Most of the dermal fillers in the U.S. markets are hyaluronic acid. These include everything EXCEPT Bellafill, Radiesse, and Sculptra. There are so many different products made from hyaluronic acid it is overwhelming. What makes one hyaluronic acid different from another is who manufactures it, and the actual size of the hyaluronic acid molecule. The larger the size the greater the lift and the deeper the product should be injected. The smaller sizes may be injected more superficially in the skin. A good analogy is thinking about cubes of ice (large particles/more rigid but give greater lift) versus crushed ice (small particles, more malleable, may be injected much more superficially). These are great for fine lines and wrinkles.
The longer lasting products are known as collagen stimulating fillers. These products work by adding particulate into the dermis that the body surrounds with collagen and elastin. This taps into the body’s natural healing and protective mechanism. Because these are foreign, (not naturally occurring in the dermis) the body produces collagen and elastin to wall them off. These particles are surrounded by the collagen to hold them in place. This increases the thickness of the dermis. When the dermis is thicker (with more collagen and elastin) the surface of the skin appears fuller and healthier. It takes a much longer time for the body to break these products down thus giving them a much longer duration.
There are different reasons that your injector will choose a hyaluronic acid filler over a collagen stimulating filler and vice versa. Depending on what your long term treatment plan goals are one or both types of filler may be used as part of your comprehensive plan. This is why the initial consultation with your injector is SO important.