Hyaluronic acid (HA) fillers are becoming the most popular temporary dermal fillers used by aesthetic practitioners today. The market for soft tissue augmentation is growing, and the U.S. Food and Drug Administration (FDA) has approved at least 10 HA fillers to date, with more under development.
Hyaluronic acid compared to collagen fillers
HA fillers have almost replaced collagen fillers, according to the Cosmetic Surgery National Data Bank Statistics (2005). HA lasts longer than collagen, lasting 6-12 months, compared with 2-4 months. Additionally, because HA occurs naturally in skin there’s no need for skin testing. HA has better pliability than collagen treatments, and fewer allergic side effects.
The amount of naturally occurring HA in human skin decreases with age. This loss of HA causes wrinkles to form, and tissues to loose elasticity and hydration—the appearance of aging. HA is the perfect substance for adding volume to skin, because it binds 1,000 times its volume in water.
Synthetic dermal fillers are currently being developed, too. Radiesse®, calcium hydroxylapatite, is probably the most popular synthetic filler.
When deciding which type of HA to use, consider clinical indication, ease of injection, degree of tissue filling, longevity, and potential post injection side effects.
FDA approved HA fillers
These HA fillers are all FDA approved for injection into the mid to deep dermis for the correction of moderate to severe wrinkles and folds, such as nasolabial folds.
HA fillers currently approved for the US market include:
- Restylane®-L Injectable Gel (contains Lidocaine) and Restylane® Injectable Gel
- Perlane®-L (contains Lidocaine) and Perlane®
- Juvederm® UltraPlus XC (contains Lidocaine), Juvederm® Ultra
- Prevelle® Silk (contains Lidocaine)
- Belotero® Balance
Lidocaine is a local anesthetic agent, which will reduce pain associated with injection.
All these HA fillers consist of hyaluronic acid particles (or varying size) suspended in a gel—apart from Juvederm®. Juvederm® is a gel made of hyaluronic acid, using a proprietary manufacturing process.
Restylane-®L Injectable Gel is the only HA approved for lip augmentation (for patients 21 and older).
Degree of tissue filling
Hardness, or stiffness, of the gel may influence choice of HA. Stiffness is measured in G’ (G-prime), and is the gel’s resistance to deformation. HA fillers with higher G’ values (such as Juvederm® Ultra Plus and Perlane®) should be used in deeper lines and folds, such as nasolabial folds and marionette lines, cheeks and mid face and jaw shaping. More fluid products with mid G’ and low G’ values (such as Restylane® and Juvederm ®Ultra & Prevelle® Silk & Belotero®) are better suited for areas which need softer gels, such as the tear trough and lips and more superficial creasing.
Most of these HA fillers will last six months or longer. The effects of Juvederm® Ultra Plus may last for up to a year.
Temporary side effects for all HA fillers can include:
- localized swelling
- localized redness
- post-injection site pain
- localized bruising
- hardening of tissue at the injection site
- localized itching
- delayed reactions such as the formation of lumps and bumps
HAs are not recommended in patient with a history of severe allergies or anaphylactic reaction.
Sources for this article include Clinical Interventions in Aging: Hyaluronic acid gel (Juvederm) preparations in the treatment of facial wrinkles and folds