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What are dermal fillers?

Dermal filler is a broad term that includes many different substances used to achieve the same goal. These substances can be natural, such as hyaluronic acid, derived from our own bodies such as PRP and autologous fat, or synthetic like PLLA and PMMA. They can be temporary treatment, long lasting biodegradable treatments or permanent non-biodegradable substances.

They work in different ways and not all of them are right for each indication and injection area; for this reason, a plastic surgeon may prefer using one over another to provide the results that meet the expectations of the patient. 

Indications of dermal fillers

Injectable soft tissue fillers have many different cosmetic indications and are used to improve the look and appearance in several different ways. Dermal fillers can:

  • Smooth fine lines on the face, like crow’s feet and vertical lip lines (smoker’s lines).
  • Fill wrinkles, like the horizontal forehead lines and the frown lines.
  • Soften creases and skin folds on the face, like the nasolabial fold and marionette lines.
  • Fill hollows, such as the under-eye hollows that cause black circles and a tired appearance or the submalar hollow when cheek volume is loss due to aging.
  • Reshape features, such as the chin and the nose
  • Augment features, such as lips and cheeks
  • Restore lost volume, in many facial areas but also in the aging hands
  • Improve the look of scars, such as acne scars and other depressed scars

How long do dermal filler lasts?

Different classes of fillers have different duration of the effects. Different formulations of the same class of fillers also have different duration. Duration is also affected by the site of injection, technique used for the injection, amount of product injected, patient’s metabolism and individual characteristics, and if it is the first treatment or a follow-up treatment.

The main types of dermal fillers are :

Hyaluronic acid (HA) is a natural occurring molecule in the human body. It is also found in the skin where it keeps it plump and hydrated. HA has the ability to bind 1000 times its weight in water, helping to retain it in the skin. Photodamaged and aging skin in general see a decrease in concentration of hyaluronic acid due to its degradation and reduced synthesis resulting in loss of volume, wrinkling and altered elasticity. Hyaluronic acid as an injectable filler may be chemically modified (crosslinked) to make it last longer in the body.

Collagen is a naturally occurring and most abundant protein found in the human body. Collagen is a major component of the skin giving it strength and support. Collagen deteriorates over time and is easily damaged and degrades when hit by UV rays. There are different collagen products on the market, some are derived from animal sources (bovine and porcine) and other are derived from human sources (cadaveric skin or lab cell cultures). 

Fat grafting is a procedure that utilizes autologous fat as filling material. Fat grafting is also known as fat transfer, fat transplant or lipofilling. Fat is another component of the subcutaneous tissue that is loss due to the aging process and its loss contributes to sagging and wrinkling skin as we age; this loss happens in the face and hands mainly while fat storage is increased in other areas of the body such as the waist in women and the abdomen in men. Fat is usually obtained through liposuction of the lower abdomen and after centrifugation and processing it is ready for reinjection. Not all transplanted fat cells will survive, and the survival rate varies greatly depending on the surgical techniques used and the ability of the surgeon. The damaged cells and those that can’t receive blood and nutrient supply in the recipient area will be resorbed with time. The survival rate ranges 10-90% and the use of PRP in conjunction with fat grafting seems to be promising in guaranteeing a higher survival rate of the fat cells.

PRP injections to the face are also known as “vampire lift”. Blood is drawn from the arm and after centrifugation and processing the PRP is separated from the other blood components and is ready for reinjection. PRP is rich in growth factors which increase fibroblast proliferation; fibroblasts are cells that synthetize the extracellular matrix (ECM) which is composed by proteins such as collagen and elastin, and by other molecules such as hyaluronic acid, all of which are lost due to the aging process. By increasing fibroblast and their production of ECM components, PRP effectively rejuvenates the skin, decreasing the signs of aging and increasing elasticity and volume,and may stimulate or speed up the healing process, shortening healing time for injuries, decreasing pain and even encouraging hair growth.

Polylactic acid is a synthetic but resorbable dermal filler used for many years in the medical field such as in dissolvable stitches. PLLA works by stimulating the tissue to synthetize new collagen over several weeks while slowly being resorbed.

Calcium hydroxylapatite is a biodegradable substance naturally found in human bones and teeth. As a filler, CaHA is made in the lab as microspheres suspended in a soluble gel which is resorbed and helps in the dispersion of the microspheres. Calcium hydroxylapatite stimulates collagen production, increasing volume over several months in the areas where it was injected, and it is eventually resorbed.

PMMA is a biocompatible but permanent filler. Microspheres of PMMA are suspended in a collagen gel which helps for an even distribution of the product. While collagen is quickly resorbed, PMMA microspheres stimulate our own collagen production providing volume in the treated areas.

PCL is a biocompatible and biodegradable polymer. Microspheres of PCL are suspended in an aqueous gel and injected in the desired area. The aqueous gel provides immediate volume restoration and is then resorbed over 2 to 3 months. The PCL microspheres stimulate collagen production overtime providing a longer lasting effect.