With age, characteristic changes occur in the central third of the face.
A youthful midface is characterized by prominent cheeks and a smooth transition between the lower eyelid and cheek. Structural, soft tissue, and skin changes develop as wrinkles and creases, progressive ptosis, and general atrophy of the structures.
Pessa confirmed the changes seen in the bony structures of the face, and these include a downward migration of cephalometric points.
The downward migration manifests as a change in soft tissue volume. The effects of gravity and repeated animation of the face also directly affect the soft tissue that overlies the mimetic musculature.
The results of magnetic resonance imaging (MRI) evaluations have helped to determine that the mimetic muscles themselves remain intact; however, the attachment to the overlying soft tissue and skin changes. The repeated action of smiling results in deepening of the nasolabial fold at the point at which the superficial musculoaponeurotic system (SMAS) inserts into the dermis.