Microspheres: what they are in fillers

Microspheres are spherical particles of microscopic size present in the composition of some injectable products. The spherical shape is used to try to reduce tissue irritation and allow the material to be well distributed. Each product uses a different material, and it is the material, more than the shape, that defines how it behaves in the body.

What are microspheres for?

Depending on the product, microspheres can play two roles:

• Suspension in a carrier gel: the particles are dispersed in a vehicle (such as carboxymethylcellulose gel) that gives immediate volume while it is absorbed, and the particles remain as support for the body's response.
• Tissue stimulation: some particles induce fibroblasts to produce collagen around them, with a long-term effect.

This is the reasoning behind products such as calcium hydroxyapatite and other collagen biostimulators. The vehicle (see carboxymethylcellulose) is reabsorbed, and the particles follow another fate, depending on the material.

What are the safety issues?

Permanence is the central point. Biodegradable materials are reabsorbed by the body over time (see biodegradability). Non-degradable materials can remain indefinitely, which brings them close to permanent fillers and carries important implications:

• there is no enzyme that dissolves these materials, unlike hyaluronidase for hyaluronic acid;
• late reactions, such as nodules and granulomas, can appear months or years later;
• removal, when necessary, may involve surgery.

The material's biocompatibility and the product's regulatory registration are checkpoints before any use.

How do you explain it to the patient?

Patients often do not know the difference between absorbable and long-lasting products. Explaining it clearly, and in writing, is part of informed consent.

In Harmy

The app simulates the visual effect by volume in ml in the marked areas and does not distinguish product, material or microspheres. The projection is illustrative and does not indicate the choice of material, which is the qualified professional's decision.

Also called: spherical particles, polymer spheres.