Excessive gum exposure during smiling or laughing defines the gummy smile. From an aesthetic point of view, your client may feel this is undesirable to present with type of smile. Clients usually are not aware of it and only realise it after being photographed. In some cases, it is considered quite upsetting, especially for women. Some clients are prone to have this kind of smile, such as those with a short distance between the nasal base and Cupid’s bow as well as those with a facial convex profile with a prominent nose and an underdeveloped chin. These clients are mainly mouth breathers with upper lip retraction and visible upper incisors. Deep nasolabial folds are also found in these clients.
The orbicularis oris is a sphincter muscle around the mouth. It is a bilateral circumferential muscle that closes and puckers the mouth and forms a purse string. It anchors to the nasal septum and the maxilla above and to the medial part of the mandible beneath. The deeper layers of the orbicularis oris are the fibres of the buccinator and are reinforced by the incisive bundles. From the skin, short oblique fibres traverse the thickness of the lip in the direction of the mucosa. The more superficial layer is formed by the insertion of seven small muscles: five elevators and two depressors. At the corner of the mouth, there is an area denominated modiolus, this is where the muscles that elevate and depress the lip interdigitate.
The elevators consist of the zygomaticus major and minor, levator labii inferioris, levator labii superioris alaeque nasi and levator anguli oris. The zygomaticus major muscle originates from the zygoma (anterior to the zygomaticotemporal suture) and runs inferiorly and medially towards the angle of the mouth and contributes to the modiolus. The zygomaticus minor muscle arises from the malar bone (behind the maxillary suture) and passes downward and inward and in continuity with the orbicularis oris at the outer edges of the levator labii superioris. The action of the zygomaticus major is to elevate the corner of the mouth and it has little or no effect on the nasal labial fold. It is both the levator labii superioris and the m. levator labii superioris alaeque nasi that create and move the middle- and the medial-most portions on the nasal labial fold, respectively.
The zygomaticus major elevates and lifts the corner of the mouth and has little or no effect on the nasolabial fold. The main elevator of the lip is the levator labii superioris and it arises from the lower margin of the orbit just above the infraorbital opening and its fibres insert into the midportion of the nasal labial fold. The levator labii superioris alaeque nasi arises from the frontal process of the maxilla and inserts on the alar cartilage and medial upper lip. It dilates the nares and everts and lifts the medial upper lip. It deepens the medial upper nasolabial fold. The gummy smile can result from excessive action of the levator labii superioris alaeque nasi and/or the m. levator labii superioris.
Aim of Treatment
The aim of treating a gummy smile with botulinum toxin is to avoid gums showing at rest and to reduce excessive gum exposure during a smile.
The client should be analysed in a static and dynamic perspective. The static analysis should focus on the lips and the nose. In general, clients with a gummy smile have a short distance between the upper lip and the base of the nose. The upper lip is mainly thin, and the nasal labial angle is 90 degrees or less. The upper lip is often retracted, and the upper incisors are visible at rest. It is called the open lip posture.
On animation or during a smile, the gum is highly visible. On the frontal and profile views, there is excessive gum show and, normally a drooping of the tip of the nose. The upper lip can also invert becoming even thinner. This is also one of the cases where lip augmentation with fillers presents an inefficient result. Clients and aestheticians get disappointed with the lip augmentation procedure, mainly because it results in an excessive lip augmentation, leading to an unnatural look. The dynamic or muscle component which provokes the upper lip thinning is not treated. As there are many muscles that act upon the perioral area with synergistic and antagonistic behaviour, careful client selection is vital. To minimise complications, you should select clients with a very short upper lip at static position and a major gummy show at rest and during animation.
At this level, the muscle is superficial and only the first third (+/- 3 mm) of the 30-gauge needle should be inserted into the skin and muscle. The dose should be 2 or 3 units of botulinum toxin at each side, at the Yonsei point, which indicates the location of the centre of the triangle formed by:
After 15 days the client should be evaluated, focusing on the treatment effect and asymmetries. In the case of a partial result, an extra dose can be given, from 50 to 100% of the initial dose according to the percentage of the effect obtained. If asymmetry results, you will need to determine which side is still elevating excessively and an extra dose should be given to balance both sides.
The most common complications with the treating gummy smiles are asymmetries and upper lip drooping. As nobody is 100% symmetric, it is important that any asymmetry should be shown to the clients before the treatment. Photographic documentation should also be undertaken. Symmetrical injections in asymmetrical clients may result in asymmetry becoming. worse. Usually, static analysis does not show any sign of imbalance; it is seen only during animation.
Mild asymmetries are tolerable and should be corrected as required by the clients. However, moderate to severe asymmetries should be corrected as soon as they are evidenced. To avoid further complications, 25 to 50 % of the initial dose should be administered and the outcome evaluated after 7–15 days.
Excessive drooping of the medial part of the upper lip can occur if excessive blocking is undertaken. As a consequence, there is excessive lateral pulling of the zygomaticus major, and the ‘joker’ smile may result. A slight blocking of the zygomaticus major may reduce the excessive lateral pulling.