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Masseter treatment — clenching, and a softer jawline

Privé Aesthetics 5 October 2026 ~6 min read

Two completely different people book this treatment. One has a jaw that aches by mid-afternoon and a dentist who has mentioned the word grinding. The other has looked at photographs and decided the lower third of their face has squared off. Both are treated the same way, and both should understand what they are actually signing up for.

What the masseter is

It is the muscle that closes the jaw — you can feel it bulge under your fingers at the back of the cheek when you clench. It is one of the strongest muscles in the body for its size, and like any muscle it grows with use. Chronic clenching and grinding build it, and a built masseter widens the jawline.

What treatment does

A neuromodulator placed into the muscle reduces how forcefully it can contract. Two things follow, on different timelines.

  • The functional effect — less clenching force, which usually means less jaw ache, fewer tension headaches and less wear on teeth. Most people notice this within one to two weeks.
  • The shape effect — a muscle that is contracting less loses bulk over time. The jawline softens gradually across six to twelve weeks. This is not a quick change and it should not be.
The relief arrives in a fortnight. The shape change takes three months. Judging it at week two is judging the wrong thing.Privé Aesthetics

What it does not do

It does not sharpen a jawline that is soft because of skin laxity or submental fullness — those are different problems with different answers. It does not treat the joint itself; genuine TMJ disorder is a dental and medical conversation, and while masseter treatment often reduces the load on the joint, it is not a diagnosis or a cure.

And it will not make a narrow face narrower to good effect. In someone who already has a slim lower face, reducing masseter bulk can look gaunt. We will tell you if that is you.

Dosing, honestly

This is a larger, stronger muscle than the ones treated in the upper face, and it is dosed accordingly — which also means it is a treatment where restraint matters. Overtreated, chewing tough food becomes genuinely tiring and the smile can change. Our default is conservative, reassess at two weeks, and add if it is needed. Adding is easy; waiting out too much is not.

How long it lasts

Three to four months for the functional effect, same as elsewhere. The shape change tends to hold longer once the muscle has reduced, and people often find they can stretch the interval after the first year — particularly if the underlying clenching has also been addressed with a night guard.

Worth saying

If you grind at night, treatment here helps the symptom. It does not address why you are grinding, and stress and sleep are usually part of that picture. We would rather say so than let you think a syringe solved it.

Booking

A consultation, an examination of the muscle while you clench, and a plan. If your primary complaint is pain rather than shape, tell us — it changes the assessment and it may mean a conversation with your dentist first.

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