Turning a sad smile into a happy smile can be done with botulinum toxin. The depressor anguli oris is the muscle that pulls the corners of the mouth when you frown. Botox injections in this area can relax the muscle enough to enable the elevators to subtly lift/re-position the corners of the mouth in a more cephalad position to resume their normal contour.
Botulinum toxin is best injected at the insertion point of the muscle near the corner of the mouth. I ask patients to show me their lower teeth or say the letter “E”, to allow visualization of the bulge of the depressor anguli oris muscle. If a second injection is required, it is best placed lower along the border of the mandible. When the botulinum toxin relaxes this muscle the corner of the mouth is elevated by approximately 1-2 millimeters and can improve a sad face appearance. These injections may also minimally help the appearance of marionette lines.
A misplaced botulinum toxin injection when treating the depressor anguli oris muscle results in an asymmetric smile (not a droop) since the botulinum toxin is misplaced and/or diffuses into the adjacent depressor labii inferioris muscle.
Gentle elevation of downturned corners of the mouth corners is possible by injecting the depressor anguli oris with botulinum toxin. The effect of the botulinum toxin lasts only about 4 months maximum. Better correction of the downturned corners often requires botulinum toxin combined with hyaluronic acid filler. This both turns the corners of the mouth and replaces lost volume in the marionette area, leading to a more dramatic result.
