Facial fillers are substances injected into the face in order to fill volume deficits and improve surface contours. They have rapidly gained remarkable acceptance over the past decade as a method of reliably enhancing the topographic features of the human face.
Clinical Pharmacology and Product Comparisons
Several classes of facial fillers are available. The safest and most widely accepted filler is cross-linked hyaluronic acid (HA). The lowest rate of antigenicity and least risk of cross-species infection is from nonanimal source HA, which is obtained from the outer cell wall of streptococci. HA is considered a volumizer in that its effect depends largely on the bulk effect of the injected product rather than inflammation and the stimulation of collagen production. HA also may be immediately dissolved by injection of hyaluronidase. The tissue-volumizing effect usually lasts up to 12 months for most HA fillers.
Fillers that create volume primarily through foreign-body reaction (eg, poly-L-lactic acid, dextran) or collagen stimulation (eg, polymethylmethacrylate, calcium hydroxyapatite) are classified as stimulators. Fillers vary considerably in safety, duration, cost, complications, and reversibility (Table 1). Overall, nonanimal source HAs are the safest and most reliable fillers for novice injectors.
With facial aging comes the appearance of deeper lines, tissue descent, and volume loss in the areas of the nasolabial folds, melolabial folds, jaw line, glabellar furrows, and tear trough. Also there may be hollowing of the cheeks, loss of fullness (or volume) in the lips, and fading of the distinct vermillion border (Figure 1).
Anesthesia and Skin Preparation
Filler injection requires local anesthesia in most patients. Topical anesthetic cream, such as tetracaine 6.0%/lidocaine 6.0%/phenylephrine 0.01% cream, may be applied 30 to 45 minutes before the procedure. Alternatively, local anesthetic may be delivered to the mental and infraorbital nerves and the superior and inferior gingival sulci. Some dermal fillers come premixed with lidocaine (eg, Prevelle Silk, Mentor, Santa Barbara, California; Juvéderm XC, Allergan, Irvine, California; and Restylane-L and Perlane-L, Medicis, Scottsdale, Arizona); otherwise, the injector may add 0.2 ml lidocaine 2% per 1 to 2 ml of filler to the syringe. Skin preparation to reduce the surface bacterial count will help reduce the risk of infection.
Several injection techniques are useful for filler deposition (Figure 2). The simplest technique for novice injectors is serial puncture, where multiple pinprick deposits of filler are placed. With experience, linear threading may be used: the needle is advanced at a uniform tissue depth, then filler is deposited as a linear thread during withdrawal. With further mastery, the filler is deposited as the needle is advanced: this push-ahead method is useful in the vermillion border area and may help to reduce bleeding because the flowing product displaces vessels and tissue away from the cutting edge of the needle.
With cross-hatching, multiple linear depositions may be deposited in parallel rows, followed by an overlying or underlying perpendicular array of linear deposits. This is useful in bulking up deeply corrugated folds such as the nasolabial folds. Fanning consists of an array of linear deposits fanning out from a central injection point and is useful when filling triangular depressions such as the upper melolabial fold.
The nasolabial fold is a common area of filler placement (Figure 3). Folds may be primarily visible due to a discrete furrow; a broad, smooth valley; or a combination thereof. A discrete superficial furrow is best filled by linear threading, whereas a broad valley may require cross-hatching. Fanning is useful at the juncture of the upper nasolabial fold and the nasal alar rim.
The glabella is sometimes injected without any supplemental anesthesia, but most patients are injected after the area has been numbed with ice or topical anesthetic. The glabella responds well to filler, but caution is indicated to avoid aggressive filling because of reports of dermal necrosis due to vascular compromise. Slowly injected intradermal filler is used for treating wrinkles in the glabella. Deeper and forceful injections have been associated with retrograde embolization of the central retinal artery and visual loss.
The tear trough area is best treated by experienced injectors because of the complex topography, confluence of thick cheek skin and thin eyelid tissues, underlying visual apparatus, embolic hazard, vasculature, and tendency to bruising. Any nodularity in this area can be quite noticeable. Preperiosteal injection of filler followed by aggressive digital molding is a useful method. One method is to make 3 to 5 deep supraperiosteal injections per side and mold these into position (Figure 4). Additional layered deposits may be used to enhance the final contour. Reactive fillers (stimulators) should never be placed superficially in this area.
The cheeks may suffer over time from descent of the malar fat pad, subcutaneous volume loss (“deflation”), and hollowing. Direct subcutaneous filler injection is useful when restoring “high cheekbones” and reversing the underlying volume loss due to descent of the malar fat pads. The cheek hollows respond well to subcutaneous filler. Larger volumes of filler are often required in the cheek areas. One must be cautious to avoid underfilling, overfilling, or lumpiness. Often the “tear trough” depression may be noted to spill over onto the cheek in the area of the mid-inferior orbital rim. Treating this area, as well as the tear trough and the cheek, will often reverse much of the tired appearance associated with descent of the midface.
Melolabial Folds or Marionette Lines
The melolabial folds extend inferiorly from the oral commissures and angle slightly laterally to end at the mandibular border (Figure 3). The melolabial folds often require large, deep deposits of filler to lift the depressed fold. Where the fold meets the commissure, there is often a triangular depression bordered by the lateral vermillion of the lower lip and the nasolabial fold. This area often is treated with aggressive fanning.
Lips: Vermillion, Commissure, Vertical Lip Lines, and Volume
The sensitive vermillion border of the upper and lower lips may be enhanced by push-ahead linear filling and using a filler that is safe for intradermal injection. Usually 6 injections are used on the upper lip and 4 to 6 on the lower lip (Figure 3). Vertical lip lines may be filled with very superficial intradermal injection along the base of each wrinkle, with care taken not to overfill (Figure 5). Very small doses of supplemental botulinum toxin are also helpful with these lines. Sad and downturned atrophic commissures may be perked up by aggressively filling the lateral vermillion border of the commissure, adding volume to deficient lateral lips, and by aggressively filling the superior aspect of the adjacent melolabial fold. The volume of the lip is augmented by superficial submucosal filler. One should try to maintain a slightly fuller lower lip compared to the upper lip, with a vertical height of 60% lower lip and 40% upper lip. Herpes simplex virus prophylaxis (eg, acyclovir) is warranted in susceptible patients.
Jowling may be blunted by aggressive filling of the melolabial fold combined with filling the trough where the jowl crosses the mandibular border. The skin is quite thin along the mandibular border, so it is best to inject deep and parallel to mandibular border in order to avoid visible nodularity. One should be careful to avoid injecting the mental vessels.
Complications of fillers vary from mild and insignificant to severe and disabling. Common mild complaints include bruising, several days of discomfort, mild swelling, and mild transient erythema. Superficial injections may create a bluish discoloration (Tindall effect). Some patients may demonstrate allergic reactions and nodules, although this is much less common with modern HA fillers when compared to older collagen-based products. Rarely, severe swelling may occur, especially in the lips, and this may be treated with oral steroids. One should inject less in the glabellar area because of the risk of dermal vascular compromise resulting in glabellar necrosis, but vascular compromise may occur in any area with excessive filler. Dermal ischemia should be treated with heat and transdermal nitroglycerin ointment (nitropaste), and, in the case of HA fillers, hyaluronidase injection. Fluctuant or painful nodules that develop shortly after injection may represent bacterial infection (Figure 6), whereas nodules that occur several weeks after injection may be due to atypical mycobacterial infection. Non-tender nodularity is usually due to overfill, superficial injection, or placement of a reactive filler in an area of thin, distensible tissue (Figure 7), such as lips or tear trough. HA is the most forgiving filler as it may be immediately dissolved with hyaluronidase injection. Embolization may result in distal injury to the retinal circulation; therefore, cautious injection following syringe aspiration is useful in the tear trough, glabella, and mandibular border.