Comparative physical properties of hyaluronic acid dermal fillers.

BACKGROUND Hyaluronic acid (HA) fillers are becoming the material of choice for use in cosmetic soft tissue and dermal correction. HA fillers appear to be similar, but their physical characteristics can be quite different. These differences have the potential to affect the ability of the physician to provide the patient with a natural and enduring result. OBJECTIVE The objective of this article is to discuss the key physical properties and methods used in characterizing dermal fillers. These methods were then used to analyze several well-known commercially available fillers. METHODS AND MATERIALS Analytical methods were employed to generate data on the properties of various fillers. The measured physical properties were concentration, gel-to-fluid ratio, HA gel concentration, degree of HA modification, percentage of cross-linking, swelling, modulus, and particle size. RESULTS The results demonstrated that commercial fillers exhibit a wide variety of properties. CONCLUSION Combining the objective factors that influence filler performance with clinical experience will provide the patient with the optimal product for achieving the best cosmetic result. A careful review of these gel characteristics is essential in determining filler selection, performance, and patient expectations.