What Is the Articular Eminence?
To understand how the articular eminence changes with age, it is first essential to grasp its purpose. The articular eminence (AE) is a bony prominence on the temporal bone of the skull, located just in front of the mandibular fossa. Together with the condyle of the mandible (lower jaw), it forms the temporomandibular joint (TMJ), which acts as a hinge, allowing the jaw to move up and down and side to side. The slope, or inclination, of the AE is a critical factor that guides the forward and downward movement of the condyle when you open your mouth widely or push your jaw forward. Its shape is a major determinant of how the jaw functions and is susceptible to various influences over a lifetime.
The Journey from Development to Maturity
The articular eminence is not present at birth, developing almost entirely postnatally under the influence of growth hormones and functional stresses. In fact, it undergoes rapid development during childhood and adolescence. Studies have shown that the AE's inclination increases significantly during these formative years, reaching up to 90% of its adult value by around age 20 and full maturity by age 30. This initial period of steepening is a preparation for the mechanical loads of adult masticatory function.
Aging vs. Functional Remodeling
For decades, it was believed that the flattening of the articular eminence was a direct result of the natural aging process. However, modern research paints a more complex picture, suggesting that functional factors play a far more significant role than chronological age in isolation. The TMJ is a load-bearing joint and constantly undergoes a process of remodeling to adapt to mechanical demands, even into older age.
The Impact of Missing Teeth
One of the most profound functional factors influencing the AE's morphology is the loss of teeth, known as edentulism. When teeth are missing, the distribution of masticatory (chewing) forces changes dramatically, leading to a loss of occlusal support. This alters the biomechanics of the TMJ and can trigger significant remodeling of the AE, often resulting in a flatter incline. The flattening is a direct response to the altered functional demands on the jaw. This explains why studies have found significant AE flattening in edentulous older adults compared to those of similar age who have maintained their occlusal support zones.
Comparing Age-Related and Functional Changes
| Feature | Physiological Aging Alone | Functional Changes (e.g., Tooth Loss) |
|---|---|---|
| Primary Cause | Natural tissue degradation, slower cellular processes | Altered mechanical forces on the joint |
| Effect on AE Slope | Subtle or no significant change in healthy individuals | Significant flattening in the posterior slope |
| Timeline of Change | Slow, gradual over a lifetime | Can be accelerated by major dental events |
| Impact on TMJ | Reduced fibrocartilage resilience; less notable bony changes | Bone remodeling, degenerative joint disease, potential TMJ dysfunction |
Degenerative Joint Disease and the Articular Eminence
The cumulative effect of lifelong mechanical stresses and functional changes can lead to degenerative joint disease (DJD) in the TMJ, which is more common with increasing age. In individuals with DJD, radiographic changes in the articular eminence, including flattening, erosion, and sclerosis, are frequently observed. This highlights that while age is a risk factor, it's often the associated pathological processes, such as degenerative wear and tear, that drive the most noticeable changes in the AE's shape.
Factors That Exacerbate Change
Several factors can worsen the remodeling effects and accelerate changes to the articular eminence, including:
- Bruxism: Chronic teeth grinding or clenching places excessive force on the TMJ, accelerating wear and tear.
- Trauma: Injuries to the jaw or head can damage the joint and affect its biomechanics.
- Hormonal Changes: Fluctuations in hormones, especially estrogen, may play a role in TMJ degeneration, particularly in women.
- Systemic Conditions: Autoimmune diseases or other systemic issues can affect joint health and remodeling.
What Can Be Done to Mitigate Changes?
While you can't stop the physiological process of aging, you can manage the functional and degenerative factors that impact your articular eminence. Maintaining good oral and dental health is a cornerstone of this effort. Promptly replacing missing teeth with prosthetics, such as implants or bridges, can help preserve occlusal support and prevent the negative remodeling effects seen in edentulous patients. Additionally, using a mouthguard to protect against bruxism can alleviate excessive strain on the TMJ. Physical therapy for the jaw, stress management techniques, and a healthy lifestyle can also support overall joint health and function. For personalized advice, a dental or oral health professional can assess your specific situation and recommend a tailored management plan.
Conclusion
In summary, the question of whether the articular eminence change with age is nuanced. While physiological aging does involve subtle changes and a reduced capacity for repair, it is often the functional stressors and pathological conditions, like tooth loss and degenerative joint disease, that drive the more significant morphological changes, particularly the flattening of its slope. By focusing on mitigating these controllable factors through proper dental care and lifestyle habits, individuals can help preserve the health and function of their temporomandibular joint as they get older.
