Gummy Smile Treatment: Proposal for a Novel Corrective Technique and a Review of the Literature

Abstract

Background

A perfect smile is dictated by the balance among 3 parameters: the white (teeth), the pink (gum), and the lips: excessive gingival display while smiling has been a cause of esthetic embarrassment for many patients, thus affecting their psychosocial behavior. With respect to different etiologies, treatment of gummy smile must be properly planned: treatment options include facial surgery, oral surgery, or laser.

Objectives

Given the growing demand for less invasive techniques and observed complications secondary to botulinum toxin injection, we present a novel treatment option aimed at correcting gummy smile using hyaluronic acid injection and review the published techniques and the anatomy of the involved facial muscles.

Methods

The treatment was performed by infiltration in the paranasal area, in the location of the most cranial portion of the nasojugal fold, about 3 mm lateral to the alar cartilage wing, according to a vector perpendicular to the cutaneous plane, to gently compress the lateral fibers of the levator labii superioris alaeque nasi without invading it. A Vycross^® technology filler was used for all the treatments.

Results

All patients had an immediate improvement, with a maximum duration ranging from 186 to 240 days (mean, 213 days), according to parameters of the Global Aesthetic Improvement Scale (GAIS 4.06).

Conclusions

This new, less invasive and safer technique to correct dynamic excessive gingival display was shown to be feasible and safe with a long-lasting result. This treatment could be a novel effective option for experienced injectors to treat aesthetic facial flaws.

Level of Evidence: 4

There has been a growing demand from patients looking for aesthetic improvement of their smile: a pleasant smile can give supreme confidence and great self-esteem. Approximately 7% of men and 14% of women present with an excessive gingival display when smiling,¹ according to Peck who defined it as the exposure of more than 2 mm of gum when smiling.²

Moreover, an excessive gum-to-lip distance of 4 mm or more is classified as “unattractive” by general dentists.³

A perfect smile is dictated by a perfect balance among 3 parameters: the white (teeth), the pink (gum), and the lips: excessive gingival display while smiling has been a cause of aesthetic embarrassment for many patients, thus affecting their psychosocial behavior.^4,5 The excessive gingival display is seen to be due to an improper relationship between the pink tissue and the white teeth, with gingival tissue in excess and tooth portion in small amount.^6-8

In light of less invasive techniques being requested to correct selected cases of aesthetic flaws, and with the aim of providing a safe and feasible option, the authors here present a novel technique to correct excessive gingival display (gummy smile) using an injection of hyaluronic acid. The procedure is designed to compress the lateral fibers of the levator labii superioris alaeque nasi (LLSAN), inhibiting the motility of the deep portion of the LLSAN and mitigating upper lip elevation during smiling, to obtain an immediate improvement of the flaw.

METHODS

The study’s inclusion criteria were excessive gingival display on smiling of any etiology, with gingival exhibition of at least 3 mm on unrestricted, non-posed, “full-blown” smiling. Photographs and measurements were obtained before and immediately, and 2 weeks and 6 months after treatment.

A questionnaire was administered at checkup (2 weeks after the procedure) and completed anonymously to determine pain during the procedure and to evaluate patient satisfaction (Appendix A).

The study protocol followed the ethical guidelines of the Declaration of Helsinki, and informed consent was acquired from all patients.

The treatment was performed by infiltrating hyaluronic acid into the paranasal area, at the most cranial portion of the nasolabial fold, about 3 mm lateral to the alar cartilage wing. The procedure is illustrated in an accompanying video (Video 1).

Without performing local anesthesia and using a 30G needle, 13 mm long, a 0.22 (0.2 to 0.3) cc bolus of hyaluronic acid was infiltrated into each side, according to a vector perpendicular to the cutaneous plane once the bony surface is reached, to gently compress the lateral fibers of the LLSAN without invading it. A Vycross^® technology hyaluronic acid filler was selected for use in this treatment (Juvéderm Volift with Lidocaine; Allergan plc, Irvine, CA, USA), formulated with 17.5 mg/mL of low and high molecular weight hyaluronic acid crosslinked using the Vycross^® proprietary manufacturing process to provide performance characteristics including lift capacity, moldability, and tissue integration. The hyaluronic acid formulation also includes 0.3% lidocaine to enhance the patient’s comfort during the procedure.⁹

Subcutaneous injection with previous careful aspiration to avoid the risk of intravascular injection was performed.

The infiltration was carried out at constant pressure to allow a progressive storage of the product in the selected site without incurring compression of the vessels at the site.

The following reference points (RP) and linear measurements were established (Figure 1).

1. RP1: the lowest margin of the upper lip perpendicular and superior to the midportion of the gingival margin of the maxillary lateral incisor.

2. RP2: the gingival margin at the midpoint of the maxillary lateral incisor.

3. RP3: the midpoint of the incisal edge of the maxillary lateral incisor.

The measurements recorded were “RP1 to RP2” and “ RP1 to RP3” on the lateral incisor. The latter was recorded only for the subjects whose RP1 fell below the gingival–dental margin after injection, modified with respect to previously published data.¹⁰

RESULTS

Between February 2015 and February 2016, 32 patients were treated: 23 (71.9%) women and 9 (28.1%) men, aged between 18 and 42 years (mean, 29.7 years) (Table 1).

The average improvement of gingival display on smiling, a decrease of RP1 to RP2 of 0.95 mm, was obtained immediately, with further improvement over the next 2 weeks to an average of 1.37 mm (Figures 2-4). No patient showed a decrease of the lips lower than the gingival margin RP1 to RP3.

When evaluated according to a visual analog scale (VAS) where 0 = no pain and 10 = maximum pain, the average level of soreness reported during treatment was 2.09.

In 2 cases (6.25%), modest bruising occurred, and in 1 case (3.25%), there was a secondary lip paresthesia; resolution was spontaneous within a few days.

All patients had an immediate improvement, with maximum duration results ranging from 6.2 to 8 months (average, 7.1 months), evaluated at 2 weeks according to parameters of the Global Aesthetic Improvement Scale (GAIS 4.06).

One patient was lost to followup after the first consultation.

DISCUSSION

The LLSAN muscle has been identified as the facial muscle responsible for creating the proximal portion of the nasolabial fold, and the “levator labii superioris” (LLS) muscle defines its terminal portion.¹¹ Mimicry of the lip is the result of a synergic activity among the LLS, LLSAN, zygomatic minor (ZMI), and major (ZMJ) muscles. Among these, the LLS, LLSAN, and ZMI determine the lifting lip that occurs with a smile.

The insertion of the LLS is partially or entirely covered by that of the LLSAN and ZMI, and the 3 muscles converge on the side area lateral to the alar cartilage, suggesting a suitable injection point for the injection of botulinum toxin A. It appears that the distribution of these muscles is largely symmetrical and uniform, without significant difference between males and females or between left and right sides.¹²

On the anatomical assessment of body muscle, the LLSAN is divided into 2 layers, 1 superficial to the muscle LLS, and a deep layer underlying the LLS and placed laterally to the transverse portion of the nasalis muscle. The deep layer of LLSAN, which originates from the surface layer of the cranial LLSAN and the frontal process of the maxilla, is inserted between the levator anguli oris and the orbicularis oris. The direction of the deep layer LLSAN is therefore more oblique, towards the corner of the mouth and the orbicularis and levator anguli oris muscles rather than the surface layer: the deep layer of LLSAN elevates the upper lip side and the side of the mouth superior-medially.¹³ Other mimic muscles of the midface involved in the dynamics of the smile, the LLS, ZMI, and ZMJ, elevate the lip side and the side of the mouth superior-laterally.

The LLSAN is, therefore, the only muscle that elevates the lateral lip and the upper upper-medially, in particular with its deep portion, while the surface determines the movements of synergistic lip lateral upper and nasal ala, with the nasalis muscle receiving some fibers from the superficial layer of the LLSAN.¹³

Considering this anatomical knowledge, it must be taken into account that excessive gingival display could be secondary to:^14,15

1. Excessive maxillary bone vertical growth

2. Delayed or altered passive eruption (excessive gingival tissue covering the anatomical teeth crown)

3. Dento-alveolar extrusion

4. Incompetent or short upper lip

5. Hyperactive upper lip

With respect to different etiologies, treatment of gummy smile must be properly planned, hence considering:¹⁶

• Facial type

• Face vertical height and symmetry

• Smile line

• Lip thickness, size, and profile

• Thickness of alveolar bone

• Gingival biotype

• Size and shape of the teeth

Excessive gingival display secondary to vertical maxillary growth excess or excessive dento-alveolar extrusion can be treated by dento-alveolar or orthognathic surgery, either by repositioning the maxillary bone, by means of a LeFort osteotomy, or performing a maxillo-mandibular reposition, thus combining LeFort with Obwegeser mandibular osteotomy, in conjunction with surgical orthodontic treatment as planned. Orthodontic treatment alone could be sufficient in selected cases.¹⁷

Excessive gingival display due to delayed eruption can be treated by aesthetic crown lengthening and/or gingival recontouring, which defines the gingival margin more apically with respect to the amount of keratinized gingiva at the cement-enamel junction.⁶

In a dental office, it is easy to modify the shape of the tooth, the interdental papilla, and to define the gum line. Dental and surgical procedures aimed at restoring an aesthetic crown length have been classified, ranging from 1-stage provisional restorative dentistry and periodontal and pre-prosthetic surgery in the case of sufficient soft and keratinized pink tissue, to intermediate situations that impose a multiple-stage approach delaying the restorative dentistry until later than the surgical steps, to more dramatic situations that will benefit from referral for major surgical treatment.¹⁶

Moderate gingival display secondary to an incompetent or short upper lip that is not skeletal in origin can effectively be treated by surgical repositioning, thus limiting the retraction muscles such as ZMI, orbicularis oris, levator anguli oris, LLS, and LLSAN.¹⁸

In the past, some authors have advocated myotomy as a stand-alone procedure to detach the attachment of the smile muscles, and lip repositioning is in fact commonly used as a plastic surgical procedure, performed along with rhinoplasty, but rarely used as a dental procedure.¹⁹

Lip repositioning surgery has undergone many modifications since it was introduced. In 1979, Litton and Fournier described gummy smile correction with surgery, including elevator muscle detachment in cases of a short upper lip.²⁰ Miskinyar treated the gummy smile with myectomy and partial resection of either 1 or both of the levator LLS muscles bilaterally.²¹

Notwithstanding the technique used, its treatment involves a surgical approach to the gingival mucosa in the oral vestibulum.²²

Ishida treated excessive gingival display using a technique that involved LLS myotomy, subperiosteal dissection, and frenulectomy, with surgical access at the base of the lateral portion of the nostril and the columella between the septal cartilage and nasal wing, and the dissection of the LLSAN,²³ followed by its caudal repositioning by suture.^5,18,23 Finally, Storrer et al undertook successful gingival recontouring and repositioned the LLSAN in a patient with gummy smile.²⁴

Lasers have also been used in treating gummy smile.^25,26 Narayanan presented the cases of 2 selected patients treated with gingival recontouring by means of diode laser 810 nm excision performed in continuous mode.²⁵ The power was controlled between 0.8 and 1.5 watts, depending on the melanin spots of the gum.²⁵

The use of dental lasers is a minimally invasive procedure that can produce immediate results and is readily acceptable to the patient, but must be performed after proper selection of the patient to minimize potential dental and gingival problems and discomfort.^25,26 With these techniques, overcorrection should be avoided, because the upper lip tends to lengthen with age.²⁷

Lip repositioning surgery should be avoided in patients with an inadequate width of attached gingiva and in patients with severe vertical maxillary excess.²⁸

Gummy smile has also been treated using minimally invasive procedures with botulinum toxin.^29,30 Hyperactive upper lip can be treated with an average of 5 units (range, 4-6 U) of onabotulinumtoxin A (or 2-3 Speywood units of abobotulinumtoxin A) injected superficially at the site of insertion of the LLS, which is partially or entirely covered by that of the LLSAN and ZMI, just lateral to the nasal alar cartilage, where the nasolabial fold begins: the 3 muscles converge here, providing an injection point suitable for botulinum injection aimed at correcting gummy smile (Figure 5).

As for every field of application of this toxin, injection must be repeated every 6 to 9 months, depending on the desired aesthetic outcome. However, to date, treatment with botulinum toxin is safe and effective, if done by experienced professionals. Otherwise, complaints can arise regarding smile asymmetry.^29,30

Following our exhaustive assessment, we proposed this novel technique. The injection of a small bolus of hyaluronic acid at the anatomical site where it is usually recommended to inject botulinum toxin mitigates the upper lip elevation during smiling by inhibiting the motility of the deep portion of the LLSAN.

The injected bolus compresses this portion of the muscle and stretches its fibers. In this regard, the use of a cannula cannot be advocated, as it allows the implant to spread along the space created by the blunt dissection of the tip, losing its compression force on the muscle. In contrast, the compression resulting from the small bolus of hyaluronic acid appears to interfere with muscular contraction, and the vertical action of LLSAN is overpowered by one of the lateral elevator muscles.

No published data are currently available to support this mechanism of action in this anatomical field. In fact, this observational finding and the theoretic model are supported by a general property of muscle physiology. Once compressed by the bolus, fewer bridges between muscle fibers are allowed to form, as they are stretched by compression, thus diminishing the contractile force of the muscle.

Proper selection of the product is mandatory to achieve good results and to avoid complications: it must have a good resistance to compression in order to keep the muscle fibers properly stretched.

Given the dynamic forces occurring at the injection site, the elastic modulus G’ must be able to tolerate them and to guarantee the compressive action.

It is advisable to select fillers presenting with a normal maximum water uptake, as excessive swelling in the injected area is not desired.^31-34

The cases here presented confirm this hypothesis, and support our proposal of a new, less invasive, and safer technique to correct dynamic excessive gingival display.

The result could be immediately appreciated by the patient and the clinician, and every adjustment could be made without the need to wait for the drug to act, as required with botulinum toxin injection.

To date, several published papers have reported anatomical studies about facial mimicry and how the clinician can deal with it, by means of surgical interruption of the muscles or by their chemical denervation. However, this is the first paper that describes how the clinician could modulate the mimicry using injection of hyaluronic acid.

This novel technique and the presented results suggest that hyaluronic acid should no longer be considered just a lifting or volumizing agent. On the contrary, if injected with proper knowledge of the facial anatomy and using a codified technique, it could allow the clinician to obtain a pleasant result in modulating selected mimical flaws.

This study has some limitations, and this technique is not suitable for the correction of every case of gummy smile. Given its etiology, the technique could be transformative, or used simply as an ancillary procedure. Ideally, it could be an alternative option to botulinum toxin injection, although to compare treatment results using these same scales and photographs is difficult, because comparative data are lacking, and the evaluation criteria must be different to take into consideration the potential involvement of several muscles with respect to the spread of toxin effect.

Moreover, the toxin needs specific authorization for use in an off-label indication where the findings are intended for publication, while hyaluronic acid is classified only as a medical device. Finally, it must be considered that this was an observational study of an interesting but secondary effect of hyaluronic acid when initially used for nasolabial fold correction, not a primary indication for its use.

The injection point must be checked and carefully selected because it is placed in a noticeable “danger zone” because of the local vascular anatomy. Finally, even if safe and feasible, this technique must be utilized only by experienced injectors.

CONCLUSIONS

This novel technique to correct selected cases of excessive gingival display (gummy smile) could be used alone, as done by the authors, or integrated as part of a complex treatment, given its reversible but long-lasting results. The results are immediately perceptible to both the clinician and the patient, and it is not necessary to wait on the drug action as required when botulinum toxin injections are performed.

The authors believe this could be a novel effective option for experienced injectors to treat aesthetic facial flaws.

Acknowledgments

The authors would like to thank Ray Hill, an independent medical writer, who provided English-language editing and journal styling prior to submission on behalf of Health Publishing & Services Srl.

Disclosures

Dr Cavallini is a consultant for Allergan Inc. The other authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

This project was supported by an unrestricted grant from Allergan SpA, Rome, Italy.

REFERENCES

Author notes