Effects of botulinum toxin on jaw motor events during sleep in sleep bruxism patients: a polysomnographic evaluation

Comparison between botulinum toxin type A injection on masseter muscle only and additional injection on anterior belly of digastric muscle in sleep bruxism patients: A clinical trial

OBJECTIVE

This study aims to evaluate the effects on bite force and muscle thickness of the botulinum toxin (BoNT) injection for patients with sleep bruxism (SB) by comparing injections into the masseter muscle only and both the masseter and the anterior belly of the digastric muscle (ABDM) in a clinical trial.

METHODS

Twelve SB patients received BoNT-A injections using US-guided techniques into the masseter muscle only (Group A), while the remaining 12 SB patients received injections into both the masseter and ABDM (Group B). Bite force and muscle thickness were measured before injection, as well as 1 and 2 months after injection.

RESULTS

The bite force and masseter muscle thickness decreased in both Group A and Group B before injection, and at 1 and 2 months after injection. However, there was no significant difference (p > .05, repeated measures analysis of variance) between the two groups, and there was also no significant difference in ABDM thickness (p > .05, repeated measures analysis of variance).

CONCLUSION

This study is the first to assess the short-term effects of BoNT injected into ABDM for SB control. Results show no influence on SB reduction, suggesting the need for further research on BoNT's effectiveness in controlling intense ABDM contractions during sleep and assessing suprahyoid muscle potential impact on rhythmic masticatory muscle activity occurrence.

Use of botulinum neurotoxin Type A in the management of primary bruxism in adults: An updated systematic review

STATEMENT OF PROBLEM

The psycho-emotional effects caused by the coronavirus pandemic have increased the intensity and number of cases of bruxism, for which no treatment has been considered fully effective. Botulinum neurotoxin Type A (BoNT-A) has shown positive results as an adjunct treatment of primary bruxism; however, this off-label use does not have an established protocol, and further studies are required.

PURPOSE

The purpose of this updated systematic review was to analyze the clinical outcomes of BoNT-A in the management of primary bruxism in adults.

MATERIAL AND METHODS

The review was registered under the International Prospective Register of Systematic Reviews (PROSPERO) registration number CRD42021287653, without funding. PubMed, Web of Science, Scopus, LILACS, Cochrane Library, and Open Grey Literature databases were searched by using the Mendeley Desktop software program without language restrictions up to June 6, 2021. The risk of bias of the selected randomized clinical trials was assessed by using RoB2, and the level of evidence was measured by 2 independent researchers using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) tool.

RESULTS

A total of 741 references were obtained from the 6 databases in this systematic review. The 11 randomized clinical trials selected achieved a reduction in bruxism symptoms by injecting BoNT-A into 211 participants with different protocols. The heterogeneity of the included studies did not permit a meta-analysis.

CONCLUSIONS

All the evaluated studies supported the effectiveness of BoNT-A injections in reducing bruxism symptoms. The reduction of symptoms can be obtained with doses lower than 25U applied exclusively in the masseter muscles.

Prevalence and predictors of sleep bruxism in patients with obstructive sleep apnea and the effect of positive airway pressure treatment

BACKGROUND

Sleep bruxism (SB) is often found to co-exist with obstructive sleep apnea (OSA). However, there are no data on prevalence and risk factors of SB in patients with OSA patients regarding the effect of optimal positive airway pressure (PAP).

OBJECTIVE

This study aimed to study prevalence and risk factors of SB in OSA and to compare SB episodes during pre-treatment versus during optimal PAP therapy.

METHODS

This investigation was a retrospective study including randomly selected patients with OSA who underwent split-night polysomnography. Data were collected from August 2021 to October 2022. Clinical demographic data and SB data were analyzed. The association between SB episodes and obstructive respiratory events were manually reviewed. If most of the SB episodes were observed within 5 s following obstructive respiratory events, SB was defined as SB associated with OSA. Comparison of SB index (SBI) was made between baseline portion of the study versus during optimal PAP.

RESULTS

Among 100 patients enrolled, mean age was 50.8 ± 16.7 years and 73 subject (73%) were male. Mean respiratory disturbance index (RDI) and mean nadir oxygen saturation were 52.4 ± 33.4 and 79.3 ± 11.2% respectively. During the baseline portion of the study, 49 patients (49%) had SB and 31 patients (31%) had severe SB (SBI ≥ 4). Sleep bruxism associated with OSA was observed in 73.5% of all SB. The risk factor for SB was endorsement of nocturnal tooth grinding (odds ratio (OR) 5.69, 95%CI 1.74-18.58). Risk factors for severe bruxism were male sex (OR 4.01, 95%CI 1.02-15.88) and endorsement of nocturnal tooth grinding (OR 9.63, 95%CI 2.54-36.42). Risk factors for SB associated with OSA were non-supine RDI (OR 1.02, 95%CI 1.001-1.034) and endorsement of nocturnal tooth grinding (OR 5.4, 95%CI 1.22-23.93). In SB group, when comparison was made between baseline portion and during optimal PAP, significant reduction of SBI was observed (5.5 (3.2, 9.3) vs. 0 (0, 2.1), p < 0.001). Median difference of SBI between baseline portion and during optimal PAP was 4.4 (2.0, 8.3) (p < 0.001).

CONCLUSIONS

In this group of patients with OSA, almost half was observed to have SB in which the majority were associated with OSA. Optimal PAP resulted in a significant reduction in SB episodes. In addition to endorsement of nocturnal tooth grinding, non-supine RDI was observed to be a potential risk factor for SB associated with OSA.

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.

Comparison of the efficacy of occlusal splint and botulinum toxin therapies in patients with temporomandibular disorders with sleep bruxism

PURPOSE

This study aims to evaluate the efficacy of occlusal splint and botulinum toxin (BTX) therapies for improving the pain scores and mouth opening in patients with temporomandibular disorders (TMD) with sleep bruxism (SB).

MATERIALS AND METHODS

A retrospective cohort study was conducted based on clinical record reviews of patients with TMD symptoms (e.g., temporomandibular joint [TMJ] pain, masticatory muscle pain, TMJ internal derangements, joint sounds, and limited mouth opening) and SB. The patients were divided into two groups: occlusal splint group and BTX group. Maximum unassisted mouth opening (MMO) and pain score on a visual analogue scale (VAS) before treatment and at 1‑, 3‑, and 6‑month follow-up were analyzed to evaluate the clinical outcomes.

RESULTS

A total of 60 patients (49 women and 11 men, mean age 34.63 ± 11.85 years) were enrolled. Each group had 30 patients. The comparisons of the groups at 1 and 3 months after treatment indicated that the BTX group had higher MMO values (P = 0.013 and 0.034, respectively) and lower VAS scores than the occlusal splint group (P = 0.000 and 0.001, respectively). No difference between the two groups was observed 6 months after treatment (P > 0.05).

CONCLUSIONS

Both occlusal splint and BTX treatment methods were successful in treating TMD with SB. BTX provided patients with rapid relief in the early period; therefore, BTX can be recommended as a primary treatment option in patients with greater pain.

Can botulinum toxin injection alleviate the pain of bruxism? A Bayesian network analysis and a single-arm analysis

Background/purpose

There is inconsistent evidence regarding whether the botulinum toxin A (BTA) injection can relieve pain caused by bruxism. This study aimed to estimate the efficiency of BTA injection in relieving pain caused by bruxism at different follow-up periods.

Materials and methods

Five electronic databases were searched from 2005 to 2022 using search terms related to botulinum toxin and bruxism. Only controlled clinical trials were included. Two investigators reviewed each article and discussed any disagreements until a consensus was reached. Pain outcomes as evaluated by the visual analogue scale (VAS) were subjected to single-arm and Bayesian network meta-analyses. Pooling data were measured by a random-effects model.

Results

Eleven studies with a total of 365 bruxism patients were included. According to the single-arm analyses of the pooled data, the reduction in bruxism-related pain after BTA injection measured 4.06 points (95% CI = 3.37 to 4.75) on the VAS, and the pain relief was significant in the first 6 months after treatment (P < 0.01). According to the Bayesian analysis, BTA also resulted in significantly greater pain relief than oral splinting (mean difference (MD), -1.5; 95% credible interval (CrI) = -2.7 to -0.19) or saline injection (MD, -3.3; 95% CrI = -6.2 to -0.32).

Conclusion

BTA significantly relieves the pain of bruxism for 6 months after injection, and its therapeutic efficacy was higher than that of oral splinting. Nevertheless, further long-term follow-up randomized controlled trials comparing BTA with other management or drugs are warranted.

Facial and mandibular landmark tracking with habitual head posture estimation using linear and fiducial markers

This study compared the accuracy of facial landmark measurements using deep learning-based fiducial marker (FM) and arbitrary width reference (AWR) approaches. It quantitatively analysed mandibular hard and soft tissue lateral excursions and head tilting from consumer camera footage of 37 participants. A custom deep learning system recognised facial landmarks for measuring head tilt and mandibular lateral excursions. Circular fiducial markers (FM) and inter-zygion measurements (AWR) were validated against physical measurements using electrognathography and electronic rulers. Results showed notable differences in lower and mid-face estimations for both FM and AWR compared to physical measurements. The study also demonstrated the comparability of both approaches in assessing lateral movement, though fiducial markers exhibited variability in mid-face and lower face parameter assessments. Regardless of the technique applied, hard tissue movement was typically seen to be 30% less than soft tissue among the participants. Additionally, a significant number of participants consistently displayed a 5 to 10° head tilt.

Sleep architecture as a candidate for phenotyping sleep bruxism: A narrative physiological review

BACKGROUND

Sleep bruxism (SB), an oral behaviour in otherwise healthy individuals, is characterised by frequent rhythmic masticatory muscle activity (RMMA) during sleep. RMMA/SB episodes occur over various sleep stages (N1-N3 and rapid eye movement (REM)), sleep cycles (non-REM to REM), and frequently with microarousals. It currently remains unclear whether these characteristics of sleep architecture are phenotype candidates for the genesis of RMMA/SB.

OBJECTIVES

This narrative review investigated the relationship between sleep architecture and the occurrence of RMMA as a SB phenotype candidate.

METHODS

PubMed research was performed using keywords related to RMMA/SB and sleep architecture.

RESULTS

In non-SB and SB healthy individuals, RMMA episodes were most frequent in the light non-REM sleep stages N1 and N2, particularly during the ascending phase of sleep cycles. The onset of RMMA/SB episodes in healthy individuals was preceded by a physiological arousal sequence of autonomic cardiovascular to cortical activation. It was not possible to extract a consistent sleep architecture pattern in the presence of sleep comorbidities. The lack of standardisation and variability between subject complexified the search for specific sleep architecture phenotype(s).

CONCLUSION

In otherwise healthy individuals, the genesis of RMMA/SB episodes is largely affected by oscillations in the sleep stage and cycle as well as the occurrence of microarousal. Furthermore, a specific sleep architecture pattern cannot be confirmed in the presence of sleep comorbidity. Further studies are needed to delineate sleep architecture phenotype candidate(s) that contribute to the more accurate diagnosis of SB and treatment approaches using standardised and innovative methodologies.

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.

Assessing change in functional outcomes and quality of life in myogenic temporomandibular disorders undergoing botulinum toxin injection: A before and after comparison

PURPOSE

This prospective study aimed to evaluate the changes in functional outcomes and quality of life after the injection of botulinum toxin (BTX) into the masticatory muscles for the management of myogenic temporomandibular disorders (TMDs).

MATERIALS AND METHODS

This study was conducted with 45 individuals who presented with clinically myogenic TMDs according to the Diagnostic Criteria for Temporomandibular Disorders. All patients received BTX injections in the temporalis and masseter muscles. The Oral Health Impact Profile-Temporomandibular Dysfunction (OHIP-TMD) questionnaire was used to evaluate the effects of treatment on quality of life. The OHIP-TMD, visual analogue scale (VAS), and maximum mouth opening (MMO) scores before and 3 months after BTX injection were evaluated.

RESULTS

The preoperative and postoperative assessments revealed a statistically significant reduction (p ≤ 0.001) in the average overall OHIP-TMD scores. A significant increase in the MMO scores and a significant decrease in the VAS scores were observed (p < 0.001).

CONCLUSIONS

The injection of BTX into the masticatory muscles is beneficial for improving the clinical and quality of life parameters in the management of myogenic TMD.

Effectiveness of Botulinum Toxin Injection on Bruxism: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The present study compiled evidence on the efficacy of botulinum toxin A (BTX) for management of bruxism.

METHODS

A literature review that included randomized control, cohort, as well as observational studies published between January 2000 and November 2022 was conducted. All studies related to BTX injections administered into the masseters of patients with bruxism were included. Primary outcomes were measured by performing a meta-analysis of changes in maximal biting forces and pain severity and meta-regression of the effects of the BTX dose.

RESULTS

Ten studies were included for quantitative analysis. The analysis of the maximal biting force after BTX injections demonstrated a significant reduction at 1 month or less compared with both oral splints (P < 0.000001) and saline injections (P = 0.01). BTX continued to outperform oral splinting (P = 0.001) and saline placebos (P = 0.03) at 3 months. Between 3 and 6 months, a significantly higher maximal biting strength was observed in the BTX group than the oral splinting group (P < 0.00001). No significant differences in the maximal biting force were observed between the BTX and saline placebo groups (P = 0.50). A similar trend was observed in the analysis of pain reduction after botulinum treatment. Additionally, for every unit increase in the BTX dose, pain severity decreased by 0.0831 points (P = 0.0011).

CONCLUSION

BTX is effective in reducing biting strength and pain severity. BTX effects are evident at less than 4 weeks, peak between 5 and 8 weeks, and last for up to 24 weeks. Higher BTX doses result in greater improvement in pain. Although BTX benefits manifest earlier, they gradually diminish, and oral splinting exerts a more enduring effect, especially after 9-12 weeks. BTX injections into masseters are recommended as management options for bruxers, especially for those having difficulties complying with wearing oral splints or those seeking earlier symptom relief. However, future studies should determine BTX effects beyond 24 weeks and after repetitive injections and how bruxers of different ages or genders respond to treatment.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effect of botulinum toxin A on pain, bite force, and satisfaction of patients with bruxism: A randomized single-blind clinical trial comparing two protocols

Purpose

The current study aims to evaluate bite force, perception of orofacial pain, and treatment satisfaction of patients with bruxism using two protocols of botulinum toxin A (BTX-A) injections.

Material and Methods

Two groups of patients seeking bruxism treatment and presenting bilateral orofacial pain of muscle origin were randomly created according to BTX-A injection sites: masseter muscle only, bilaterally (3 points in each muscle, 10 U per point), and masseter and temporal muscles (3 points in each masseter muscle and 2 points in each temporal muscle, 10 U per point). The patients were evaluated preoperatively and longitudinally at 15, 90, 120, and 180 days by the use of visual analog scales for pain and treatment satisfaction and a gnathodynamometer for bite force recording.

Results

The final sample included 10 participants in each group. Both groups presented mitigation of pain at 15, 90, 120, and 180 days in comparison with baseline; however, reduction in the posterior bite force was noted only at 15, 90, and 120 days. Quite high treatment satisfaction was reported from both groups at 15, 90, 120, and 180 days. No differences were observed between the groups in all evaluations and study periods.

Conclusion

In general, considering pain relief, reduction in bite force, and treatment satisfaction, both protocols of BTX-A seem to be somewhat equally effective in the short-term management (up to 120 days) of bruxism.

Managements of sleep bruxism in adult: A systematic review

This systematic review aimed to update the management of sleep bruxism (SB) in adults, as diagnosed using polysomnography (PSG) and/or electromyography (EMG). Management methods covered were oral appliance therapy (OAT) with stabilization splints, cognitive-behavioral therapy (CBT), biofeedback therapy (BFT), and pharmacological therapy. A comprehensive search was conducted on MEDLINE, Cochrane Library, and Web of Science up to October 1st, 2021. Reference list searches and hand searches were also performed by an external organization. Two reviewers for each therapy independently performed article selection, data extraction, and risk of bias assessment. The reviewers resolved any disagreements concerning the assortment of the articles by discussion. Finally, 11, 3, 14, and 22 articles were selected for each therapy. The results suggested that OAT tended to reduce the number of SB events, although there was no significant difference compared to other types of splints, that the potential benefits of CBT were not well supported, and that BFT, rabeprazole, clonazepam, clonidine, and botulinum toxin type A injection showed significant reductions in specific SB parameters, although several side effects were reported. It can be concluded that more methodologically rigorous randomized large-sample long-term follow-up clinical trials are needed to clarify the efficacy and safety of management for SB.

Efficacy of botulinum toxin type a in the targeted treatment of sleep bruxism: a double-blind, randomised, placebo-controlled, cross-over study

Background

Intramuscular injections of botulinum toxin A (BTX-A) have been used in the treatment of sleep bruxism (SB) however controlled trials are limited and the optimal injection strategy and dose is not known.

Methods

This double-blind, randomised, placebo-controlled, cross-over study evaluated the efficacy and safety of BTX-A in participants with SB. Average bruxism events per hour of sleep (Bruxism Index, BI) was calculated using surface electromyography. Participants with BI >5 were included and randomised by order of injection (active or placebo with the opposite 20 weeks later) and into one of three differing treatment groups: bilateral masseter (60 units(U)), bilateral masseter and temporalis (90U) and bilateral masseter, temporalis and medial pterygoid muscles (120U). Change in BI and subjective measures of headache, pain, and bruxism at 4 and 12 weeks was calculated following intervention, and differences between treatment groups analysed.

Results

41 participants were recruited, 35 randomised and data from 22 participants (14 female) were analysed. BI was significantly lower at 4 weeks after active treatment when compared with placebo (mean=−1.66, p=0.003), not sustained at 12 weeks. The difference was greater with higher doses injected and among those with greater baseline BI. There was no difference in subjective measures at any time point. Five participants injected had mild, transient side effects.

Discussion

Targeted BTX-A injection is a safe and effective treatment for SB. A greater benefit may be achieved by administering BTX-A into more muscles and at higher total doses and among those with higher baseline BI.

Trial registration number

ACTRN12618001430224.

The dental demolition derby: bruxism and its impact - part 2: early management of bruxism

Bruxism is a term that encompasses a range of presentations of rhythmic and repetitive muscular activity. For many, this is not a significant problem but for some, the behaviour leads to significant problems and extensive tissue damage. This is different to temporomandibular disorders. This paper will review methods of managing cases where bruxism is destructive, or potentially destructive, before needing to resort to full reconstruction.

Bruxism is challenging to control. The aim for early management is to limit tissue damage at an early stage rather than await extensive destruction that is then difficult to manage.

There is also a significant financial burden to delaying intervention.

Interventions at this stage range from pharmacological to splint therapy. Guidance on splint choice and design is provided.

Botulinum Toxin Therapy for Oromandibular Dystonia and Other Movement Disorders in the Stomatognathic System

Various movement disorders, such as oromandibular dystonia, oral dyskinesia, bruxism, functional (psychogenic) movement disorder, and tremors, exist in the stomatognathic system. Most patients experiencing involuntary movements due to these disorders visit dentists or oral surgeons, who may be the first healthcare providers. However, differential diagnoses require neurological and dental knowledge. This study aimed to review scientific advances in botulinum toxin therapy for these conditions. The results indicated that botulinum toxin injection is effective and safe, with few side effects in most cases when properly administered by an experienced clinician. The diagnosis and treatment of movement disorders in the stomatognathic system require both neurological and dental or oral surgical knowledge and skills, and well-designed multicenter trials with a multidisciplinary team approach must be necessary to ensure accurate diagnosis and proper treatment.

Efficacy of botulinum-A for nocturnal bruxism pain and the occurrence of bruxism events: a meta-analysis and systematic review

The purpose of this study was to explore the treatment efficacy of botulinum-A (BTX-A) in nocturnal bruxism. Five electronic databases (PubMed, Web of Science, Cochrane, Embase and Clinical Trials) were searched to identify related randomised controlled trials up to September 1, 2020. Five evaluation indices were extracted, namely, the pain at rest and at chewing (PR and PC), the number of bruxism events (NBE) and the self-assessment by patients (SA), to assess the treatment efficacy of BTX-A in bruxism. All data analyses were conducted using Review Manager (Version 5.3; The Cochrane Collaboration, London, United Kingdom). Six studies were included in this review. The sample was composed of 148 participants. Compared with the placebo group, the BTX-A group showed the significantly improved the PR index scores (MD, 1.16 cm; 95%CI, 0.65 to 1.67 cm; p < 0.00001), slightly improved the PC index scores (SMD, 0.25; 95%CI -0.14 to 0.64; p = 0.21), and the NBEs were significantly decreased in the before-injection group compared with that in the after-injection group (MD, 1.72; 95%CI, 0.60 to 2.85; p = 0.003). The results of this study suggest that BTX-A possesses significant therapeutic efficiency for the relief of pain and events of bruxism. However, whether the events of bruxism would recur or rebound after botulinum toxin injection needs more follow-up clinical evidence.

Botulinum Toxin for Treating Temporomandibular Disorders: What is the Evidence?

AIMS

To systematically review the scientific literature for evidence concerning the clinical use of botulinum toxin (BTX) for the management of various temporomandibular disorders (TMDs).

METHODS

A comprehensive literature search was conducted in the Medline, Web of Science, and Cochrane Library databases to find randomized clinical trials (RCT) published between 2000 and the end of April 2021 investigating the use of BTX to treat TMDs. The selected articles were reviewed and tabulated according to the PICO (patients/problem/population, intervention, comparison, outcome) format.

RESULTS

A total of 24 RCTs were selected. Nine articles used BTX injections to treat myofascial pain, 4 to treat temporomandibular joint (TMJ) articular TMDs, 8 for the management of bruxism, and 3 to treat masseter hypertrophy. A total of 411 patients were treated by injection of BTX. Wide variability was found in the methods of injection and in the doses injected. Many trials concluded superiority of BTX injections over placebo for reducing TMD pain levels and improving maximum mouth opening; however, this was not universal.

CONCLUSION

There is good scientific evidence to support the use of BTX injections for treatment of masseter hypertrophy and equivocal evidence for myogenous TMDs, but very little for TMJ articular disorders. Studies with improved methodologic design are needed to gain better insight into the utility and effectiveness of BTX injections for treating both myogenous and TMJ articular TMDs and to establish suitable protocols for treating different TMDs.

Biphasic Injection for Masseter Muscle Reduction with Botulinum Toxin

Masseter Muscle Hypertrophy (MMH) is a well-known clinical benign condition that is not gender-specific and it can be monolateral or bilateral. Botulinum Toxin type A (BoNTA) injection has been widely described for MMH treatment and non-surgical facial slimming. BoNTA masseter injections have high efficacy and safety profile, but the risks of side effects remain. Muscular bulging during mastication is a complication due to the superficial overcompensation of masseteric fibers in response to neurotoxic weakening of the deep masseter. We present a biphasic-injection technique for BoNTA administration, based following anatomical concept and developed in order to prevent paradoxical bulging. A total of 98 treatments from 2015 to 2020 were performed with this technique. No remarkable complications occurred in our study. No cases of loss of full smile, difficulty in mouth opening, dizziness, headache, neurapraxia, and xerostomia were reported. A case of asymmetric smiling was self-resolved within a week. No patient claimed transient muscle weakness as distressing. No cases of paradoxical bulging were observed. Extensive knowledge of muscular anatomy and appropriate injection technique are key factors in achieving the desired result and avoiding complications. We feel that sharing this tip could be helpful for all the physicians involved in MMH treatment with BoNTA.

Botulinum Toxin in Movement Disorders: An Update

Since its initial approval in 1989 by the US Food and Drug Administration for the treatment of blepharospasm and other facial spasms, botulinum toxin (BoNT) has evolved into a therapeutic modality for a variety of neurological and non-neurological disorders. With respect to neurologic movement disorders, BoNT has been reported to be effective for the treatment of dystonia, bruxism, tremors, tics, myoclonus, restless legs syndrome, tardive dyskinesia, and a variety of symptoms associated with Parkinson's disease. More recently, research with BoNT has expanded beyond its use as a powerful muscle relaxant and a peripherally active drug to its potential central nervous system applications in the treatment of neurodegenerative disorders. Although BoNT is the most potent biologic toxin, when it is administered by knowledgeable and experienced clinicians, it is one of the safest therapeutic agents in clinical use. The primary aim of this article is to provide an update on recent advances in BoNT research with a focus on novel applications in the treatment of movement disorders. This comprehensive review of the literature provides a critical review of evidence-based clinical trials and highlights recent innovative pilot studies.

Clinical outcomes of botulinum toxin type A injections in the management of primary bruxism in adults: A systematic review

STATEMENT OF PROBLEM

Botulinum toxin has been used for various therapeutic and esthetic purposes for nearly 4 decades and has shown positive outcomes in patients with bruxism. However, the effectiveness of botulinum toxin injections as an alternative to traditional therapies in the management of primary bruxism is still unclear.

PURPOSE

The purpose of this systematic review was to analyze the clinical outcomes of the use of botulinum toxin type A injections in the management of primary bruxism in adults.

MATERIAL AND METHODS

Databases such as PubMed, Web of Science, Scopus, LILIACS, Cochrane Library, and Open Grey Literature were searched without language or date restrictions until October 6, 2019. Using Mendeley Desktop software to organize the references, 2 independent researchers selected the published clinical studies (Study type) on the improvement of symptoms (Outcome) in human adults with primary bruxism (Participants/Population) who received botulinum toxin type A injections (Intervention), placebo injections, saline injections, no injections, or other treatments (Comparator(s)/Control) for the management of bruxism.

RESULTS

A total of 601 references were initially obtained from the 6 databases. Six randomized clinical trials and 4 case series were selected and critically appraised according to the Fowkes and Fulton guidelines. Heterogeneity among the studies did not allow for a meta-analysis. All studies supported the efficacy and safety of botulinum toxin injections in reducing the symptoms of primary bruxism.

CONCLUSIONS

Botulinum toxin type A injections are effective in the treatment of the symptoms of primary bruxism in adults. Randomized clinical trials are still needed to establish a protocol for using botulinum toxin as an alternative to traditional therapies in the management of primary bruxism.

Botulinum Toxin Therapy for Managing Sleep Bruxism: A Randomized and Placebo-Controlled Trial

The purpose of this study is to evaluate the effects of botulinum toxin type A (BoNT-A) for managing sleep bruxism (SB) in a randomized, placebo-controlled trial. Thirty SB subjects were randomly assigned into two groups evenly. The placebo group received saline injections into each masseter muscle, and the treatment group received BoNT-A injections into each masseter muscle. Audio-video-polysomnographic recordings in the sleep laboratory were made before, at four weeks after, and at 12 weeks after injection. Sleep and SB parameters were scored according to the diagnostic and coding manual of American Academy of Sleep Medicine. The change of sleep and SB parameters were investigated using repeated measures analysis of variance (RM-ANOVA). Twenty-three subjects completed the study (placebo group 10, treatment group 13). None of the SB episode variables showed a significant time and group interaction (p > 0.05) except for electromyography (EMG) variables. The peak amplitude of EMG bursts during SB showed a significant time and group interaction (p = 0.001). The injection decreased the peak amplitude of EMG bursts during SB only in the treatment group for 12 weeks (p < 0.0001). A single BoNT-A injection cannot reduce the genesis of SB. However, it can be an effective management option for SB by reducing the intensity of the masseter muscle.

The effect of botulinum toxin injections on bruxism: A systematic review

OBJECTIVE

To systematize evidence on the efficacy of botulinum toxin type A (BTA) in the treatment of bruxism measured through bite force or electromyography (EMG) at the masseter muscle.

METHOD

Identification of relevant articles through databases PubMed, Web of Science, SCOPUS, Ovid and EBSCO and manual search were performed for sources from review articles. Studies scoring less than 3 on the Jadad Scale were excluded.

RESULTS

Four articles were included after an exclusion of 333 articles. 3 articles measured EMG and 1 bite force. 1 article did not record a significant drop of activity, 1 article recorded reduction midway and at final endpoint. 2 articles recorded initial reduction, but a non significant difference at later follow up.

CONCLUSION

The available research is inconclusive and does not show enough evidence that bruxism can be treated with BTA injections. However, promising results have been shown in individual studies and further research in this area is needed.

Botulinum Toxin Type A in Dental Medicine

Botulinum toxins (BoNTs) are a product of the bacteria Clostridium botulinum. By entering nerve endings, they cleave and inactivate SNARE proteins, which are essential for neurotransmitter release. Prevention of acetylcholine release at the neuromuscular junction causes long-lasting and potentially fatal flaccid paralysis-a major feature of botulism. However, an intramuscular injection of minute amounts of BoNTs, primarily type A (BoNT-A), has useful long-lasting muscle relaxation effects on spastic motor disorders. This characteristic of BoNT-A is widely used in neurology and cosmetics. Over the last few decades, it has been demonstrated that the functions of BoNT-A are not limited to muscle-relaxing or autonomic cholinergic effects but that it can act as an analgesic agent as well. More recently, it was revealed that this antinociceptive effect starts after entering the sensory nerve endings, where these agents are axonally transported to the central nervous system, suggesting that at least part of their analgesic effect might be of central origin. Because of its antinociceptive effect, BoNT-A is currently approved for treatment of chronic migraine; nonetheless, case reports and preclinical and clinical experiments indicating its benefit in numerous potential painful conditions have increased. In the field of dentistry, the US Food and Drug Administration approved BoNT-A for the treatment of sialorrhea only. Legal status of the use of BoNT-A in other countries is less known. However, there are controlled clinical trials suggesting its efficacy in other conditions, such as bruxism, temporomandibular disorders, and trigeminal neuropathic pain. Thereby, using criteria of the American Academy of Neurology, we critically reviewed the uses of BoNTs in oral medicine and found it effective for trigeminal neuralgia (category A) and probably effective in temporomandibular disorders and bruxism.

A systematic review of botulinum toxin in the management of patients with temporomandibular disorders and bruxism

Introduction The medical and cosmetic use of botulinum toxin (BTX) is now widespread. With an increased number of clinicians adopting the use of BTX in the management of temporomandibular disorders (TMD) and/or bruxism, as either a standalone treatment or as an adjunct, affirmation is required in regards to whether it has a clinically justifiable position among the current spectrum of available treatment modalities.Objectives To establish the usefulness of BTX when treating patients with TMD and/or bruxism, and thereby determine whether there may be an appropriate purpose for the prescription of BTX in the management of these patients.Data sources and data selection A systematic review of the relevant literature was conducted. The literature search was carried out by applying key terms to appropriate data sources (Medline, Embase, Pubmed, Cochrane Central Register of Controlled Trials, and OpenSIGLE). The resultant papers were subjected to inclusion and exclusion criteria, which were then assessed for bias using a framework outlined in the Cochrane Handbook.Results A total of 11 trials met the inclusion criteria. The primary outcome measure was changes in pain experience in groups that had been treated with BTX, relative to an appropriate control group. Secondary outcomes included changes in the frequency of bruxism events, changes in maximum mouth opening, changes in occlusal force and changes in electromyography (EMG) readings of muscles of mastication.Conclusion The evidence to support the use of BTX in the management of TMD and/or bruxism is not entirely unequivocal. A number of studies that have met the inclusion criteria have shown promising results and thereby justify further investigation. Given the current evidence, BTX should certainly be considered but due to financial implications and possible side effects, it seems appropriate that conservative options, such as self-management with explanation and physical therapies, should be exhausted first.

Masticatory muscle stretching for the management of sleep bruxism: A randomised controlled trial

BACKGROUND

Sleep bruxism is a phenomenon associated with masticatory muscle hyperactivity. While stretching of limb and trunk muscles has been extensively studied for musculoskeletal disorders, little is known about the effectiveness of stretching of masticatory muscles in the management of bruxism.

OBJECTIVE

The aim of this study is to determine the effectiveness of stretching of the masticatory muscles for sleep bruxism.

METHODS

Twenty four pain-free individuals with sleep bruxism were randomly assigned to either an intervention group or a control group. Both groups were given sleep hygiene advice and the intervention group additionally received muscle-stretching exercises for 10 days. Primary outcome measures, bruxism bursts and episodes per hour of sleep, were measured by ambulant polysomnography. Secondary outcome measures were among others pain-free active maximum mouth opening (MMO) and masseter pressure pain threshold (PPT).

RESULTS

The number of bruxism episodes per hour of sleep increased more in the intervention group than in the control group (by 1.1 episodes, P = 0.066), as did the number of bruxism bursts per hour of sleep (by 8.6 bursts, P = 0.049). MMO and PPT increased significantly more in the intervention group (by 3.2 mm, P = 0.020; and by 1.0 kg/cm² , P = 0.036, respectively).

CONCLUSION

Static stretching of the masticatory muscles resulted in a minor increase in sleep bruxism episodes (not significant) and bursts (significant). It also led to a significant increase in MMO and PPT. Therefore, masticatory muscle stretching was not effective in reducing sleep bruxism in the absence of pain and/or dysfunction.

Microstructural investigation of masticatory muscles: a pre- and post-treatment diffusion tensor imaging study in a bruxism case

We evaluated, by means of a non-invasive procedure based on MRI, the masticatory muscular microstructure in a 55-year-old-female patient affected by bruxism. The patient underwent MR examination before and after 1 month of splint therapy, when she mentioned the complete disappearance of all symptoms. By means of diffusion tensor imaging we observed changes at microstructural level of masticatory muscular complex. We conclude that diffusion tensor imaging may be a useful instrument both to perform panoramic reconstruction of the masticatory muscle complex and to investigate microstructural modifications related to the pain relief in bruxism.

Onabotulinum toxin-A injections for sleep bruxism: A double-blind, placebo-controlled study

OBJECTIVES

To test the safety and efficacy of onabotulinum toxin-A (BoNT-A) injections into the masseter and temporalis muscles in patients with symptomatic sleep bruxism.

METHODS

Participants 18 to 85 years old with clinically diagnosed sleep bruxism confirmed by polysomnography were enrolled in this randomized, placebo-controlled, 1:1, parallel-design trial with open-label extension. Participants were injected with BoNT-A 200 units (60 into each masseter and 40 into each temporalis) or placebo and were evaluated at 4 to 8 weeks after the initial treatment visit. The primary efficacy endpoint was clinical global impression (CGI), and the secondary efficacy endpoint was a visual analog scale (VAS) of change in bruxism and in pain at 4 to 8 weeks after injection. Exploratory endpoints included modified Montreal Bruxism Questionnaire, Headache Impact Test-6, total Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Self-Rated Anxiety Scale, and polysomnography data, including EMG recordings of the masseter and temporalis muscle bruxing events. Adverse events were recorded.

RESULTS

Thirty-one participants were recruited and 23 were randomized (19 female, age 47.4 ± 16.9 years). All 13 randomized to BoNT-A and 9 of 10 randomized to placebo completed the study. CGI (p < 0.05) and VAS of change (p < 0.05) favored the BoNT-A group. None of the exploratory endpoints changed significantly, but total sleep time and number/duration of bruxing episodes favored the BoNT-A group. Two participants randomized to BoNT-A reported a cosmetic change in their smile. No dysphagia or masticatory adverse events were reported.

CONCLUSIONS

BoNT-A effectively and safely improved sleep bruxism in this placebo-controlled pilot trial. A large multicenter trial is needed to confirm these encouraging data.

CLINICALTRIALSGOV IDENTIFIER

NTC00908050.

CLASS OF EVIDENCE

This study provides Class II evidence that botulinum injections into the masseter and temporalis muscles improve subjective bruxism and painful symptoms associated with sleep bruxism.

OnabotulinumtoxinA effectiveness on chronic migraine, negative emotional states and sleep quality: a single-center prospective cohort study

BACKGROUND

OnabotulinumtoxinA (OnabotA) is considered effective in in patients with chronic migraine (CM) who failed on traditional therapies. This study was designed to evaluate the effect of OnabotA injection series on migraine outcome, negative emotional states and sleep quality in patients with CM.

METHODS

A total of 190 patients with CM (mean (SD) age: 39.3 (10.2) years; 87.9% were female) were included. Data on Pittsburgh sleep quality index (PSQI), headache frequency and severity, number of analgesics used, Migraine Disability Assessment Scale. (MIDAS) scores and Depression, Anxiety and Stress Scale (DASS-21) were evaluated at baseline (visit 1) and 4 consecutive follow up visits, each conducted after OnabotA injection series; at week 12 (visit 2), week 24 (visit 3), week 36 (visit 4) and week 48 (visit 5) to evaluate change from baseline to follow up.

RESULTS

From baseline to visit 5, significant decrease was noted in least square (LS) mean headache frequency (from 19.5 to 8.4, p = 0.002), headache severity (from 8.1 to 6.1, p = 0.017), number of analgesics (from 26.9 to 10.4, p = 0.023) and MIDAS scores (from 67.3 to 18.5, p < 0.001). No significant change from baseline was noted in global PSOI and DASS-21 scores throughout the study.

CONCLUSIONS

Our findings revealed that OnabotA therapy was associated with significant improvement in migraine outcome leading to decrease in headache frequency and severity, number of analgesics used and MIDAS scores. While no significant change was noted in overall sleep quality and prevalence of negative emotional states, patients without negative emotional states at baseline showed improved sleep quality throughout the study.

The Evaluation of the Clinical Effects of Botulinum Toxin on Nocturnal Bruxism

OBJECTIVES

Nocturnal bruxism can be managed by botulinum toxin (Botox®) in patients who have not responded to conservative treatment. The aim of this study was to evaluate the efficacy of botulinum toxin A (BTXA) in the treatment of nocturnal bruxism.

MATERIAL AND METHODS

The retrospective study comprised 25 female patients, aged 23-55 years (mean 35.84 ± 8.41 years). All patients received a single injection of BTXA in the right and left masseters. Evaluation was made by Visual Analogue Scale (VAS) values, complaint duration, onset of effect, and duration of effectiveness.

RESULTS

BTXA produced significant improvements in pain scores. Only 2 adverse events (8%) were recorded.

CONCLUSION

BTX-A is effective in the treatment of nocturnal bruxism.

[Sleep bruxism in children]

Bruxism is defined as repetitive activity of the masticatory muscles, characterized by clenching the teeth or teeth grinding and/or by tapping and swaying. This study investigated sleep bruxism. The etiology is multifactorial: mainly central (neuropathic disorder, anxiety) but also genetic and local (posture, mouth breathing). The diagnosis is based primarily on the anamnesis and examination of dental wear and progression over time (photos and dental castings). A diagnostic guide is proposed in this article. Frequently found in children, bruxism is not always considered pathological. The severity criteria relate intensity (number of dental attrition facets) as well as the context found in children: anxiety, ventilation disorders, and fragile dental structures. Management is multidisciplinary and depends on the etiologic diagnosis.

Treatment of chronic pain associated with nocturnal bruxism with botulinum toxin. A prospective and randomized clinical study

Background

To evaluate the role of botulinum toxin type A (BTX-A) in the treatment of pain associated with nocturnal bruxism.

Material and Methods

Fifty subjects reporting nocturnal bruxism were recruited for a randomized clinical trial. Twenty five bruxers were injected with botulinum toxin in both masseters, and twenty five were treated with traditional methods of treating bruxism. Patients were evaluated at 3rd week, 2nd and 6th month and one year after injection and then used to calculate bruxism events. Bruxism symptoms were investigated using questionnaires.

Results

Mean pain score due to Bruxism events in the masseter muscle decreased significantly in the botulinum toxin injection group A (P =0.000, highly significant). However, in the conventional treatment group, mean pain score does not show improvement with time (p>0.05).

Conclusions

Our results suggest that botulinum toxin injection reduced the mean pain score and number of bruxism events, most likely by decreasing the muscle activity of masseter rather than affecting the central nervous system.

Key words:Temporomandibular pain, nocturnal bruxism, botulinum toxin.

Effects of Myofascial Trigger Point Dry Needling in Patients with Sleep Bruxism and Temporomandibular Disorders: A Prospective Case Series

Objectives

To investigate the effects of deep dry needling (DN) of myofascial trigger points (MTrPs) of the masseter and temporalis on pain, pressure pain threshold (PPT), pain-free maximal jaw opening and temporomandibular disorder (TMD)-related disability in patients with sleep bruxism (SB) and myofascial TMD.

Methods

Seventeen subjects (11 women, 6 men) aged 39±13 years (range 23–66) diagnosed with SB and myofascial TMD were invited to participate in this prospective case series study. Each subject received a deep DN intervention in the masseter and temporalis MTrPs. Pain intensity, PPT, pain-free maximal jaw opening and TMD-related disability were assessed before treatment, immediately after treatment and at 1-week follow-up. Jaw disability was assessed using the jaw disability checklist (JDC) at baseline and 1 week post-treatment only.

Results

One-way analyses of variance showed significant improvements in pain intensity, PPT and jaw opening (p<0.001). Post-hoc analysis revealed significant differences between baseline and post-intervention follow-up time points in pain (immediate: Cohen's d=1.72, p<0.001; 1 week: d=3.24, p<0.001), jaw opening (immediate: d=0.77, p<0.001; 1 week: d=1.02, p<0.001) and PPT in the masseter (immediate: d=1.02, p<0.001; 1 week: d=1.64, p<0.001) and temporalis (immediate: d=0.91, p=0.006; 1 week: d=1.8, p<0.001). A dependent t-test showed a significant improvement in jaw functioning, reflected by a large reduction in 1-week JDC scores relative to baseline (d=3.15, p<0.001).

Conclusions

Deep DN of active MTrPs in the masseter and temporalis in patients with myofascial TMD and SB was associated with immediate and 1-week improvements in pain, sensitivity, jaw opening and TMD-related disability.

Trial registration number

Results.

Sleep bruxism: Current knowledge and contemporary management

Bruxism is defined as the repetitive jaw muscle activity characterized by the clenching or grinding of teeth. It can be categorized into awake and sleep bruxism (SB). Frequent SB occurs in about 13% of adults. The exact etiology of SB is still unknown and probably multifactorial in nature. Current literature suggests that SB is regulated centrally (pathophysiological and psychosocial factors) and not peripherally (morphological factors). Cited consequences of SB include temporomandibular disorders, headaches, tooth wear/fracture, implant, and other restoration failure. Chairside recognition of SB involves the use of subjective reports, clinical examinations, and trial oral splints. Definitive diagnosis of SB can only be achieved using electrophysiological tools. Pharmacological, psychological, and dental strategies had been employed to manage SB. There is at present, no effective treatment that “cures” or “stops” SB permanently. Management is usually directed toward tooth/restoration protection, reduction of bruxism activity, and pain relief.

Anatomical recommendations for safe botulinum toxin injection into temporalis muscle: a simplified reproducible approach

PURPOSE

The objective of this study was to simplify the anatomically safe and reproducible approach for BoNT injection and to generate a detailed topographic map of the important anatomical structures of the temporal region by dividing the temporalis into nine equally sized compartments.

METHODS

Nineteen sides of temporalis muscle were used. The topographies of the superficial temporal artery, middle temporal vein, temporalis tendon, and the temporalis muscle were evaluated. Also evaluated was the postural relations among the foregoing anatomical structures in the temporalis muscle, pivoted upon a total of nine compartments.

RESULTS

The temporalis above the zygomatic arch exhibited an oblique quadrangular shape with rounded upper right and left corners. The distance between the anterior and posterior margins of the temporalis muscle was equal to the width of the temporalis rectangle, and the distance between the reference line and the superior temporalis margin was equal to its height. The mean ratio of width to height was 5:4.

CONCLUSIONS

We recommend compartments Am, Mu, and Pm (coordinates of the rectangular outline) as areas in the temporal region for BoNT injection, because using these sites will avoid large blood vessels and tendons, thus improving the safety and reproducibility of the injection.

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.

Current Treatments of Bruxism

Despite numerous case reports, the evidence for treatment of bruxism is still low. Different treatment modalities (behavioral techniques, intraoral devices, medications, and contingent electrical stimulation) have been applied. A clinical evaluation is needed to differentiate between awake bruxism and sleep bruxism and rule out any medical disorder or medication that could be behind its appearance (secondary bruxism). A polysomnography is required only in a few cases of sleep bruxism, mostly when sleep comorbidities are present. Counselling with regard to sleep hygiene, sleep habit modification, and relaxation techniques has been suggested as the first step in the therapeutic intervention, and is generally considered not harmful, despite low evidence of any efficacy. Occlusal splints are successful in the prevention of dental damage and grinding sounds associated with sleep bruxism, but their effects on reducing bruxism electromyographic (EMG) events are transient. In patients with psychiatric and sleep comorbidities, the acute use of clonazepam at night has been reported to improve sleep bruxism, but in the absence of double-blind randomized trials, its use in general clinical practice cannot be recommended. Severe secondary bruxism interfering with speaking, chewing, or swallowing has been reported in patients with neurological disorders such as in cranial dystonia; in these patients, injections of botulinum toxin in the masticatory muscles may decrease bruxism for up to 1–5 months and improve pain and mandibular functions. Long-term studies in larger and better specified samples of patients with bruxism, comparing the effects of different therapeutic modalities on bruxism EMG activity, progression of dental wear, and orofacial pain are current gaps of knowledge and preclude the development of severity-based treatment guidelines.

Botulinum toxin in masticatory muscles of the adult rat induces bone loss at the condyle and alveolar regions of the mandible associated with a bone proliferation at a muscle enthesis

In man, botulinum toxin type A (BTX) is injected in masticatory muscles for several indications such as trismus, bruxism, or masseter hypertrophy. Bone changes in the mandible following BTX injections in adult animal have therefore became a subject of interest. The aim of this study was to analyze condylar and alveolar bone changes following BTX unilateral injections in masseter and temporal muscles in adult rats. Mature male rats (n = 15) were randomized into 2 groups: control (CTRL; n = 6) and BTX group (n= 9). Rats of the BTX group received a single injection of BTX into right masseter and temporal muscles. Rats of the CTRL group were similarly injected with saline solution. Rats were sacrificed 4 weeks after injections. Masticatory muscles examination and microcomputed tomography (microCT) were performed. A significant difference of weight was found between the 2 groups at weeks 2, 3 and 4 (p < 0.05). Atrophy of the right masseter and temporal muscles was observed in all BTX rats. MicroCT analysis showed significant bone loss in the right alveolar and condylar areas in BTX rats. Decrease in bone volume reached -20% for right alveolar bone and -35% for right condylar bone. A hypertrophic bone metaplasia at the digastric muscle enthesis was found on every right hemimandible in the BTX group and none in the CTRL group. BTX injection in masticatory muscles leads to a significant and major mandible bone loss. These alterations can represent a risk factor for fractures in human. The occurrence of a hypertrophic bone metaplasia at the Mus Digastricus enthesis may constitute an etiological factor for tori.

Management of sleep bruxism in adults: a qualitative systematic literature review

This paper updates the bruxism management review published by Lobbezoo et al. in 2008 (J Oral Rehabil 2008; 35: 509-23). The review focuses on the most recent literature on management of sleep bruxism (SB) in adults, as diagnosed with polysomnography (PSG) with audio-video (AV) recordings, or with any other approach measuring the sleep-time masticatory muscles' activity, viz., PSG without AV recordings or electromyography (EMG) recorded with portable devices. Fourteen (N = 14) papers were included in the review, of which 12 were randomised controlled trials (RCTs) and 2 were uncontrolled before-after studies. Structured reading of the included articles showed a high variability of topics, designs and findings. On average, the risk of bias for RCTs was low-to-unclear, whilst the before-after studies had several methodological limitations. The studies' results suggest that (i) almost every type of oral appliance (OA) (seven papers) is somehow effective to reduce SB activity, with a potentially higher decrease for devices providing large extent of mandibular advancement; (ii) all tested pharmacological approaches [i.e. botulinum toxin (two papers), clonazepam (one paper) and clonidine (one paper)] may reduce SB with respect to placebo; (iii) the potential benefit of biofeedback (BF) and cognitive-behavioural (CB) approaches to SB management is not fully supported (two papers); and (iv) the only investigation providing an electrical stimulus to the masseter muscle supports its effectiveness to reduce SB. It can be concluded that there is not enough evidence to define a standard of reference approach for SB treatment, except for the use of OA. Future studies on the indications for SB treatment are recommended.