The jaw, composed of the upper jaw (maxilla) and the lower jaw (mandible), is a dynamic structure that undergoes continuous changes throughout life. While often perceived as static once fully developed, the bony framework, dental components, and surrounding soft tissues all change significantly with age. These alterations are deep structural modifications that affect facial profile and function. The transformation involves bone resorption, dental movements, and the dynamics of facial fat and skin.
Changes in Mandibular and Maxillary Bone Density
Bone remodeling becomes unbalanced with age, leading to a net loss of bone mass known as resorption. This loss of skeletal volume occurs in both the maxilla and the mandible, reducing structural support for the lower face. Studies have demonstrated a measurable decline in the jaw’s volume over time, affecting lower face and neck aesthetics.
In the mandible, the angle between the vertical and horizontal parts increases markedly with age. This change, combined with a decrease in the height of the vertical part (ramus), causes the jaw to appear less defined and potentially shorter. The loss of teeth dramatically accelerates bone atrophy in the alveolar ridge, the part of the jawbone that holds the tooth sockets. Without stimulation from the teeth roots, the alveolar bone resorbs faster, reducing the height and projection of the jaw in those areas.
The maxilla also experiences bone resorption, particularly in the mid-face area, contributing to a receding or flattened upper jaw. Although overall bone volume decreases, volumetric bone mineral density (vBMD) in the mandible may increase in some areas until age 50 before declining. The cumulative effect of these skeletal changes is a reduction in chin projection and a loss of underlying support for facial soft tissues.
How Teeth Shift and Affect Your Bite
Teeth undergo continuous movement and wear throughout life, leading to significant alterations in the bite (occlusion). Teeth can continue to drift and shift into adulthood, often resulting in increased crowding, particularly in the lower front teeth. This crowding occurs due to the cumulative pressure exerted by surrounding soft tissues, such as the lips and cheeks.
Changes in the upper jaw can sometimes lead to the formation of small gaps between the front teeth, known as a diastema. Daily use causes attrition on the chewing surfaces of the teeth, gradually reducing their height. This loss of vertical dimension changes how the upper and lower teeth meet, which can cause the bite to deepen over time.
Changes in the bite are frequently compounded by gum recession, which is common with age and can be exacerbated by periodontal disease. As gum tissue recedes, the roots of the teeth are exposed, making the teeth appear longer. When the alignment between the dental arches is disrupted, it creates malocclusion. This misalignment can lead to discomfort in the temporomandibular joint (TMJ), affecting function and causing symptoms like jaw pain or headaches.
The Appearance of the Aging Jawline
Visible changes to the jawline are a direct consequence of underlying bone and dental changes combined with the aging of soft tissues. The skin loses structural components like collagen and elastin, resulting in a loss of elasticity and increased laxity. This laxity causes the facial envelope to drape and sag over the reduced bony framework.
Fat pads in the mid-face begin to atrophy or migrate downward due to gravity and loss of structural support. This downward movement, coupled with the reduced volume of the mandible and chin, leads to the formation of jowls. Jowls are the drooping skin and fat that accumulate below the chin and jawline, blurring the sharp angle of a younger profile.
The combination of a reduced underlying bony structure and the drooping of soft tissue creates a less sculpted appearance. The loss of bone volume means the skin has less surface area to stretch over, which amplifies the visible effects of skin laxity. The jawline transitions from a taut, crisp line to a softer, more blended contour between the face and the neck.