The cheekbone, or zygomatic bone, is a paired facial bone that forms the prominence of the cheek and contributes to the structure of the eye socket. Most people notice subtle differences between the left and right sides of their face, and observing that one cheekbone appears higher than the other is common. Facial asymmetry, where the two sides do not perfectly mirror each other, is the norm in the human population. Understanding the variety of factors—from inherent biological programming to long-term habits—helps explain why your zygomatic bones may sit at different heights.
How Normal Development Causes Variation
Perfect bilateral symmetry is rare in human biology, as the face naturally develops with slight, random variations. These minor differences in bone and soft tissue development are called fluctuating asymmetry and are a normal part of the genetic blueprint. Genetic factors establish the foundational structure of the face, influencing the size and shape of bones, including the zygomatic complex. Subtle variations in facial bone and muscle development are often inherited traits.
The growth process itself can introduce asymmetry through varying mechanical pressures during developmental years. Studies using three-dimensional imaging show that the zygomatic bones typically display a slight deviation from perfect symmetry. This minor asymmetry in the facial skeleton is inherent, usually involving differences of only a few millimeters, and represents natural variation.
Lifestyle Factors That Influence Asymmetry
Many asymmetries are acquired through repetitive daily habits that place uneven stress on the facial structure. A consistent dominant sleeping position, such as favoring one side of the face against a pillow, is a common factor. Long-term pressure exerted during sleep can compress soft tissues and potentially influence the underlying bone remodeling of the cheek area. This uneven pressure can cause one side of the face to appear flatter or less defined than the other.
Habitual chewing patterns also contribute significantly to muscle and bone development. Favoring one side while eating leads to increased use and subsequent hypertrophy (enlargement) of the masseter and temporalis muscles. Over time, this difference in muscle mass can make the cheek and jawline on the dominant side appear fuller or more robust. Consistently resting the chin or cheek on one hand can also apply sustained, localized force that subtly affects the alignment of the jaw and surrounding soft tissue.
Structural Issues and Underlying Medical Causes
More pronounced cheekbone asymmetry can result from underlying structural or medical conditions affecting the facial skeleton and muscular attachments. Past facial trauma, even if minor, can lead to permanent asymmetry if the zygomatic arch or surrounding bones healed improperly. Fractures in the zygomatic bone can result in a flattened cheek appearance on the injured side, making the opposite cheekbone appear higher. This skeletal misalignment often requires detailed imaging for diagnosis.
Dental malocclusion (misalignment of the bite and teeth) also has a direct mechanical effect on the facial skeleton. Conditions like a crossbite or overbite can force the jaw to shift laterally to achieve a comfortable bite position. This chronic, off-center jaw alignment gradually affects the position of the maxilla, which articulates with the zygomatic bone, creating an uneven skeletal foundation.
Temporomandibular Joint (TMJ) Dysfunction
TMJ dysfunction is another common source of asymmetry, as chronic tension or misalignment in this joint affects the entire jaw complex. TMJ disorders often cause chronic muscle tension, leading to uneven development in the chewing muscles and pulling the facial structure unevenly. In rare cases, severe asymmetry is due to congenital conditions such as hemifacial microsomia, where one half of the face, including the jaw, ear, and soft tissues, is underdeveloped from birth.
When to Consult a Specialist
While mild facial asymmetry is normal, consulting a specialist is advisable if you observe certain warning signs. Professional evaluation is warranted if the asymmetry has a sudden onset, changes rapidly, or is accompanied by pain. Other red flags include difficulty chewing, jaw stiffness, or a sudden unevenness in your smile, which could indicate a nerve or joint problem.
The diagnostic process typically begins with a physical exam followed by advanced imaging to assess the underlying bone structure. Specialists involved can include:
- Orthodontists, who focus on bite and jaw alignment.
- Oral and maxillofacial surgeons, who address bone structure.
- Facial plastic surgeons.
Diagnostic tools like X-rays or 3D cone-beam CT scans provide a detailed view of the facial skeleton to pinpoint the exact cause of the variation. The consultation aims to establish a precise diagnosis and explore options for addressing both function and appearance.