Dermal fillers have become an integral part of aesthetic medicine. Among these, the most frequently used are hyaluronic acid fillers. However, the process behind their creation remains a mystery to many. This article aims to demystify the process, helping you understand how hyaluronic acid fillers are made and how they work once injected into the skin.
The Basis of Hyaluronic Acid Fillers: A Natural Substance
Hyaluronic acid, a natural substance found in our bodies, is the primary component of most fillers in the market today. It’s present in our skin, joints, eyes, and other tissues. Due to its ability to bind significant amounts of water, it keeps our tissues hydrated and flexible.
However, the characteristics of hyaluronic acid fillers go beyond their base substance. Depending on their intended use, different fillers have different properties, including varying particle sizes.
Transformation of Natural Hyaluronic Acid into Filler Gel
Hyaluronic acid is a type of sugar molecule that forms long, naturally entangled chains, much like cotton in a cotton swab. These chains are constantly breaking down and reforming in the body. If injected into the skin as they are, these chains would be broken down and removed within a day.
To create hyaluronic acid fillers that persist in the body for months, or even over a year, the hyaluronic acid is stabilized into a gel using a process called cross-linking. This process connects the hyaluronic acid chains to each other, resulting in a non-soluble hydrogel that the body cannot immediately transport away.
A synthetic substance called BDDE (1,4-Butanediol diglycidyl ether) is added to cross-link the hyaluronic acid strands. Over time, the body breaks down both the hyaluronic acid and the cross-linker into harmless byproducts identical to substances already present in the skin.
The Origin of Hyaluronic Acid for Filler Production
Creating the hydrogel is only part of the process. The hyaluronic acid used in filler production comes from many sources, with all Restylane® fillers produced at Galderma’s facility in Uppsala, Sweden. This site has been producing hyaluronic acid filler gels longer than any other company and is one of the most modern filler production facilities globally.
When Restylane was launched, it became the first non-animal stabilized hyaluronic acid filler in the market. Prior to this, fillers contained hyaluronic acid of animal origin, sourced from rooster combs. The hyaluronic acid in the first Restylane product came from bacterial fermentation. Since then, almost all filler brands have been using this source. However, before it can be turned into a gel, the hyaluronic acid must be purified.
Purification and Creation of Different Gel Characteristics
According to Senior Analytical Scientist Åke Öhrlund and Chief Design Expert Per Winlöf of Galderma, the hyaluronic acid used to produce Restylane is of top-quality pharmaceutical grade. The purification process involves several steps to remove residuals such as proteins and endotoxins before the hyaluronic acid is cross-linked into a filler gel.
Two different cross-linking technologies are used to produce Restylane fillers: NASHA, which creates firmer gels, and OBT, producing softer, more flexible gels. Firmer fillers, like Restylane® LYFT, do not integrate much into the tissues and are therefore ideal for building facial structure.
Softer, more flexible fillers integrate more into the tissue and are suitable for parts of the face that move a lot, such as the lips and cheeks. An example of this is the lip filler Restylane® KYSSE.
The Role of Gel Particle Size
Gel particle size also plays a significant role in the unique characteristics of each filler. Once the hyaluronic acid has been cross-linked into a hydrogel, it can have a volume of several liters. The gel bulk is then pressed through a stainless steel mesh with a very precise mesh size, producing gel particles of a controlled size. Each Restylane product is developed to a gel particle size that provides the best clinical effect for each product and indication.
Quality Control in Filler Production
Quality control is one of the most crucial and time-consuming aspects of hyaluronic acid filler production. According to Åke and Pelle, the quality control of Restylane fillers includes more steps than most people outside this business could imagine. In fact, the largest part of yearly person-hours goes into some form of quality control work.
No matter how high the quality of the filler is, it cannot solely guarantee a natural and individualized result. Equally important is consulting a qualified healthcare practitioner who can tailor the treatment to your unique anatomy and the result you wish to achieve.