# Biostimulator Types: PLLA, Calcium Hydroxylapatite, PCL

> Poly-L-lactic acid, calcium hydroxylapatite and polycaprolactone: the structure, duration of effect, when results appear, number of sessions, areas used,…

Published: 9 November 2026 · Medically reviewed by: Op. Dr. Murat Alpay

**Poly-L-lactic acid, calcium hydroxylapatite and polycaprolactone: the structure, duration of effect, when results appear, number of sessions, areas used, risks and differences of the three biostimulator substances.**

All biostimulators used on the face stimulate the skin's own collagen production, but **they do not work in the same way, take effect over the same time or suit the same areas.** Three substances stand out in the sources: poly-L-lactic acid (PLLA), calcium hydroxylapatite (CaHA) and polycaprolactone (PCL). These substances are sold under commercial product names; however, the decision is made not by product name but by **the structure of the substance, the area to be treated and the person's skin structure.** This article puts the three substances side by side and explains their differences. You can read what biostimulators are and how they differ from filler in [what are biostimulators](https://www.muratalpay.com.tr/en/blog/biyostimulatorler-nedir-kolajen-uyaran-yuz-enjeksiyonlari-kimlere-uygun/), and about types of fillers on our [filler](https://www.muratalpay.com.tr/en/tedaviler/dolgu/) page.

## What the Three Substances Have in Common

- When placed in the tissue, all three start a mild, controlled reaction that stimulates the collagen-producing cells (fibroblasts).
- All three break down in the body over time.
- All three **cannot be dissolved with the enzyme hyaluronidase.** There is no "reverse it with an enzyme" option as with hyaluronic acid filler.
- For all three, use in thin or very mobile areas such as around the eyes and the body of the lips is not recommended because the risk of firm lumps (nodules) is high.

## Poly-L-Lactic Acid (PLLA)

**Structure:** A synthetic substance compatible with the body, from the same family as the raw material of the dissolvable surgical suture. It comes as a powder and is prepared by mixing with a liquid before the procedure. Its particles have an irregular shape and are about 40-60 micrometres across (about one twentieth of a millimetre).

**How it works:** It triggers collagen formation (type 1 and type 3 collagen). The substance itself does not give volume. The fullness seen right after the procedure comes from the liquid used in preparation and temporary swelling, and it recedes within days. The real fullness forms over weeks and months with your own collagen.

**Result and duration:** The first response begins in 1-2 months and the full result settles in 3-4 months (3-6 months according to some sources). Duration is reported in the sources as 18-24 months, up to 3 years.

**Number of sessions:** Usually 3-5 sessions 4-8 weeks apart.

**Areas used:** Cheeks, mid-face, temples, jawline, lines from the nose to the lips and from the corners of the mouth downward; also facial fat loss related to ageing or some conditions, the décolleté and, according to some sources, sunken areas of the body.

**Massage at home:** With PLLA, a massage programme described by the physician is needed after the procedure; in the sources this is mentioned as 5 times a day, 5 minutes each, for 5 days. The aim is even spread of the particles and a lower nodule risk. The physician sets the programme.

**Visible on X-ray:** No.

**Who it is considered for:** People with volume loss, hollowness and thinning of the skin over a broad area of the face who want the result to build gradually.

## Calcium Hydroxylapatite (CaHA)

**Structure:** In a gel carrier (carboxymethylcellulose, a substance that gives the gel its consistency) there are spherical calcium-based beads about 25-45 micrometres across. It comes ready in a syringe.

**How it works:** It works in two stages. It gives volume at the moment of injection thanks to the gel carrier. The carrier is absorbed by the body in the first 2-3 months; the beads that remain act like a scaffold in the tissue and stimulate collagen and new vessel formation.

**Result and duration:** The effect starts immediately and collagen stimulation continues after the 2nd-3rd month. Duration is reported in the sources as about 12-18 months on average.

**Number of sessions:** Usually a single session.

**Areas used:** Cheeks, cheekbones, jawline, chin, temples, nose-to-lip lines and the back of the hands. It is not recommended in the body of the lips, under the eyes and in the thin skin around the eyes.

**Massage at home:** The physician shapes it during the procedure; a regular intensive home massage programme is not needed.

**Visible on X-ray:** Yes. Because it contains calcium (it is radiopaque, meaning it shows on X-ray), it can be seen on X-ray and CT. This image does not mask the surrounding tissue; still, if you have had it, it is sensible to tell your physician before imaging.

**Who it is considered for:** People with medium to thick skin who want support at the jawline and cheekbones, or with marked tissue loss at the back of the hands or in deep grooves.

## Polycaprolactone (PCL)

**Structure:** A long-lasting medical polymer with small polycaprolactone beads in a gel carrier. It comes ready in a syringe and needs no extra dilution.

**How it works:** After the carrier gel is absorbed in 6-8 weeks, the beads stimulate the tissue. The sources report that it increases type 1 collagen markedly more than type 3. The effect begins with the gel volume and then continues with the rise in collagen.

**Result and duration:** Duration is reported in the sources as ranging from 1 to 4 years.

**Number of sessions:** Usually a single session.

**Areas used:** Cheek, cheekbone, jawline, chin, nose-to-lip lines, temples, neck and décolleté. It is not recommended in the lips, between the brows and under the eyes.

**Massage at home:** The physician spreads it during the injection; a special home programme is not essential.

**Visible on X-ray:** No.

**Who it is considered for:** People who want a longer-lasting effect and have loss of skin elasticity and sagging.

## The Three Side by Side

- **Structure:** PLLA is a powder, CaHA and PCL are ready-to-use gels.
- **Volume in the first days:** In PLLA from liquid and swelling, in CaHA and PCL from the gel carrier.
- **Duration (as reported in the sources):** PLLA 18-24 months, CaHA 12-18 months, PCL 1-4 years.
- **Sessions:** PLLA 3-5 sessions, CaHA and PCL usually a single session.
- **Home massage programme:** Needed with PLLA, not essential with the other two.
- **On X-ray:** Only CaHA is visible.
- **Can it be dissolved:** None of the three can.

These durations and numbers are averages from the sources; they vary from person to person and with the area treated and the amount used.

## Which One Is Chosen?

There is no single substance that suits everyone. Which one is suitable is decided at the examination by looking at:

- How widespread the volume loss is and where it is
- The thickness and quality of the skin
- Whether the result is expected to build gradually or start earlier
- How long the effect is wanted for
- Medical history and medicines used

Different approaches can also be considered for different areas in the same person. For approaches planned together with botox and filler, see our [botox in the face](https://www.muratalpay.com.tr/en/blog/yuz-bolgesinde-botoks-botulinum-toksin-uygulamasi-nedir/) article.

## Shared Risks

- **Temporary effects:** Swelling, bruising, redness and tenderness. Swelling can be more noticeable with PLLA.
- **Nodules and papules:** Firm lumps can form with placement close to the surface, an unsuitable technique or, with PLLA, inadequate massage. Treatment can include massage, breaking them up with a needle, treatments given into the lump or surgical removal. Hyaluronidase does not dissolve these substances.
- **Blocked blood vessel:** A very rare but serious complication; if the needle enters a vessel or pressure from outside restricts it, tissue circulation can be impaired. Slow injection and proper technique lower the risk.
- **Late granuloma:** Rarely, lumps caused by a strong reaction of the body to the foreign substance can appear months later.

## Who Should Not Have It?

- People with an active infection or inflammation in the area to be treated
- During pregnancy and breastfeeding
- People with a known hypersensitivity to the product's components or to the local anesthetic (an anesthetic that numbs the area)
- People with an active autoimmune or connective tissue disease or taking drugs that suppress immunity
- People with a bleeding disorder or taking blood thinners
- People with unrealistic expectations or a body image disorder

## Frequently Asked Questions

### Which biostimulator type lasts longest?

The sources report the longest duration for polycaprolactone (1-4 years), then PLLA (18-24 months) and the shortest for calcium hydroxylapatite (12-18 months). Durations vary from person to person, and duration alone is not the selection criterion.

### Which gives an immediate result?

Calcium hydroxylapatite and polycaprolactone give volume at the procedure thanks to their gel carriers. With PLLA the volume in the first days is temporary; the real result forms over months.

### Which needs more than one session?

According to the sources, PLLA usually needs 3-5 sessions 4-8 weeks apart. Calcium hydroxylapatite and polycaprolactone are usually planned as a single session; this still varies from person to person.

### Is it visible on X-ray afterwards?

Only calcium hydroxylapatite can be seen on X-ray and CT. The other two are not visible.

### Can it be reversed if I am not satisfied?

None of the three can be dissolved with the enzyme hyaluronidase. This is why the area, amount and substance are planned carefully before the procedure.

Results of any surgical or interventional procedure may vary from person to person. It is recommended that you get detailed advice from your physician before the procedure.

Written and reviewed by

**Op. Dr. Murat Alpay**

Specialist in Obstetrics and Gynaecology · Istanbul University, Istanbul Faculty of Medicine (Çapa)

[Full biography →](https://www.muratalpay.com.tr/en/hakkinda/)

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Original page: https://www.muratalpay.com.tr/en/blog/biyostimulator-cesitleri-plla-kalsiyum-hidroksiapatit-pcl-farklari-hangisi-kimlere-uygun/  
Last updated: 2026-11-09

Op. Dr. Murat Alpay — Specialist in Obstetrics and Gynaecology  
Op. Dr. Murat Alpay Practice, Tekelioğlu Cd. No:51 B Kat:2, Filo Apt., 07160 Muratpaşa / Antalya  
0505 351 77 88 · Monday – Saturday 09:00 – 18:00 · Closed on Sunday

*This information is for general guidance only and does not replace examination, diagnosis or treatment.*