Implants
Implants
INTRODUCTION
The use of fillers and injectable implants for facial rejuvenation is one of the most important forms of minimally invasive correction, and represents a key class of interventions for the aging face. These interventions can be largely grouped into the four “R’s”: redrape (surgical procedures that pull, lift, or tighten); resurface (chemical peels, dermabrasion, ablative or nonablative lasers); relax (chemodenervation with neuromodulatory agents); and replace or recontour (injection of filler agents for softtissue augmentation). The last has become increasingly popular, as the number of safe, effective dermal filling agents has increased and as the public’s demand for minimally invasive approaches has grown.
Tissue augmentation dates back to the 1890s when Neuber used autologous fat to correct atrophic facial defects.1 Decades later, Baronders published a review of liquid silicone for permanent-tissue augmentation in 1953, though it was not until 1981 that the US Food and Drug Administration (FDA)-approved bovine collagen as the first implantable/injectable agent for soft-tissue augmentation.2 Marketed under the name Zyderm® and its successors Zyderm II and Zyplast®, this xenograft remained the standard of care for more than two decades, but fell out of favor with the introduction of new classes of injectables. Bovine collagen is no longer available in the United States due to high manufacturing costs, limited duration of efficacy (2–4 months)3, and risk of hypersensitivity in approximately 3% of patients.4 Bovine collagen products are historically important, nonetheless, since they served as comparators in the pivotal phase 3 clinical trials for most modern-day fillers.
FDA approval of the first hyaluronic acid (HA) filler, Restylane®, in 2003 marked the beginning of a new period in injectable agents for facial rejuvenation. HA fillers quickly supplanted all other products. Current FDA-approved formulations fall into three families: Restylane/Perlane® (now marketed as Restylane Lyft), Juvederm/Juvederm Voluma® and Belotero®. Hyalorm®, derived from rooster coombs;
Captique®, a plant-based HA; Elevess®; and Prevelle Silk® are other approved agents no longer sold in the United States.3,5 The FDA has also approved two longer-acting agents (poly-L-lactic acid [Sculptra®] and calcium hydroxylapatite [Radiesse®]), as well as one permanent filler, polymethylmethacrylate (PMMA) (Bellafill®, formerly marketed as Artefill®).2