Dermal fillers are one of the main resources of modern aesthetic medicine for correcting wrinkles, restoring volume and harmonising facial contours. They differ in chemical composition, durability and mechanism of action, with materials ranging from temporary resorbables to non-degradable permanents. Their evolution reflects research increasingly oriented towards biocompatibility, naturalness and clinical safety.
Based on duration, fillers are divided into:
- Temporary: biodegradable, with an average duration of 6 to 18 months (e.g. hyaluronic acid).
- Semi-permanent or biostimulators: they stimulate neocollagenesis and persist for up to 24 months (e.g. calcium hydroxyapatite, poly-L-lactic acid).
- Permanent: non-resorbable, with multi-year duration (e.g. PMMA).
With regard to temporary fillers, it should be noted that hyaluronic acid (HA) is the most widely used substance due to its tissue compatibility and reversibility via hyaluronidase. It is a molecule naturally present in the extracellular matrix, responsible for skin hydration and turgidity. In fillers, it is chemically cross-linked to modulate viscosity, elasticity and durability. Light formulations are used for the eye and lip contour, dense ones for cheekbones, chin and nasolabial folds.
Clinical studies show that hyaluronic acid can indirectly stimulate neocollagenesis and improve dermal quality. Average duration: 6-12 months. Collagen-based fillers, which are less common today, offer natural but transient results and require allergy tests on animal derivatives.
Calcium hydroxyapatite (CaHA) combines volumetric effect and fibroblast stimulation. Mineral microspheres suspended in a gel induce collagen type I and III synthesis, lasting 12-18 months. It is indicated for structural areas such as cheekbones, jawbone and deep furrows. Poly-L-l-lactic acid (PLLA) acts as a pure biostimulator: it does not fill immediately, but generates a progressive improvement in 2-3 months. It is used in patients with lipoatrophy or diffuse loss of skin tone. Other emerging materials include polycaprolactone (PCL) and hybrid HA+CaHA fillers, with dual function of filling and regeneration.
Permanent fillers, such as polymethyl methacrylate (PMMA), contain inert microspheres embedded in a collagen vehicle. They offer a stable and long-lasting effect but with a risk of granulomas and migration. For this reason, the indication is limited to selected cases. The use of liquid silicone or paraffin, once common, is now banned due to the high risk of chronic inflammatory reactions.
The choice of the ideal filler depends on anatomical and clinical variables: type of wrinkles, depth, skin quality and desired duration. From the rheological point of view, parameters such as elasticity (G’), viscosity and cohesiveness determine the material's resistance and behaviour under mechanical stress. A filler with high G’ is suitable for structural support, one with low viscosity for mobile or superficial areas. The experienced practitioner also assesses biocompatibility, reversibility and immunological risk.
With respect to complications, the most common include oedema, ecchymosis, nodules and infections. More rare but serious are vascular obstructions, which require immediate treatment with hyaluronidase or corticosteroids. Permanent fillers, due to their irreversibility, carry higher risks of granulomas and fibrosis. Correct injection technique, adherence to vascular lines and knowledge of anatomy are essential to reduce adverse events. The use of intraoperative ultrasound is now recommended for high-risk areas.
Research is moving towards bioactive and regenerative fillers, capable of interacting with tissues through biomimetic peptides, amino acid complexes and intelligent vehicle matrices. New generations of hyaluronic acid exploit hybrid cross-linking technologies to balance cohesiveness and dermal integration. Other emerging trends involve the combined use of fillers with PRP, stem cells and radiofrequency for trophic synergy. The goal is natural, gradual and biologically sustainable rejuvenation.
Dermal fillers represent the most advanced evolution of the regenerative aesthetic medicine concept. From simple volumetric correction we have moved on to biological tissue stimulation. The correct selection of the product, the injection technique and the management of complications are decisive in obtaining safe and harmonious results. In a context where naturalness is the new frontier of aesthetics, fillers become instruments of biological balance, rather than morphological transformation.
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