Professional Tips for Lip Augmentation

Lip augmentation is a challenging aesthetic procedure that requires a thorough understanding of the aging process. In addition, practitioners need to be familiar with the lip anatomy in order to create appealing and attractive lips. They should also be aware of the desirable anatomical features in the “ideal” lips.

The treatment outcomes are affected by a number of factors such as the amount and type of the filler, the unique anatomy of patients and the injection technique. To ensure optimal results, doctors should recognize and overcome the challenges related to lip augmentation while respecting the anatomy. In this article, we will discuss about the anatomical considerations for lip augmentation. We will also discuss about the patient selection process.

Analyzing the anatomical features of a youthful lip

The upper lip of young Caucasians is typically narrower compared to the lower lip. The ideal upper lip to lower lip ratio is around 40:60. For patients of Afro-Caribbean descent, the ratio should be approximately 50:50.3. A noticeable sign of youthful lips is the smooth appearance of the skin right above the vermilion border. Youthful lips should not have any visible rhytids in this area. At the same time, the cupid’s bow and the philtral columns should be well defined. The lower lip should have 2 lateral protrusions and a central depression. On the other hand, the upper lip should have bilateral depressions with a prominent medial tubercle.

When viewed laterally, the upper cutaneous white lip should have a concavity approaching the red lip. In addition, it should be projected about 2 millimeters more than the lower lip. Based on research, the anatomical features that constitute an “attractive” female lip are increased mentolabial angle, nasolabial angle, and vermilion height.

Analyzing the anatomical features of an aging lip

Some of the major characteristics of an aging lip include:

  • Flattened cupid’s bow;
  • Reduced nasolabial angle;
  • Lengthened cutaneous upper lip;
  • Reduced vermilion pigmentation;
  • Reduced mentolabial angle;
  • Reduced vermilion border;
  • Increase visual of lower teeth;
  • Reduced visual of upper teeth;
  • Development of visible rhytids;
  • Flattened philtral columns;
  • Loss of projection fullness;
  • Inverted lower lip.

A perioral collapse can further accentuate these undesirable features. The collapse typically results from a combination of factors such as the hyperkinetic activity of the orbicularis oris, fat atrophy, and the resorption of the craniofacial skeleton. A deflated lip is typically caused by the redistribution of the lip thickness, rather than an overall loss in lip volume. Decreased elasticity can give the illusion of volume loss; however, there is no actual loss of lip volume.

The anatomy of the lip

Being the prominent part of the central facial triangle, the lips can greatly affect the overall appearance. Apart from that, they also play a vital role in masticatory competence, articulation of speech and facial expression. The lips helps to define the soft tissue boundaries of the teeth while keeping the oral seal. The thickness and shape of the lips can vary greatly among ethnic groups and individuals.

1. Orbicularis oris muscle

The orbicularis oris muscle is made of an upper and a lower part connected to the modiolus. These parts consist of the pars peripheralis and pars marginalis portions, which have different functions. Located in the cutaneous lip, the pars peripheralis has a dilatory function. Acting as a sphincter, the pars marginalis can be found in the vermilion. While originated from the same modiolus, the fibers of the pars peripheralis and pars marginalis are directed differently (i.e. not in the same plane). The pars peripheralis is located behind the pars marginalis, which contributes to the curved shape of the lips.

2. Arterial blood supply

The arteries that supply the lips vary greatly in terms of location, diameter, course, and number. Originated from the facial artery, the superior labial artery is usually at the same level of (or superior to) the labial commissure. However, the artery can sometimes be inferior to the labial commissure. The superior labial artery is typically 1 to 1.8mm in diameter. Traveling towards the upper lip, the superior labial artery passes deep into the Zygomaticus major muscle (a muscle of facial expression that alters the angle of the mouth posteriorly and superiorly when smiling). Compared to the inferior labial artery, the superior labial artery is generally more tortuous in the course and bigger in size. In the upper lip, the artery goes into the orbicularis oris muscle, traveling between the mucosa and the muscle along the edge. Branched form the facial artery, the inferior labial artery is located at the level of (or below) the labial commissure. It is uncommon to find the inferior labial artery above the labial commissure. On average, the diameter ranges from 1.2 to 1.4mm. Similar to the superior labial artery, the distance between the labial commissure and the origin of inferior labial artery can differ greatly, ranging from 0.5 to 4cm. The average distance is around 2 to 2.5cm.

The artery travels upward tortuously to the depressor anguli oris muscle. Penetrating into the orbicularis oris muscle, it tortuously travels along the edge of the lower lip located between the mucous membrane and the muscle.

Factors to consider when selecting patients

As a general rule, patients should be medically fit for an aesthetic procedure. If patients have a high risk of getting herpes simplex, practitioners should prescribe an anti-viral treatment prior to the procedure. Do not perform the treatment if there is a visible herpes simplex infection. Be aware that some medicines can increase the risk of bruising. This includes vitamin E, anticoagulant medications, non-steroidal anti-inflammatory drugs (NSAIDs), and pain killers. Before undergoing the procedure, patients must clearly sign and initiate each page of the written consent. It is important to take pictures pre-operatively and post-operatively in several views (including the lateral and frontal views). These pictures can help identify any existing asymmetry. Patients should be informed of the asymmetry before starting the treatment.  When needed, these pictures can be used as an evidence (e.g. if patients complain that the lips are uneven or look no different).

When consulting the patients, practitioners should identify the patient expectations and expected outcomes. Some of the patient’s requests may lead to an aesthetically unacceptable results. For instance, patients may request for an upper lip augmentation alone. However, this could cause an undesirable duck lip appearance. As suggested by a study published in The Laryngoscope, duck lip (i.e. larger upper lip) is deemed to be the most unattractive feature. Patients should be made aware of this before receiving the treatment. Counsel and educate the patients with tools such as laminated pictures of lip dimensions associated with facial aesthetic. Studies found that a lip enhancement of 53% tends to result in the highest degree of facial attractiveness. Patients should be advised against using a large amount of filler, as this could lead to overfilled lips. As well, patients should be aware of the potential post-operative complications such as bruising and swelling. They must also understand that the downtime associated with the treatment can range from 2 to 10 days. Tools such as patient alignment checklist (which outlines the criteria of a suitable candidate for the treatment) can be useful during the patient selection process. Keep in mind that careful patient selection is the key to successful treatment.


Lip augmentation is a technically challenging treatment that requires careful evaluation of lip functions and a good knowledge of lip anatomy. Enhancement of the existing lip architecture tends to produce the best results. When screening suitable candidates for the treatment, it is important to take into account all the important factors, including the medical and medication histories. Practitioners should understand the expectations of patients, and provide professional advice as needed. Lastly, patients should be aware of all potential risks associated with the treatment. Adequate education can help patients make an informed decision. This is the first part of the article. In the next part, we will discuss about the products and techniques used in lip augmentation.