Beneficial effects of benzodiazepine on masticatory muscle dysfunction induced by chronic stress and occlusal instability in an experimental animal study.

Psychological stress and occlusal alteration are important etiologic factors for temporomandibular/masticatory muscular disorders. In particular, the exact physiologic mechanism underlying the relation by occlusal alteration and temporomandibular disorders remains unclear. Our purpose was to test the hypothesis that benzodiazepine therapy is able to prevent metabolic and vascular changes in the medial pterygoid muscle of rats under chronic stress after 14 days of unilateral exodontia. Adult Wistar rats were submitted to unpredictable chronic mild stress (10 days) and/or unilateral exodontia and their plasma and medial pterygoid muscles were removed for analysis. A pre-treatment with diazepam was used to verify its effect on stress. The parameters evaluated included anxiety behavior, plasma levels of corticosterone, metabolic activity by succinate dehydrogenase, capillary density by laminin staining and ultrastructural findings by transmission electron microscopy. Occlusal instability induced anxiety-like behavior on elevated plus-maze test and diazepam administration blocked the appearance of this behavior. Unilateral exodontia promoted in the contralateral muscle an increase of oxidative fibers and capillaries and modification of sarcoplasmic reticulum. Chronic stress caused increased glycolytic metabolism, reduced capillary density and morphological changes in mitochondria on both sides. Association of both factors induced a glycolytic pattern in muscle and hemodynamic changes. Pharmacological manipulation with diazepam inhibited the changes in the medial pterygoid muscle after stress. Our results reveal a preventive benzodiazepine treatment for stress and occlusal instability conditions affecting masticatory muscle disorders. In addition, provide insights into the mechanisms by which chronic stress and exodontia might be involved in the pathophysiology of masticatory muscular dysfunctions.

Tratamento de disfunções temporomandibulares com toxina botulínica tipo A / Treatment of temporomandibular disorders with botulinum toxin type A

Introdução: a disfunção temporomandibular (DTM) abrange muitos problemas clínicos nas articulações, na musculatura e em outras regiões da oroface. A origem multifatorial e sua etiologia envolvem fatores psicocomportamentais, oclusais e neuromusculares, seu diagnóstico é realizado pela anamnese detalhada, com a identificação dos fatores predisponentes, iniciadores e perpetuantes, e pelo exame físico, que consiste em palpação da musculatura, mensuração da movimentação ativa e verificação dos ruídos articulares. Objetivo: sistematizar as evidências científicas e verificar a eficácia do tratamento de disfunções temporomandibulares de origem muscular com a toxina botulínica do tipo A (TBX-A). Materiais e método: a busca bibliográfica foi realizada nas bases de dados PubMed e SciELO, com os descritores: "myofascial pain", "botulinum toxin" e "masticatory muscles". Foram analisados ensaios clínicos randomizados, que apresentaram tratamento para DTM com a utilização da TBX-A em pacientes de ambos os sexos. A qualidade metodológica dos artigos selecionados foi verificada de acordo com a escala de Jadad. Considerações finais: observou-se que o tratamento para a DTM por meio da TBX-A auxilia no tratamento de dores orofaciais permanentes como coadjuvante, aliado a tratamentos conservadores. Os estudos que demonstraram resultados clínicos significativos utilizaram uma dose total de 100 U de TBX-A, sendo 30 U nos músculos masseteres e 20 U nos músculos temporais, bilateralmente. (AU)

Introduction: temporomandibular dysfunction (TMD) involves a number of clinical problems in joints, muscles, and other orofacial regions. The multifactorial origin and etiology involve psychobehavioral, occlusal, and neuromuscular factors. The diagnosis is performed by a detailed anamnesis with the identification of predisposing factors, initiators and perpetuants, and the physical examination, which consists of muscle palpation, measurement of the active movement, and verification of joint noises. Objective: to systematize the scientific evidence and to verify the efficacy of treatment of temporomandibular disorders of muscular origin with botulinum toxin type A (TBX-A). Materials and method: the bibliographic search was performed in the PubMed and SciELO databases, with the descriptors of "myofascial pain", "botulinum toxin", "masticatory muscles". Randomized clinical trials that presented treatment for TMD with the use of TBX-A in patients of both sexes were analyzed. The methodological quality of the articles selected was verified according to the Jadad scale. Final considerations: it was observed that treatment for TMD using TBX-A helps to treat permanent orofacial pain as a support, along with conservative treatments. The studies showing significant clinical outcomes used a total dose of 100 U of TBX-A, considering 30 U for the masseter muscles and 20 U for the temporal muscles, bilaterally. (AU)

Toxina botulínica tipo A nas DTM musculares: há eficácia? / Botulinum toxin type A in muscle TMD: There's effectiveness?

Os objetivos dessa revisão da literatura foram verificar a eficácia da toxina botulínica tipo A (BTX-A) na diminuição da dor em indivíduos com DTM e identificar os parâmetros ideais para o local, número de aplicações, dosagens e tempo de duração. Foram selecionados 19 artigos das bases de dados do Google Acadêmico e PubMed, que incluíram 14 artigos de pesquisa clínica e 5 de revisão sistemática. Foi possível concluir a respeito da toxina botulínica que os músculos indicados para a aplicação são principalmente os masseteres e os temporais, podendo ser aplicado também nos músculos pterigoideos, lateral e medial, digástrico e platisma. Os locais de escolha são os que apresentam maior volume e sensibilidade à palpação (pontos-gatilho) ou maior atividade eletromiográfica em repouso. As dosagens variam de um total de 10U a 400U de BTX-A por indivíduo, sendo distribuídas pelos músculos indicados. A BTX-A, em geral, é aplicada em dose única, porem alguns autores preconizam uma segunda aplicação se a primeira não fez o efeito esperado. O efeito da toxina botulínica sobre os músculos e a dor, em geral, tem duração variada, sendo relatado desde 3 a 4 semanas até 3 a 5 meses. A maioria dos estudos observou à eficácia da BTX-A na diminuição da dor de indivíduos com DTM. Porém é necessário que mais estudos clínicos randomizados, duplo cegos, multicêntricos e controlados sejam realizados para que a eficácia da BTX-A seja comprovada e para que um protocolo de atendimento seja realizado.(AU)

The objectives of this literature review were to verify the efficacy of botulinum toxin type A (BTX-A) in reducing pain of TMD patients and to identify the optimal parameters for the location, number of applications, dosages and duration. We selected 19 articles from Google Scholar and PubMed databases that included 14 articles of clinical research and 5 systematic reviews. It was concluded about BTX-A that the muscles appropriate to the application are mostly masseter and temporal and can also be applied in the pterygoid muscle lateral and medial, digastric and platysma. The choices of locations are those who have higher volume and sensitivity to palpation (trigger points) or higher EMG activity at rest. Dosages vary from a total of 10U to 400U of BTX-A by individual, being distributed by the indicated muscles. BTX-A in general is applied in a single dose, but some authors recommend a second application if the first did not make the expected effect. The effect of BTX-A on muscle and pain in general has varying duration, being reported from 3 to 4 weeks for 3 to 5 months. Most studies have noted at the effectiveness of BTX-A in patient pain reduction DTM. However more randomized, double-blind, multicenter, controlled clinical trials needs to be carried out so that the effectiveness of BTX-A could be confirmed and a management protocol, stabilished.(AU)

Effect of ß-hydroxy-ß-methylbutyrate in masticatory muscles of rats.

The aim of this research was to examine the influence of ß-hydroxy-ß-methylbutyrate (HMB) on changes in the profile of muscle fibers, whether these alterations were similar between the elevator and depressor muscles of the jaw, and whether the effects would be similar in male and female animals. Fifty-eight rats aged 60 days (29 animals of each gender) were divided into four groups: the initial control group (ICG) was sacrificed at the beginning of the experiment; the placebo control group (PCG) received saline and was fed ad libitum; the experimental group (EG) received 0.3 g kg(-1) of HMB daily for 4 weeks by gavage as well as the same amount of food consumed by the PCG in the previous day; and the experimental ad libitum group (EAG) received the same dose of the supplement along with food ad libitum. Samples included the digastric and masseter muscles for the histoenzymological analysis. Data were subjected to statistical analysis with a significance level of P < 0.05. Use of HMB caused a decrease in the percentage of fast twitch glycolytic (FG) fibers and an increase in fast twitch oxidative glycolytic (FOG) fibers in males in both experimental groups (EG and EAG). However, it produced no increase in the muscle fiber area, in either gender, in the masseter muscle. In the digastric muscle, the HMB did not change the frequency or the area of any muscle fiber types in either gender. Our data suggest that the use of HMB caused small changes in the enzymological profile of fibers of the mastication muscles; the changes were different in the elevator and depressor muscles of the jaw and the results were different depending on gender.

Use of onabotulinumtoxinA in post-traumatic oromandibular dystonia.

PURPOSE: Post-traumatic oromandibular dystonia (PTOD) is a disorder whose symptoms can include bruxism, muscle pain, and involuntary muscle contraction, among others. The use of onabotulinumtoxinA (ObT-A) is helpful in controlling the symptoms of patients with PTOD. The aim of this study was to evaluate the use of ObT-A in the treatment of PTOD. MATERIALS AND METHODS: In this prospective case-series study, the population consisted exclusively of patients diagnosed with PTOD, without distinction by age or gender, from January 2007 to December 2010. The patients were diagnosed with PTOD and treated with ObT-A infiltration (primary predictor) at the Department of Maxillofacial Surgery at the Hospital Clínico Mutual de Seguridad (Santiago, Chile). The primary outcome variables were bruxism, muscle pain, and involuntary muscle contraction. The data were obtained through questionnaires registered in tables at each control. Systat 13.1 was used for statistical analysis. The statistical test used to compare patients' evolution over time was the test of signs. RESULTS: Thirty male patients 18 to 65 years old diagnosed with PTOD were treated with ObT-A infiltrations. The signs and symptoms associated with oromandibular dystonia (bruxism, muscle pain, and involuntary muscle contraction) were decreased in all patients after ObT-A infiltrations. CONCLUSIONS: The positive results and the absence of complications recommend the use of the infiltration protocol presented in this study for the treatment of PTOD.

Local anesthetics inhibit Ca-ATPase in masticatory muscles.

Local anesthetics have myotoxic effects and inhibit Ca-ATPase activity and Ca transport in skeletal muscles. Such effects have not been fully elucidated in masticatory muscles. We tested the hypothesis that local anesthetics increase myoplasmic calcium in masticatory muscles by inhibiting Ca-ATPase at a concentration similar to that of dental cartridges. The effects of lidocaine and bupivacaine on Ca-ATPase from rabbit masseter and medial pterygoid muscles were tested with radioisotopic and colorimetric methods. Bupivacaine had an action similar to that of lidocaine on Ca-ATPase activity, but less effect on calcium transport. The pre-exposure of the membranes to the anesthetics enhanced the Ca-ATPase activity in the absence of calcium ionophore, supporting their permeabilizing effect. The results demonstrate that amide-type anesthetics do not inhibit calcium binding, but do reduce calcium transport and enzyme phosphorylation by ATP, and suggest that the myoplasmic calcium increase induced by lidocaine and bupivacaine might promote masticatory muscle contraction and eventual rigidity.

Effects of use of anabolic steroids on the masticatory system: a pilot study.

The use of androgenic anabolic steroids (AAS) has increased significantly among athletes in Brazil and other countries. These drugs alter the physiological behavior of bone and muscles, also affecting these structures in masticatory system. This paper aims to evaluate bone and dental changes in users of AAS, as well as the incidence of temporomandibular dysfunction (TMD), compared to athletes not using AAS. Eight athletes were equally divided in two groups, AAS users and non-users. The groups were evaluated using Helkimo index, McNamara cephalometric tracing and cast analysis. The AAS users presented more intense TMD signs and symptoms (Di total value, P = 0.096, Mann-Whitney test), increased cephalometric measures (Co-A, P = 0.020, Mann-Whitney test) and Angle Class II malocclusion, compared to the non-users. These results suggested that the use of AAS alters masticatory structures and increases the incidence of TMD.

Botulinum toxin in a case of hemimasticatory spasm with severe worsening during pregnancy.

Hemimasticatory spasm (HMS) is a rather uncommon movement disorder with a pathophysiology that is still unclear, although temporomasseter entrapment at the temporal fossa has been advanced. The authors present a case of HMS in a woman who experienced marked worsening in episode frequency and severity during pregnancy. Treatment with botulinum toxin led to marked improvement.

Therapeutic response of benzodiazepine, orphenadrine citrate and occlusal splint association in TMD pain.

Loss of function, muscle inflammation, and pain are some of the signs and symptoms of temporomandibular dysfunction (TMD). Pharmacological strategies to minimize the clinical manifestation of these disorders often focus on blocking or inhibiting the pain-causing symptom. Resources such as muscle-relaxants, anxiety-relief drugs, and splint therapy are often used to reduce muscular hyperactivity related to TMD muscle pain. This study compares the effect of a randomly ordered association of occlusal splint therapy (S), nonsteroid anti-inflammatory with a muscle-relaxant drug (orphenadrine citrate) (O), and an anxiety-relief drug (benzodiazepine) (B), to ease painful TMD muscle symptoms. Clinical and anamnestic analyses were recorded in accordance with the Helkimo TMD index and applied before and after treatments. Twenty-one group two Helkimo TMD adult female patients were treated, all of whom were subjected to the three random therapeutic associations proposed: SBO, BOS, and OSB. The same operator applied the three specific associations over a period of 21 days in the proposed sequence, seven days for each therapy. The results show that all the groups presented the best results in terms of relief from pain after the therapeutic association (28.5% showed a decrease and 47.6% showed an absence of symptoms). No significant difference was observed among association therapeutic protocols.

Masticatory muscle spasm in a non-Japanese patient with Satoyoshi syndrome successfully treated with botulinum toxin.

A non-Japanese patient with Satoyoshi syndrome is presented. Severe masticatory muscle spasms interfered with feeding, but were successfully treated with botulinum toxin.