Why You Shouldn't Use the 4.5mm Tip on Your Jawline — A Doctor's Take

Shurink Jawline:

Why You Shouldn't Use the 4.5mm Tip As-Is

"As long as you get enough shots with Shurink,

your jawline will tighten up."

You've probably heard that before.

In reality, it's almost the opposite.

What determines your jawline results isn't the number of shots —

it's which tip depth was used, and how far it reached.

Even with the same 300 shots, the outcome looks completely different

between someone treated with only 4.5mm

and someone treated with a combination of 3.0mm and 4.5mm.

The bottom line.

With Shurink jawline procedures, results come down to

tip depth selection.

What makes the difference.

How far you go with 4.5mm,

and how much you blend in 3.0mm.

What we're covering today.

Why depth should come before shot count — and how to think about it.

Three Things to Take Away from This Post

• The problem with using 4.5mm directly on the jawline

• Shot count vs. depth — what actually drives results

• How to distribute tip ratios based on BMI and skin thickness

What Determines Shurink Jawline Results?

It's Not the Shot Count.

It comes down to tip depth, not the number of shots.

Shurink is a Lifting procedure that uses High-Intensity Focused Ultrasound (HIFU)

to create Thermal Coagulation Points in the Dermis and SMAS Layer.

There are three tip options: 1.5mm, 3.0mm, and 4.5mm —

each targeting a specific tissue layer.

The 1.5mm tip targets the Dermis,

the 3.0mm tip targets the superficial fat and shallow SMAS Layer,

and the 4.5mm tip targets the deep SMAS Layer.

That's precisely why the choice of tip and treatment zone

can lead to completely different outcomes.

Why Is It Risky to Use the 4.5mm Tip

Directly on the Jawline?

Key Insight from

Dr. Wi Young-jin

The skin along the jawline is thin —

firing the 4.5mm tip directly here carries a greater risk

of nerve irritation than actual benefit.

Switching to the 3.0mm tip allows you to safely

define the contour in the same area.

The common assumption that "deeper is always better with 4.5mm"

actually works in reverse when it comes to the jawline.

Unlike other facial zones, the jawline has thinner skin

and a thinner subcutaneous fat layer,

with the mandible sitting very close to the surface.

When the 4.5mm tip is fired directly,

the energy passes through the SMAS Layer and reaches the bone.

The moment it contacts bone, Pain spikes sharply —

and more importantly, there's a heightened risk

of irritating the marginal mandibular nerve running nearby.

That's why during jawline procedures,

we switch to the 3.0mm tip —

to precisely target the SMAS Layer

while minimizing the risk of nerve irritation.

Last Wednesday, a 43-year-old patient came in for a consultation.

"I had 600 shots of Shurink done somewhere else,

but my jawline barely changed. Why?"

When I examined her with ultrasound, she had relatively thin skin —

and from the previous procedure, the entire jawline

had been treated with 4.5mm only.

For patients like her, adding more shots isn't the answer.

The priority is increasing the proportion of 3.0mm

to accurately target the superficial SMAS Layer.

Dr. Wi Young-jin's Key Takeaways

• For the jawline, using 4.5mm alone

  carries more risk than benefit.

• Blending in 3.0mm allows precise SMAS targeting

  while avoiding nerve irritation.

• Even with the same 600 shots, different depth distributions lead to different results.

Shot Count vs. Depth —

Where Are Results Actually Determined?

Depth comes first. Shot count comes after.

Many patients lead with "how many shots did you use?" —

but in clinical practice, there are quite a few cases

where even a high shot count yields minimal results.

On the other hand, some patients see their jawline definition improve noticeably

with fewer shots, simply because the energy reached the right layer.

For Shurink facial contouring, a roughly equal mix

of 4.5mm and 3.0mm is the general baseline.

That said, this ratio isn't one-size-fits-all.

Patients with a higher BMI and fuller subcutaneous fat

benefit from a higher proportion of 4.5mm,

targeting both the deep SMAS Layer and the fat layer.

Patients who are leaner with thinner skin

do better with a higher proportion of 3.0mm,

precisely targeting the superficial SMAS and sub-dermal layer.

For Shurink jawline procedures, I generally recommend

spreading the sessions out — approximately 3 sessions at 3-week intervals.

Shurink works by accumulating Collagen over shorter intervals,

gradually pulling the sagging fat closer to the underlying muscle through the SMAS Layer.

Shurink Jawline —

How Is It Applied Differently for Each Patient?

Around the same time, I had a 52-year-old patient with a similar concern.

She had a higher BMI and noticeable submental fat beneath the chin.

For her, I set the ratio at 60% for 4.5mm

and 40% for 3.0mm.

The progression of results across sessions typically follows this pattern:

• Immediately after session 1 through week 2

  Temporary Swelling followed by a subtle tightening sensation

• Weeks 3–4

  Collagen remodeling begins; early jawline contour changes become visible

• After sessions 2–3 (cumulative)

  Sagging fat moves closer to the underlying muscle

• At the 6-month mark

  Contour maintained through cumulative effect

Of course, for patients with very little fat but significant sagging,

Shurink alone has its limitations.

In those cases, combining a Radiofrequency (RF) device

or corner-of-mouth Botox tends to deliver better results.

Shurink Jawline —

Three Questions I Hear Most in the Clinic

Q1. How many sessions do I need

to see noticeable jawline results with Shurink?

Honestly, there's a clear answer to this:

3 sessions at 3-week intervals.

Because Shurink works by accumulating Collagen over shorter cycles,

it's not a procedure that delivers full results in a single session.

Q2. Is the 4.5mm tip the most painful?

What kind of anesthesia is used?

You may feel a sharp, electric-like Pain

when the 4.5mm tip contacts the bone.

Topical anesthetic cream is usually sufficient,

but adding a nerve block can significantly reduce discomfort.

Q3. Are there side effects like Bruising or nerve numbness

after Shurink?

Bruising and minor Swelling are common and typically resolve quickly.

Marginal mandibular nerve irritation is a risk when the 4.5mm tip

is fired directly along the inner jawline —

which is why adjusting to 3.0mm in that area is essential.

If there's one thing to take away from today —

the answer to better Shurink jawline results isn't more shots.

It's rethinking your tip depth strategy.

In the next post, I'll break down

'Shurink 3 sessions at 3-week intervals vs. 2 sessions at 6-week intervals —

where Collagen actually accumulates more effectively.'

This has been Dr. Wi Young-jin.