May 8, 2023


Dr Tim Pearce was questioned about using botulinum toxin (Botox®) in the lower face and particularly in treating the depressor anguli oris (DAO), including the potential side effects and risks from treatment. But, in answering this question, he wanted to discuss how dermal fillers can be very effective when treating a downturned mouth, explaining the positive effect that they can have on the DAO, before we all reach for the Botox.

In this blog, Dr Tim will discuss his approach to treating ‘sad face’ presentations in otherwise happy patients, and what products he uses to treat the DAO.

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Treating the depressor anguli oris (DAO) with botulinum toxin

Firstly, it is important to consider the anatomy in the lower face, and this should be covered in advanced training courses.

Injecting the DAO can be quite tricky as you build up your practice and skills. The problem occurs if you inject the botulinum toxin into the wrong place, including a little too deeply or a fraction too medially of the DAO, because then you risk hitting the depressor labii inferioris muscle; this is the muscle that allows an individual to pull their lower lip down or to the side. This results in an asymmetrical smile that appears crooked and less U-shaped because the lower lip is not pulling downwards on one side. This is very noticeable to others and can be very distressing for your patient.

Grumpy Face Wrinkles Ageing TreatmentTo avoid this, it is worth realising, from looking at the anatomy, that to the left of the DAO is a triangular area between the masseter, risorius and DAO where there is no muscle presence. Locating this triangle – using tactile feedback on your patient – will help you to locate the border of the DAO. The lower down you go on the DAO border, closer to the angle of the jaw, the more likely you are to intercept with the depressor labii inferioris again. Injections are therefore better placed in the midpoint of the DAO border that forms this triangle.

Treating this area with botulinum toxin can be less predictable and less adjustable than when using dermal fillers, notes Dr Tim. This is primarily because you must wait two weeks after product placement to see the effect, hoping that you have placed your dosing in the correct spot, and avoided asymmetry. If it works first time this is marvellous, but if not, you can get into a cycle of minor adjustments. However, it does have a cost benefit over dermal fillers, being cheaper by the amount (unit) required to treat.

Treating the depressor anguli oris (DAO) with dermal fillers

Using dermal fillers, particularly in older patients, can create a very similar effect to treatment with botulinum toxin, i.e., reducing the downturned appearance.

As we age, muscles become less supported from underneath, for two reasons, a loss of bone and a loss of fat. The underlying bone shrinks with ageing meaning the muscle can contract more readily due to a lack of resistance thanks to less stretch over the now reduced bone. Similarly, there is more movement in older faces because they also lose fat from the fat pads on top of the muscle and some from underneath. Again, this means the muscle can contract more easily with fewer obstacles in its way, creating a degree of hyper dynamic muscle activity resulting in downturned faces in an older patient cohort.

Changes in the fat pads have significant impact on the downturned nature of the face, and solving the overarching problem can be both quite complex and patient dependent. With ageing, the jowl fat pad and the lateral cheek fat pad become disproportionate, laterally becoming smaller, the middle cheek getting bigger, and the jowl fat or the nasolabial fold can also enlarge, and become heavier, pushing downwards in the area where the DAO is also pulling downwards unhindered. Depending on the presentation, it can be beneficial to replace lost fat or volume in the area using dermal filler, and if the bone is affected, deeper placement, underneath the muscle can give instant lift and support to the muscle as you emulate lost bone.

However, when treating this area of the lower face, it is not as simple as choosing between botulinum toxin or dermal filler, concludes Dr Tim. There will be occasions when a combined approach is more appropriate for your patient, so treat each one as an individual case.

Read more on this topic from Dr Tim in know your muscle anatomy to avoid side effects from Botox in the lower face and 10 negative expressions caused by facial ageing.

If you have any further questions about Botox treatments, Dr Tim would love to hear them, you can find Dr Tim Pearce on Instagram.

Botox® is a registered trademark of Allergan Aesthetics plc.

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Aesthetics Mastery Show

What Product Do I Use For The Depressor Angularis Oris (DAO)?

In this episode, Dr Tim looks at how aesthetic injectables can work in cases of a sad face on a happy person. Watch the full Aesthetics Mastery Show here.

The show has had over 28k views and over 20 comments from practitioners and patients, including:

Practitioner @idgafortunecookie, who asked:

“How deep should you inject the DAOs?”

Dr Tim’s Clinical Advisor, Mary, replied:

“This is not a deep injection.”

Another practitioner, @cap’n sean said:

“Dr Tim, thank you. I’ve been injecting DAO for a long time. Never had a problem, but I’ve noticed everyone I learn from has a differing approach to finding this injection point(s). At long last, a clear and precise explanation that I can use to teach others from. Many thanks.”

To which @drtimpearce replied:

“Glad I could help.”

BOTOX (Botulinum Toxin) and Dermal Filler eLearning Courses

If you want to increase your knowledge of popular injectable treatment techniques, Dr Tim Pearce offers two foundation courses:

Both give CPD and certificates on completion and are highly rated by our delegates.

In addition, browse our FREE downloadable resources.

Dr Tim Pearce eLearning

Dr Tim Pearce MBChB BSc (Hons) MRCGP founded his eLearning concept in 2016 in order to provide readily accessible BOTOX® and dermal filler online courses for fellow Medical Aesthetics practitioners. His objective was to raise standards within the industry – a principle which remains just as relevant today.

Our exclusive video-led courses are designed to build confidence, knowledge and technique at every stage, working from foundation level to advanced treatments and management of complications.

Thousands of delegates have benefited from the courses and we’re highly rated on Trustpilot. For more information or to discuss which course is right for you, please get in touch with our friendly team.

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