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Year : 2019  |  Volume : 10  |  Issue : 5  |  Page : 560-563  

Evaluation of a neurotoxin as an adjunctive treatment modality for the management of gummy smile

1 Department of Dermatology, NSCB Government Medical College, Jabalpur, Madhya Pradesh, India
2 Consultant Orthodontist (Jabalpur Hospital and Research Centre), Jabalpur, Madhya Pradesh, India

Date of Web Publication28-Aug-2019

Correspondence Address:
Neha Gupta
Department of Dermatology, NSCB Government Medical College and Hospital, Jabalpur, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/idoj.IDOJ_365_18

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Introduction: Excessive gingival display while smiling mars facial aesthetics, this condition is referred to as “gummy smile” (GS). Available literature suggests that Botulinum toxin type A (BTX-A) is effective in the management of excessive gingival display by denervating hyperfunctional muscles. This study was conducted to statistically assess the effects of BTX-A for the management of GS. Materials and Methods: A total of 10 patients between the ages of 18–27 years were selected for this study, they received BTX-A (Botox; Allergan, Irvine, CA, USA) injections for reduction of excessive gingival display at “Yonsei point” on both sides. Gingival display was measured as the vertical distance from the zenith of the gingiva of the upper right central incisor to the inferior border of the upper lip before beginning treatment (T0). The patients were then recalled after 15 days to measure the gingival display (T1). Standardized photographs to document changes were obtained at T0 and T1. Results: A statistically significant reduction in gingival display, while smiling was observed from T0 (7.5 ± 1.35 mm) to T1 (3.2 ± 0.91 mm) in all 10 patients (t = 16.5168, P value = 4.87, P < 0.05). Conclusions: Administration of BTX-A is recommended as an adjuvant to orthodontic treatment where the GS is caused due to hyperfunctional upper lip elevator muscles.

Keywords: Botulinum toxin, gummy smile, neurotoxin

How to cite this article:
Gupta N, Kohli S. Evaluation of a neurotoxin as an adjunctive treatment modality for the management of gummy smile. Indian Dermatol Online J 2019;10:560-3

How to cite this URL:
Gupta N, Kohli S. Evaluation of a neurotoxin as an adjunctive treatment modality for the management of gummy smile. Indian Dermatol Online J [serial online] 2019 [cited 2021 Dec 3];10:560-3. Available from: https://www.idoj.in/text.asp?2019/10/5/560/259287

   Introduction Top

Facial aesthetics are of major importance for individuals seeking cosmetic medical treatment. So much so that several individuals seek professional help to address psychosocial problems caused by an unaesthetic facial appearance.[1] Of these problems, commonly reported is that of a “gummy smile” (GS).

An excessive display of gingival (gum) tissue while smiling is referred to as “gummy smile”. This term is well known to health care givers delivering cosmetic treatment for, e.g., dermatologists. When a more than acceptable (excessive) amount of gum tissue is visible during smiling and/or, even during speech it constitutes an aesthetic problem. Several treatment modalities have been put forth for its management. These include both surgical and nonsurgical interventions such as orthognathic surgery.[2],[3],[4] orthodontic treatment using temporary anchorage devices,[5] crown lengthening procedures,[6] muscle resection,[7] and lip re-positioning.[8]

When caused due to a hyperfunctional upper lip musculature, orthodontic treatment alone is unable to resolve the issue completely as it primarily addresses the hard tissue and not the adjacent soft tissue matrix. Many individuals reject treatment plans involving orthognathic surgery that would help correct lip musculature. Surgical procedures can cause extreme discomfort, edema, swelling; they may lead to relapse and undesirable outcomes such as infection, scar contraction, etc.

Neurotoxins such as botulinum toxin (BTX) have documented use in the dermatologic office for management of keloids, hypertrophic scars, pemphigus like dermatosis, genodermatosis, acne inversa, psoriasis, facial erythema, eccrine nevus, etc. Botulinum toxin type A (BTX-A) has also been used for effective management of hyperfunctional musculature.[9],[10],[11] The mechanism of action of BTX is that, it cleaves the synaptosomal-associated protein (SNAP-25) and inhibits the release of acetylcholine, thereby preventing muscle contraction. There are seven serologically distinct types of BTX available, of which type A (BTX-A) seems to be the most potent and is most frequently used in clinical practise. Polo has demonstrated that usage of BTX-A is an effective and minimally invasive technique to achieve a reduction in gingival display for patients with hyperfunctional lip elevator muscles.[9] These findings are corroborated by similar investigations.[12],[13],[14]

The purpose of this study is to evaluate the role of BTX-A as an adjunctive treatment modality to orthodontic treatment wherein gummy smile is due to a hyperfunctional upper lip musculature. The null hypothesis established is that there is no significant difference in gingival display on smiling after administration of BTX-A.

   Materials and Methods Top


A total of 10 patients between the ages of 18–27 years, who presented with a chief complaint of excessive gum display while smiling were recruited. Sample size was measured after conducting a power analysis keeping in mind previous publications on the use of botulinum toxin for management of gummy smile. On pretreatment examination, at a full unopposed smile the gingival display ranged from 6 to 9 mm in the incisor region, and in the buccal region the gum display was observed to be 5–8 mm. During pretreatment examination, standardized frontal photographs at rest and at smiling were obtained (T0) [Figure 1]a and [Figure 1]b; also measurements of the amount of gingival display while smiling were recorded in mm. Clinical examination pointed to a hyperfunctional upper lip musculature.
Figure 1: (a) Frontal photograph at rest demonstrating lip incompetency (T0). (b) Frontal photograph while smiling displaying an unaesthetic gummy smile (T0)

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After assessing the diagnostic records, patients were informed about the need of orthodontic treatment and the possibility of a surgery to address the hypermobile upper lip. Patients rejected the surgical option. They were later educated about the use of BTX-A neurotoxin to address the upper lip to which they agreed. Complete medical examination was done for all patients and systemic disorders were ruled out. Informed consent was obtained from all patients.

After orthodontic treatment, it was seen that about 6–8 mm of gingival display at smiling still persisted, and even at rest the lips were incompetent. At this stage, it was decided to inject BTX-A neurotoxin. BTX-A (Botox, Allergan, Irvine, CA, USA) was injected at the “Yonsei point” as described by Hwang et al.[12] BTX-A was supplied as a freeze-dried powder of 100 units and was re-constituted with 2 mL normal saline (0.9%) solution to make a 5.0 units/0.1 mL dose according to the manufacturer's instructions, and 3.0 units was injected at each “Yonsei point” on both sides. Patients were then recalled at 15 days (T1) to obtain facial photographs and measurements regarding the gingival display.

Data collection

Standardized pre-treatment photographs of patients while smiling were obtained. Measurement of gingival display in the incisor region was recorded. 15 days after BT injection, the patients were recalled and standardized frontal photographs at rest and while smiling where obtained (T1) [Figure 2]a and [Figure 2]b.
Figure 2: (a) Frontal photograph at rest demonstrating an improvement in lip posture (T1). (b) Frontal photograph while smiling presenting a reduction in gum display (T1)

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   Statistics Top

All statistical analyses were performed using Statistical Package for the Social Sciences for Windows (v. 10.0; SPSS, Chicago, Ill, USA). Descriptive analysis was performed and calculated for gingival display at T0 and T1 as defined earlier [Table 1]. Comparisons between the two intervals with respect to gingival display were made using paired sample Student's t-test (two tailed). In this study, the level of significance for Student's t-test was determined as P < 0.05.
Table 1: Descriptive analysis at T0 and T1

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   Results Top

At T0, gingival display while smiling was measured to be 7.5 ± 1.35 mm, while at T1 it was reduced to 3.2 ± 0.91 mm. Descriptive statistics are given in [Table 1]. The measured t value obtained is t 16.5168. The P value returned by Student's t test is 4.87. This is greater than the critical value for the sample (degrees of freedom, df = 9). The null hypothesis established was thus rejected. This shows that there was a statistically significant difference in the amount of gingival display while smiling between T0 and T1 (P < 0.05).

   Discussion Top

Smile is a dynamic voluntary activity which occurs between the framework of the circumoral musculature, teeth and bony maxillary morphology. The upper lip elevator muscles namely levator labii superioris, levator labii superiosis alaeque nasi, and zygomaticus minor play a major role while smiling. A hyperfunction of these muscles increases the muscular capacity to raise the upper lip while smiling, thereby giving rise to a gummy smile.[15] Effective management would need denervation of these three muscles. In order to achieve this, BTX-A was injected at the “Yonsei point” [Figure 3]. The “Yonsei point” lies at center of the muscle vectors of levator labii superioris, levator labii superioris alaeque nasi, and zygomaticus minor, and all the three elevator muscles converge at this point lateral to the ala.[12] It is a safe and reproducible point to inject BTX-A. Although other sites have also been suggested,[16] it is recommended that the “Yonsei point” is used because it affects the whole of levator labii superioris, levator labii superioris alaeque nasi, and zygomaticus minor, rather than influence individual activation of each muscle. When injected, BTX-A caused a denervation of these muscle by blocking neuromuscular transmission by inhibiting the release of acetylcholine.[17] This denervation in turn causes a reduction in hyperactive muscle activity.
Figure 3: Location of “Yonsei Point”

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This investigation was carried out on ten female individuals who complained of unaesthetic excessive gingival display while smiling. The gingival display on smiling was measured before BTX-A administration (7.5 ± 1.35 mm) (T0) and 15 days after BTX-A injection (3.2 ± 0.91 mm) (T1). The results of the study showed that there was a statistically significant reduction in the amount of gingival display while smiling (P<.05). This helped in achieving the goal of improving facial aesthetics by eliminating excessive gingival display. These findings were similar to those reported by Polo,[9] Hwang et al.,[12] Mazucco and Hexsel,[10] Gracco,[13] and Suber et al.[14]

The authors caution that diligence must be observed before injecting BTX-A due to it's reported potential side effects, such as allergic reactions, trouble breathing and/or swallowing, muscle stiffness, dystonia, etc.,[18] and, should be administered by qualified dermatologists only. There were no adverse effects observed in any of the patients administered with BTX-A, thereby making it a relatively safer option when compared to other surgical options. In this investigation, only 3.0 units were injected at each “Yonsei point,” this is significantly lesser than previous reported studies like Suber et al. where an average of 5.0 units were injected bilaterally at three sites,[14] or other studies[9],[10] wherein 2.5 units were injected at three different sites to denervate the levator labii superioris, levator labii superioris alaeque nasi, and zygomaticus minor muscles individually. Hence, it can be inferred that the technique employed in this study uses a much lesser quantity of neurotoxin at a single site than that utilized in previous studies, and is much safer.

Further, studies are needed to rigorously assess the effectiveness and safety of this method. It would also be useful if further investigations are conducted to assess the long-term stability of treatment effects with a larger sample size.

Gummy smile when caused due to hyperactivity of the lip elevator muscles is not amenable to orthodontic treatment alone, and can be best treated by adjunctive administration of BTX-A.

   Conclusion Top

  1. Administration of BTX-A is a reliable and minimally invasive method to reduce excessive gingival display in individuals with hyperfunctional upper lip elevator musculature
  2. It is a useful adjunctive treatment modality in the management of gummy smile not amenable to orthodontic treatment alone.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Flannary C. The psychology of appearance and psychological impact of surgical alteration of the face. In: Bell WH, editor. Orthognathic and Reconstructive Surgery. 1. Philadelphia: W B Saunders; 1992. p. 2-21.  Back to cited text no. 1
Nishiyama A, Ibaragi S, Yoshioko N, Shimo T, Sasaki A. Case of maxillary protrusion and gummy smile treated by multi-segmental horseshoe le fort I osteotomy. Int J Oral Maxillofac Surg 2017;46:327-9.  Back to cited text no. 2
Shimo T, Nishiyama A, Jinno T, Sasaki A. A case of maxillary protrusion and gummy smile treated by multi-segmental horseshoe le fort I osteotomy. Acta Medica Okayama 2013;67:55-60.  Back to cited text no. 3
Fowler P. Orthodontics and orthognathic surgery in the combined treatment of an excessively “gummy smile”. New Zealand Dent J 1999;95:53-4.  Back to cited text no. 4
Kim TW, Kim H, Lee SJ. Correction of deep overbite and gummy smile by using a mini-implant with a segmented wire in a growing Class II Division 2 patient. Am J Orthod Dentofac Orthop 2006;130:676-85.  Back to cited text no. 5
Roshna T, Nandakumar K. Anterior esthetic gingival depigmentation and crown lengthening: Report of a case. J Contemp Dent Pract 2005;6:139-47.  Back to cited text no. 6
Ishida L, Ishida LC, Ishida J, Grynglas J, Alonso N, Ferreira MC. Myotomy of the levator labii superioris muscle and lip repositioning: A combined approach for the correction of gummy smile. Plast Reconstr Surg 2010;126:1014-9.  Back to cited text no. 7
Gaddale R, Desai SR, Mudda JA, Karthikeyan I. Lip repositioning. J Indian Soc Periodontol 2014;18:254-8.  Back to cited text no. 8
[PUBMED]  [Full text]  
Polo M. Botulinum toxin type A (Botox) for the neuromuscular correction of excessive gingival display on smiling (gummy smile) Am J Orthod Dentofacial Orthop 2008;133:195-203.  Back to cited text no. 9
Mazucco R, Hexsel D. Gummy smile and botulinum toxin: A new approach based on the gingival exposure area. J Am Acad Dermatol 2010;63:1042-51.  Back to cited text no. 10
Indira AS, Biswas PP, Vineet VT, Yeshaswini T. Botox as an adjunct to orthognathic surgery for a case of severe vertical maxillary excess. J Maxillofac Oral Surg 2011;10:266-70.  Back to cited text no. 11
Hwang WS, Hur MS, Hu KS, Song WC, Koh KS, Baik HS, et al. Botox as an adjunct to orthognathic surgery for a case of severe vertical maxillary excess. Angle Orthod 2009;79:70-7.  Back to cited text no. 12
Gracco A, Tracey S. Botox and the Gummy smile. Prog Orthod 2010;11:76-82.  Back to cited text no. 13
Suber JS, Dinh TP, Prince MD, Smith PD. Onabotulinumtoxin a for the treatment of a “Gummy Smile”. Aesthetic Surg J 2014;34:432-7.  Back to cited text no. 14
Peck S, Peck L, Kataja M. The gingival smile line. Angle Orthod 1992;62:91-100.  Back to cited text no. 15
Kane MA. The effect of botulinum toxin injections on the nasolabial fold. Plast Reconstr Surg 2003;112:66S-72S.  Back to cited text no. 16
Blasi J, Chapman ER, Link E, Binz T, Yamasaki S, De Camilli P, et al. Botulinum neurotoxin A selectively cleaves the synaptic protein SNAP-25. Nature 1993;365:160-3.  Back to cited text no. 17
Cote T, Mohan A, Polder JA, Walton MK, Braun MM. Botulinum toxin type A injections: Adverse events reported to the US food and drug administration in therapeutic and cosmetic cases. J Am Acad Dermatol 2005;53:407-15.  Back to cited text no. 18


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1]


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