Polycaprolactone threads in HOF: what they are and what we know

On the timeline of facial threads, PDO was the first to become popular, followed by poly-L-lactic acid threads and, more recently, by polycaprolactone threads, or PCL. The proposal is familiar: a biodegradable material, but with slower degradation, that would keep stimulating the tissue for longer. It sounds good, and precisely for that reason it is worth reviewing what is really known, what is still supposition and what changes in the consent when the material stays longer.

This guide is a review. It explains what the material is, how it compares with other threads, what the literature describes and which precautions apply. It does not include insertion technique, gauges or protocol, which are decisions for the qualified professional, according to the package insert and the rules of their professional council. For the overview, see types of PDO threads and absorbable and permanent threads.

What is polycaprolactone?

Polycaprolactone is a synthetic biodegradable polyester, used in medicine for decades in sutures, implants and drug delivery devices. Its profile is that of a biocompatible material, which the body breaks down by hydrolysis over a prolonged period, much longer than materials such as PDO. In aesthetics, it also appears in microspheres for injectable biostimulation, a separate topic covered in polycaprolactone and poly-L-lactic acid.

In the context of threads, PCL is used in threads with different designs (smooth, barbed, with cones, depending on the product), with the idea of combining lifting or stimulation with longer permanence. Slower degradation may favor prolonged neocollagenesis stimulation, but it also means a foreign body stays in the tissue for longer.

How does it compare with other threads?

The table shows a logic: the longer the material stays, the greater the potential for stimulation, and also the longer the window in which a late event can occur. This does not mean PCL is more dangerous, but that long-term safety data are even more important, and less available. Degradation times vary with the product and the literature, and the manufacturer's data should be checked in the package insert.

What does the literature describe?

The literature on PCL threads is smaller than that on PDO. There are material characterization studies, studies in models, case series and a few clinical studies with follow-up of months. In general, reports describe improved contour and firmness in selected cases, with an adverse event profile similar to that of other threads. But the studies are small, many with short follow-up, with no direct comparison with PDO or PLLA, and frequently with industry involvement.

In terms of levels of evidence in HOF, this is a field of low to moderate evidence, still under construction. The critical reading approach is the same as for other threads, and is covered in PDO threads: what the literature shows and how to read a clinical trial of injectables.

What are the risks?

The general thread risks apply: pain, swelling, bruising, dimples, asymmetry, palpable or visible thread, extrusion, infection, nodules and granulomas. What changes with PCL is the time window: a thread that stays longer in the tissue can produce late events, such as inflammation that returns, a thread that becomes palpable as the face changes, or infection associated with biofilm. It is also important to remember that the face ages and changes while the material is still there.

For this reason, consent for longer-permanence threads should be more detailed, including the possibility of removal and prolonged follow-up. For management of complications, see complications with PDO threads, thread extrusion and visibility and indications for thread removal.

How to choose between materials?

The choice is not "the best thread" but the one most suited to the goal, the area and the patient. A few questions help:

• Is the goal traction, stimulation of skin quality, or both?
• Does the patient have skin thick enough for a longer-permanence material?
• Is there a product registration for the purpose and the area?
• Does the available literature support this use, and how was the follow-up?
• Does the patient understand and accept the longer residence time and the possibility of removal?

Recording the lot and product is especially important for longer-permanence materials, since the patient may need care from another professional years later. See traceability of injectables.

What should you tell the patient?

The most sensitive communication point is time. Patients tend to like the idea of "lasts longer", and it needs to be balanced with the idea of "stays longer in the body". Avoid promising how long the effect lasts: the variation is large.

Where does Harmy fit in?

Harmy does not simulate threads, whether PDO, PLLA or PCL. It works in visual planning by volume in areas marked on the frontal photo, with an illustrative projection. It can be useful in the conversation about "what do I want to change", but it does not predict the result of any specific thread. The simulation is illustrative and does not promise results. The app's History also helps keep the patient's records organized over the years.

Summary

Polycaprolactone threads are a slow-degrading option, with a proposal of prolonged stimulation and clinical evidence that is still limited. Know the product, weigh the benefit of time against the risk of longer permanence, detail the consent, record the lot and keep up the follow-up.