Use of Botulinum Toxin in Orofacial Clinical Practice

Modern Approaches to the Treatment of Acute Facial Pain

PURPOSE OF REVIEW

Acute facial pain presents a complex challenge in medical practice, requiring a comprehensive and interdisciplinary approach to its management. This narrative review explores the contemporary landscape of treating acute facial pain, delving into pharmacological, non-pharmacological, and advanced interventions. The significance of tailored treatment strategies, rooted in the diverse etiologies of facial pain, such as dental infections, trigeminal neuralgia, temporomandibular joint disorders, sinusitis, or neurological conditions like migraines or cluster headaches, is underscored. We particularly emphasize recent advances in treating trigeminal neuralgia, elucidating current treatment concepts in managing this particular acute facial pain.

RECENT FINDINGS

Recent research sheds light on various treatment modalities for acute facial pain. Pharmacotherapy ranges from traditional NSAIDs and analgesics to anticonvulsants and antidepressants. Non-pharmacological interventions, including physical therapy and psychological approaches, play pivotal roles. Advanced interventions, such as nerve blocks and surgical procedures, are considered in cases of treatment resistance. Moreover, we explore innovative technologies like neuromodulation techniques and personalized medicine, offering promising avenues for optimizing treatment outcomes in acute facial pain management. Modern management of acute facial pain requires a nuanced and patient-centric approach. Tailoring treatment strategies to the individual's underlying condition is paramount. While pharmacotherapy remains a cornerstone, the integration of non-pharmacological interventions is essential for comprehensive care. Advanced interventions should be reserved for cases where conservative measures prove inadequate. Furthermore, leveraging innovative technologies and personalized medicine holds promise for enhancing treatment efficacy. Ultimately, a holistic approach that considers the diverse needs of patients is crucial for effectively addressing acute facial pain.

Systematic review of the histological and functional effects of botulinum toxin A on masticatory muscles: Consideration in dentofacial orthopedics and orthognathic surgery

INTRODUCTION

Botulinum toxin type A causes muscle paralysis and is widely used in the masticatory muscle for stomatognathic diseases, such as temporomandibular disorder, bruxism, or masseteric hypertrophy. Nonetheless, its muscular effect remains unclear. Better understanding could aid improved use and perhaps new indications, particularly in dentofacial orthopaedics and orthognathic surgery.

METHODS

This systematic review explored the histologic and functional effects of botulinum toxin in animal and human masticatory muscles and was conducted in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The MEDLINE, Web of Science, and Cochrane Library electronic databases were searched for relevant articles. The inclusion criteria were human or animal masticatory muscle analysis after botulinum toxin injection(s) AND histological structural/ultrastructural analysis by optical or electronic microscopy OR functional effect analysis by bite force evaluation (occlusal force analyzer) and muscle activity (electromyography).

RESULTS

Of an initial 1578 articles, 44 studies were eventually included. Botulinum toxin injection in the masticatory muscle altered its histological structure and functional properties. The human and animal studies revealed ultrastructural change, atrophy, and fiber type modifications of the masticatory muscles after one injection. Botulinum toxin decreased bite force and muscle activity, but recovery was uncertain.

CONCLUSIONS

Muscle forces applied on the skeleton is a key feature of facial growth. Masticatory muscle paralysis changes mechanical stress on bones, which rebalances the force applied on facial bones. This new balance could benefit dental deformity or surgical relapse. Therefore, botulinum toxin could limit the orthognathic effect of the masticatory muscles in such patients. Given the uncertain recovery, multiple injections should be avoided, and usage should not deviate from established consensus.

Clinical and electroencephalographic correlates of carbamazepine-associated hiccups in epileptic patients

Carbamazepine, a commonly prescribed antiepileptic drug, is known to induce hiccups in a subset of epileptic patients. Although relatively uncommon, can have significant clinical implications. This comprehensive review delves into the clinical and electroencephalographic correlates of carbamazepine-associated hiccups, aiming to enhance understanding and management of this neurological side effect. The authors' review synthesizes qualitative epidemiological data, revealing that carbamazepine-induced hiccups occur in a subset of patients receiving the medication, with reported incidence rates ranging from 2.5 to 40%. Despite its relatively low prevalence, hiccups pose substantial challenges for patients and healthcare providers. Complications associated with carbamazepine-induced hiccups include disruption of sleep, impaired social functioning, and decreased quality of life, underscoring the clinical significance of this side effect. Effective management strategies can be implemented through a multidisciplinary approach, including collaboration among neurologists, pharmacists, and other healthcare professionals. These may include dose adjustments, medication discontinuation, and adjunctive therapies such as diaphragmatic breathing exercises or acupuncture. Additionally, close monitoring for adverse effects and timely intervention are essential to mitigate the impact of hiccups on patient well-being. Essentially, carbamazepine-induced hiccups represent a clinically relevant phenomenon that warrants attention in the management of epilepsy. By recognizing the clinical manifestations, understanding the underlying pathophysiology, and implementing evidence-based management strategies, healthcare providers can optimize patient care and improve outcomes in this patient population.

Repeated unilateral injections of botulinum toxin in masticatory muscles in adult rats do not amplify condylar and alveolar bone loss nor modify the volume of the hypertrophic bone proliferation at enthesis

OBJECTIVES

Botulinum toxin is used in human in repeatedly masticatory muscles injections. A single BTX injection in animal induces mandibular bone loss with a muscle enthesis hypertrophic metaplasia. Our aim was to evaluate mandibular bone changes after unilateral repeated injections of BTX in adult rats.

STUDY DESIGN

Mature male rats were randomized into 3 groups: one, two or three injections. Each rat received injections in right masseter and temporalis muscles. The left side was the control side. Microcomputed tomography was used to perform 2D and 3D analyses.

RESULTS

Bone loss was evidenced on the right sides of alveolar and condylar bone. Alveolar bone volume increased in both control left side and injected right side whereas condylar bone volume remained constant in all groups, for both sides. Enthesis bone hypertrophic metaplasias were evidenced on the BTX injected sides without any modification with the number of injections.

CONCLUSION

BTX repeated injections in masticatory muscles lead to major mandibular condylar and alveolar bone loss that does not worsen. They lead to the occurrence of an enthesis bone proliferation that is not dependent on the number of injections. These results are an argument for the safety of BTX injections in masticatory muscles in human.

Botulinum Toxin Type A and Hyaluronic Acid Dermal Fillers in Dentistry: A Systematic Review of Clinical Application and Indications

Background

Botulinum toxin type A (BoNT-A) and hyaluronic acid (HA) dermal fillers are increasingly utilized in dentistry for therapeutic and aesthetic purposes. However, a comprehensive synthesis of their clinical applications and indications in dentistry is lacking. This systematic review aimed to analyze the clinical application and indications of BoNT-A and HA dermal fillers in dentistry, providing insights into their efficacy, safety profiles, and limitations.

Methods

A systematic search was conducted in PubMed/MEDLINE databases to identify relevant studies published between 2018 and 2024. Medical Subject Headings (MeSH) terms and keywords related to BoNT-A, HA dermal fillers, dentistry, clinical applications, and indications were used. Study selection criteria included randomized controlled trials (RCTs) and non-RCTs involving human participants of any age group. Data extraction and synthesis followed established guidelines, focusing on study characteristics, participant demographics, intervention details, outcome measures, and key findings related to BoNT-A and HA dermal fillers' clinical application in dentistry.

Results

Systematic searches across electronic databases and grey literature identified 857 records, with an additional 73 from hand searches. After screening titles and abstracts, 542 records were excluded, leaving 374 full-text publications for evaluation. Ultimately, 12 RCTs and 13 non-RCTs were included. The systematic review encompassed diverse geographic locations: Brazil, Italy, Spain, Syria, India, Egypt, Korea, and the Netherlands, involving samples sizes ranging from 14 to 143 participants. The review synthesized findings on HA's efficacy in various areas, including bone repair, gingivitis management, temporomandibular joint disorders, postoperative swelling reduction, periodontal defect treatment, chin and check projection and lips augmentation. BoNT-A exhibited promising efficacy in managing orofacial pain conditions, gummy smile treatment and neuromodulation of the lower third muscles. Safety profiles varied among studies, with some reporting minimal adverse effects while others noted dose-related concerns.

Conclusion

BoNT-A and HA dermal fillers offer a wide array of clinical applications in dentistry, ranging from therapeutic interventions to aesthetic enhancements. Despite promising efficacy, careful consideration and monitoring of safety outcomes are essential when integrating these interventions into clinical practice. Further research addressing methodological limitations and safety concerns is warranted to optimize their utilization and improve patient care in dentistry.

Concomitant Botulinum Toxin Injections for Neurogenic Detrusor Overactivity and Spasticity-A Retrospective Analysis of Practice and Safety

As multiple indications for botulinum toxin injections (BTIs) can coexist for neurological patients, there are to date no description of concomitant injections (CIs) to treat both spasticity and neurogenic detrusor overactivity incontinence (NDOI) in patients with spinal cord injuries (SCIs) and multiple sclerosis (MS). We therefore identified patients followed at our institution by health data hub digging, using a specific procedure coding system in use in France, who have been treated at least once with detrusor and skeletal muscle BTIs within the same 1-month period, over the past 5 years (2017-2021). We analyzed 72 patients representing 319 CIs. Fifty (69%) were male, and the patients were mostly SCI (76%) and MS (18%) patients and were treated by a mean number of CIs of 4.4 ± 3.6 [1-14]. The mean cumulative dose was 442.1 ± 98.8 U, and 95% of CIs were performed within a 72 h timeframe. Among all CIs, five patients had symptoms evocative of distant spread but only one had a confirmed pathological jitter in single-fiber EMG. Eleven discontinued CIs for surgical alternatives: enterocystoplasty (five), tenotomy (three), intrathecal baclofen (two) and neurotomy (one). Concomitant BTIs for treating both spasticity and NDOI at the same time appeared safe when performed within a short delay and in compliance with actual knowledge for maximum doses.

Efficacy and Safety of Botulinum Toxin in the Management of Temporomandibular Symptoms Associated with Sleep Bruxism: A Systematic Review

Sleep bruxism, characterized by involuntary grinding or clenching of teeth during sleep, poses significant challenges in management due to its potential to induce temporomandibular joint disorders (TMDs) and other related symptoms. The use of Botulinum toxin Type A (BoNT-A), also known as Botox®, has been proposed as a therapeutic intervention. This systematic review aims to evaluate the efficacy and safety of BoNT-A in the management of sleep bruxism, focusing on pain reduction, improvement in jaw function, reduction in bruxism episodes, and the incidence of adverse effects. An exhaustive search was conducted across PubMed, Scopus, and Embase databases up to January 2024, adhering to the PRISMA guidelines. Nine randomized clinical trials (RCTs) involving 137 participants were analyzed for efficacy and safety outcomes. The studies demonstrated a significant reduction in mean pain scores (from 7.1 to 0.2 at 6 months and 1 year post-treatment in one study) and a notable decrease in the number of bruxism events (from 4.97/h to 1.70/h in the BoNT-A group in another study). Additionally, improvements were observed in jaw stiffness and total sleep time. Adverse effects varied but were generally mild and transient, including injection site pain in 20% of participants in one study and cosmetic changes in smile in 15.4% of patients in another. These findings suggest that BoNT-A injections may provide some benefits for treating nocturnal bruxism, potentially reducing TMD symptoms like pain and improving jaw function. However, these findings are preliminary due to variability in study designs and the absence of detailed statistical analysis.

A Case of Parotid Gland Fistula After Microtia Reconstruction Successfully Treated With Botulinum Toxin Type A

Parotid gland fistula after microtia reconstruction is relatively rare, with only 3 cases having been reported in the literature. It may be caused by the presence of an accessory parotid gland or surgical damage to parotid gland tissues. The principal treatment is dressing the wound. Here, we report the first case of parotid fistula after microtia reconstruction using a delayed retroauricular flap, which healed following wound dressing and an injection of botulinum toxin type A (CBTXA) into the parotid gland.

Effect of botulinum toxin-A injection applied to the mentalis muscle on free gingival graft operation: A retrospective study

OBJECTIVE

The purpose of this retrospective study was to investigate the effects of Botulinum Toxin-A (BTX-A) injection into the mentalis muscle on the free gingival graft (FGG).

MATERIALS AND METHODS

Forty patients with keratinized gingiva insufficiency and Cairo's RT 2 gingival recession (formerly classified as Miller class III) in their mandibular central incisors were randomly divided into two groups: FGG and FGG + BTX. Plaque index (PI), gingival index (GI), probing pocket depth (PPD), keratinized gingiva width (KGW), attached gingiva width (AGW), clinical attachment level (CAL), gingival thickness (GT), gingival recession amount (GRA), gingival recession width (GRW), and root closure percentage (RCP%) parameters were measured at baseline and at first, third, and sixth months after the operation.

RESULTS

There was no difference in PI, GI, and PPD levels in both groups (p > 0.05). While the change in GT and RCP% levels were found to be statistically significantly higher at FGG + BTX group than FGG group, the change in GRW and CAL levels were statistically significantly lower (p < 0.05).

CONCLUSION

The findings of this study indicate that BTX-A injection applied to the mentalis muscle after FGG operation may have positive effects in terms of KGW, AGW, GT, RCP%, GRW, and CAL parameters.

CLINICAL SIGNIFICANCE

As a result of the fact that BTX-A injection into the mentalis muscle contributed to the nutrition and immobility of FGG, positive developments were obtained in terms of clinical periodontal parameters. BTX-A injection into the mentalis muscle may be an alternative method that increases the success rate of Cairo's RT 2 gingival recession.

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.

Lateral pterygoid muscle ultrasound-guided injection: A technical note

BACKGROUND

Temporomandibular disorders (TMDs) are a frequent cause of orofacial pain, causing functional disability and a negative impact on quality of life. Botulinum toxin (BTX-A) injection in lateral pterygoid muscle (LPM) is one of the treatment modalities proposed, but the blind puncture guided by EMG carries a risk of vascular puncture or diffusion of the toxin to nearby muscles. We describe an ultrasound-guided approach and evaluate the spread of the injection in a fresh human cadaver.

METHODS

A fresh human cadaver was injected. An out-of-plane approach was performed using a convex probe, injecting 1.0 ml of 0.25% methylene blue dye into the LPM. After, a dissection was performed to isolate the lateral pterygoid muscle and assess the spread of the dye.

RESULTS

Ultrasound-guided injection allowed to visualize in real-time the spread of the dye within the LPM. The deep and superficial muscles nearby to LPM were not stained by the dye, but upper and lower head of LPM was heavily stained.

CONCLUSION

Ultrasound-guided approach for the injection of BTX-A into the LPM could be considered a successful and safe treatment for myofascial pain related to TMD. Therefore, further clinical studies are needed to study the reproducibility of ultrasound guided LPM injection and to evaluate the clinical results.

The psychological and psychosocial effects of facial paralysis: A review

Facial nerve function is essential for a multitude of processes in the face, including facial movement; expression; and functions, such as eating, smiling, and blinking. When facial nerve function is disrupted, facial paralysis may occur and various complications for the patient may result. Much research has been conducted on the physical diagnosis, management, and treatment of facial paralysis. However, there is a lack of knowledge of the psychological and social effects of the condition. Patients may be at an increased risk for anxiety and depression, as well as negative self and social perceptions. This review analyzes the current literature on the various adverse psychological and psychosocial effects of facial paralysis, factors that may play a role, and treatment options that may help improve patients' quality of life.

Editorial to the Special Issue "The Effect of Exercise Intensity and Psychological Intervention on Musculoskeletal Disorders"

Musculoskeletal disorders are responsible for the most prevalent form of pain, and necessitate a comprehensive approach to rehabilitation [...].

Hiccups, Hypersalivation, Hallucinations in Parkinson's Disease: New Insights, Mechanisms, Pathophysiology, and Management

Parkinson's disease (PD) is a chronic, progressive neurological disorder and the second most common neurodegenerative condition. We report three common but overlooked symptoms in PD-hiccups, hypersalivation, and hallucinations-in terms of their prevalence, pathophysiology, and up-to-date evidence-based treatment strategies. Whilst all these three symptoms do occur in many other neurological and non-neurological conditions, early recognition and treatment are paramount. Whilst hiccups affect 3% of healthy people, their rate of occurrence is higher (20%) in patients with PD. Hypersalivation (Sialorrhea) is another common neurological manifestation of many neurological and other neurodegenerative conditions such as motor neuron disease (MND), with a median prevalence rate of 56% (range: 32-74%). A 42% prevalence of sialorrhea is also reported in sub-optimally treated patients with PD. Hallucinations, especially visual hallucinations, are commonly reported, with a prevalence of 32-63% in PD, and a 55-78% prevalence is noted in patients with dementia with Lewy bodies (DLB), followed by tactile hallucinations, which are indicated by a sensation of crawling bugs or imaginary creatures across the skin surface. Whilst mainstay and primary management strategies for all these three symptoms are carried out through history taking, it is also essential to identify and treat possible potential triggers such as infection, minimise or avoid causative (such as drug-induced) factors, and especially carry out patient education before considering more definitive treatment strategies, such as botulinum toxin therapies for hypersalivation, to improve the quality of life of patients. This original review paper aims to provide a comprehensive overview of the disease mechanisms, pathophysiology, and management of hiccups, hypersalivation, and hallucinations in Parkinson's disease.

The Masticatory Structure and Function in Children with Cerebral Palsy—A Pilot Study

(1) Background: Muscle tension around the head and neck influences orofacial functions. The data exist concerning head posture during increased salivation; however, little is known about muscle tightness during this process. This study aims to investigate whether or not any muscles are related to problems with eating, such as drooling in individuals with cerebral palsy; (2) Methods: Nineteen patients between the ages of 1 and 14 were examined prior to the physiotherapy intervention. This intervention lasted three months and consisted of: relaxing muscles via the strain-counterstrain technique, functional exercises based on the NeuroDevelopmental Treatment-Bobath method, and functional exercises for eating; (3) Results: the tone of rectus capitis posterior minor muscle on the left side (p = 0.027) and temporalis muscle on the right side (p = 0.048) before the therapy, and scalene muscle on the right side after the therapy (p = 0.024) were correlated with drooling behavior and were considered statistically significant. Gross motor function was not considered statistically significant with the occurrence of drooling behavior (p ≤ 0.05). Following the therapeutic intervention, the frequency of drooling during feeding decreased from 63.16% to 38.89% of the total sample of examined patients; (4) Conclusions: The tightness of the muscles in the head area can cause drooling during feeding.

QNZ exposure induces development toxicity and mechanisms of hatching inhibition in large-scale loach (Paramisgurnus dabryanus) embryos

QNZ is a quinazoline-type NF-κB inhibitor and is one of the hot anti-inflammatory drug candidates in recent years. With its development and application, QNZ will inevitably enter the aquatic environment posing a threat to aquatic organisms. To investigate the potential toxicity of QNZ in the early life stages of the organism, this study exposed embryos of large-scale loach (Paramisgurnus dabryanus) to 0, 20, 40, 60, and 80 nM of QNZ. The hatching of embryos was significantly inhibited and hatching time was delayed. We explored the mechanism of hatching delay and failure. The results suggested that QNZ exposure reduced the number of hatching gland cells (HGCs) and hatching enzyme activity. Also, the frequency of spontaneous movements was inhibited by interfering with the expression of genes related to the cholinergic system and skeletal muscle development. Further, QNZ exposure induces a series of morphological changes (spine deformation, pericardial edema, tail deformation, and yolk sac edema) in embryos and newly-hatched larvae, and finally increased the deformity rate and mortality rate of newly-hatched larvae. The information presented in this study will provide a scientific basis for further studies into the potential toxicity of QNZ on aquatic organisms.

Preliminary Findings of the Efficacy of Botulinum Toxin in Temporomandibular Disorders: Uncontrolled Pilot Study

Temporomandibular disorders are a common pathology affecting up to 70% of the population, with a maximum incidence in young patients. We used a sample of twenty patients recruited in the Maxillofacial Surgery Service of the University Hospital of Salamanca (Spain), who met the inclusion criteria, with unilateral painful symptomatology of more than three months' duration. All patients were randomly treated by intramuscular and intra-articular injections of botulinum toxin (100 U) in eight predetermined points. Pain symptomatology was assessed by the visual analog scale (VAS) at the different locations, together with joint symptomatology, at baseline and six weeks after treatment. Adverse effects were also evaluated. In 85% of the patients, pain upon oral opening improved and 90% showed improvement in pain upon mastication. A total of 75% of the patients reported improvement in joint clicking/noise. Headaches improved or disappeared in 70% of the patients treated. Despite the limitations of the study and the preliminary results, intramuscular and intra-articular infiltrations with botulinum toxin were effective in the treatment of symptoms associated with temporomandibular disorders (TMDs), with minimal adverse effects.

Cosmetic Treatment Using Botulinum Toxin in the Oral and Maxillofacial Area: A Narrative Review of Esthetic Techniques

Botulinum toxin (BoNT) is an anaerobic rod-shaped-neurotoxin produced by Clostridium botulinum, that has both therapeutic and lethal applications. BoNT injection is the most popular cosmetic procedure worldwide with various applications. Patients with dynamic wrinkles in areas such as the glabella, forehead, peri-orbital lines, nasal rhytides, and perioral rhytides are indicated. Excessive contraction of muscles or hyperactivity of specific muscles such as bulky masseters, cobble stone chins, gummy smiles, asymmetric smiles, and depressed mouth corners can achieve esthetic results by targeting the precise muscles. Patients with hypertrophic submandibular glands and parotid glands can also benefit esthetically. There are several FDA-approved BoNTs (obabotuli-numtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, letibotulinumtoxinA, prabotulinumtox-inA, daxibotulinumtoxinA, rimbotulinumtoxinB) and novel BoNTs on the market. This paper is a narrative review of the consensus statements of expert practitioners and various literature on the injection points and techniques, highlighting both the Asian and Caucasian population separately. This paper can serve as a practical illustrative guide and reference for optimal, safe injection areas and effective doses for application of BoNT in the face and oral and maxillofacial area. The history of BoNT indications, contraindications, and complications, and the merits of ultrasonography (US)-assisted injections are also discussed.

Botulinum toxin in the management of myalgia in temporomandibular disorders: are all injections equal?

Botulinum toxin (BTX) is becoming widely used as an adjunct to conservative management of myalgia-predominant temporomandibular disorders (TMDs) with reports of improved quality of life. There is, however, no consensus on the optimal dosage. Based on previous studies, dose regimens vary between clinicians, and we know of no standard dose protocol for the administration of BTX for the purpose of TMD management. A survey was sent to members of the British Association of Oral and Maxillofacial Surgeons (BAOMS) Temporomandibular Joint Sub-Specialty Interest Group (TMJ SSIG) and an international mailing list of high-volume TMJ surgeons (the TMJ Internetwork) to ascertain variations in dose regimens between different clinicians. The survey found that 41 respondents offered BTX to patients. The masseter muscle group was the most commonly injected site, and the majority of respondents (34/41) used Botox® (Allergan). Brands less commonly used included Dysport® (Ipsen), and Xeomin® (Merz Pharma). Botox® doses varied between 30 and 100 units, whilst Dysport® doses ranged from 50 - 300 units/muscle. The number of injection sites/muscle also varied. This survey demonstrates the wide variation in practice amongst clinicians with respect to BTX administration. To ensure optimal dose and response titration, further studies and evidence-based research are needed to standardise its use for the treatment of TMDs.

Concentration-Dependent Inhibition of Hypertrophic Scar Formation by Botulinum Toxin Type A in a Rabbit Ear Model

BACKGROUND

Hypertrophic scar (HS), as a disappointing result of wound healing, adversely affects the patient, both physically and psychologically. Botulinum toxin type A (BTXA) has been revealed to prevent and improve HS. We conducted this study to assess the effect of different BTXA concentrations on inhibiting HS in a rabbit ear model.

METHODS

Eight healthy New Zealand long-eared rabbits were included in the experiment for modeling. Four wounds of 1 cm in diameter were created on both ears, which separately received an injection of a given BTXA concentration immediately after surgery. On postoperative days 40, scar tissue was obtained and subjected to hematoxylin and eosin (HE) staining for the hypertrophic index (HI) and immunohistochemical staining for CD31, Ki67, and transforming growth factor-beta 1 (TGF-β1) expression. The HI was assessed for scar proliferation, and CD31 and Ki67 expression were used to assess the effect of BTXA on angiogenesis and fibroblast proliferation, respectively.

RESULTS

All rabbits healed well without infection or mortality. From the HE staining, the HI showed a significant decrease with increasing BTXA concentration (p < 0.05). BTXA also inhibited angiogenesis and TGF-β1 expression in a concentration-dependent manner, with significant differences between the groups (p < 0.05). BTXA inhibited fibroblast proliferation with increasing BTXA concentration. However, there was no significant difference between the 0.5 U/0.1 ml and 0 U/0.1 ml groups (p > 0.05).

CONCLUSION

Immediate postoperative BTXA injection inhibited angiogenesis, fibroblast proliferation, and TGF-β1 expression in a concentration-dependent manner, thus suppressing HS formation in rabbit ears.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/journal/00266 .

Ultrasonographic observation of the masseter muscle after injection of different botulinum toxin type A

BACKGROUND

Botulinum toxin type A (BoNT-A) injection is a popular cosmetic procedure in East Asian countries, and there are multiple types of toxins on the market. Whether different toxin types induce different changes in the masseter has not been studied.

OBJECTIVE

We aimed to investigate and compare the changes induced by injection of different types of BoNT-A in the masseter.

METHODS

Upon retrospective review of clinical records and routine ultrasound examination results of patients who underwent BoNT-A injection, four groups were set for comparison: unapproved toxin, OnabotulinumtoxinA, LanbotulinumtoxinA, and non-injected. Clinical records and ultrasound images were collected. Ultrasound images were taken in both horizontal and coronal planes. Elasticity of the masseter muscle was also investigated by measuring the surface wave speed.

RESULTS

A total of 24 patients were included (six patients per group). All patients were young females. For the non-injected group, the deep inferior tendon was clear and the muscle bundles were arranged, with little fibrous content. Patients who received unapproved toxin injection showed highly disarranged muscle and fiber bundles, with much fiber content present. The changes in OnabotulinumtoxinA and LanbotulinumtoxinA groups were in between those in the non-injected and unapproved toxin groups. Muscle rigidity was the highest in the unapproved toxin group, and generally higher in injected groups compared with the non-injected group.

CONCLUSION

Different types of BoNT-A may induce different changes in the masseter.

Effect of Botulinum Toxin Injection on EMG Activity and Bite Force in Masticatory Muscle Disorder: A Randomized Clinical Trial

Botulinum toxin type A (BoNT-A) is increasingly used in treating masticatory muscle pain disorder; however, safe doses and reinjection intervals still need to be established. The purpose of this randomized clinical trial was to evaluate the degree and duration of the impairment of masticatory muscle performance. Fifty-seven subjects were randomly divided into two groups: one of which received BoNT-A first (n = 28) while the other received saline first (n = 29), with the cross-over being in week 16, and a total follow-up period of 32 weeks. A total dose of 50 U of BoNT-A was injected in the masseter and temporal muscles bilaterally. Electromyographic (EMG) activity and bite forces were assessed. A significant reduction in EMG activity was observed up to week 18 (p ≤ 001), with total recovery at week 33. A significant reduction in maximum bite force was observed up to week 11 (p ≤ 005), with total recovery at week 25. In conclusion, when treating masticatory muscle pain disorder with 50 U of BoNT-A, a reinjection interval of 33 weeks can be considered safe since the recovery of muscle function occurs by that time.

Can Botulinum Toxin-A Contribute to Reconstructing the Physiological Homeostasis of the Masticatory Complex in Short-Faced Patients during Occlusal Therapy? A Prospective Pilot Study

The physiological homeostasis of the masticatory complex in short-faced patients is too robust to be disintegrated and reconstructed due to the powerful masseter muscle. This study innovatively introduced the botulinum toxin-A (BTX-A) into the field of dental occlusal treatment, providing a novel and minimally invasive therapy perspective for the two major clinical problems in these patients (low treatment efficiency and high rates of complications). In total, 10 adult patients with skeletal low angle seeking occlusal treatment (age: 27.0 ± 6.1 years; 4 males and 6 females) were administered 30−50 U of BTX-A in each masseter muscle and evaluated before and 3 months after injection based on cone-beam computed tomography (CBCT). We found a significant reduction in the thickness of the masseter muscle (MMT) (p < 0.0001). With regards to occlusion, we found a significant increase in the height of the maxillary second molar (U7-PP) (p < 0.05) with significantly flattened occlusal curves (the curve of Spee [COS] (p < 0.01), and the curve of Wilson [COW] (p < 0.05)). Furthermore, the variations in the temporomandibular joint exhibited a significant reduction in the anterior joint space (AJS) (p < 0.05) and superior joint space (SJS) (p < 0.05). In addition, the correlation analysis of the masticatory complex provided the basis for the following multiple regression equation: MMT = 10.08 − 0.11 COW + 2.73 AJS. The findings from our pilot study indicate that BTX-A, as a new adjuvant treatment attempt of occlusal therapy for short-faced patients, can provide a more favorable muscular environment for subsequent occlusal therapy through the adjustment of the biting force and may contribute to the reconstruction of healthier homeostasis of the masticatory complex. However, further research is required to establish the reliability and validity of these findings.

Botulinum toxin A in dentistry and orofacial surgery: an evidence-based review - part 1: therapeutic applications

Objective An evidence-based review on the safety and efficacy of botulinum toxin type-A (BoNTA) in orofacial conditions, focusing on the therapeutic applications and role of BoNTA as an adjuvant treatment.Data source and selection Data was collected using PubMed (Medline), Cochrane Library of Systematic Reviews and Cochrane Central Register of Controlled Trials electronic databases. Having satisfied the search parameters, 32 studies for therapeutic applications and 26 for BoNTA as an adjunctive treatment were included. The quality of relevant studies was assessed using the Best Evidence Topics (BETs) Critical Appraisal Tool.Data extraction The highest level of evidence (LOE) behind BoNTA safety and efficacy was for wound healing and scar management in the orofacial surgery context, where BoNTA was presented as an adjunctive modality. Level-I evidence was controversial for temporomandibular disorders and bruxism. However, it showed promising results for painful temporomandibular disorders of myogenic origin refractory to conservative therapies, and to decrease muscle contraction intensity in sleeping bruxism. There was only one level-II study for persistent recurrent aphthous stomatitis. Data showed limited level-III evidence for orofacial pain conditions (temporomandibular joint recurrent dislocation and pain, burning mouth syndrome or atypical odontalgia), oral cancer complications, or as an adjuvant to maxillofacial and orthognathic surgeries. Benefits of BoNTA in prosthodontics had weak level-IV evidence. No evidence was found among the periodontology field.Conclusion There is growing evidence to support the safety and efficacy of BoNTA in the investigated orofacial pathological conditions, with high levels of satisfaction from the patient and clinician perspective. However, there are some inconsistencies and limited high-quality evidence available. Well-designed controlled clinical trials are necessary to evaluate long-term safety, efficacy and cost-effectiveness before BoNTA is widely adopted with irrefutable evidence-based clinical guidelines.

Management of temporomandibular disorders: a rapid review of systematic reviews and guidelines

Temporomandibular disorders (TMD) impact a significant proportion of the population. Given the range of management strategies, contemporary care should be evidence-informed for different TMD types. A knowledge-to-action rapid review of systematic reviews published in the past 5 years and guidelines published in the past 10 years concerning the management of TMD was conducted. The Cochrane, Embase, MEDLINE, PEDro, and PubMed databases were searched. A qualitative data analysis was undertaken, with quality assessment completed using the AMSTAR 2 checklist. In total, 62 systematic reviews and nine guidelines considering a range of treatment modalities were included. In concordance with current guidelines, moderate evidence supports a multi-modal conservative approach towards initial management. Contrary to existing guidelines, occlusal splint therapy is not recommended due to a lack of supporting evidence. The evidence surrounding oral and topical pharmacotherapeutics for chronic TMD is low, whilst the evidence supporting injected pharmacotherapeutics is low to moderate. In concordance with current guidelines, moderate quality evidence supports the use of arthrocentesis or arthroscopy for arthrogenous TMD insufficiently managed by conservative measures, and open joint surgery for severe arthrogenous disease. Based on this, a management pathway showing escalation of treatment from conservative to invasive is proposed.

Potential adjunct therapies for the management of temporomandibular disorders: An evidence-based review

OBJECTIVE

The aim was to review the role of adjuvant therapies that may potentially contribute toward the management of temporomandibular disorders (TMD).

METHODS

The addressed focused question was, "Are there any adjuvant therapies that may contribute toward the management of TMD?". Indexed databases were searched up to June 2021. The eligibility criteria were the following: (a) original clinical studies and (b) randomized controlled clinical trials (RCTs).

RESULTS

Adjuvant therapies were comprised of acupuncture, manual therapy, jaw exercises, dietary modifications, botulinum toxin therapy, and photobiomodulation. Short-term follow-up results from each of these RCTs showed beneficial effects in terms of pain reduction and improvements in jaw movement among patients with TMD. There are no long-term follow-up results in this regard.

CONCLUSION

The most effective adjunct treatment for managing TMD remains unknown, primarily due to a lack of sufficient scientific evidence.

The Use of Botulinum Toxin A in the Management of Trigeminal Neuralgia: a Systematic Literature Review

OBJECTIVES

The purpose of this article is to systematically review the use, efficacy, differences between botulinum toxin type A doses and side effects of botulinum toxin type A therapy in patients with trigeminal neuralgia.

MATERIAL AND METHODS

The search for the performed reviews was done in PubMed and Cochrane library in English language from January 2010 up to February 2020. Inclusion criteria: full-text studies in English language, in which visual assessment scale (VAS) was present, in which patients with trigeminal neuralgia (TN) were participated and the comparison between botulinum toxin type A (BT-A) and saline was done.

RESULTS

The review included 4 randomized, double-blind, placebo-controlled trials with 8 to 12 weeks follow-up to observe changes in VAS and in frequency of TN attacks, differences between dosages of BT-A in therapy and side effects. Mean VAS of BT-A group decreased by approximately 68% and of palcebo group decreased by approximately 21.6% after the therapy. Mean frequency of TN attacks in 3 studies of BT-A group decreased by 85%, while in palcebo by only 15.9%.

CONCLUSIONS

Botulinum toxin type A injection therapy is a safe and effective method in management of trigeminal neuralgia. No differences between dosages of botulinum toxin type A were found. Maximum efficacy was noticed between 6 weeks and 3 months after the procedure. Side effects were mostly facial asymmetry after injection, headaches, haematoma, which disappeared in one week.