Botox is an effective treatment for reducing a prominent, disproportionate, or asymmetric jaw line caused by hypertrophic (enlarged) muscles of mastication. These muscles along the posterior jaw are used to chew and clench the teeth, and are commonly enlarged if you clench or grind your teeth while sleeping. Non-surgical jaw reduction with Botox is a temporary solution for those who would like to smooth a sharp jaw line contour from squared to a more feminine oval shape. The treatment works by reducing the size of the muscles injected, thereby smoothing the facial contour Results may last approximately eight months, which is longer than the average duration for the most commonly treated facial Botox areas (i.e. frown lines, forehead, and crowsfeet, which last an average of three to four months). It is important to note that this treatment is only effective on patients with enlarged jaw muscles; it will not change a squared jaw line that is defined by a squared jaw bone. If this is the case, surgical intervention would be required.