How Dermal Fillers Work: Composition, Mechanism and Longevity

Dermal fillers are now a routine part of aesthetic practice, but the category has changed considerably since the earliest products reached the market in the 1970s. Understanding how filler composition has evolved — and what each generation of material means for behaviour in the skin — is useful groundwork for explaining product choice to patients and for selecting the right formulation for a given treatment area.

The First Generation: Synthetic, Non-Biodegradable Fillers

Early dermal fillers were composed of materials such as silicone and paraffin, which are non-biodegradable — the body does not break them down or clear them over time. Products of this type still exist, and their durability is, in one sense, their selling point: results persist indefinitely because the material does not react with surrounding tissue or degrade. The trade-off is a set of well-documented drawbacks, including a tendency to migrate from the original injection site over time and a comparatively higher rate of allergic or granulomatous reaction, since permanence also means any adverse reaction is far harder to resolve.

Semi-Permanent, Biostimulatory Fillers

A second generation of products moved toward materials the body tolerates more readily while still offering longevity well beyond hyaluronic acid. Radiesse, based on calcium hydroxylapatite suspended in a gel carrier, and Sculptra, based on synthetic poly-L-lactic acid, are the best-known examples. Both work partly by adding immediate volume and partly by stimulating the body's own collagen production over subsequent weeks and months, which is why results with these products tend to build gradually rather than appearing fully formed at the time of treatment. Effects commonly last up to two to three years. The trade-off is reduced reversibility compared with HA fillers and a similar, though generally lower, risk of the product shifting from the treated area if placed incorrectly.

Biodegradable Hyaluronic Acid Fillers

The category most widely used today is hyaluronic acid filler, which is fully biodegradable and metabolised by the body over time. HA is naturally present in skin tissue, where it plays a role in hydration and volume, which is part of why HA fillers are generally well tolerated, with a comparatively low rate of adverse reaction relative to earlier synthetic materials. Well-established options across the dermal fillers range include product lines such as Juvéderm Ultra, formulated in a range of viscosities for different treatment depths and areas.

The main trade-off with HA fillers is shorter duration compared with semi-permanent or non-biodegradable materials — typically six months to around two years depending on the specific formulation, treatment area and individual metabolism — which means most patients plan for periodic maintenance rather than a single lasting treatment.

Why Product Selection Matters as Much as the Treatment Itself

A common misconception is that any HA filler will perform equivalently across the face. In practice, different areas call for gels engineered with different particle size, cross-linking density and viscosity: a formulation well suited to a deep nasolabial fold will not necessarily perform well beneath the thin skin of the periorbital area, and vice versa. This is the underlying reason product ranges are organised by area and depth rather than as a single undifferentiated category, and it is worth explaining to patients who assume filler is filler.

What Happens as Filler Breaks Down

A frequent patient question is whether treated areas will look worse once filler has fully resorbed. In most cases the answer is no: several filler types support increased collagen production while present, meaning skin quality in the treated area can be modestly improved even after the added volume itself has gone. This is one reason most patients who discontinue treatment do not report lines or folds appearing more pronounced than before their first treatment.

The Takeaway

Dermal filler composition ranges from permanent synthetic materials through biostimulatory semi-permanent products to fully biodegradable hyaluronic acid, and each category offers a different balance of longevity, reversibility and safety profile. Matching that trade-off to the patient and treatment area, rather than defaulting to one product family, is the core of good filler practice.

To compare HA and biostimulatory filler options by treatment area, browse the dermal fillers catalogue.