Hyaluronic Acid (HA) fillers are compounded from a glycosaminoglycan polymer that occurs naturally within the body. Hyaluronic Acid fillers are manufactured by cross linking molecules into a 3-dimensional network. This cross-linking method is what determines the type and extent of the filler’s viscosity and stability. Cross-linking of the molecule prevents oxidative stress and enzymatic degradation.

The popularity of HA fillers is based on the low risks of allergic reaction & complications over the fillers used in years gone by which were mainly bovine, human collagen & silicone derived. The derivatives of HA vary between the source of the HA, the particle size of the HA and the concentration.  In addition, whether the HA has been cross-linked or not & the type of crosslinking agent used creates further variations.

Hyaluronic Acid is a naturally occurring glycosaminoglycan that is the building block of the skin’s dermis and a major component of all connective tissue. The chemical structure of this polysaccharide is uniform throughout all mammals. There is no potential for immunologic reactions to Hyaluronic Acid in humans. The HA molecules in the skin bind water and create volume.

HA is a monomer (a molecule that can be bonded to other identical molecules to form a polymer) that is composed of sodium glucuronate combined with N-acetylglucosamine. The HA filler is manufactured as a ‘polymer’ that is composed of multiple monomers bound together like a string of beads. When HA is in a non-cross-linked form it is essentially a liquid because the molecules are suspended individually in the solution, meaning the HA will not remain ‘still’ or stable’ if injected into a line or wrinkle.

When HA is cross-linked it increases the cohesiveness of the product and the liquid and product are blended into a gel. The viscosity of the gel correlates with the amount of cross-linking present in the compound. Other factors that affect the viscosity of the gel include the HA concentration & the sizing of the gel particles within the compound itself.  The hardness of the gel is typically altered by adding non-cross-linked HA to cross-linked HA to thin down the compound and increase flow when the product is injected. Variations occur by adding smaller HA gel particles.

Dermal Fillers are an effective treatment for treating fine lines and wrinkles, enhancing facial features such as lips & exaggerating facial contours such as cheeks, jawline/chin & correcting facial asymmetry or defects in noses. Dermal filler saw a huge rise in popularity in the last fie years within aesthetic practise notably for Lip Augmentation.