A practical guide to selecting facial fillers

Dermal fillers have created a multi‐billion‐dollar industry. They are the second most popular form of injectable, as they primarily address volume loss, augmentation, and provide immediate results. The most popular form includes hyaluronic acid‐based fillers, however, alternatives exist.


| OVERVIE W
As not every patient is a good surgical candidate, or may request nonsurgical approaches, there are a growing number of alternative treatments that can be used for facial rejuvenation. 1Injectable fillers have become a mainstay in the nonsurgical treatment of facial deflation and regional augmentation.The most prevalent form of filler is hyaluronic acid (HA)-based, however, alternative, longer lasting fillers are also commercially available. 1HA is a ubiquitous member of the glycosaminoglycan (GAG) group of polysaccharides that is commonly found in most mammalian tissues. 2 In humans, the majority of HA is found in the skin, particularly the dermis. 3HA has many unique rheological, viscoelastic, and biological properties, which are primarily dependent on the size and preparation of the polymer. 2 HA is negatively charged due to the repeating units of glucuronic acid, as a result, it is hydrophilic, which is a property that provides turgor, elasticity, moisture, and volume to the skin. 4HA fillers have been around since the 1980s and have evolved with every passing generation. 1 Common filler materials include the following:

| HYALURONI C ACID (HA )
Hyaluronic acid fillers are typically soft and gel-like.The viscosity and structure of HA can be altered to provide a softer, more skin-like texture, or a more rigid formulation to create structure. 5The results typically last 6-12 months or longer, depending on the rate at which hyaluronidase, a naturally occurring human enzyme, fragments the larger, high molecular weight HA into smaller fragments which are absorbed naturally. 6,7

| C ALCIUM HYDROX YL APATITE (C aHA )
Calcium hydroxylapatite (CaHA) is a naturally occurring compound, most commonly found in human bone.The microscopic calcific particles take the body longer to degrade, therefor lasting for over 12 months. 8As the microscopic particles create more structure, the resultant product is more viscous than the equivalent HA filler, and appropriate gauged equipment needs to be considered.CaHA is FDA-approved (Radiesse) and was found to naturally stimulate collagen production and improve skin tone and quality. 9

| P OLY-L-L AC TI C ACID (PLL A )
Poly-L-lactic acid is a synthetic biodegradable and bio-stimulatory compound, most commonly found in dissolvable sutures.Similarly, to CaHA fillers, PLLA fillers (FDA-approved-Sculptra) stimulate collagen production and replace volume.As PLLA fillers primarily work on collagen synthesis, final results can take several months to appear; however, the results can last several years. 10,11
It is composed of microspheres suspended in bovine collagen as an injection medium. 12These synthetic microspheres are not absorbed by the body, therefor, PMMA fillers are commonly referred to as "permanent".Similarly, to the above categories, PMMA (FDA approved-Bellafill) fillers have a thick consistency, therefor, provide robust structure, while also being approved for more subcutaneous injections to stimulate collagen and provide continued results over time. 12,13

| OBJEC TIVE
In this article we propose clinical charts to help injectors choose the appropriate dermal HA filler from currently available manufacturers in North America, injection recommendations from our senior authors and management of common complications.

| PROCEDUR AL CONS IDER ATIONS
Injectable fillers require topical anesthetics for more sensitive areas and patient preference/comfort.The delivery of HA fillers can be with either an appropriate gauge needle to the viscosity of the product, or with a cannula for more superficial approaches and contouring. 14Deeper injections, with a higher viscosity, are recommended to be on periosteum and a needle would be the safest method of delivery.The use of ultrasonography, for direct visualization and injection of fillers, particularly in higher risk areas (glabella, temporal, tear-trough, nose, and nasolabial) is becoming more common. 15r all procedures, facial assessment and patient counseling need to be thoroughly addressed.Counseling regarding facial harmony and alternative treatments which may provide better results for current concerns need to be prioritized over financial gain.Injectable HA fillers are primarily created to address deflation and may not reliably provide a "lifting" effect to the areas of concern. 16Skin quality, facial laxity, and noticeable pre-procedural asymmetries (static and dynamic) need to be discussed prior to injection.Finally, consent and photographic records must be kept for all patients.HA fillers are graded based on their viscosity/consistency, this is referred to as "G-prime" or "G".The higher the G, the more viscous and rigid the texture of the filler, and the inverse is true regarding the lower G products. 18The higher G products are recommended for injection at the level of the periosteum to build structure, as the product would feel too hard and "nodular" if injected more superficial. 17,18Based on this G rating, a chart with the most used fillers from manufacturers available in North America was created (Tables 1 and 2) The alternative fillers (PMMA, PLLA, CaHA) can be considered for any of these regions, depending on depth of injection.PLLA fillers can add value superficially, while PMMA and CaHA fillers are more valuable deeper, to create longer lasting structure and volume 6 (Table 3).

| S PECIAL CONS IDER ATIONS
Prior to the procedure, expectations and complications should be discussed in detail with the patient.Hyaluronidase should be available in the clinic space, checked for date and an adequate supply compared to the amount of filler to be used (1:1 ratio).For certain patients, the use of a skin test is indicated, particularly those with a history of moderate to severe hypersensitivity reactions to injectables or granuloma formations.Skin testing is also recommended for PMMA (Bellafill) fillers as they contain a bovine collagen carrier, which has the potential of being immunogenic. 19her complications to be discussed include erythema/bruising, infection, bleeding, hypersensitivity reactions, asymmetry, migration, nodules, Tyndall effect (bluish discoloration with superficial injections), and vascular occlusion. 20Injectors are to be aware of the signs of the above complications and be able to manage them appropriately (Table 4) HA fillers can be reversed using hyaluronidase and if necessary, the use of ultrasonography to help define the appropriate plane.Due to the biological composition of the alternatively mentioned fillers, they cannot be reversed using hyaluronidase.A novel method to remove a CaHA (can theoretically be applied to PMMA) filler has been described

Fine lines
Inject into both the reticular and papillary dermis to create structure.Avoid large boluses as this will cause palpable nodularity.A slight "peau d'orange" effect is normal.
Note: Current recommendations and pearls are highlighted in the "notes" section.Please refer to Table 1 for selecting the filler based on color/ number.
by the senior author, Cohen et al. 21In brief an 18G needle is used to puncture the skin, a "grater" type cannula is inserted to ream and aspirate the injected filler, with the objective of correcting contour deformities.

| CON CLUS ION
The overall assessment of facial harmony, laxity, and patient selection is critical.All HA fillers are temporary and primarily address TA B L E 3 Non-HA fillers.

Class Product Preparation Notes
PLLA Sculptra Reconstitute with 5 mL of sterile water and shake.Add an additional 3 mL and shake again.Swirl in 1 mL of 2% lidocaine immediately prior to injection.When drawing up the solution, avoid the foam as this will clog the equipment and increase risk of nodularity.*Above volumes can be adjusted slightly for a more or less viscous solution depending on the level of injection.
Viscosity is dependent on reconstitution.Can inject deep for structure or widespread subcutaneous to eliminate wrinkles and stimulate collagen.Note: Current complication rates along with current management recommendation (Green -minor, no intervention; Amber -requires intervention; Red -requires immediate medical intervention).

17
photographic records must be kept for all patients.17

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FILLER CHOI CEFillers are provided in 0.5 cc (lips) or more commonly 1 cc syringes.
Currently available fillers from each manufacturer (US/Canada).Each row represents a varying G-prime.Level 1 has the highest G-prime, while Level 7 has the lowest G-prime.The numerical and color coding of each row will represent filler selection in Table2.This table is to be used as a reference in selecting fillers based on G-prime and as a legend/key for Table2.Anatomically based chart to help with filler selection based on achieving structure and/or contour.
TA B L E 1 TA B L E 2 Common sites-Buccal loss, mid face wrinkles, perioral rhytids and neck.Possible to inject Bellafill at the dermal subcutaneous junction, however, caution regarding the risk of palpable nodularity.Common sites-Deep cheeks, jaw, chin and nose.Avoid in the lips.Commonest complications associated with injectable dermal fillers.Due to vascular occlusion or compression.Dissolve injected material with hyaluronidase (150-200 IU per ml of injected filler).("Flood with Hyaluronidase") *Repeat every 60 min for up to 4 cycles Warm compresses and vigorous massage to stimulate vasodilation.Regular (q2-4h) application of 2% nitroglycerin paste to the affected area.Consider 325 mg of Aspirin to avoid clot formation (Continue for 2-3 days following treatment).*If no improvement in 24-48 h, consider other vasodilator adjuncts, including, sildenafil, low molecular weight heparin, IV prostaglandin, and hyperbaric oxygen.Ocular specific: Contact emergency ophthalmology for support.Apply firm pressure to the globe.Consider retrobulbar hyaluronidase injections.
*TA B L E 4Infection <1% risk.Prepare skin in an aseptic manner.If an infection is reported, treat accordingly with antibiotics (cellulitis) and drainage if indicated (abscess/collection).