Injectable soft-tissue fillers: clinical overview.

LEARNING
OBJECTIVES: After studying this article, the participant should be able to: 1. Know the composition and biology of injectable fillers. 2. Understand the advantages and disadvantages of each injectable filler. 3. Understand the U.S. Food and Drug Administration regulatory status of each type of injectable filler, including their indications.
BACKGROUND: The use of injectable filling agents for soft-tissue facial defects has a long history of successful use based on xenogeneic collagen materials. New materials of differing compositions for injection treatments either are now available or will soon be available for clinical use.
METHODS: A review of the medical literature was performed to provide chemical compositions, methods of preparation, biological behavior, and clinical outcomes for every known injectable filler material that is either currently used or being evaluated in clinical trials.
RESULTS: Hyaluronic acid-based materials have now replaced animal or human-derived collagen as the standard injection materials. Synthetic alternatives offer the potential of longer lasting results, but the long-term outcome with their use in large numbers of patients is not yet known.
CONCLUSIONS: As there is no single injectable filler that has all of the desired characteristics, understanding the advantages and disadvantages of one filler over another is extremely helpful in guiding the patient to an informed decision. Although all of the reviewed injectable fillers are safe, the concepts of their long-term volume persistence and how they compare with each other remain largely anecdotal, with few prospective controlled clinical trials.