Nasal breathing is the intended and healthier method of respiration, filtering, warming, and humidifying the air before it reaches the lungs. Chronic mouth breathing, which involves bypassing the nasal passage, signals an underlying issue that can influence physical structure, especially during the years of rapid growth. Scientific evidence suggests that the manner in which a person breathes has a profound influence on the growth pattern of the craniofacial complex. This phenomenon is driven by the dynamic balance of muscular forces within the mouth and face. This article explores the scientific link between chronic mouth breathing and changes in jaw and face shape.
The Role of Tongue Posture in Craniofacial Development
The tongue’s resting position is a primary determinant of how the upper and lower jaws develop. When breathing correctly through the nose, the tongue naturally rests against the entire roof of the mouth, or the palate. This position creates a constant, gentle internal pressure that acts as a natural orthopedic expander for the upper jaw, known as the maxilla. This pressure encourages the maxilla to grow wide and forward, which in turn supports the lower jaw, or mandible, allowing it to achieve its full, forward-projecting potential. A broad, well-developed maxilla provides the necessary space for all the teeth to align properly.
Chronic mouth breathing requires the lips to remain open, which forces the tongue to drop away from the palate to the floor of the mouth to clear the airway. This downward shift removes the essential outward and forward scaffolding pressure from the maxilla. Without the tongue’s influence, the upper jaw is subjected only to the inward pressure from the cheeks and facial muscles, leading to restricted growth. This imbalance of muscular forces is the mechanism that fundamentally alters the growth trajectory of the entire facial structure.
Specific Structural Changes Linked to Mouth Breathing
The absence of the tongue’s expansive pressure leads to a series of identifiable structural alterations in the face and jaw, particularly in children whose bones are still forming. The upper jaw can become narrow, leading to what is known as a high or vaulted palate. This lack of lateral growth creates a lack of space, often resulting in dental crowding and various forms of malocclusion, or misaligned bites.
The mandible is also affected because the tongue’s low posture forces the jaw to rotate downward and backward. This backward rotation can lead to a less defined jawline and a tendency toward a receding chin, a condition technically termed retrognathia. When the jaw rotates in this manner, it also increases the vertical height of the face, contributing to a characteristic known as “long face syndrome.” These changes are often accompanied by an inability to comfortably seal the lips, creating a perpetually open-mouthed appearance.
Common Causes of Chronic Mouth Breathing
Chronic mouth breathing is rarely a conscious choice; it is typically an adaptation to a physically obstructed airway. The body defaults to breathing through the mouth when it cannot get sufficient air through the nose. One of the most frequent causes, especially in children, is the enlargement of the adenoids or tonsils, which are lymphoid tissues located at the back of the throat and nasal cavity.
Other common physical obstructions include chronic allergies or persistent colds that lead to nasal congestion and inflammation. Structural issues within the nose, such as a deviated septum or nasal polyps, can also physically block the nasal passages. Once an obstruction is resolved, the habit of mouth breathing may persist due to poor muscle memory and weakened oral posture. In these cases, the mouth breathing has become a learned behavior, even when the nasal airway is clear.
Addressing and Correcting Mouth Breathing Habits
Correction of chronic mouth breathing requires a multi-pronged approach that first addresses the underlying cause of the nasal obstruction. An Ear, Nose, and Throat (ENT) specialist can determine if enlarged tonsils, adenoids, or a deviated septum are physically blocking the airway. Surgical intervention may be necessary to remove these tissues or correct structural abnormalities to open the nasal passage for airflow.
Once the physical airway is clear, the focus shifts to retraining the muscles of the face and mouth through a program called myofunctional therapy. This therapy involves a series of personalized exercises designed to strengthen the tongue and facial muscles and establish a proper oral rest posture. The goal is to condition the individual to maintain lip closure, breathe through the nose, and keep the tongue resting on the palate. For structural changes that have already occurred, an orthodontist may intervene with treatments like palatal expansion to widen the maxilla and create space for the tongue and teeth.