Anatomical Considerations Regarding the Location and Boundary of the Depressor Anguli Oris Muscle with Reference to Botulinum Toxin Injection:

Lifting With Neuromodulators

BACKGROUND

The use of botulinum toxins for facial rejuvenation and improvement of dynamic wrinkles has become a mainstay in the aesthetic treatment armamentarium. However, using these same neuromodulators (NMs) for lifting the structures of the face, is a newer addition to antiaging protocols. The muscles of facial animation all interplay with each other. Lifting can be accomplished by treating those muscles that are responsible for depression, leaving the elevators unopposed and resulting in a rejuvenated, lifted outcome. Brow lifting, cheek lifting, and even contouring of the lower face and jawline are all possibilities using NMs.

OBJECTIVE

To review the literature and current practices in techniques for lifting the different anatomic facial zones.

METHODS

The authors present and discuss the published data and personal experiences of using NM for lifting and retraining of the facial musculature. This article will discuss the effects and approaches to lifting with botulinum toxin injections, including the potential success and side effects associated with these off-label injections.

RESULTS/CONCLUSIONS

The use of botulinum toxins has expanded beyond its traditional use as a reducer of dynamic wrinkles. A significant amount of published data now exists for the off-label use of botulinum toxins for lifting and shaping the face. These can be considered advanced techniques as each region has its own anatomic intricacies and side effects can occur. More placebo-controlled objective data would also help elucidate exact dosing strategies for each region.

Botulinum toxin treatment for hemifacial spasm: harmonising neurological and aesthetic outcomes

Hemifacial spasm (HFS) represents a challenging cranial movement disorder primarily affecting the facial nerve innervated muscles, with significant prevalence among Asians. Botulinum toxin type A (BoNT/A) injections, established as a primary therapeutic intervention since FDA approval, offer considerable effectiveness in alleviating spasms, albeit accompanied by challenges such as temporary effects and potential adverse events including facial asymmetry. This comprehensive review underscores the crucial need for harmonising neurological benefits and aesthetic outcomes in HFS management. The discussion delves into the interplay between facial aesthetics and neurological objectives in BoNT/A injections, emphasising precise techniques, dosages, and site considerations. Distinct aspects in neurological and aesthetic domains are also examined, including detailing the targeted muscles and injection methodologies for optimal therapeutic and aesthetic results. Importantly, evidence regarding various BoNT/A formulations, recommendations, and reconstitution guidelines in both neurology and aesthetics contexts are provided, along with a schematic approach outlining the stepwise process for BoNT/A injection in HFS treatment, addressing critical areas such as orbicularis oculi muscle sites, eyebrow correction strategies, mid- and lower-face considerations, contralateral injection sites, and post-injection follow-up and complication management. By highlighting the culmination of neurological efficacy and facial esthetics in BoNT/A treatment for HFS patients, this review proposes a holistic paradigm to achieve balanced symptomatic relief and natural aesthetic expression, ultimately enhancing quality of life for individuals grappling with HFS.

Sonoanatomy of injecting botulinum neurotoxin into the facial muscles

INTRODUCTION

Ultrasonography (US) has become an essential tool for guiding botulinum neurotoxin (BoNT) injections in facial muscles, enhancing precision and safety. This narrative review explores the role of US in BoNT administration, particularly in complex anatomical regions, highlighting its impact on treatment customization, real-time visualization, and complication reduction.

MATERIALS AND METHODS

A comprehensive literature search was conducted using PubMed, MEDLINE, Embase, and Cochrane Library for articles published from January 2018 to December 2023. Search terms included "Botulinum neurotoxin," "facial anatomy," "ultrasonography guided injection," and "facial muscle sonoanatomy." Studies focusing on US-guided BoNT injections in facial muscles were included. Data extraction and synthesis were performed independently by two reviewers, focusing on study design, ultrasonography techniques, outcomes, and conclusions.

RESULTS

The review found that US guidance significantly enhances the precision of BoNT injections by providing real-time visualization of facial muscles and blood vessels, thereby reducing the risk of adverse events. US enables tailored injection strategies, ensuring symmetrical facial expressions and minimizing over-treatment. The technique also offers immediate feedback, allowing for on-the-spot adjustments to improve treatment efficacy and safety. However, the review identified limitations, including potential selection bias and variability in US techniques across different studies.

CONCLUSION

US guidance for BoNT injections into facial muscles offers substantial benefits in terms of precision, safety, and treatment customization. Despite the identified limitations, the integration of US into clinical practice is poised to enhance patient outcomes in aesthetic and therapeutic procedures. Further research is needed to standardize US techniques and broaden the inclusivity of studies to validate these findings comprehensively.

Deciphering Depressor Anguli Oris for Lower Face Rejuvenation: A Prospective Ultrasound-based Investigation

BACKGROUND

The depressor anguli oris muscle (DAO) is a pivotal treatment target when creating a harmonic jawline. However, evidence of its live morphology remains scarce.

OBJECTIVES

In this study we aimed to reevaluate the DAO with a facile ultrasound analysis and thereby guide safer and more effective botulinum toxin type A (BTX-A) injection.

METHODS

A prospective ultrasound assessment was conducted in 41 patients. Morphology of the DAO and its relative position to neighboring structures were appraised at the ubiquitous facial landmark, the labiomandibular fold (LMF). Three-dimensional images were captured before and after the patient received the BTX-A injection based on sonographic evidence.

RESULTS

The skin-to-muscle depths of the DAO on average (measured from the medial to lateral border) were 5.26, 5.61, and 8.42 mm. The DAO becomes thinner and wider from zone 1 to zone 3 (P < .001). Overlapping lengths of the DAO and the depressor labii inferioris increased from zone 1 to zone 3: 4.74, 9.68, 14.54 mm (P < .001). The medial border of the DAO was located at 4.33, 6.12, 8.90 mm medial to the LMF (zone 1-3), and no muscle fibers of the DAO were observed in zone 1 or zone 2 in nearly one-third of patients. Improvement of the mouth corner downturn angle upon receiving BTX-A injection at zones 2 and 3 were 88.3%, 32.3%, and 14.7% for the neutral, maximum smile, and down-turning mouth corner expressions.

CONCLUSIONS

This work established an informative ultrasound portrait of the DAO and structures in the perioral region, which suggested the LMF as a convenient landmark for locating the DAO. Injection at the middle and lower thirds of the LMF at a 4- to 5-mm depth is recommended.

Botulinum Toxin Injection Technique for Reducing the Masseter Size and Enhancing the Jawline

BACKGROUND

The injection of botulinum toxin into the masseter muscle is an important method for improving hypertrophy. However, some patients may experience adverse reactions, such as sagging of the lower jaw. Therefore, we proposed a method of injecting botulinum toxin into the masseter and platysma muscles that would reduce masseter size and enhance the jawline.

OBJECTIVES

The aim of this study was to reduce the masseter size while enhancing the jawline.

METHODS

Twenty patients received botulinum toxin injections into the masseter and platysma muscles. Pain levels were evaluated with the visual analog scale. All patients were photographed before and 6 months after treatment. Evaluations were performed based on standardized criteria. The lift index, reduction index, and symmetry index were performed to assess the degree of jawline elevation, masseter size reduction, and jawline symmetry before and after treatment.

RESULTS

The mean visual analog scale score of the 20 patients was 2.80 (±1.24). The mean lift index score decreased from 4.93 (±0.34) to 4.53 (±0.37), P < .05. The mean reduction index score decreased from 3.13 (±0.27) to 2.74 (±0.27), P < .05. The mean symmetry index score changed from 0.0393 (±0.0296) to 0.0257 (±0.0246), P < .05.

CONCLUSIONS

Botulinum toxin injections into the masseter and platysma muscles through nerve block reduced the masseter size, elevated the jawline, and improved symmetry.

LEVEL OF EVIDENCE: 4

The three layered structure of orbicularis oris and buccinator complex with partial connection at the modiolus and partial direct continuation

PURPOSE

This study aimed to clarify the structural arrangement of the orbicularis oris (OOr), the buccinator, and the other perioral muscles around the modiolus.

METHODS

The perioral muscles in seventeen cadavers fixed with formalin were dissected in situ and/or in isolated muscle specimens, and their layers were reconstructed schematically upon pantomographic view of the skeleton to evaluate their actions.

RESULTS

The buccinator was composed of three parts including upper and lower oblique parts in its superficial layer and a middle transverse part in its deep layer. The superior and inferior OOr were composed of an inner marginal part (IM) and an outer labial part (OL) in each. The perioral muscles as a whole were arranged in three layers. The first layer consisted of the depressor anguli oris and the OL of superior OOr connected at the modiolus in a vertical direction. The second layer consisted of the upper and inner oblique part of buccinator and a part of the OL of inferior OOr connected at the modiolus in a horizontal direction. The third layer contained the middle transverse part of buccinator continuous with the IM of both OOr and a part of the OL of inferior OOr without connection to the modiolus.

CONCLUSIONS

The different arrangement of the three layers of perioral muscles around the modiolus could serve as a good basis to predict the actions of the individual perioral muscles on the movement of lips in open/close of the oral fissure and widening/narrowing of the lip width.

Why Do Nasolabial Folds Appear? Exploring the Anatomical Perspectives and the Role of Thread-Based Interventions

The classification of nasolabial folds into three types, each with distinct causative factors and mechanisms, is explored. Age-related changes in facial skin and connective tissues are examined in detail, revealing variations across different facial regions due to variances in tissue firmness and thickness. The innovative 'Reverse Technique,' involving cog threads to enhance tissue traction and effectiveness in thread-lifting procedures, is introduced. Detailed technical guidelines, anatomical considerations, and safety measures are provided, emphasizing the importance of identifying optimal vectors and fixing points to achieve maximum lifting effects while minimizing potential risks, particularly those associated with vascular structures. Additionally, the 'Cross Technique using volumizing thread' is discussed, designed to smooth tissue boundaries and rejuvenate sagging areas. Facial anatomy, including the positioning of arteries and ligaments, is underscored as essential for ensuring the safety and efficacy of procedures. In conclusion, this review stands as a comprehensive guide for practitioners, offering insights into innovative thread-lifting methods and their applications in addressing nasolabial folds. The primary focus is on achieving optimal aesthetic results while prioritizing patient safety.

Preoperative assessment of depressor anguli oris to prevent myectomy failure: An anatomical study using high-resolution ultrasound

BACKGROUND

Myectomies of the lower lip depressor muscles have unexplained high failure rates. This study aimed to examine the depressor anguli oris (DAO) muscle using high-resolution ultrasound to identify potential anatomical explanations for surgical failures and to determine the accuracy of utilizing preoperative ultrasound assessment to improve myectomies.

METHODS

Anatomical features of DAO and the surrounding anatomy were examined in 38 hemifaces of human body donors using high-resolution ultrasound and dissection.

RESULTS

The ultrasound and dissection measurements showed the DAO muscle width to be 16.2 ± 2.9 versus 14.5 ± 2.5 mm, respectively, and the location of the lateral muscle border 54.4 ± 5.7 versus 52.3 ± 5.4 mm lateral to the midline. In 60% of the cases, the facial artery was either completely covered by lateral DAO muscle fibers or was found to be in direct contact with the lateral border. Significant muscle fiber continuity was present between the DAO and surrounding muscles in 5% of cases, whereas continuity between the depressor labii inferioris and surrounding muscles was considerably more common and pronounced.

CONCLUSIONS

High-resolution ultrasound can accurately reveal important preoperative anatomical information in myectomies. Two potential explanations for the surgical failures were discovered: an overlap of lateral DAO muscle fibers over the facial artery could lead to inadequate resections and continuity with the surrounding muscles might lead to muscle function takeover despite adequate resections. Both can be uncovered preoperatively by the surgeon through a brief, directed ultrasound examination, which may allow for modification of the surgical plan to reduce surgical failure.

Mechanism and clinical use of botulinum neurotoxin in head and facial region

PURPOSE

Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region.

STUDY SELECTION

MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles.

RESULTS

The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia.

CONCLUSIONS

BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Use of LetibotulinumtoxinA for Aesthetic Treatment of Asians: A Consensus

Treatment of wrinkles and dynamic lines with botulinum toxin has been a routine practice for years in aesthetic clinical settings. The effective treatment of wrinkles requires a comprehensive understanding of facial expression muscles and their interactions, the mechanism of action of botulinum toxin, and individual patient preferences. The dose adjustment practice and injection technique of physicians are affected by cultural differences; most Asian patients prefer natural-looking results. This article aims to present an expert consensus on the injection sites, doses, and levels of botulinum toxin for various indications in Asians, with the hope of providing guidance to some clinicians. This consensus paper reviews LetibotulinumtoxinA for patient evaluation, dosage, and delivery techniques in Asians from the time LetibotulinumtoxinA was approved up to December 2022. Panelists proposed individualized treatment plans for botulinum toxin type A (BTxA) treatments in 3 areas-wrinkle removal, contour adjustment, and face lifting-for Asians based on their extensive experience and knowledge of facial anatomy. When using a different BTxA, clinicians should start with a conservative dose and carefully individualize the treatment for each patient, and adjust it according to feedback to obtain a higher satisfaction level.

LEVEL OF EVIDENCE: 5

Correlation of social smile symmetry with facial symmetry

BACKGROUND

This study aimed to assess the correlation of social smile symmetry with facial symmetry.

METHODS

In this cross-sectional study, frontal view photographs were obtained from 169 eligible patients at rest and smiling with a camera at the level of their nose tip. Several landmarks were selected for facial symmetry and measured at rest and social smiling at the two sides of the face. The respective formula was used to calculate the asymmetry index (AI). The mean values for each AI were calculated, and the correlation between the criteria for a symmetric smile in a social smile with the criteria for facial symmetry, and the correlation between the difference in symmetry criteria at rest and social smiling with facial symmetry criteria were analyzed.

RESULTS

Significant correlations were noted between Oc-b AI (smile) and Sn-B (rest) facial AI (P = 0.046), An-a (smile) AI and Gn-a (rest) facial AI (P = 0.002), An-b (smile) AI and Sn-b (rest) facial AI (P < 0.001), Pog-a (smile) and Sn-a (rest) facial AI (P < 0.001), Nt-a (smile) and Sn-a (rest) facial AI (P < 0.001), Nt-b (smile) and Sn-b (rest) facial AI (P < 0.001), Ph-a (smile) and Sn-a (rest) facial AI (P < 0.001), Ph-b (smile) and Sn-b (smile) facial AI (P = 0.007), Oc-b AI (difference) and Gn-b (rest) facial AI (P = 0.031), Oc-Pog (difference) AI and Gn-b (rest) facial AI (P = 0.041), An-b (difference) AI and Sn-b (rest) facial AI (P < 0.001), Nt-a (difference) and Sn-a (rest) facial AI (P = 0.006), Nt-b (difference) and Sn-b (rest) facial AI (P < 0.001), and Ph-b (difference) and Sn-b (rest) facial AI (P < 0.001).

CONCLUSIONS

A significant correlation exists between social smile symmetry and facial symmetry.

A Novel 3-Point Injection Technique for OnabotulinumtoxinA in the Upper Depressor Anguli Oris

BACKGROUND AND OBJECTIVE

To evaluate the efficacy and safety of onabotulinumtoxinA (ONA) injections to the depressor anguli oris (DAO) to improve downturned mouth.

PATIENTS AND METHODS/MATERIALS

This prospective, placebo-controlled, study enrolled subjects aged 18 to 65 years. Injections were performed using a novel 3-point technique in the upper DAO (1.5 U/injection site). The primary end point was a DAO contraction scale 1-grade improvement. Subjective evaluation was performed using the Global Aesthetic Improvement Scale (GAIS).

RESULTS

Ten subjects received ONA and 10 placebo (saline) injections. In ONA-treated subjects, DAO scores showed significant improvements at Weeks 4 and 12 ( p < .001) compared with baseline. No significant difference between visits was observed for placebo-injected subjects. Global Aesthetic Improvement Scale scores showed that 100% of subjects were improved compared with baseline at Week 4% and 90% at Week 12. By contrast, 90% and 80% of placebo-treated subjects had "no change" in their DAO appearance at Weeks 4 and 12. Subject GAIS assessments matched the live evaluator at Week 4; 60% continued to report improvement at Week 12. Treatment was well tolerated.

CONCLUSION

OnabotulinumtoxinA injections to the DAO using a 3-point technique provide clinically meaningful improvements in appearance. Treatment was well tolerated and in most individuals lasted at least 12 weeks.

IDENTIFIER

ClinicalTrials.gov NCT04240535.

A Retrospective and Anatomical Study Describing the Injection of Botulinum Neurotoxins in the Depressor Anguli Oris

SUMMARY

The depressor anguli oris acts to lower the lateral corners of the mouth and can cause an individual to appear sad or angry and contribute to the development of the labiomental folds. Many patients can benefit from the injection of small amounts of botulinum neurotoxin into the depressor anguli oris to enable the lip elevators to reposition the corners of the mouth. Although effective, the procedure is off-label, and the proximity of the depressor anguli oris to the depressor labii inferioris, particularly inferiorly, can lead to inadvertent treatment of the latter, resulting in lip asymmetry. The authors have taken a threefold approach to establish a depressor anguli oris injection technique that provides optimal aesthetic outcomes with a low incidence of adverse events. This involved, first, reviewing the limited existing literature for studies discussing depressor anguli oris anatomy and botulinum neurotoxin treatment technique; second, supplementing information from the published literature with information from cadaver dissections to demonstrate the relationship between the depressor anguli oris and surrounding anatomical structures; and third, performing a retrospective chart review of 275 patients treated with the authors' three-point injection technique. Combining data from published studies, cadaver dissections, and clinical experience, the authors demonstrate that a three-point technique performed in the upper half of the depressor anguli oris is associated with good clinical outcome and avoids common side effects related to injection or spread of neurotoxin to adjacent muscles.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Creating Lift in the Lower Face With Botulinum Toxin A Treatment: An Anatomical Overview With Videos and Case Studies Illustrating Patient Evaluation and Treatment

Background

Relaxation of depressor muscles in the lower face with botulinum toxin A (BoNT-A) can create a lifting effect and dramatically improve jawline contour and resting facial expression. Even with the recent increase in interest in lower face rejuvenation, BoNT-A is a relatively under-recognized tool for treatment of this area. When treating the lower face, an understanding of anatomy and the relationship between the facial muscles is especially important, as injection patterns must be customized for consistently positive outcomes.

Objectives

This study was aimed to provide basic knowledge of the activities of the muscles in the lower face and neck and to describe the basis for injecting BoNT-A to create lift in this area. Expert guidance for injection is also provided.

Methods

As part of a continuing medical education course on differentiating botulinum toxin products, a panel of 4 expert physician injectors participated in a live webinar to discuss the implications of increasing toxin use.

Results

The practical guidance in this manuscript is based on the most frequently requested information by audience members and the information considered critical for success by the authors. The authors outline the functional anatomy of the lower face most relevant for BoNT-A treatment and case studies as well as methods for patient evaluation and injection technique are also provided. Videos showing treatment planning and injection technique for the lower face and neck are included.

Conclusions

BoNT-A is an important nonsurgical tool for creating lift in the lower face.

Level of Evidence 5

Current Use of Cosmetic Toxins to Improve Facial Aesthetics

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Compare and contrast the various types of botulinum toxin on the market. 2. Appropriately select patients for treatment with cosmetic botulinum toxin. 3. Understand the common injection patterns for treating various regions of the face with cosmetic botulinum toxin. 4. List the complications associated with treating various regions of the face with cosmetic botulinum toxin.

SUMMARY

Nonsurgical rejuvenation of the face with botulinum toxin is one of the most commonly performed procedures in the United States. This article reviews the current evidence in treating different regions of the face: upper face, lower face, masseter, and platysma. Dosing and complications associated with different facial regions are reviewed.

Depressor Anguli Oris Myectomy versus Transfer to Depressor Labii Inferioris for Facial Symmetry in Synkinetic Facial Paralysis

BACKGROUND

 Postparalytic synkinesis presents with a combination of hypo- and hypertonic muscles, leading to facial asynchrony with animation and at rest. One ubiquitous finding is a hypertonic depressor anguli oris (DAO) muscle and a weak depressor labii inferioris (DLI) muscle. The goal of this study was to evaluate the utility of DAO myectomy with or without its transfer to the weakened DLI in improving critical components of the dynamic smile.

METHODS

 From 2018 to 2020, this single-center, prospective study included of postparetic facial synkinetic patients with evidence of DAO hypertonicity who underwent DAO myectomy with or without transfer to DLI. Objective facial measurements were used to compare the effectiveness of DAO to DLI transfer to pure DAO myectomy in improving asymmetry of the synkinetic hemiface.

RESULTS

 Twenty-one patients with unilateral postparetic facial synkinesis with DAO hypertonicity were included; 11 underwent DAO myectomy, while 10 underwent DAO to DLI transfer. Baseline demographics and facial measurements were similar between the groups. DAO myectomy resulted in increased modiolus resting position, closed-mouth smile modiolus angle and excursion, open-mouth smile modiolus angle, excursion, dental show, and decreased lower lip height deviation. DAO to DLI transfer demonstrated similar findings but lacked significant increase in excursion and resulted in worsened lower lip height deviation.

CONCLUSION

 These findings illustrate the utility of DAO myectomy in improving imbalance in the synkinetic patient and necessitate further technical refinements for DAO transfers or a different approach for improving lower lip depression in this subgroup of patients.

Topographic and Neural Anatomy of the Depressor Anguli Oris Muscle and Implications for Treatment of Synkinetic Facial Paralysis

BACKGROUND

Synkinetic patients often fail to produce a satisfactory smile because of antagonistic action of a hypertonic depressor anguli oris muscle and concomitantly weak depressor labii inferioris muscle. This study investigated their neurovascular anatomy to partially explain this paradoxical depressor anguli oris hypertonicity and depressor labii inferioris hypotonicity and delineated consistent anatomical landmarks to assist in depressor anguli oris muscle injection and myectomy.

METHODS

Ten hemifaces from five fresh human cadavers were dissected to delineate the neurovascular supply of the depressor anguli oris and depressor labii inferioris muscles in addition to the depressor anguli oris muscle relation to consistent anatomical landmarks.

RESULTS

The depressor anguli oris muscle received innervation from both lower buccal and marginal mandibular facial nerve branches, whereas the depressor labii inferioris muscle was solely innervated by marginal mandibular branches. The mandibular depressor anguli oris origin was on average 39 mm wide, and its medial and lateral borders were located 17 mm from the symphysis and 41 mm from the mandibular angle, respectively. The depressor anguli oris fibers consistently passed anterior to the first mandibular molar toward their insertion into the modiolus, which was located 10 mm lateral and 10 mm caudal to the oral commissure.

CONCLUSIONS

Depressor anguli oris muscle dual innervation versus depressor labii inferioris single innervation may explain why depressor anguli oris hypertonicity and depressor labii inferioris weakness are commonly observed concomitantly in synkinetic patients. Based on treatment goals, diagnostic percutaneous injection with lidocaine can be performed on the depressor anguli oris muscle along a cutaneous line from the modiolus to the mandibular first molar border, and an intraoral depressor anguli oris myectomy can be performed along that same transmucosal line.

Three-Dimensional Evaluation of the Depressor Anguli Oris and Depressor Labii Inferioris for Botulinum Toxin Injections

BACKGROUND

Botulinum toxin type A (BoNT-A) injection administered at an inappropriate site or depth can produce an unwanted change in facial animation because the depressor anguli oris (DAO) and depressor labii inferioris (DLI) muscles are partially overlapped. Therefore, simple BoNT-A injection guidelines, based on 3-dimensional (3D) facial anatomic references and landmarks, would be very useful.

OBJECTIVES

The aim of this study was to establish novel BoNT-A injection guidelines that include the soft tissue thickness at the lower perioral region. Data were acquired with a 3D scanning system combined with dissections in order to obtain accurate injection sites and depths for the DAO and DLI.

METHODS

3D scans of the facial skin, superficial fat, and facial muscle surface were performed in 45 embalmed cadavers. The thicknesses of the skin and subcutaneous layer were calculated automatically from superimposed images at each of 5 reference points (P) in the perioral region.

RESULTS

In every case (100%), P3 and P5 were located in the DLI and DAO areas, respectively (45/45). Therefore, we defined P3 as the "DLI point" and P5 as the "DAO point." The soft tissue thicknesses at the DLI and DAO points were 6.4 [1.7] mm and 6.7 [1.8] mm, respectively.

CONCLUSIONS

The P3 and P5 described in this study are effective guidelines that only target the DLI and DAO. Clinicians, specifically, can easily use facial landmarks, such as the cheilion and pupil, to assign the DLI and DAO points without any measurement or palpation of the modiolus.

An unusual adverse event of botulinum toxin injection in the lower face

BACKGROUND

In the lower third of the face, botulinum toxin A is used to obtain a more harmonious contour. The anatomical complexity of the face requires a more precise application of botulinum toxin.

AIM

Describe the treatment of an unexpected effect after botulinum toxin A application in the lower third of the face.

PATIENT/METHODS

A 51-year-old female patient presented to our clinic for application of botulin toxin aiming to improve facial wrinkles and contour. 50 U of botulinum toxin type A were applied to the upper third and 20 U to the lower third of the face. The patient returned after 10 days with a smile asymmetry and an excessive and unconscious lowering on the right side of the lower lip while laughing. So, 3 U of botulinum toxin were applied to the center of the depressor labii inferioris muscle on the right side.

RESULTS

The patient returned with a satisfactory correction of the smile asymmetry.

CONCLUSION

Although treatments with botulinum toxin A are considered safe, unexpected results can occur. In our case, it probably occurred due to medial injection or diffusion of botulinum toxin A into depressor anguli oris muscle on the left side that may lead to paralysis of the left depressor labii inferioris muscle and downward hyperfunction of the unaffected right lower lip. The correction was made with a new injection of botulinum toxin A in the depressor labii inferioris hyperactive muscle at the right side.

A combined method of oral commissure lifting for perioral rejuvenation in Asians

BACKGROUND

A drooping oral commissure shows an appearance of ageing and sadness. To improve it with less complications has become a rising aesthetic concern for Asians.

OBJECTIVES

To share our method for oral commissure lifting by a combined technique including skin resection, oral commissure suspension, and dissection of the depressor anguli oris muscle (DAO), and to present the follow-up outcomes.

METHODS

This was a retrospective study of patients who underwent oral commissure lifting between 10/2012 and 03/2019 at the Department of Plastic Surgery, Peking University Third Hospital. The patients were routinely followed at 1 week, 1 month, and over 6 months. After operation, cases with the cheilions (oral commissure points) located above the ipsilateral lateral thickening points were considered to be effective, with the points at the same level were considered to be mildly effective, and with the cheilions below the ipsilateral lateral thickening points were considered to be ineffective treatment.

RESULTS

Surgery took around an hour. Swelling subsided within 9.2±3.4 days. The red color of the scar disappeared within 3.7±1.5 months and the natural facial expression was restored within 7.9±2.6 weeks. Among the 159 cases, 125 (78.6%) were obviously effective, 21 (13.2%) were mildly effective, and 13 (8.2%) were ineffective. After the first operation, 112 patients (70.4%) were satisfied, 39 patients (24.5%) were basically satisfied, and eight patients (5.0%) were unsatisfied.

CONCLUSIONS

The combined technique for the oral commissure lifting displayed a significant effect with little complication in Asian patients.

Mouth Corner Lift with Botulinum Toxin Type A and Hyaluronic Acid Filler

An upturned mouth corner is associated with brightness, optimism, and friendliness, whereas a downturned mouth corner not only conveys negative feelings such as sadness, depression, and tiredness, but also makes a person appear years older than they are. Surgical approaches to the correction of a downturned mouth corner can result in predictable and long-lasting results. However, because of their fear of postsurgical scars and long downtimes, many patients are reluctant to undergo surgery involving the mouth corner. As a consequence, minimally invasive procedures have become increasingly popular in recent years. Among these, botulinum toxin type A and injectable fillers play a significant role. The author uses botulinum toxin type A and hyaluronic acid filler injections as complementary procedures for lifting flat or downturned mouth corners in young patients. This method has produced reliable and consistent outcomes without severe complications such as necrosis or infection in over 100 patients, as reflected in high patient satisfaction. The combination of botulinum toxin type A and hyaluronic acid filler provides excellent results in young patients who desire an uplifted mouth corner and are reluctant to undergo surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, V.

Three-Dimensional Territory and Depth of the Corrugator Supercilii: Application to Botulinum Neurotoxin Injection

This study aimed to determine the three-dimensional (3D) territory and depth of the corrugator supercilii muscle (CSM) using a 3D structured-light scanner. Thirty-two hemifaces from Korean and Thai embalmed cadavers were used in this study, and 35 healthy young Korean subjects also participated. A 3D analysis of the CSM territory and depth was performed using a structured-light 3D scanner. The most frequently observed locations of the CSM identified in the cadaver were confirmed in healthy young subjects using a real-time two-dimensional B-mode ultrasonography system. The CSM was present in all of the cadavers and healthy young subjects at the intersection point between the vertical line passing through the medial canthus and the horizontal line passing through the glabella (Point #6). The CSM was located on the medial side of the lateral limbus in most cases. The most-medial and most-lateral origin points were at depths of 5.7 ± 1.4 mm (mean ± SD) and 6.6 ± 1.4 mm, respectively; the corresponding depths of the insertion points were 5.4 ± 1.4 mm and 5.6 ± 2.1 mm, respectively. The origin and insertion points of the CSM were at similar depths. The injection depth should be around 4 mm for botulinum neurotoxin (BoNT) injections into the CSM. Point #6 could be regarded as an effective target point for managing the glabellar frown line and preventing palpebral ptosis when injecting BoNT into the CSM. Clin. Anat., 33:795-803, 2020. © 2019 Wiley Periodicals, Inc.

Cheek-splitting technique for marginal mandibulectomy: A novel approach

When performing marginal mandibulectomy, ensuring complete tumor removal and preventing postoperative iatrogenic mandibular fracture are essential. Pathological fracture can result due to stress concentration at the site requiring acute angle resection. To perform marginal mandibulectomy without making acute angles in patients with a lesion in the molar or more posterior region, a submandibular or transbuccal approach is necessary. Compared to the submandibular approach, the transbuccal approach is considered useful as it reduces operative time and prevents injury to the facial and mental nerves. Additionally, this approach does not leave a scar in the surgical field, which is beneficial in subsequent neck dissection for late neck metastasis. Here, we report 2 cases of lower gingival carcinoma in which satisfactory aesthetic outcomes were achieved with an improved cheek-splitting technique for marginal mandibulectomy using a transbuccal approach, taking into consideration the angle of the mouth, design of the triangular flap, and modiolus.

Key words:Mandibular gingival carcinoma, cheek-splitting technique, transbuccal approach, marginal mandibulectomy.

Nonsurgical correction of drooping mouth corners using monophasic hyaluronic acid and incobotulinumtoxinA

BACKGROUND

Nonsurgical correction of drooping of the corners of the mouth requires a multimodal approach combining botulinum toxin and soft tissue filler injections.

OBJECTIVE

To validate a nonsurgical therapeutic approach for correcting a "saddened" appearance characterized by drooping mouth corners, oral commissures, and/or marionette lines.

METHODS

In this prospective, evaluator-blinded study, monophasic hyaluronic acid (MHA) was infiltrated to correct drooping mouth corners in four steps, deep oral commissures in two steps, and/or deep marionette lines in two steps, in that order. Then, incobotulinumtoxinA was injected along the depressor anguli oris and mentalis muscles.

RESULTS

The total volumes of MHA used in steps 1-4 were 0.2 mL (interquartile range [IQR]: 0.19-0.3) for the right side of the face and 0.25 mL (IQR: 0.2-0.3) for the left side; total volumes in steps 5-8 were 0.18 mL (IQR: 0-0.4) for the right side and 0.15 mL (IQR: 0-0.33) for the left side. The total mean dose of incobotulinumtoxinA was 26.5 units (IQR: 24-28). The median degrees of drooping of the mouth corners were -4° (IQR: -7° to -2°) at baseline, -1° (IQR: -3° to 1°) at post-treatment 2 weeks, and -1° (IQR: -3° to 0°) at post-treatment 3 months. Median Global Aesthetic Improvement Scale scores were 3 (IQR: 2-3) at post-treatment 2 weeks and 3 (IQR: 2-3.75) at 3 months.

CONCLUSION

Our results demonstrated that nonsurgical treatment with MHA and incobotulinumtoxinA provides satisfactory therapeutic outcomes in patients with a saddened appearance by correcting drooping of the mouth corners, deep oral commissures, and/or deep marionette lines.

Facial Expressions of Basic Emotions in Japanese Laypeople

Facial expressions that show emotion play an important role in human social interactions. In previous theoretical studies, researchers have suggested that there are universal, prototypical facial expressions specific to basic emotions. However, the results of some empirical studies that tested the production of emotional facial expressions based on particular scenarios only partially supported the theoretical predictions. In addition, all of the previous studies were conducted in Western cultures. We investigated Japanese laypeople (n = 65) to provide further empirical evidence regarding the production of emotional facial expressions. The participants produced facial expressions for six basic emotions (anger, disgust, fear, happiness, sadness, and surprise) in specific scenarios. Under the baseline condition, the participants imitated photographs of prototypical facial expressions. The produced facial expressions were automatically coded using FaceReader in terms of the intensities of emotions and facial action units. In contrast to the photograph condition, where all target emotions were shown clearly, the scenario condition elicited the target emotions clearly only for happy and surprised expressions. The photograph and scenario conditions yielded different profiles for the intensities of emotions and facial action units associated with all of the facial expressions tested. These results provide partial support for the theory of universal, prototypical facial expressions for basic emotions but suggest the possibility that the theory may need to be modified based on empirical evidence.

The Use of Neurotoxins in the Male Face

Injection of neurotoxin is the most commonly performed cosmetic procedure in the United States, and the total number of male patients seeking botulinum has steadily increased over the years. Because of their unique aesthetic goals, expectations, and anatomy, men require differing botulinum toxin doses and techniques. This article provides an evidence-based approach to botulinum toxin in men. Each area of the face is discussed separately, focusing on gender differences in anatomy, treatment goals, and injection method.

Injectable and topical neurotoxins in dermatology: Basic science, anatomy, and therapeutic agents

Botulinum toxin is a potentially deadly anaerobic bacterial toxin that acts by inhibiting release of acetylcholine at the neuromuscular junction, thereby inhibiting contraction of the exposed striated muscle. There are currently 4 botulinum toxin preparations approved by the US Food and Drug Administration (FDA): onabotulinumtoxin, abobotulinumtoxin, incobotulinumtoxin and rimabotulinumtoxin. While significant overlap exists, each product has unique properties and specifications, including dosing, diffusion, and storage. Extensive physician knowledge of facial anatomy, coupled with key differences of the various neurotoxin types, is essential for safe and successful treatments. The first article in this continuing medical education series reviews key characteristics of each neurotoxin, including new and upcoming agents, and provides an anatomic overview of the most commonly injected cosmetic sites.

Applications of botulinum toxin in dentistry: A comprehensive review

The horizons of treatment options in dentistry are broadening rapidly. In this scenario, applications of unconventional treatment options like use of botulinum toxin (BT) are gaining momentum. The use of BT has been popularly accepted in esthetic procedures like management of facial wrinkles; however, it has been documented to be successful in a variety of conditions. Of particular interest to this paper are applications of BT in the maxillofacial region, concerned to dentistry. BT offers a transient, reversible, relatively safe treatment option to many conditions of interest to a dental practitioner. Dental surgeons by their virtue of being extensively aware of the anatomy of faciomaxillary region are a potential pool of operators who can use BT in their armamentarium with minor skill enhancement and thus widen the perspective of alternative, minimally invasive options to refractory conditions or invasive protocols.