Maxillary bone resorption: The skeletal foundation of facial aging
While we often associate facial aging with skin sagging and wrinkles, modern research has shown that changes to the underlying bone structure are a primary driver of these aesthetic shifts. The maxilla, the central bone of the midface, is particularly susceptible to age-related bone resorption, a process where old bone is broken down faster than new bone is created. This selective resorption affects key areas of the midface, leading to a cascade of changes that redefine facial contours over time.
The mechanism of maxillary bone resorption
The maxilla's journey through life begins with growth and development, but eventually, the balance shifts toward resorption. Unlike earlier beliefs that suggested constant expansion, 3D imaging studies demonstrate that the adult facial skeleton undergoes selective remodeling. This remodeling is not uniform and particularly impacts the areas of the maxilla that are subject to lesser biomechanical stress or have different developmental origins, such as the dental regions. The rate and extent of these changes vary among individuals and can be influenced by factors such as sex and lifestyle.
Maxillary changes and their visible impacts
Resorption in the maxilla contributes directly and indirectly to the most common signs of facial aging. The loss of bony projection means the overlying soft tissues are no longer adequately supported, causing them to drape, fold, and gather in new ways.
- Midface retrusion: As the maxilla and other midface bones recede and flatten, the entire central portion of the face loses its forward projection. This contributes to a flatter, less convex facial profile.
- Deepened nasolabial folds: One of the most noticeable effects is the deepening of the nasolabial folds. Bone loss, especially around the lower piriform aperture and maxillary wings, reduces the skeletal support for the nose and upper lip, causing the tissues to descend and the folds to become more prominent.
- Orbital enlargement: The eye sockets (orbits) widen and increase in size as the bone around the superomedial and inferolateral orbital rims resorbs. This makes the eye appear more deep-set or hollow and can contribute to crow's feet and drooping eyelids.
- Changes to the nose: The weakening support from the maxilla and piriform aperture causes the tip of the nose to droop and the nose to appear longer with age.
- Dental and smile changes: Maxillary bone resorption affects dental alignment and the appearance of the smile. Studies have found a decrease in maxillary incisor exposure with age due to these changes.
Comparison of maxilla aging: dentate vs. edentulous individuals
Tooth loss, or edentulism, significantly accelerates the aging process of the maxilla. This is because the biomechanical forces of chewing stimulate bone, and without teeth, this stimulation ceases, leading to accelerated alveolar bone loss.
| Feature | Dentate Individuals (With Teeth) | Edentulous Individuals (Toothless) |
|---|---|---|
| Maxillary Resorption | Gradual, selective resorption over decades. | Rapid and pronounced, especially in the alveolar process. |
| Maxillary Height | Decreases slowly with age. | Significantly lower due to accelerated bone loss. |
| Orbital Changes | Eye sockets widen with age due to bone resorption around the rim. | Orbits are wider compared to dentate counterparts in the same age group due to enhanced skeletal changes. |
| Facial Profile | Gradually flattens as the maxilla recedes. | Becomes much flatter and more retruded due to jawbone atrophy. |
| Soft Tissue Impact | Creates subtle sagging and deepened folds over many years. | Results in more pronounced facial sagging, deeper wrinkles, and loss of lip support. |
The influence of other factors on maxillary bone aging
While age is the primary factor, other elements can impact the rate and severity of maxillary changes. Menopause, for example, is associated with decreased maxillary bone density in women. Masticatory forces play a critical role; individuals with a coarser diet in historical populations showed slower rates of resorption, suggesting that chewing forces help maintain bone density. Additionally, congenital skeletal inadequacies can predispose individuals to manifest signs of aging prematurely due to less initial bone support.
The periosteum and ligament alterations
Age-related changes in the maxilla also affect the periosteum, the membrane covering the bone. As the bone recedes, the periosteum retrudes, which in turn alters the position of facial ligaments and muscle attachments. This shift can reduce the mechanical advantage of facial muscles and retaining ligaments, further contributing to soft tissue descent and sagging.
Aesthetic and clinical implications
Understanding how the maxilla changes with age has revolutionized facial rejuvenation. Rather than focusing solely on lifting sagging soft tissues, modern approaches also address the underlying skeletal deficiencies. By restoring bone projection with implants or fillers in specific areas of the midface, plastic surgeons and dermatologists can achieve more harmonious and natural-looking results.
Conclusion: The dynamic foundation of the aging face
The maxilla is far from a static structure; it is a dynamic component of the craniofacial skeleton that undergoes significant, albeit gradual, changes throughout life. The process of selective bone resorption, exacerbated by factors like tooth loss, fundamentally alters the framework of the midface. This leads to predictable shifts in facial contours, affecting the appearance of the eyes, nose, cheeks, and mouth. By recognizing the critical role of these skeletal changes, healthcare professionals can better diagnose the root causes of facial aging and develop more effective, long-lasting rejuvenation strategies. The interplay between bone, fat, and skin illustrates that truly addressing the effects of time requires an approach that considers the face from the inside out.
Electronic supplementary material for Mendelson and Wong paper featuring skeletal animations
