The maxilla, or upper jaw, is a foundational bone of the face, composed of two separate bones that fuse together during development. It provides the structural support for the midface and plays a significant part in the overall architecture of the face. The maxilla forms the upper jaw, houses the upper teeth, and separates the nasal cavity from the oral cavity. Its position and size influence not only appearance but also functions like chewing and breathing.
This bone is centrally located, connecting with several other facial structures. It forms part of the floor of the orbit, which houses the eyes, and the walls of the nasal cavity. Within the body of the maxilla are the maxillary sinuses, which are air-filled cavities that reduce the weight of the skull and contribute to voice resonance.
Postural and Myofunctional Techniques
Myofunctional therapy focuses on the relationship between the muscles of the face and mouth and how their function can influence facial growth and dental development. The techniques involved center on training the muscles to function properly during resting, swallowing, and speaking.
A popular concept within this field is maintaining proper tongue posture, sometimes referred to as “mewing.” This involves consciously keeping the entire tongue pressed against the roof of the mouth, or palate, with the lips sealed and breathing occurring through the nose. The theory suggests that the gentle, constant pressure from the tongue can stimulate the expansion of the palate.
Beyond tongue placement, the act of chewing can also be a factor. A diet that includes tough, fibrous foods requires more vigorous chewing, which in turn engages the masticatory muscles more intensely. This increased muscular activity is thought to provide the necessary mechanical stimulation for bone growth in the jaws.
The effectiveness of these techniques, particularly in fully grown adults, is a subject of scientific discussion. While myofunctional therapy is applied in clinical settings to address issues like incorrect swallowing patterns, its ability to alter the bone structure of the maxilla in adults is not definitively established. Overall body posture may also play a role, as the alignment of the head and neck can affect jaw position and muscle tension.
Orthodontic Expansion and Realignment
Orthodontic interventions offer clinical methods for directly influencing the width and position of the maxilla, especially before skeletal maturity is reached. These treatments use specialized appliances to apply force to the bone and teeth, guiding growth and correcting alignment issues. The primary goal is often to address a narrow upper jaw, which can cause dental crowding and bite problems.
A common appliance used for this purpose is the palate expander. A Rapid Palatal Expander (RPE) is fixed to the upper molars and has a screw in the center. When the screw is turned, it pushes the two halves of the maxilla apart at the mid-palatal suture, the line where the bone is joined. This process stimulates new bone to form in the gap, effectively widening the upper jaw.
For older adolescents and adults whose suture is already fused, a Miniscrew-Assisted Rapid Palatal Expansion (MARPE) device may be used. This appliance is similar to a traditional expander but is anchored directly to the bone of the palate with small surgical screws. This direct anchorage allows for more effective force transfer to the bone, making it possible to separate the suture even after it has started to fuse.
Braces and other orthodontic appliances also improve the relationship between the upper and lower jaws. By moving the teeth into their correct positions, orthodontists can improve the bite and the overall facial profile. While braces primarily act on the teeth and the bone that holds them, their effects can lead to a more harmonious jaw alignment.
Surgical Correction
For adults with significant discrepancies in jaw size or position, orthognathic surgery provides a method for correction. This surgery is considered when jaw growth is complete and orthodontics alone is insufficient to resolve functional or aesthetic issues. The procedures are performed by oral and maxillofacial surgeons to realign the jawbones.
A primary surgical procedure for repositioning the upper jaw is the Le Fort I osteotomy. During this procedure, a horizontal cut is made in the bone of the maxilla above the level of the teeth. This allows the surgeon to detach and move the entire upper jaw—including the palate and all the upper teeth—as a single unit. The jaw can then be repositioned forward, backward, up, or down to achieve the desired alignment.
Candidates for this surgery often present with conditions such as a severe underbite, where the lower jaw protrudes past the upper jaw, or a significant open bite, where the front teeth do not meet. It can also address a retrusive, or set-back, mid-face, which can affect both appearance and breathing. The repositioned bone is secured in its new location with small titanium plates and screws.
The goal of orthognathic surgery is to correct the underlying skeletal issue, leading to an improved bite, better function, and a more balanced facial appearance. The surgery is carefully planned using advanced 3D imaging to ensure precise results.
Developmental Considerations in Childhood
The development of the maxilla is significantly influenced by various factors and habits during childhood.
Chronic mouth breathing is one of the factors that can negatively impact maxillary development. When a child consistently breathes through their mouth instead of their nose, the tongue is typically held in a low position, away from the palate. This lack of pressure from the tongue can lead to the development of a high, narrow palate and a narrower overall facial structure. This may also be associated with dental crowding.
Prolonged habits such as thumb sucking or excessive pacifier use, particularly beyond the age of three, can also affect the growth of the upper jaw. The constant pressure from a thumb or pacifier can push the front teeth forward and narrow the arch of the maxilla. This can result in an open bite, where the front teeth do not overlap, or a crossbite, where the upper teeth sit inside the lower teeth.
Certain early life experiences are thought to promote healthy maxillary growth. Breastfeeding, for instance, requires a different and more vigorous sucking action than bottle-feeding, which engages the facial and jaw muscles more intensely. A diet that requires children to chew their food thoroughly can also stimulate the growth of the jawbones, helping to ensure there is adequate space for all the adult teeth to erupt properly.