All those interested in getting a dermal filler treatment asked themselves this question, to which the answer seems to be straightforward and consistent among cosmetic practitioners and among different hyaluronic acid filler brands and products: 6 to 18 months.
But is this true and is this always the case? A new paper published on the Journal of the American Society of Plastic Surgeons challenges this dogma for the first time.
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How long does cross-linked hyaluronic acid really last in the tissues?
Naturally occurring hyaluronic acid (HA) in connective tissues has a fast turnover rate: about 24 hours for HA in the skin and between 1 and 3 weeks for HA in the joints (cartilage).
Because of this fast turnover, pharmaceutical companies had to engineer their hyaluronic acid preparations to make them longer lasting, by making it more difficult for an enzyme known as hyaluronidase to break down the bonds of the molecule. This is done with what is called “cross-linking” which means that further bonds, sometimes called links or bridges, are created between the small building blocks that constitute the larger HA molecule.
According to the paper authored by Dr. Mobin Master, Australian radiologist and aesthetic physician, 10 out of 10 patients who denied having any dermal filler injection for more than 2 years at the time of the investigation actually had MRI evidence of hyaluronic acid filler still in the tissues. Half of those patients (5 out of 10) had no dermal filler injections for more than 6 years and 1 patient had no fillers done for over 12 years! Nevertheless, MRI imaging showed evidence of HA fillers still in place or migrated to neighboring areas.
What does this study mean?
Due to the limited sample size no definitive conclusions can be drawn from this single paper, but the evidence provided warrants for further studies recruiting a larger sample of patients.
If the results will prove to be consistent also in larger samples, this will definitely result in big changes in the industry with the development of both different treatment protocols and possibly of new dermal filler products by the pharmaceutical giants.
For example, it may be possible that in the future, prior to repeating a hyaluronic acid filler injections, patients will be advised to undergo treatment with hyaluronidase, to sort of wipe out all previous work and start with a blank canvas.
Why do patients repeat filler treatment after just 4-6 months if they last for several years?
When it comes to clinical practice, most practitioners know that patients come back far sooner than the declared “up to 18 months” filler duration, as soon as 3-4 months after treatment and usually at the 6 months mark.
In general, the vanishing of the cosmetic improvement would be attributed to personal metabolism (faster breakdown of HA in some subjects than others), or due to being injected in an area with a lot of muscular activity and movement.
According to Dr. Gavin Chan, aesthetic practitioner and director of the Victorian Cosmetic Institute in Melbourne (AUS), who already had the intuition to think that filler may last longer than 6-18 months before this paper was published, this may be due to filler migration: taking the lip filler for example, it is injected on top of a very active muscle, the orbicularis oris, which constantly contracts as we speak, eat, do facial expressions, etc. This activity may cause the filler to migrate over time, flattening the area where it was originally injected (vermillion) and spreading the hyaluronic acid in a larger region between the lip and the nose and causing the “duck face” look.
This process of migration coupled with fillers lasting many years more than expected would also explain why some VIPs, who have access to the best available treatments and surgeons, look swollen and unnatural after many years of repeated cosmetic procedures.
Do all dermal fillers really migrate?
Other dermal fillers have a different mechanism of action and declared duration of the effects, so as of now there is no evidence to say they migrate from the original site of injection.
When it comes to hyaluronic acid dermal fillers, thanks to this study we know that this may actually be true, but as said before more data is needed before any definitive conclusion can be drawn.
On the other hand, most cosmetic practitioners would swear that migration may occur only right after the injection (by massaging the area for example) or if the injection was done by someone poorly trained or if the product used wasn’t FDA approved. And they are just saying what they have been taught and heard for years, so can’t be blamed for that. Hopefully this paper will make them challenge some of these dogmas over hyaluronic acid fillers, pushing for further studies on the subject.
- Hyaluronic acid: A key molecule in skin aging.
E Papakonstantinou – Dermatoendrocrinology Journal, Jul 2012
- Hyaluronic Acid Filler Longevity and Localization: Magnetic Resonance Imaging Evidence.
M Master – Plastic and Reconstructive Surgery Journal, Jan 2021