A heightened cultural emphasis on youth and beauty has resulted in an increase in cosmetic surgery in the Western world. Lip augmentation is one of the most popular cosmetic procedures done because full lips are considered youthful and voluptuous. With reliable and improved techniques, it is possible to change the appearance of the lips utilizing injectable materials and surgical techniques. This article focuses on popular materials and techniques utilized to augment the size and volume of the lips—the most common are dermal fillers. Lip augmentation requires a thorough understanding of anatomy and managing patient expectations, available materials, and techniques.
Key points
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An important anatomic border is the junction of the cutaneous portion to the mucosa, also called the vermilion border, which contains the white roll: a raised area of skin of variable prominence and useful landmark for lip augmentation techniques.
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The subunits of the lip should be considered as they relate to the context of the face as well as the golden ration, which describes the classic proportions of the lips relative to the natural face. It is important for clinicians to preserve these characteristics when augmenting the lips because a failure to appreciate the delicate contours can yield undesired looks.
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There is a wide range of options for augmentation, from nonsurgical methods, such as fillers, to open surgical methods, including the subnasal lip lift procedure. The injection of dermal fillers is the most popular nonsurgical procedure to increase the volume and shape of the lips.
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Various injection techniques have been described for lip augmentation; however, there is no clear consensus as to what constitutes the superior technique.
Introduction
In recent decades, a heightened cultural emphasis on youth and beauty has resulted in a significant increase in cosmetic surgery in the Western world. Among the most popular cosmetic procedures done today is lip augmentation; full lips are desired aesthetically because they are considered youthful and voluptuous. An enlarged lip is not beautiful, however, if its shape is not attractive, and trends amplified through modern social media perpetuate a desire to create the “perfect lip.” With reliable and improved techniques, it now is possible to change the appearance of the lips utilizing several injectable materials and surgical techniques. This article focuses on the popular materials and techniques utilized to augment the size and volume of the lips, the most common of which are dermal fillers. Although there is no single formula for successful lip augmentation, to a large degree it is an art that necessitates a thorough understanding of anatomy and managing patient expectations, available materials, and techniques. The objective is to create a form that aesthetically harmonizes with a patient’s unique facial features and ethnic background as well as educating the patient regarding normal lip proportions in order to obtain a pleasing result. Furthermore, the process of normal human aging must be taken into account, because with age, the properties of the lips change, including gradual volume loss, a thinner appearance, and lengthening of the upper lip. Therefore, it is important to understand and appreciate the central concepts of lip anatomy and physiology in the context of the aging face in order to achieve optimal cosmetic results.
Lip anatomy and physiology
The lip anatomy first can be divided by its external components: skin and mucosa. The relaxed skin tension lines of the lip are oriented radially from the vermillion border. The upper lip consists of the skin from subnasale to the vermilion border and further inferiorly to the mucosa. The cutaneous portion contains hair and sebaceous glands. An important anatomic border is the junction of the cutaneous portion to the mucosa, also called the vermilion border, which contains the white roll, a raised area of skin of variable prominence that is a useful landmark for lip augmentation, in particular for injection-based techniques. The mucosa also consists of the dry (exposed to air) and the wet (more inner surface) portions. Because of the absence of keratin and underlying vascular plexus, the vermillion is red in color. Deep to the visual surface exists the orbicularis oris muscle, which provides tissue bulk and is responsible for maintaining oral competence. The muscle is innervated by the facial nerve and sensory innervation from V2 and V3 of the trigeminal nerve. The arterial blood supply originates from the labial artery (a branch of the facial artery) and is located deep to the mucosa and orbicularis oris.
The function of the lips is 2-fold. The first is to act as a sphincter, which is accomplished via the orbicularis musculature. The upper and lower lips function somewhat differently in this regard, because the lower lip is less mobile and acts more like a dam, aiding in oral competence. The upper lip is more mobile and functions more like a curtain, draping over the upper dentition. The second function of the lips relates to facial expression, which aids significantly in communication. Speech, smiling, laughing, and grimacing are important communicative functions.
Lip aesthetics
It is critical to consider the appearance of the lips within the context of the face as a whole. The lips should be in balance with the surrounding soft tissue and skeleton of the midface specific to an individual’s appearance. For instance, excessive augmentation in a person with relative midface hypoplasia may appear unnatural.
When dealing with facial aesthetics, the anatomy is broken up into subunits, first described by Burget and Menick. There are 3 subunits within the upper lip, the central philtrum and 2 lateral subunits. A single subunit makes up the lower lip. Common facial analysis divides the face into horizontal thirds ( Fig. 1 ). The lips are located within the lower third, which is bounded by inferiorly at the menton to the most superior part, the subnasale. The lower lip (menton to vermilion border) is twice the height of the upper lip complex (subnasale to upper vermilion border).
The golden ratio, which has been described in the context of many disciplines, including art, architecture, biology, and mathematics, has been applied to describe the classic proportions of the lips relative to the rest of the face. In youthful whites, the ideal ratio of the vertical height of the upper lip to that of the lower lip is 1:1 , ( Fig. 2 ).
The upper lip is most notable for the Cupid’s bow complex, which is created by 2 high points of the vermilion adjacent to the inferior point of the philtral ridges, characterized by a sloping depression between them in the central lip. It is important to preserve these characteristics when augmenting the lips, because a failure to appreciate the delicate contours yields a characteristic duck or sausage look. ,
When examining lip aesthetics, it also is vital to look at the projection from the profile view ( Fig. 3 ). Ideal aesthetic projections of the upper and lower lip exist. A line may be drawn from the subnasale to the pogonion, and the upper lip should lie 3.5 mm anterior to this line, with the lower lip 2.2 mm anterior. Most investigators agree that the upper lip should project more than the lower lip. ,
Another factor influencing projection is the underlying dentoalveolar structures. The dentition and alveolar ridges provide the structure upon which the soft tissues of the lips rest. It is important to keep in mind when considering lip augmentation, the natural tooth show in women and men. In women, the natural anterior tooth show is 3 mm to 4 mm. Care should be taken to preserve these standards when augmenting the lips in a woman with a small tooth show for instance. Furthermore, camouflaging lip augmentation may be addressed in part by orthodontic treatment.
The aging face: lips
It is worthwhile to consider factors specific to the aging face when assessing an older patient. With age, the lips undergo numerous changes. Causes of these aging changes are multifactorial, including genetics and social factors. These can be classified as intrinsic and extrinsic processes. Intrinsically, the most significant changes occur in the dermis, where the ground substance decreases and the ratio of type I to type III collagen diminishes. Elastic fibers become thin and fragmented leading to a decrease in amount of collagen. Extrinsically, actinic damage from sunlight exposure and smoking may accelerate this process. The aging process begins with a proliferative phase from birth to puberty, represented by glandular and muscular hypertrophy, resulting in full, youthful-appearing lips. The most obvious sign of aging is that loss of ideal fullness and projection of the lips.
There are several additional changes that occur during the aging process. Skin laxity increases with a down-turning of the oral commissures. The musculature, subcutaneous fat, and even dentoalveolar structures lose volume with increased age. Visually, the aging lip is characterized by a decrease in vermillion show, blunting of the Cupid’s bow, and an attenuated white roll. , The repetitive activity of the orbicularis muscle can lead to vertical rhytids of the upper and lower lips. Over time, marionette lines also may form, which are characterized by vertical lines at the oral commissures, resulting in an expression of sadness.
Options for augmentation
Introduction
There is a wide range of lip enhancement options, from nonsurgical methods, such as fillers, to open surgical methods, including the subnasal lip lift procedure. Surgical implants and autologous fat transfer have been described but rarely are used today.
The injection of dermal fillers is the most popular nonsurgical procedure to increase the volume and shape of the lips. Although most cosmetic injectable fillers have been studied in facial augmentation, a smaller number have been tested specifically for lip enhancement. The ideal filler material for lip augmentation remains a subject of debate. , Myriad natural and synthetic compound are used, but none is wholly superior. Fillers can be human derived, animal derived, or synthetic with temporary, semipermanent, or permanent effects due to resorbable or nonresorbable characteristics.
Dermal fillers are a thriving business and the overall market size in North America has expanded in 2019 to roughly 1.7 billion dollars. The most popular material is derived from hyaluronic acid (HA) which makes up nearly 77% of market shares. The semipermanent dermal fillers, such as calcium hydroxyapatite and poly- l -lactic acid, as well as permanent fillers are not preferred for lip augmentation because they have an increased risk of irregularity and nodule formation. Other less common options include implants, neurotoxins, lasers, and micropigmentation.
Fillers can be categorized in multiple ways, including by material type or origin of the material used. Among the temporary biodegradable fillers are those derived from bovine collagen (Zyderm and Zyplast), those from human collagen (CosmoDerm and CosmoPlast; Allergan), and 1 derived from porcine collagen (Evolence). Implants, such as acellular human dermis (AlloDerm sheets and Cymetra injectable dermis) and allogeneic human tissue collagen matrix (Dermalogen) have shown some promise.
There are temporary fillers derived from HA in addition to bacterial or nonanimal stabilized HAs, such as the Restylane and Juvederm family. Finally, serial autologous fat grafting is an option; however, there is some debate as to the long-term effectiveness of this technique. In addition to autologous fat grafting, other options like surgical lip implants, Botox (onabotulinumtoxin A), ablative and nonablative skin resurfacing can be used mainly as adjunctive therapies.
Autologous Fat Injection
The use of fat injection as a way of transplanting free fat graft was established soon after the introduction of liposuction. In 1893, Neuber made the first attempt at fat graft transfer for the clinical treatment of facial deformity. , Since then, free fat grafting has been widely used for various types of facial tissue repair. Gyuron and Majzoub developed a core fat graft technique for lip augmentation and correction of malar and buccal deficiency. Alternatively, the microlipoinjection technique can be utilized for harvesting via the tumescent injection for fat harvest from ideal donor sites that include the groin, gluteal fold, and lateral gluteal area. The fat cells then are purified from the serosanguineous debris. Finally, a large-bore needle then is used to inject fat into the subcutaneous areas that warrant volume enhancement. The general requirements include selection of a cosmetically concealed donor site, proper preparation, and secure placement of the graft into the recipient site with meticulous hemostasis. It also is important to overcorrect approximately 30% to 50% due to the rapid resorption of the graft, which leads to variable survival, ranging from 40% to 80%. In perioral regions, fat injection may be beneficial; however, in the lips, its limited longevity and irregular surface contours have restricted its use. Now it is used mostly as an adjuvant therapy for lip augmentation.
Collagen Fillers
Collagen has been used for more than 2 decades and was one of the first fillers used in the aesthetic setting. The earliest fillers were derived from bovine collagen with the introduction of Zyderm and Zyplast into the cosmetic surgery market in the early 1980s. In 2003, human-derived collagen, obtained from neonatal foreskin (CosmoDerm and CosmoPlast) was developed. These products—unlike the bovine collagen fillers—do not require an allergy skin test and were approved for restoration of the lip border. Both Zyplast and CosmoPlast are cross-linked and used for moderate to deep lines and enhancing the vermillion-cutaneous junction of the upper and lower lips. Although no studies have demonstrated a causal link between collagen and dermatoinflammatory conditions, collagen has largely fallen out of favor and been overshadowed by newer, more efficacious filler materials. Most of them, therefore, have been discontinued. Lastly, collagen has an average duration of only 3 months, compared with HA fillers that generally last an average of 6 months to 12 months.
Hyaluronic Acid
The next group of fillers is derived from HA, a glycosaminoglycan found in the dermis and numerous other tissues throughout the body. The HA fillers have become the most popular choice of fillers due to their effectiveness, biocompatibility, and safety profile. An added benefit of HA fillers is their hydrophilic nature, which further augments soft tissue volume by attracting water from surrounding tissues. There is no skin test required and they are easily obtainable. HAs have a duration of activity lasting between 6 months and 12 months. Nonanimal HAs can be cross-linked with other molecules. Cross-linking of HA impedes the destruction of HA by hyaluronidase. The cross-linked molecule in both biphasic and monophasic HAs is 1,4 butanediol diglycidyl ether. Cross-linked HA products are either biphasic or monophasic.
In biphasic products, cross-linked HA is sieved through a screen to isolate particles of a uniform size. An example of this is Restylane, first approved by the Food and Drug Administration in 2003 for treatment of moderate to severe facial wrinkles and folds. Both Restylane and Perlane (larger particle sizes) have been used extensively for lip enhancement over the past decade.
Among the newer HA-derived fillers is Juvederm, approved by the Food and Drug Administration in 2004 for the correction of nasolabial folds; however, its use now has expanded to lip augmentation. Juvaderm is an example of a monophasic monodensified HA, which persists up to 6 months to 9 months when injected into the lips. Monophasic HA fillers are not sieved and thus contain a mixture of HA molecules of varying sizes and shapes. The higher degree of cross-linking in Juvaderm confers longevity. The Hylacross gel technology gives it a softer, smoother, and more natural feel rather than the particulate or granular consistency seen with other HA fillers. They come in 2 formulations, 24 mg/mL and 30 mg/mL. Juvaderm is an ideal choice for the body of the lip as well as enhancing the vermilion border.
With an understanding of the aging lips and various filler materials (summarized in Table 1 ), the techniques specifically with injection of filler material and basic rules to follow for achieving natural results are described.
