Title: Neurotoxin Application for Correcting Downturned Mouth Corners (DAO treatment)
Difficulty Level: Moderate
Patient Satisfaction: Moderate
Risk Level: Moderate
Purpose:
The application of neurotoxins to the depressor anguli oris (DAO) muscles can help lift the corners of the mouth, which often appear downturned. Typically, neurotoxins are used alone in this area, but they are usually combined with dermal fillers for enhanced results (refer to additional information in Chapter 43).
Anatomical Background:
The DAO muscle begins along the mandible’s oblique line and attaches at the modiolus. When the DAO contracts, it pulls the mouth corners downward. Inhibiting these muscles allows for an upward pull by the zygomaticus muscles, thereby lifting the mouth corners.
Injection Method:
It is advisable to administer a single injection per muscle, which patients generally tolerate well. The location of the DAO muscle should be confirmed by palpation while the patient frowns. If the muscle is not palpable, estimate its position by moving 1 cm laterally and 1 cm down from the mouth corner, and inject 2 to 5 BU or 6 to 15 DU deeply into each muscle.
Alternative Approach:
To avoid affecting nearby perioral muscles, place the injection at the lower part of the muscle. Inject just above the jawline, angled down and away from the mouth corner.
Safety Measures:
This procedure is unlikely to correct severely sagging mouth corners or marionette lines.
Post-Procedure Guidelines:
Typically, there is no special care required post-injection, and bruising is rare.
Potential Risks:
Misplacement of the injection is the primary risk, potentially impacting the adjacent depressor labii inferioris muscle, which can alter the smile. Typically, the improvements are mild, especially in cases with thicker surrounding skin.
Expert Tips:
For mild cases of downturned mouth corners, neurotoxin might suffice. For more pronounced cases, consider combining with hyaluronic acid fillers. Inform patients that the improvement will likely be subtle.
- Different injection sites.
- Our preference is the lower injection site to protect risorius.
