Versatility of Botulinum Toxin at the Yonsei Point for the Treatment of Gummy Smile

CLINICAL RESEARCH

Versatility of botulinum toxin at the Yonsei point for the treatment of gummy smile

Hessa Al Wayli, BDS, MSc Consultant, Department of Oral Medicine, Ministry of Health, Dental Directorate, Al-Roda, Riyadh, Saudi Arabia

Correspondence to: Dr Hessa Al Wayli Consultant, Department of Oral Medicine, Dental Administration Riyadh Health, Ministry of Health, Dental Directorate, Al-Roda, Riyadh, Saudi Arabia 13215; Tel: +966 505445212; Email: [email protected], [email protected]

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Abstract assessed at 2, 12, 24, and 36 weeks postinjection. The data were evaluated using mean standard de- The purpose of the present study was to evaluate viation, analysis of variance (ANOVA), and Tukey’s the efficacy of a single dose of botulinum toxin post hoc test. The results of the study revealed that (BTX) at the Yonsei point for the treatment of gum- a single dose of BTX-A injected at the Yonsei point my smile (GS). A total number of 45 female patients was effective in the treatment of GS P( < 0.05) and were enrolled in the study at a private clinic over a achieved better results than multiple injections at period of 24 months. Three units of onabotulinum- various sites. toxinA (BTX-A) per site (90 hemifacies) were initially injected at the Yonsei point. The patients were then (Int J Esthet Dent 2019;14:86–95)

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Introduction frequently recommended. In contrast, the use of BTX represents a simple, fast, and ef- Gummy smile (GS) is a well-known condition. fective method for the esthetic correction Treatment involves a myriad of modalities, of GS.4,5 However, treatment with BTX in- ranging from medical treatment to surgery, volves a variety of commonly observed involving fairly well-established techniques. complications, including injection-site pain, Recently, botulinum toxin (BTX) was included needle marks, edema, bruising, hematoma, in the treatment of GS, involving multiple in- and mild erythema.6-8 It is well known that jections in the facial muscles, with some BTX spreads in a halo of 1 to 2 cm around complications. the injection site. The diameter of the halo The present study involved the use of a depends mainly on the dilution used and single-injection technique, whereby one in- the depth of the injection. On the face, jection of onabotulinumtoxinA (BTX-A) (Bo- where there are several small, operationally tox; Allergan) was administered at the Yon- sensitive muscles arranged very closely to- sei point into the facial muscles responsible gether, the diffusion of BTX tends to partial- for GS. The study showed that this tech- ly relax the muscles in close proximity to nique achieved better results with fewer those being treated. Therefore, during the complications than the multiple-injection correction of GS, the other muscles of the technique. upper lip elevator complex may be relaxed The smile is probably both the most by the BTX, which creates unnecessary pleasing and most complex element in the worry for both the patient and the clinician. appearance of the human face. Although it However, for many years, lower dilutions has long been the subject of both artistic have been recommended when there is a and philosophical debate, from an anatomi- need to inject BTX into small, functionally cal and physiological point of view the smile sensitive areas of muscle.9 This is a recom- is the result of the exposure of the teeth and mendation that is supported by contempo- gums during the contraction of the muscle rary authors, and the current guidelines are groups in the middle and lower thirds of the to use a minimal dose of BTX in the specific face. Smile esthetics are influenced by three group of muscles (multiple-injection sites) components: the teeth, gums, and lips.1,2 An responsible for GS, with minimal side ef- attractive smile depends on the proper pro- fects. portion and arrangement of these three The treatment goal is to identify a con- components.3 Ideally, the upper lip should sistent, minimally invasive alternative for the symmetrically expose up to 3 mm of the correction of GS caused by hyperfunctional gum, and the gumline should follow the upper lip elevator muscles. In 2009, Hwang contour of the upper lip.1 The exposure et al10 described the Yonsei point, which is of > 3 mm of the gum during smile is known the confluence of three muscles – the leva- as a gingival or gummy smile. tor labii superioris (LLS), the levator labii su- For some patients, GS represents an es- perioris alaeque nasi (LLSAN), and the zygo- thetic disorder for which various correction maticus minor (Zm). These three muscles methods are proposed, including gingivo- are primarily responsible for the smile. plasty, orthodontic treatment, orthognathic In order to minimize the complications surgery, and bone resection.1 As these are associated with multiple injections of BTX, highly complex procedures involving mod- the present study was designed with the erate to severe morbidity, a high cost, and prime purpose of evaluating the efficacy of considerable time, they have become less one injection of BTX at the Yonsei point as a

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minimally invasive approach in the treat- Fig 1 Linear ment of GS. measurements and reference points for pre- and postinjec- Material and methods tion assessments.

RP1 A simple, nonrandomized prospective study RP2 A was conducted at a private practice over a B period of 24 months, from August 2015 to RP3 August 2017. All procedures performed in the study involving human subjects were in accordance with the ethical standards of the institutional and/or national research committee as well as with the 1964 Decla- ration of Helsinki and its later amendments birth control during the study; breastfeed- or comparable ethical standards. The re- ing; the participation in a study of another gional Institutional Review Board approved drug or device; the use of certain medica- the study. tions such as aminoglycosides, anticholin- The sample size of the study was deter- esterases, and other agents interfering with mined by nMaster software. The level of sig- neuromuscular transmission; and vertical niﬁcance was set at ʴ = 5%, the power at maxillary excess. A negative blood pregnan- 80%, and the conﬁdence interval (CI) at cy test (ʵ-hCG test), performed 1 to 4 h be- 95%. A sample size of 45 (90 hemifacies) pa- fore the BTX-A injection, was required for all tients was calculated for the study. The pro- subjects of child-bearing age. cedure was explained to all the study partic- The trial protocol, risks of the interven- ipants, who gave their informed consent. tion, possible side effects of BTX-A, and le- The inclusion criteria were: female pa- gal rights were presented to the subjects tients; age 18 to 45 years; excessive gingival and their parent/s (where applicable, ie, if display on smiling, secondary to hyperfunc- the subject was younger than 21 years) be- tional upper lip elevator muscles (when eti- fore participation in the study. All subjects ology also included another factor, ie, de- (or parent/s, where applicable) signed an in- layed passive dental eruption or excessive formed consent. gingival tissue due to hypertrophy, the sec- During the initial visit, all the forms and ond factor was corrected before the study); consents were again explained to each sub- at least 3.0-mm gingival display on unre- ject. The forms were signed, and each sub- stricted ‘full-blown’ smiling; and no vertical ject’s medical history was reviewed. Before maxillary excess, as determined by lateral the injection, all subjects underwent a stan- radiographic skull views and cephalometric dardized photographic session. measurements. The exclusion criteria were: The following reference points (RPs) and a known allergy to BTX-A or albumin or a linear measurements were established history of previous BTX-A injections to the (Fig 1): head or neck; amyotrophic lateral sclerosis, 1. RP1: the lowest margin of the upper lip motor neuropathy, myasthenia gravis, or perpendicular and superior to the mid- Lambert-Eaton myasthenic syndrome; portion of the maxillary central incisor’s pregnancy or those planning a pregnancy gingival margin. or able to become pregnant due to not us- 2. RP2: the maxillary central incisor’s gingi- ing or not willing to use a reliable form of val margin at its midpoint.

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The injection sites were determined by Levator labii superioris alaeque nasi muscle animation (smiling) and palpation muscle on contraction to ensure precise muscle lo- Levator labii superioris muscle cation before injection because small anatomical variations in localization sometimes Zygomaticus minor muscle occur. For the injections, 0.3 ml syringes were used with a 31-gauge, 8-mm needle, and the BTX-A was injected into the subcu- taneous tissue. Yonsei Zygomaticus major muscle point Depressor septi nasi muscle A review of pertinent anatomical consid- Risorius muscle erations in anatomy textbooks is highly recommended. No local anesthesia was administered. No electromyographic guidance was used. Fig 2 Musculature of the face: the Yonsei point. Reprinted with the permission The patients were advised not to lie of Dr Kanhu Charan Sahoo. down, do any exercise, or massage the treated area during the first 4 h after the 3. RP3: the midpoint of the incisal edge of procedure. the maxillary central incisor. Follow-up visits were at 2, 12, 24, and 36 weeks postinjection. At the 2-week postin- The measurements recorded were A = RP1 jection visit, all subjects completed a statisti- to RP2 and B = RP1 to RP3 minus RP1 to cally validated questionnaire, reporting the RP2. The latter measurement was recorded onset of changes in upper lip position on only for the subjects whose RP1 fell below smiling; side effects, if any; rate of satisfac- the gingival–dental margin after injection. tion (esthetic improvement of smile on a 1 The BTX-A was diluted according to the to 5 point scale, where 5 = excellent, manufacturer’s recommendations to yield 5 4 = very good, 3 = good, 2 = fair, and units per 0.1 ml by adding 2.0 ml normal sa- 1 = poor); their willingness to undergo the line solution to 100 units of vacuum-dried same procedure again in the future; and Clostridium botulinum toxin type A. whether they would recommend it to oth- The dose equivalence adopted by the ers with a similar condition. current authors was 3:1 IU between botuli- The data were subjected to computer numtoxinA (Dysport; Ipsen Biopharm Limit- statistical analysis using SPSS, version 23.0 ed) and BTX-A, which is supported in the (SPSS Inc). The statistical tests used for ana- literature.6 lyzing the data were mean standard devia- Before the injections, the patients re- tion, analysis of variance (ANOVA), and ceived topical anesthesia with a cream con- Tukey’s post hoc test. The level of signifi- taining lidocaine and prilocaine. Two to cance was set at P < 0.05. three units of BTX-A were then injected in all subjects at one site per side (a total of two Results sites) in both overlapping points of the right and left LLSAN and LLS and Zm muscle sites Forty-five female patients with excessive at the Yonsei point, as described by Hwang gingival display secondary to hyperfunc- et al.10 The Yonsei point is located at the tional upper lip elevator muscles were en- center of the triangle formed by the LLS, rolled in the study, ranging in age from 18 to LLSAN, and Zm muscles (Fig 2). 45 years (mean 30.5 ± 9.43 years). The

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Table 1 Postinjection follow-up visits

Baseline 2 weeks 12 weeks 24 weeks 36 weeks

Patients (n) 45 45 45 45 45

Table 2 Comparison of mean and standard deviation (SD) of BTX-A for reducing gummy smile

Serial number Mean SD

1 Baseline 7.20 1.77

2 12 weeks 1.15 0.74

3 24 weeks 6.78 0.74

4 36 weeks 7.09 1.43

Repeated measures of ANOVA.

Table 3 Tukey’s post hoc test to evaluate the effectiveness of the Yonsei point

Baseline After 12 weeks After 24 weeks After 36 weeks

Baseline - 0.00* 0.00* 0.181

After 12 weeks - - 0.00* 0.004*

After 24 weeks - - - 1.000

After 36 weeks - - - -

*Signiﬁcance of relationship at P < 0.05

number of patients evaluated at baseline fore, at the 12-week follow-up visit as well as and at each follow-up appointment are at the successive follow-up visits, all nega- shown in Table 1. All 45 subjects were eval- tive values were set to zero gingival display. uated at the 2-, 12-, 24-, and 36-week fol- The gingival display (in millimeters) was low-up visits. Compliance rates of 100% for at its maximum at baseline, followed by 36 all subjects were seen. Preinjection gingival weeks, and then 24 weeks. It was at its min- display averaged 7.2 mm (± 1.77) in all 45 imum at 12 weeks (Figs 3 to 5). patients. At 12 weeks postinjection, mean On applying Tukey’s post hoc test for in- gingival display had declined to 1.15 ± tergroup comparison, signiﬁcant differen- 0.74 mm in all 45 patients (Table 2). The av- ces were found at baseline and 12 weeks, erage lip drop at 12 weeks postinjection was baseline and 24 weeks, 12 weeks and 24 1.15 mm. In all 45 patients, the upper lip weeks, and 12 weeks and 26 weeks. The dif- position at 12 weeks postinjection was be- ference failed to reach the level of signiﬁ- low the gingival–dental border, resulting in cance between baseline and 36 weeks, and negative values of gingival display. There- 24 weeks and 36 weeks (Table 3).

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3 4 5

Figs 3 to 5 Effects of BTX-A at the Yonsei point on excessive gingival display: preinjection (top row) and postinjection (bottom row) follow-up of three subjects.

Responses to the questionnaires were major advantage of the single-injection positive. All subjects reported the upper lip technique is that it is easily reproducible, “starting to feel somewhat different upon can be learned by inexperienced clinicians, smiling” 1 to 5 days after the procedure. All is easy to administer, involves a minimal noted results at 2 days postinjection (mean: dose of BTX, has no side effects, and in this 2.5 days). When asked when “a definite study enjoyed 100% patient acceptability of change upon smiling” was noticed, answers the treatment. ranged from 1 to 6 days (mean: 2.8 days). In The results of this study confirm the hy- terms of their satisfaction with therapy, the pothesis that a single injection of BTX ad- subjects rated their perception of improve- ministered at the Yonsei point is a better ment in smile esthetics on the 1 to 5 scale treatment of GS for a given amount of time. (see earlier), obtaining a mean of 4.18. All It also prevents complications associated subjects responded positively regarding with multiple injection techniques. The their willingness to undergo the procedure mean gingival display was 7.2 ± 1.77 prein- again, and all said they would recommend jection (baseline), 1.15 ± 0.74 at 12 weeks, the procedure to others with a similar con- and 6.78 ± 0.74 at 24 weeks, respectively dition. (P < 0.001, which is highly significant). How- The BTX-A treatment was safe and well ever, the mean gingival display at 36 weeks tolerated. None of the patients reported pain was 7.09 ± 1.43 (P > 0.05). Based on the re- at the injection site. There were no com- sults of this study, the use of a single BTX plaints of headache, dizziness or twitching. injection at the Yonsei point is warranted and could be associated with a decreased Discussion risk of undesirable side effects such as headache, paralysis of facial muscles or twitch- The main purpose of this study was to eval- ing, at a reduced cost for the patient. uate the effectiveness of a single injection Since the discovery of the cosmetic use of BTX at the Yonsei point, as described in of BTX11 it has been rapidly incorporated the literature,6-8 for the treatment of GS so into the arsenal of effective treatments for as to avoid unwarranted complications of the improvement of unesthetic facial condi- BTX associated with multiple injections. A tions. During the more than two decades

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that BTX has been used for cosmetic pur- The muscles of facial expression respon- poses, several new indications have been sible for upper lip elevation and lateral re- found, and application techniques are contraction upon smiling are the LLSAN, LLS, stantly being refined. In addition to being Zm, zygomaticus major (ZM), risorius, and, the first-choice treatment for wrinkles locat- to a lesser degree, the depressor septi nasi ed on the upper third of the face, BT is also muscles. All these muscles interact with the widely used in the prevention and correc- orbicularis oris muscle in the production of a tion of changes caused by muscle contrac- smile (Fig 1). The mechanism involved is well tion in the middle and lower thirds of the described in two cadaver studies (Rubin et face and neck, including GS.12 al17 and Pessa18). Both investigations evaluat- Goldstein13 classified the smile line (con- ed the origin of the nasolabial fold. Rubin et sisting of the lower edge of the upper lip al17 concluded that the LLS, the ZM, and the during smiling) into three types, according to superior fibers of the buccinator muscles the degree of exposure of the teeth and under the nasolabial fold are responsible for gums: high, medium, and low. A high smile the production of a full smile. Pessa18 estab- line is characterized by the exposure lished the fact that the LLSAN is responsible of > 3 mm of gum during smiling, which for the formation of the medial portion of clinically translates as GS. Tjan and Miller14 re- the nasolabial fold, and is minimally respon- ported gender differences in the smile line: A sible for the elevation of the upper lip and low smile line is predominant in men (2.5:1), smile formation. This author also found that whereas a high smile line is predominant in the ZM and Zm muscles are primarily re- women (2:1). Perhaps, for this reason, GS is a sponsible for the production of the smile. more common occurrence in women. In another review, Rubin19 classified Various causes have been described for smiles into three types: the “Mona Lisa” GS, including lip length, clinical crown smile, with sharply elevated corners of the length,15 and mainly altered passive eruption mouth, dominated mostly by the action of or vertical maxillary excess.1 On the other the ZM; the canine smile, with the strong el- hand, the behavior of perioral muscles criti- evation of the upper lip near the midline; cally influences the structure of the smile,15 and the full-denture smile, with significant and, according to Peck et al,16 patients with contracture of all upper lip elevator and GS have at least 20% greater facial muscular lower lip depressor muscles, resulting in a capacity to raise the upper lip when smiling. significant exposure of the maxillary and Such cases constitute an indication for mandibular dentition. The canine smile, or treatment with BTX, which should be con- GS, is dominated by the excessive contrac- sidered during the initial assessment of the tion of the LLS muscles. patient. Other factors that make BTX a first- The safety of BTX must be thoroughly in- line therapy for this condition are the ease vestigated. The injection dose of BTX that and safety of its application, the use of small should be used has been stated in a number affordable doses, the fast onset of action, of reports, yet it differs among studies. the low risk, and its reversible effect. This Polo20 attempted multiple serial injections last factor is particularly interesting for cases into each elevator muscle, with variable in which orthodontic or surgical procedures doses ranging from 0.625 to 2.5 IU at differ- are recommended or planned, but for ent phases, under electromyographic guid- which BTX will provide a quick cosmetic ance.21 Similarly, Kane22 treated excessive benefit to the patient who intends to under- gingival display through improvement of the go a more invasive procedure at a later time. nasolabial fold, targeting the LLSAN muscle

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with a dose of 5 IU per side. The injection by Hwang et al10 is formed by the conglom- dose was 1 IU initially, with the subsequent eration of the LLSAN, LLS, and Zm muscles, dose determined at the 2- to 3-week fol- and this was the basis for the present study. low-up, depending on the clinical response. The injection point for BTX-A suggested in Clinically, muscle weakness was seen ap- this study is easily located, and targets the proximately 2 to 4 days postinjection, with whole of the LLSAN, LLS, and Zm muscle the full effect apparent after 7 to 10 days. area with a single injection, as opposed to Garcia and Fulton23 recommended that 2 to one injection for each muscle.10 5 IU of BTX was as effective as higher doses. The limitations of the present study are In contrast to larger muscles elsewhere in the small sample size and the lack of con- the body, doses around 5 IU are considered trol. In order to gain a more comprehensive appropriate for the facial muscles. However, understanding of BTX-A injections at the this author has treated GS with a single- Yonsei point, future studies should consider injection technique at Yonsei point using expanding the sample size and assembling only 2.0 to 3.0 IU per side in order to safe- a more representative sample with multi- guard the patient against unwarranted com- centric trials. plications of BTX due to overdose of toxin.6-8 The method of identifying the injection Conclusion site in this study was based on the report by Garcia and Fulton,23 which stated that the A safe and reproducible injection point for toxin can spread through an area of 15 to BTX-A around the converging area of three 30 mm. Different efficacies of BTX-A have muscles (the Yonsei point) was evaluated been reported, with a resultant conversion and its clinical applicability evaluated. The ratio of 1:2.5 to 4 between Botox (Allergan) application of BTX-A under proper case se- and Dysport (Beaufour Ipsen Biotech).24-26 lection produced a favorable treatment for Dysport showed greater efficacy and longer patients with excessive gingival display. Fur- duration of effect, but with an increased ther studies are required to validate the possibility of side effects.25 Considering the credibility of this study. relatively smaller area of diffusion with Bo- tox compared with Dysport as well as the Acknowledgment relative safety, Botox may be more suitable for use in facial expression muscles because The author expresses sincere appreciation to highly speciﬁc deactivation of each muscle Dr Kanhu Charan Sahoo for providing the im- is indicated. The Yonsei point as described age of the facial muscles used in this article.

References

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