Chapter 16 Filler Injection of the Lips, Oral Commissure, and Mentolabial
Youthful lips are characterized by volume and a well-defined contour. An M-shaped curve of the upper vermilion border is called the Cupid’s bow, and the linear prominence that originates at the two apices of the M toward the nostrils consitutes the philtrum columns.
The characteristics of “ideal” lips have been described in the literature. In Caucasian women, the ratio from the upper lip to the lower lip is 1:1.6, i.e., the lower lip is more voluminous than the upper one, and the Cupid’s bow and the philtrum are evident. The format of the lips should be convex when seen from the side, and the upper lip should project 2 mm over the lower lip. The lips should be parallel to the imaginary line drawn between the pupils; the upper lip should be 18 to 20 mm from the nostrils and the lower lip 36 to 40 mm from the chin.
Lips lose volume with aging, meaning that they lose convexity and take on a flattened look when seen from the side. The esthetic objective of labial filling is to improve the three dimensional relationship with the rest of the face, taking into consideration the ethnic origin of the patient, cultural factors, age, and gender. 1 –. 4
The lips are formed by an internal portion, the oral mucosa (M) (comprising nonkeratinized stratified squamous epithelium, chorion rich in blood vessels, and minor or accessory salivary glands), by a transition zone, called the vermilion border (comprising keratinized stratified squamous epithelium without hair follicles, apocrine or salivary glands, and possibly with sebaceous glands), and by an external portion comprising the skin and its appendages. The internal portion is moist, whereas the other portions are dry. The muscle fibers of the orbicularis oris muscle (OOM) insert into the border between the internal portion,the oral mucosa, and the transition zone, thevermilion border. The OOM in turn delimits two compartments:
The lips are divided into three anatomical areas. The applica tion technique takes this division into consideration, as a filler injection in each of these areas yields different results, as specified below:
Lip contour: Filler injections in this area givedefinitionto the lips. The product is applied into the dermis via retrograde injection at the edge of the vermilion border. This procedure also prevents lipstick from running in patients with vertical “barcode” wrinkles.
Vermilion border: Filler injections in this area give the lipsanterior projection,(re)creating a convex format. The filler agent is injected into the SFP, above the OOM. Retrograde injection or bolus can be used.
Oral mucosa: Filler injections in this area givevolumeto the lips, as the local dental arch projects the treated area forwards. The filler agent is injected as a bolus into the DFP, below the OOM. As the labial arteries course through this pad, we recommend aspiring before performing the injec tion, and then injecting slowly in order to reduce the risk of intravascular injection. The injection should be interrupted immediately in case of sudden pain or whitening. We prefer using microcannulas for this area instead of needles. 6
Erythema and edema usually occur immediately after the procedure, resulting from needle trauma and the hygroscopic properties of the filler agent. Erythema can last from a few hours to 1 or 2 days. It is essential to warn the patient about this. The number of punctures should be minimized, and ice should be applied after the procedure to help reduce erythema and edema. Ecchymosis may also occur if the needle perforates a vessel. This disappears gradually in 5 to 10 days. Acetylsalicylic acid, oral anticoagulants, nonsteroidal anti-inflammatory drugs, and even vitamin E and herbal supplements can cause ecchymosis. Caution is required when using these medicinal products. Vascular occlusion and necrosis are consequences of embolization of the product in the lumen of the labial artery and can be avoided by using thicker microcannulas, greater than 25 G, when applying filler injections to the deep fat pad of the lips (DFPL).
The formation of noninflammatory papules is rare and results from injecting the product into the incorrect plane (very superficial) and not massaging the area after the injection.
The common “duck bill” is another undesirable effect that occurs due to excessive application of the filler agent or an inadequate filling indication. Filler injections are contraindicated when the distance between the nasal septum and the vermilion border is very large, i.e., when the superior dental arch of the patient is not easily visible when they smile. If the procedure is performed, the upper lip would become “heavy,” below the ideal height, projecting forward, and patients’ teeth would not be visible when they smile. In these cases, curvilinear resection of the excessive skin below the nostrils is recommended, using the gull-wing technique. After correction, the implant may be performed.
Oral Commissure and Mentolabial Sulcus
The signs of aging in the perioral region are the result of a combination of factors, including subcutaneous tissue volume loss, thinning of the dermis due to a reduction in collagen and elastin, and bone remodeling. Repetitive movements of the depressor muscle of the angle of the mouth and the platysma muscle also contribute to signs of aging. Clinically, ptosis of the oral commissure and deepening of the mentolabial sulcus, also called the marionette line, are visible. 7 ,. 8
Carruthers et al classified the mentolabial sulcus into the following five classes 9 :
Class 0: No visible folds; continuous skin line.
Class 1: Shallow but visible folds with slight indentation. These are easier to treat by applying HA to the middermis using a linear retrograde injection.
Class 2: Moderately deep folds, visible at normal appearan ce, but not visible when stretched.
Class 3: Very long and deep folds.
Class 4: Extremely long and deep folds. More diffcult to correct and generally requires application of HA in various layers, including the deep dermis and subcutaneous tissue.
If the aim is to lift the oral commissure and/or treat the mentolabial sulcus, the product is applied using a retrograde injection in the lateral part of the lower lip and the surrounding skin, thereby forming a horizontal pillar that supports the commissures. This is followed by three vertical supporting pillars created via retrograde injection, which form an inverted triangle in which the base is the contour of the lower lip that has already been filled. A small bolus can also be applied to the modiolus to help lift the commissure. Injection of type A botulinum toxin in the depressor muscle of the angle of the mouth and the platysma muscle is also helpful.
Vertical “barcode” wrinkles can be filled with a linear retrograde injection. Better results are obtained by injecting type A botulinum toxin to relax the OOM. Very deep wrinkles require a prior treatment with fractional laser or dermoabrasion.
In order to enhance the columns of the philter, it is important to remember that they are not parallel as they have an inverted V shape that narrows as it approaches the columella (Fig. 16.22–16.26,16.32, and16.38–16.41).