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] 86 | The International Journal of Esthetic Dentistry | Volume 14 | Number 1 | Spring 2019 AL WAYLI 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) The International Journal of Esthetic Dentistry | Volume 14 | Number 1 | Spring 2019 | 87 CLINICAL RESEARCH 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 mini mal 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 88 | The International Journal of Esthetic Dentistry | Volume 14 | Number 1 | Spring 2019 AL WAYLI 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. The International Journal of Esthetic Dentistry | Volume 14 | Number 1 | Spring 2019 | 89 CLINICAL RESEARCH 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 ana- tomical 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 rec- ommended. No local anesthesia was ad- ministered. 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.