Dermal Fillers
4 min. read
June 28, 2024

The Perfect Lip - Achieving Balance, Volume, and Natural Lip Enhancement

Written by
Dr. Maya Sinai
Dr. Maya Sinai

The lips, positioned at the heart of the face, play a complex role in aesthetics and function. They contribute to facial beauty and expression and play a vital role in speech, chewing, and maintaining the oral seal. Full and well-defined lips are often associated with youthfulness and attractiveness. As a result, lip augmentation has become a booming aesthetic procedure, with the global market expected to reach a staggering USD 11.61 billion by 2030.

The Perfect Lip - Achieving Balance, Volume, and Natural Lip Enhancement

This surge in popularity can be attributed in part to the rise of temporary, non-surgical techniques like injectables and energy-based devices. This temporary approach allows patients to experiment with different looks without committing to permanent changes. It provides the flexibility to explore styles and trends and ensure their desired outcome aligns with their evolving aesthetic goals. 

Achieving optimal lip enhancement requires a personalized approach. This is where in-depth consultations regarding desired outcomes, as well as a thorough knowledge of facial anatomy and potential complications, are essential to deliver patient satisfaction and confidence through natural-looking lip enhancements.

The Perception of Youthful Lips

From a clinical perspective, youthful lips2 exhibit several key characteristics that can guide treatment decisions for non-surgical rejuvenation procedures. Here's a breakdown of these features:

  • Perioral Rhytids: The absence of visible wrinkles or rhytids in the perioral region (above the vermilion border) indicates adequate dermal collagen content and skin elasticity.
  • Philtral Columns: These are the defined vertical ridges bordering the philtral depression (Cupid's bow). In youthful lips, the philtral columns exhibit sharp definition and symmetry.
  • Vermilion Border: This refers to the vermilion transition zone, the border between the red lip mucosa and the paler perioral skin. In young individuals, the vermilion border is well-defined and sharply demarcated.
  • Cupid's Bow: This is the central depression of the upper lip, typically heart-shaped. Youthful lips have a well-developed Cupid's bow with distinct, crisp borders.
  • Tubercles and Depressions: The upper lip features a prominent central tubercle, a rounded projection flanked by bilateral depressions on either side. The lower lip mirrors this with a central depression.
  • Vermilion Height: This refers to the visible red portion of the lips. Youthful lips exhibit a balanced proportion between the upper and lower vermilion heights, often with a fuller appearance than aged lips.
  • Lip Projection: In a youthful profile, the upper lip naturally projects slightly more than the lower lip. This difference is typically around 2 millimeters when measured laterally.
  • Nasolabial and Mentolabial Angles: These angles are formed by the intersection of the nasolabial folds and mentolabial folds, respectively. While not directly part of the lips, these angles can influence lip aesthetics. These angles may be slightly more defined in younger individuals due to increased skin support and tissue volume.

While these guidelines offer a helpful framework, lip shape, and size naturally vary from person to person. Additionally, ethnicity10 plays a crucial role in what constitutes aesthetically pleasing lips. 

Age Changes in Lips and the Lower Third of the Face

Over time, the lower third of the face, including the perioral region, chin, and jawline, experiences significant transformations. These are often influenced by various factors like genetics and lifestyle choices. Understanding these age-related changes allows aesthetic practitioners to effectively guide tailored treatments and address individual concerns. The table below highlights the impact of aging2 in different parts of the lower third.

Aspect Age Changes
Perioral Region Loss of definition, shape, and fullness
Flattening and retrusion of the lips
Lengthening of the ergotrid
Diminished prominence of the vermilion border and Cupid’s bow
Widening of Cupid’s peaks
Formation of perioral wrinkles and folds
Vertical Lip Lines \n(bar code lines or lipstick bleed lines) Development of wrinkles perpendicular to the direction of orbicularis oris muscle contraction
Most evident in individuals who repetitively purse their lips, such as smokers
Horizontal Lines Contraction of the levator labii superioris and depressor septi nasi muscles may lead to horizontal lines
Unsightly lines may form due to muscle activity.
Other Signs of Aging in Perioral Area Drooping of oral commissures
Formation of labiomandibular folds, also known as marionette lines
Exacerbation of labiomandibular folds due to loss of cheek support
Chin Zone Decreased chin projection in women due to mandibular rotation
Increased chin projection in men due to forward mandibular rotation
Racial variations in chin recession
Jawline Loss of definition due to prominent jowls with age
Increase in cervicomental angle
Bony changes, including mandible recession and formation of anterior mandibular groove
Skin laxity and deflation of jowl fat compartments contribute to sagging
Contribution of downward pull from platysma contraction to loss of jawline definition
Distinct feature of aged Caucasian faces, but may also affect individuals with skin of color.

Indications for Lip Augmentation

Lip augmentation offers a range of benefits for patients seeking medical and aesthetic improvements. Here's a breakdown of the key indications:


  • Correction of Lip Symmetry: In some cases, individuals may have uneven lips due to congenital defects or trauma. Lip augmentation procedures can help restore symmetry and improve facial balance.
Cosmetic enhancement
  • Symmetry Correction: Addressing asymmetry in lip shape and size.
  • Volume and Fullness: Enhancing thin or less voluminous lips.
  • Definition Improvement: Accentuating lip borders and contours for a refined appearance.
  • Aging Signs: Countering volume loss, thinning, and wrinkles.
  • Genetics: Addressing genetic predispositions for desired lip aesthetics.

Contraindications for Lip Augmentation

While lip augmentation offers various benefits, it's not suitable for everyone. 

  • Facial nerve disorders.
  • Active Infections.
  • Severe hypertension.
  • Autoimmune disorders.
  • Uncontrolled diabetes.
  • History of multiple allergies.
  • Active herpes simplex lesions.
  • Pregnancy and breastfeeding.
  • Neuromuscular disorders such as myasthenia gravis.
  • Certain medications including,some text
    • Calcium channel blockers.
    • Penicillamine.
    • Quinine.
    • Aminoglycosides.
    • Neuromuscular blocking agents (Pancuronium, Tubocurarine, Succinylcholine)
    • Blood thinners (Anticoagulants, Aspirin, Vitamin E).

Anatomic Considerations

The Aesthetic Subunits

The lips can be divided into five aesthetic subunits1,2,6, which are important for understanding lip anatomy and cosmetic procedures. These subunits help guide treatments for lip augmentation, reconstruction, and rejuvenation:

  • Cupid's Bow: Located centrally on the upper lip, the Cupid's Bow is a distinct "M" shape formed by the peaks of the philtral columns. 
  • Philtral Columns: These are vertical ridges or columns that extend from the base of the nose to the vermillion border of the upper lip. They frame the Cupid's Bow and play a crucial role in defining the shape of the upper lip.
  • Vermillion Border: It is the sharp demarcation between the colored portion of the lip (vermillion) and the adjacent skin. It is more pronounced in some individuals and contributes to lip definition.
  • Tubercle: A small, prominent projection located centrally on the upper lip, just below the Cupid's Bow. It adds to the natural contour and fullness of the upper lip.
  • Oral Commissures: Also known as the corners of the mouth, the oral commissures are where the upper and lower lips meet laterally. These areas can be prone to drooping or downturn with age and impact overall lip appearance.

In addition to these subunits, designated zones5 are helpful in the precise placement of injectables:

  • Zone A: This zone includes the area from the upper lip border (vermilion) to the fold beneath the nose (columella nasi). It's often wider due to the philtral area, which can sometimes be augmented with Botox injections in this zone.
  • Zone B: This zone occupies the middle section between the lower lip border (vermilion) and the upper border of the next zone.
  • Zone C: This zone extends from the lower border of Zone B to the bottom edge of the red lip area (wet-dry line).

Lip Proportion Classification for Facial Aesthetics

This classification system categorizes lips based on the ratio between the fullness of the upper lip and the lower lip:

  • Normal, Anatomical Ratio (1:1.6):  Often considered the ideal proportion, the upper lip is approximately 1.6 times smaller than the lower lip. This ratio creates a balanced and aesthetically pleasing appearance.
  • Decreased Ratio (1:3):  The upper lip is significantly smaller than the lower lip, leading to an unbalanced look.
  • Equal Ratio (1:1):  Less common, some individuals naturally have lips of equal size.
  • Increased Ratio (2:1):  The upper lip is significantly larger than the lower lip, potentially appearing disproportionate.
Characteristics Details
Morphology and Structure Color: Primarily due to capillary loops in the submucosal layer;
Ruby red in color normally;
May exhibit pallor or cyanosis in certain conditions.
Thickness: Variable between upper and lower lips and different regions. Classified into
Moderately Thick,
Thick, and
Thick and Protrusive.
Fullest near the midline, forming Cupid's bow.
Has complicated anatomy with important landmarks for esthetics.
Muscles Classified into
Upper group,
Lower group,
Orbicularis oris, and
Upper Group: This includes
Zygomaticus major,
Zygomaticus minor,
Levator labii superioris,
Levator labii superioris alaeque nasi, and
Levator anguli oris muscles.
Lower Group: This includes
Depressor anguli oris,
Depressor labii inferioris, and
Orbicularis Oris:
Circular muscle around oral fissure;
Primary muscle for oral closure;
Aids in various facial movements.
Quadrilateral muscle aiding in mastication and facial expression.
Layers Skin,
Subcutaneous tissue,
Muscular layer,
Blood Supply Blood Supply:
Superior and inferior labial arteries arise from the facial artery, located 1mm posterior to the mucocutaneous border.
Labial arteries lie deep to the orbicularis oris muscle and anastomose to form an arterial ring at the midline.
Facial artery
Mental artery
Lymphatic Drainage Upper and lower lateral lip drain into the submandibular nodes.
Lymph from the medial part of the lower lip passes to the submental lymph nodes.

The perioral region is a crucial aesthetic unit on the face.  Lip revitalization procedures within this unit address various concerns. These include restoring lost volume,10 enhancing lip symmetry, minimizing fine wrinkles around the mouth corners, and improving definition and structure.

Pre-Treatment Assessment3,12

A thorough lip examination is the cornerstone of successful lip augmentation or rejuvenation procedures. Healthcare professionals should evaluate the following key areas:

  • Lip Shape: Projection (lip protrusion) is influenced by bone structure, teeth, and soft tissue volume. Volume loss is a common concern. Contour analysis identifies areas for enhancement, like defining Cupid's bow.
  • Symmetry & Proportion: Ideal lips are symmetrical and have a balanced ratio between upper and lower vermilion for facial harmony.
  • Perioral Area: The depth and location of fine lines determine the best filler type and injection technique for smoothing. Dynamic lip function during speech, smiling, and pursing ensures filler placement doesn't compromise natural movement.
  • Skeletal and Dentoalveolar Components: The maxillomandibular relationship and dentition significantly impact lip support and aesthetics. Discrepancies can affect lip closure and contribute to facial profile variations.
  • Soft Tissue Evaluation:  This analysis focuses on lip lines, activity (function during animation), morphology (form including height, thickness, and contour), posture, and prominence.  Sexual dimorphism and ethnicity play a crucial role in lip morphology. Examining lip function at rest and during animation guides filler selection to minimize complications.
  • Smile Analysis: A beautiful smile integrates elements like lip aesthetics, symmetry, and dental alignment. Assessing the smile from both frontal and profile views is essential.
  • Additional Considerations: Skin quality around the lips and patient preferences regarding desired outcomes and aesthetics are considered for a personalized treatment plan.

To add to the methods above, the Ricketts E line is an assessment tool used in facial aesthetics to examine the relationship between the upper and lower lips. Developed by orthodontist Dr Robert Ricketts, this imaginary line is drawn from the nose tip to the chin and helps determine ideal lip proportions.  In average Caucasian faces, the lower lip should be 2mm behind this line, and the upper lip 4mm behind. While variations are normal for patients of different ethnic backgrounds, the Ricketts E line provides a guideline for achieving harmonious lip proportions and facial aesthetics.

Choosing the Right Filler7

Achieving optimal results with facial fillers is incomplete without considering patient-specific and treatment-related factors. Selecting a lip filler involves prioritizing natural results and maintaining dynamic lip function are important. 

Varied degrees of particle size and cross-linking within hyaluronic acid (HA) fillers create a spectrum of gel consistencies. For lip augmentation, softer gels with high flexibility are preferred. These allow for natural movement and expression during speech and animation. This distributed product integration is particularly well-suited for individuals with thinner tissue coverage in the lips.  Conversely, structural fillers tackle deeper folds and chin augmentation due to their robustness. 

Ultimately, the chosen filler should offer both contouring and volumization while seamlessly integrating with the surrounding facial features, particularly the lower face areas like the chin and pyriform space.  An excellent and long-term safety profile is of paramount importance for optimal patient outcomes.

Knowing these details helps tailor filler choices for natural-looking results that complement the patient's features and preserve dynamic function.

HA Application

When considering the use of hyaluronic acid (HA) for dermal filler injections, the choice between a needle and a cannula can significantly impact the outcome and patient experience.

For precise and targeted injections in delicate areas such as the lips, oral commissures, and pyriform fossa, a needle ranging from 29 to 34 gauge is commonly preferred. This finer gauge needle allows for meticulous control over the placement of the filler, ensuring precise augmentation and contouring while minimizing trauma to surrounding tissues.

On the other hand, when aiming for broader distribution or when performing techniques like dermal subcision, a microcannula can offer distinct advantages. Typically ranging from 23 to 25 gauge with lengths of 38 or 50 mm, microcannulas are especially useful for creating a more uniform distribution of filler and reducing the risk of bruising or vascular compromise.

When using a microcannula, insertion points are typically located approximately 1 cm lateral to the oral commissure. Patients are often instructed to gently open their mouths during the injection process, allowing for better access and visualization of the treatment area.

One notable advantage of using a microcannula is its ability to perform dermal subcision. This technique involves separating the labiomandibular ligament from the skin, starting from below the commissure and extending towards the prejowl sulcus. By creating a space medial to the ligament, HA filler can be strategically placed to restore volume and improve the overall contour of the lower face.

While both needles and cannulas have their respective advantages, the choice between them depends on factors such as the desired injection technique, the area being treated, and the patient's individual anatomy and preferences.

Neurotoxin in Action - Botox4,8

With its proven safety profile and remarkable efficacy, Botulinum toxin type A (Botox) has become a popular choice for individuals seeking non-invasive cosmetic enhancements and therapeutic interventions. 

Mechanism of Action:

Botox exerts its aesthetic effects through a highly specific mechanism that includes temporary inhibition of neuromuscular transmission at the injection site. This occurs due to the toxin's ability to cleave SNAP-25, a presynaptic protein essential for neurotransmitter release. The resulting disruption in acetylcholine release leads to localized chemodenervation and subsequent relaxation of targeted muscle fibers. 

When seeking aesthetic enhancements, patients of different age groups pose with their unique challenges.5 The table below can be used as a quick guide before proceeding further with the treatment.

Age Group (Years) Key Points to Remember
20 - 30 Greater overfill potential in this age group.

Plan to augment isolated planes to achieve a natural appearance (i.e., Segment 2, Zone B of the upper lip).

Differential diagnosis may be needed to evaluate if the patient will benefit from dental, orthodontic, or orthognathic treatment.
30 - 40 Patients in this age group are highly influenced by media and peers regarding lip augmentation trends.

The recommended injection technique involves four to six injection points per lip, starting from the corners and working inwards.

Careful sculpting in Zone A may be necessary, especially for older individuals in this group.

Less filler is preferred initially.
40 - 50 Deeper nasolabial lines and rhytids start to appear.

Complete cosmetic history is essential, especially for patients with prior augmentation.

Combination therapies like Botox/filler augmentations can be introduced.
50+ Oral-facial skin tends to be thin and fibrotic, which contributes to a loss of volume and definition.

Lips may appear thin and indurated, with a noticeable loss of anatomy, particularly in the vermilion borders.

Factors like intrinsic and extrinsic aging and skeletal and dental changes contribute to these lip changes.

Zone A fillers can address volume loss, improve lip contour, and rejuvenate the area.

Clinical Applications:

  • Relax Oral Rhytids (Perioral Lines): Botulinum toxin type A (BoNT-A) is injected into the orbicularis oris muscle and other perioral muscles to reduce muscle activity. This technique aids in diminishing the visibility of wrinkles and fine lines encircling the mouth (oral rhytids). 
  • Upper and Lower Lip Eversion: By administering BoNT-A into the depressor labii inferioris and depressor anguli oris muscles, the tension pulling downward on the lower lip is relieved, allowing the lips to gently curl upwards, creating a fuller appearance. This approach, commonly referred to as a "lip flip," enhances lip fullness without the requirement for additional volume.
  • Gummy Smile: Overactivity of the zygomaticus minor and levator labii superioris alaeque nasi (LLSAN) muscles can cause excessive retraction of the upper lip during smiling, exposing excessive gum tissue (gummy smile). can help reduce excessive upward lip movement, minimizing gum exposure.
  • Overactive DAO: The depressor anguli oris (DAO) muscle, positioned near the modiolus, plays a key role in pulling down the corners of the lips. Strategically injecting Botox near the insertion site of the DAO muscle results in its denervation. This, in turn, prompts the opposing perioral elevator muscles to lift the corners of the mouth, to give a more uplifted appearance.
  • Overactive Mentalis Muscle and Chin Dimpling: The mentalis muscle controls the downward movement of the chin and lower lip. In some cases, an overactive mentalis muscle can contribute to chin dimpling. Botox injections here can help achieve relaxation and potentially diminish the appearance of dimpling. 

Injection Techniques and Considerations:

  • Injection Points: Common injection sites include the orbicularis oris muscle fibers surrounding the vermilion border and the zygomaticus major muscles for gummy smile correction. The mentalis muscle may be targeted for chin dimpling concerns. The exact number and location of injections will be determined based on individual anatomy and desired outcomes.
  • Dosage: A typical starting point might involve 6 injections around the lips, with 1 unit of Botox per injection point. Gummy smile correction might involve 2 units per zygomaticus major muscle. Chin dimpling treatment may require 2-3 units per injection point in the mentalis muscle. Individualization of dosage is based on patient response and aesthetic goals.
  • Expertise and Anatomical Knowledge: Botox injections in the delicate lip region demand a high degree of expertise and a thorough understanding of facial musculature. This ensures optimal results and minimizes the risk of complications such as temporary weakness or asymmetry. Careful consideration is given to maintaining natural facial expressions and function.

The Role of Energy-Based Devices

Ultraformer III: 

Ultraformer III leverages High-Intensity Focused Ultrasound (HIFU) technology to provide a non-surgical approach to facial rejuvenation for both men and women. The following principles determine its efficiency:

Targeted Thermal Coagulation & Neocollagenesis:
  • Precise Energy Delivery: Ultraformer III focuses ultrasound waves deep into targeted facial tissues (dermis and SMAS) without collateral damage.
  • Controlled Thermal Disruption: High-density ultrasound creates localized thermal coagulation points, initiating a controlled inflammatory response and subsequent fibroplasia.
  • Neocollagenesis Induction: The body's healing cascade triggers neocollagenesis - the increased production of new collagen fibers within the treated area.
Clinical Significance:
  • Collagen Remodeling & Tightening: Newly formed collagen fibers remodel and strengthen the existing network result in visible improvements in facial laxity, wrinkle reduction, and overall skin texture.
  • Long-Term Results: The newly formed collagen lasts longer because it's better organized than old collagen, therefore ensuring long-lasting results. 


  • Provides skin tightening, lifting, and contouring to address concerns in the lips and perioral region.
  • Improves skin tone and strength.

A thorough evaluation helps determine suitable treatment parameters (depth, energy level) based on individual needs and goals. The optimal number of sessions and intervals vary depending on individual factors. Typically, a series spaced several weeks apart is recommended.


Morpheus8 is a minimally invasive device harnessing the combined power of microneedling and radiofrequency (RF) technology. This synergistic approach delivers fractional coagulation within the subcutaneous tissue and significantly improves facial aesthetics.

Mechanism of Action:
  • Fractional Coagulation: Morpheus8 utilizes interchangeable microneedling tips to create controlled micro-injuries within the targeted treatment area. Simultaneously, RF energy is delivered, inducing localized thermal coagulation in the subdermal tissue up to a depth of 8mm. This combined action triggers a controlled wound-healing response that stimulates collagen and elastin production.
Clinical Applications:
  • Collagen Remodelling and Tightening: The induced neocollagenesis and elastogenesis (new elastin formation) lead to a visible tightening and lifting effect on the skin. Existing collagen fibers are remodeled, which helps with improved skin laxity and wrinkle reduction.
  • Enhanced Skin Texture: The treatment targets collagen and fatty tissue, to create a smoother and firmer appearance. The micro-injuries stimulate cellular regeneration that further contributes to improved texture and tone.
Treatment Longevity and Maintenance:

The effects of Morpheus8 typically persist for 12 months to 3 years and are influenced by factors such as age, initial skin condition, and lifestyle habits. To optimize and maintain these results, a comprehensive approach is recommended. This involves prioritizing healthy habits like avoiding smoking, minimizing sun exposure, and using sunscreen consistently. A personalized skincare routine tailored to your specific needs and regular follow-up appointments are essential to maintain skin health and prolong the treatment's benefits. 

Patients can expect noticeable improvements in skin texture and tone within 2-3 weeks post-treatment. The body's collagen production increases over time so continued improvement may be seen over the few months after the procedure.

Potential Complications and their Management11

Lip augmentation, while minimally invasive, carries potential complications:

Early Onset:
  • Soft Tissue Irritation: Erythema (redness), edema (swelling), ecchymosis (bruising), and pain are common post-procedural sequelae. Conservative management with ice, elevation, and NSAIDs is usually effective.
Injection Technique:
  • Asymmetries/Contour Irregularities: Improper filler placement can lead to uneven results. Superficial injection may cause visible nodules or blanching (loss of blood flow). Direct finger massage can redistribute the filler material subdermally.
Filler Migration and Granulomas:
  • Dermal Nodules: Hyaluronic acid (HA) filler migration or granuloma formation may occur. Intralesional steroid injections (Kenalog) or 5-fluorouracil can be used for correction.
HA Overcorrection:
  • Hyaluronidase Application: Excessive filler volume can be addressed with hyaluronidase, an enzyme that breaks down HA.
Vascular Complications (Extremely Rare):
  • Intravascular Infiltration/Skin Necrosis (0.001%): Accidental injection into a blood vessel and subsequent occlusion can lead to skin necrosis. Blunt-tipped cannulas and early intervention with warm compresses are crucial for minimizing risk.
The Beauty of Combination Therapy5,9

When considering both Botox and fillers for the mouth area, a staged approach is beneficial in achieving optimal results. Here's why 

  • When combining energy-based devices with injectables, skin tightening typically comes first. This prevents potential displacement of filler material or interference with the injectable's effects. Energy-based devices can also be used as part of post-procedure maintenance to prolong the results of other treatments and help maintain the effects of facial rejuvenation procedures.
  • Botox is typically administered before fillers. It relaxes targeted muscles and potentially creates a more expansive lip surface area (Zone B) without adding volume itself. This "prepares the canvas" for the next step.
  • Following the Botox treatment (which takes a few weeks to fully show its effects), fillers can be strategically injected to sculpt the desired lip shape. This two-step approach offers advantages such as:
  • Accurate Filler Placement: The relaxed muscles post-Botox allow for more precise placement of fillers, potentially minimizing the amount needed.
  • Reduced Risk of Displacement: Injecting fillers immediately after Botox can displace the Botox solution, potentially compromising its effectiveness.
  • Optimizing Results: Waiting a week after Botox allows for assessment of the initial effects. It's possible that additional augmentation with fillers might not be necessary if the Botox treatment achieves a satisfactory outcome.


Social media's "best case" portrayals of lip augmentation set unrealistic expectations. This is where healthcare practitioners can bridge this gap by presenting a "center of the bell curve" approach and managing patient goals with realistic outcomes. 

Lip augmentation offers a variety of techniques to address diverse aesthetic concerns. By understanding the unique anatomy of each patient and employing the philosophy of "less is more," achieving natural-looking enhancements is possible. A gradual approach, prioritizing subtle improvements over dramatic changes, allows for optimal results and patient satisfaction. This ensures that lip augmentation complements your existing features and enhances your natural beauty.


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  2. Swift, A., Liew, S., Weinkle, S., Garcia, J. K., & Silberberg, M. B. (2021). The Facial Aging Process From the “Inside Out”. Aesthetic Surgery Journal, 41(10), 1107-1119.
  3. Samizadeh S. Non-surgical lip enhancement: systematic preoperative assessment. The PMFA Journal. 2018;6(1):Oct/Nov.
  4. Matsa, Sainath. (2021). Botulinum Toxin and Fillers for Maxillofacial Esthetics. 10.1007/978-981-15-1346-6_33.
  5. Gordon R, Publications VD. Vermilion dollar lips.; 2007. 
  6. Liu J, Shi B. Atlas of lip and nose Plastic and cosmetic Surgery. Springer Nature; 2021.
  7. Sadick NS. Augmentation fillers. Cambridge University Press; 2010.
  8. Arora G, Arora S. Where and how to use botulinum toxin on the face and neck – Indications and techniques. 2021;1:17. doi:10.25259/CSDM_16_2021.
  9. Carruthers J, Burgess C, Day D, et al. Consensus recommendations for combined aesthetic interventions in the face using botulinum toxin, fillers, and Energy-Based devices. Dermatologic Surgery. 2016;42(5):586-597. doi:10.1097/dss.0000000000000754
  10. Kar M, Muluk NB, Bafaqeeh SA, Cingi C. Is it possible to define the ideal lips? Acta Otorhinolaryngol Ital. 2018;38:67-72. doi:10.14639/0392-100X-1511.
  11. Votto SS, Read-Fuller A, Reddy L. Lip Augmentation. Oral Maxillofac Surg Clin North Am. 2021 May;33(2):185-195. doi: 10.1016/j.coms.2021.01.004. Epub 2021 Mar 6. PMID: 33750653.
  12. Hotta TA. Lip enhancement: physical assessment, injection techniques, and potential adverse events. Plastic Surgical Nursing. 2018;38(1):7-16. doi:10.1097/psn.0000000000000211

Dr. Maya Sinai
Dr. Maya Sinai