally filtered and humidified before reaching the lungs.

What Happens When the Mouth Stays Open?

Mouth breathing almost always means the tongue is not in its proper position. Instead of supporting the palate, the tongue drops low into the mouth or floats somewhere in the middle of the oral cavity. Without the guiding pressure of the tongue, the palate grows differently — narrower, deeper, and more vaulted. The maxilla becomes longer and more constricted.

This chain reaction can lead to:

• Crowded or misaligned teeth

• Reduced space for the tongue to rest

• Difficulties with speech, swallowing, or maintaining correct rest tongue posture

• Narrower sinuses and airway

• Facial structure changes like a gummy smile

  
  

In short, chronic mouth breathing alters the entire growth pattern of the face, jaws, and upper airway — often resulting in functional issues that extend into adulthood.

Why Is Mouth Breathing So Common?

One major contributing factor is oral restrictions, or "ties" — such as tongue ties and lip ties. These are tight bands of connective tissue (fascia) that limit mobility of the tongue or lips. Scientists theorize that the addition of folic acid in fortified foods may be playing a role in heightened fascial tension, making oral ties more common today.

When the tongue is tied to the floor of the mouth, it's difficult — or impossible — for it to reach and rest in the palate. If the upper lip is restricted, achieving a full lip seal can also be difficult. Both of these challenges promote mouth breathing by default.

Tongue Substitutes and the Vagus Nerve

The tongue’s proper position also has a neurological role. Pressing against the roof of the mouth stimulates the vagus nerve, which activates the parasympathetic nervous system — helping us feel calm and grounded.

When the tongue doesn’t reach the palate, that calming stimulation is lost. This may be one reason babies and children become so attached to pacifiers or thumb-sucking — those objects mimic the tongue's contact with the palate and evoke a similar soothing response.

But over time, these objects take the tongue’s place — and can actively reshape the palate and dental arches in non-ideal ways. What begins as a coping mechanism becomes a driver of poor oral posture and jaw development.

The Health Consequences of Mouth Breathing

When we breathe through our mouths, we bypass our nasal filters and allow cold, dry, unfiltered air to hit our throat and lungs. This irritates the airway, increases inflammation, and exposes us to pollutants, allergens, and pathogens.

The more inflamed or congested we become, the harder it is to breathe through our nose — and the cycle continues. Mouth breathing becomes not just a symptom, but a self-reinforcing habit.

Perhaps most concerning is the connection between poor jaw growth and sleep quality. A narrow palate and underdeveloped jaw mean the tongue has nowhere to go at night except backward — into the airway. This is a leading contributor to sleep-disordered breathing, which includes snoring and obstructive sleep apnea.

What You Can Do

If you or your child is a mouth breather, it’s not something to ignore. A myofunctional therapist or airway-focused provider can assess tongue posture, oral restrictions, and breathing patterns to help uncover the root cause.

With proper intervention — especially when started early — it's possible to:

• Retrain tongue posture

• Support nasal breathing

• Guide proper facial and jaw growth

• Improve sleep and overall wellness