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Over time the corner of the mouth can turn down and the marionette lines can become more pronounced. Injecting in the depressor anguli oris relaxes this muscles which pulls the corner of the mouth down and allows for the muscles which lift the corner of the mouth to act more positively.
This area is often better treated in combination with fillers in the marionettes/corners of mouth and also in the cheek to stretch certain muscles to pull the corners up.
Injections are placed in the depressor anguli oris muscle in two separate spots, one either side of the midline.