Depressed Scars and Filler: Indications and Limits

A depressed scar is any scar that sits below the level of the surrounding skin because of tissue loss in the dermis or subcutaneous layer. On the face, the most common cause is inflammatory acne, but surgery, trauma, chickenpox, and some skin diseases also leave depressions. Filler can restore part of the lost volume, but it only works well for some scar types and almost never resolves the problem on its own.

This page is a guide to indications and limits for the orofacial harmonization (HOF) professional. It does not teach technique: product choice, plan, volume, and instrument are decisions for the qualified professional, in line with the rules of their professional board in Brazil and the label of the product registered with ANVISA (the Brazilian health regulator).

Which depressed scars exist?

The most widely used classification of atrophic acne scars separates three main forms. They often coexist on the same face, and recognizing each one changes the plan.

Outside the acne classification, two situations show up in the clinic: localized volume loss from fat atrophy (for example, after a corticosteroid injection or in facial lipodystrophy) and scars from autoimmune skin diseases, which need joint assessment. See autoimmune diseases and fillers.

How do you know if a scar is a candidate for filler?

The simplest test is the stretch test: with two fingers, stretch the skin around the scar. If the depression flattens well, the loss is more about volume and traction, and filler tends to help. If the scar stays visible with the skin stretched, the problem lies in the texture and surface of the dermis, and filler alone will do little.

Other points of the assessment:

1. Side lighting. Light from the side and take a photo. Rolling scars show up as shadows; under frontal light, they disappear. Use the standardized clinical photography protocol so you can compare later.
2. Tethering. Try to slide the skin over the deep plane. A scar attached to the layer below usually needs release before any volume; otherwise the product spreads around the scar instead of beneath it.
3. Acne activity. Active acne, pustules, and recent systemic medication call for postponing treatment. For oral retinoids, see isotretinoin and injectable procedures.
4. Skin type. In higher Fitzpatrick skin types, the risk of post-inflammatory hyperpigmentation weighs on the choice of combined techniques. See HOF in dark skin.
5. Overall volume loss. The scar often looks worse because the midface has lost support. Treating the underlying volume can soften several depressions at once.

Which products appear in the literature for scars?

At review level, without naming brands or protocols:

• Hyaluronic acid. Reversible with hyaluronidase, which is an advantage in thin, scarred skin. Less dense gels settle better in superficial planes, but very superficial placement can leave a bluish tint (Tyndall effect) and surface irregularity. Durability in a scar tends to be shorter than in areas of structural volume.
• Collagen biostimulators. Calcium hydroxyapatite and poly-L-lactic acid are used to improve dermal quality and support in areas with multiple scars. The effect is gradual and there is no antidote. See biostimulators: overview.
• Permanent materials. PMMA has a history of use in scars in other countries, but late complications, such as granuloma and nodule, can appear years later and are hard to treat. Check the registration and approved indications before any use, in how to look up an injectable's registration with ANVISA.
• Skin boosters and polynucleotides. They improve hydration and texture, but do not fill marked depressions. See polynucleotides in HOF.

Why does filler almost always belong in a combined plan?

An atrophic scar has three components: volume loss, traction from fibrosis, and surface change. Filler acts on the first, release of adhesions acts on the second, and dermal remodeling techniques act on the third. That is why reports of the best response usually combine approaches in spaced sessions.

When the plan includes thermal technologies, timing matters, because heat can interfere with freshly placed hyaluronic acid. The intervals described are in laser and microfocused ultrasound after filler. Some of these techniques fall outside the scope of certain professions: check what your professional board's rules allow and, where appropriate, work with a referral to dermatology.

Hypothetical example of a staged plan

Hypothetical example: a patient with rolling scars on the cheeks and a few ice pick scars over the cheekbone, with no active acne for more than a year. The plan could be split into stages: first, assessment and photos with side lighting; then, treatment of the rolling scars with release and volume, at the professional's discretion; finally, referral of the ice pick scars to focal techniques with someone trained in them. Each stage has a follow-up visit and a new photo before the next one.

What are the risks of filler in a scar?

Scar tissue is less elastic and has altered vascularity, which changes how the product behaves.

• Irregularity and surface relief, when the product does not spread beneath the fibrosis.
• Tyndall effect with superficial hyaluronic acid.
• Nodules, more feared with biostimulators and permanent materials.
• Post-inflammatory hyperpigmentation, especially with combined techniques and in higher skin types.
• Infection and biofilm, as with any injectable.
• Vascular occlusion, possible in any area. Scars near the nasolabial fold, the nose, and the glabella lie in high vascular risk areas.

What do hypertrophic scars and keloids have to do with this?

Nothing, in terms of indication: hypertrophic scars and keloids are raised, not depressed. What matters in HOF is the history. A patient prone to keloids calls for caution with any procedure that injures the skin, and the information must be recorded in the medical history and in the informed consent.

How do you align the patient's expectations?

People with acne scars often arrive after many years of distress and, sometimes, after earlier treatments that disappointed them. An honest conversation is the best investment: talk about improvement, never about erasing.

Record in the patient record what was explained, the before photos with side lighting, and the staged plan. If the main concern is diffuse texture, make it clear that filler is not the main tool.

And in Harmy?

To track progress, use "Add actual result" in History: the follow-up photo is aligned by the eyes with the starting one, which makes it easier to compare areas with scars.

Checklist before filling a depressed scar

1. Type of each scar identified (rolling, boxcar, ice pick).
2. Stretch test done and recorded by area.
3. Tethering assessed.
4. Inactive acne and recent systemic medications checked.
5. Skin type and history of keloid or hyperpigmentation recorded.
6. Product with a compatible indication on the registered label.
7. Hyaluronidase available when the product is hyaluronic acid.
8. Photos with side and frontal lighting under the same protocol.
9. Staged plan and limits explained and signed in the consent form.