How modified can a hyaluronic acid dermal filler be until it becomes a synthetic product? The more foreign the filler gel is to the body, the higher the risk of complications.1 Still, a certain degree of modification is needed to make the filler durable. Here is how modification can be minimised without compromising on durability.
Proprietary cross-linking technologies
Dermal fillers are manufactured using different technologies and vary markedly in their degree of modification.
Natural hyaluronic acid has a fast turnaround in the body. Cross-linking technologies are therefore used to prevent the body’s enzymes from breaking it down too quickly.
Cross-linking technologies create cross-links, or bridges, between the hyaluronic acid molecular chains, which ‘stabilise’ the molecules into a durable dermal filler gel.
Dermal filler manufacturers use their own proprietary technologies to create filler gels. While they all produce durable gels, the technologies differ in how this is accomplished.
Is there a limit to cross-linking?
The most commonly used cross-linking agent is 1,4-butanediol diglycidyl ether (BDDE).2 When using the synthetic additive BDDE the hyaluronic acid molecule is modified and changed from its natural and ‘pure’ structure into a more synthetic one.
When a dermal filler gel is highly cross-linked, it may be perceived by the body as foreign and has a higher potential to provoke an immunologic reaction.1
A highly cross-linked gel may also be more difficult to dissolve with hyaluronidase.1
Consequently, a challenge for manufacturers of dermal fillers is to make durable gels without unnecessary modification.
How can a low degree of modification create durable gels?
As cross-linking with BDDE is used to make dermal filler gels more durable, the logical conclusion should be that the higher the degree of modification, the more durable the gel.
But is it always the case? Could a cross-linking technology that utilises minimal modification still produce durable dermal fillers?
There are two ways of accomplishing this:
1. The naturally entangled structure of the molecules is preserved, which reduces the need for cross-links.
2. The cross-linking technology used is effective in creating bridges between the molecules, with few ‘branches’ where the link is only anchored at one side.
A cotton ball, a ball of yarn, entangled seagrass…
There are many ways of describing what natural hyaluronic acid looks like. The long molecular chains are entangled like a cotton ball, or a ball of yarn or like entangled seagrass. Whatever the metaphor, this natural entanglement reduces the need for cross-links.
The alternative is to use molecular chains of selected lengths. When these ‘straight’ molecular chains are used and modified into a gel, more cross-links using BDDE are needed to stabilise the gel.
A bridge is only effective if it reaches the other side
Half of a bridge is just as ineffective as no bridge at all, and it is almost the same with cross-linking.
Cross-linking with BDDE not only produces effective cross-links, but also branches that are only anchored on one side of the molecular chains. These branches, or pendants, do not contribute to a significant degree to gel rheology or longevity.1,3
What pendants do, however, is modifying the gel. This means you can have a highly modified gel but with a low degree of effective cross-links.
Combining naturally entangled molecules with effective cross-linking
As mentioned, you can minimise synthetic modification if you use the naturally entangled form of hyaluronic acid. Moreover, if you use an effective cross-linking technology that produces few ineffective branches modification is minimised even more.
This is in essence the SHAPE™Technology that is used to produce all Decoria® dermal fillers. Decoria is a premium filler brand from hyaluronic acid specialist BOHUS, located in Sweden.
The only dermal filler range with 1% modification
The SHAPE Technology produces durable gels with only 1% modification of the hyaluronic acid molecule.
As a comparison, common dermal filler gels can have a degree of modification of, for example, 3%, 6%, 8% or more.1 Remember, the degree of modification does not provide any clear information about durability, as the gel may have a high degree of ineffective pendants.
There are other fillers besides Decoria that have a low degree of modification. However, Decoria stands out as a dermal filler range where all fillers are minimally modified.
Another way to explain it is that the pure and biocompatible form of natural hyaluronic acid is preserved in the Decoria fillers, while still creating very long-lasting results.4
A pure price thanks to streamlined processes
The highest purity does not have to come at a premium price. Thanks to streamlined processes BOHUS can offer premium dermal fillers at an exceptionally good price. Contact the Decoria team for more information.
BOHUS is a Swedish developer of premium quality hyaluronic acid, with products sold to physicians, clinics and hospitals in over 60 markets worldwide.
References
1. Wu G.T. et al., Hyaluronic Acid Basics and Rheology, Facial Plast Surg Clin North Am. 2022 Aug;30(3):301-308.
2. De Boulle K et al., A Review of the Metabolism of 1,4-Butanediol Diglycidyl Ether–Crosslinked Hyaluronic Acid Dermal Fillers, Dermatol Surg. 2013 Dec; 39(12): 1758–1766.
3. La Gatta A. et al., Hyaluronan Hydrogels: Rheology and Stability in Relation to the Type/Level of Biopolymer Chemical Modification, Polymers (Basel). 2022 Jun 14;14(12):2402.
4. Torres S., Zygomatic Augmentation through Curved Cannulas with the Use of a New Stabilized Hyaluronic Acid Dermal Filler (Decoria® Voluma, Bohus BioTech AB, Sweden, EC): 10 Months Follow Up, Medwin Publishers 2018 Nov. 23; Vol 3, Issue 3.
