Facial aging may be more than skin deep. Robert B. Shaw, from the University of Rochester Medical Center (New York, USA), and colleagues  reviewed 120 facial CT scans , measuring changes that occurred to facial bones over time. The team used a computer program to measure the length, width, and angle of the mandible (jaw bone), finding that the angle of the jaw increases markedly with age, which results in a loss of definition of the lower border of the face.  While jaw length decreased significantly between the young and middle age groups, the decline in jaw height from the middle to old group was significant.  As a consequence, this loss of bony volume may contribute sagging facial skin, decreased chin projection, and loss of jaw-line definition. As jaw volume decreases, soft tissue of the lower face has less support, resulting in a softer, oval appearance to the lower face and sagging skin, which also affects the aging appearance of the neck. The team hopes their discovery gives physicians new insight into procedures that may include methods to suspend soft tissue -- such as chin and cheek implants -- to rebuild the structure that time has worn away, in addition to lifting and reducing excess skin.