Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial / Efeito da terapia LASER de baixa potência versus placa de Michigan CAD/CAM em pacientes com Distúrbios Temporomandibulares musculares: um ensaio clínico randomizado

Objective: This study aimed to evaluate the efficacy and sustainability of using low level LASER therapy and CAD/CAM Michigan splint on improving the range of mandibular movements, muscle activity and reducing the pain. Material and Methods: 56 female patients were randomly divided into two groups. Group A: Patients received applications of low-level LASER therapy using semiconductor InGaAsp diode LASER type 940 nm with continuous mode of operation, applied for 180 sec per session for 12 sessions. Group B: Patients received Michigan splint of 2 mm thickness constructed on their upper teeth, the splint was 3D digitally printed. Electromyography was used to evaluate muscle activity, visual analogue scale was used to evaluate the pain intensity, ARCUS digma facebow was used to evaluate range of mandibular movements, and maximum mouth opening was taken using a millimeter ruler. They were measured before the beginning of the treatment, and at three and six month follow-up periods. Results: The results revealed that both low-level LASER therapy and Michigan splint reduce the myofascial pain, improved the range of the mandibular movements, and the muscles activity, but the effect of the low-level LASER therapy was more profound and sustainable. After 6 months from the beginning of the treatment, changes in masseter muscle activity (P= 0.001; effect size= 1.757), pain intensity (P= 0.003; effect size= 3), and range of mandibular movement (P= 0.001, effect size= 1.729) differed significantly between the two groups. Conclusions: Low-level LASER therapy had a better and more sustainable effect on reducing the pain intensity and improving the muscle activity as well as the mandibular movement when compared to Michigan splint (AU)

Objetivo: Este estudo teve como objetivo avaliar a eficácia e a durabilidade do uso da terapia LASER de baixa potência e da placa de Michigan CAD/CAM na melhora da amplitude dos movimentos mandibulares, atividade muscular e redução da dor. Material e Métodos: 56 pacientes do sexo feminino foram divididos aleatoriamente em dois grupos. Grupo A: os pacientes receberam aplicações de terapia LASER de baixa potência utilizando diodo semicondutor InGaAsp LASER tipo 940 nm em modo contínuo de operação, aplicado por 180 segundos por sessão durante 12 sessões. Grupo B: os pacientes receberam a placa de Michigan com uma espessura de 2 mm confeccionada sobre a arcada superior, a placa foi impressa digitalmente em 3D. A eletromiografia foi utilizada para avaliar a atividade muscular, a escala visual analógica foi utilizada para avaliar a intensidade da dor, o arco facial ARCUS digma foi utilizado para determinar a amplitude dos movimentos mandibulares e a abertura máxima da boca foi medida com uma régua milimétrica. Todas as medidas foram realizadas antes do início do tratamento e nos períodos de acompanhamento de três e seis meses. Resultados: Os resultados revelaram que tanto a terapia LASER de baixa potência como a placa de Michigan reduziram a dor miofascial, aumentaram a amplitude dos movimentos mandibulares e melhoraram a atividade muscular, mas o efeito da terapia LASER de baixa potência foi mais profundo e duradouro. Após 6 meses do início do tratamento, as alterações na atividade do músculo masseter (P= 0. 001; tamanho do efeito= 1,757), intensidade da dor (P= 0,003; tamanho do efeito= 3), e amplitude de movimento mandibular (P= 0,001, tamanho do efeito= 1,729) diferiram significativamente entre os dois grupos. Conclusão: A terapia com LASER de baixa potência teve um efeito melhor e mais duradouro na redução da intensidade da dor e na melhora da atividade muscular, bem como do movimento mandibular, quando comparada à placa de Michigan(AU)

Bite Force, Thickness, and Thermographic Patterns of Masticatory Muscles Post-Hemorrhagic Stroke.

OBJECTIVE: Stroke is a neurological deficit of cerebrovascular origin, considered a 21st-century epidemic that causes functional changes in the human body. This study aimed to evaluate the stomatognathic system of patients after hemorrhagic stroke through the bite force, thickness, and skin temperature in the region of the masseter and temporalis muscles. MATERIAL AND METHODS: Twenty-four subjects were divided into groups: post-hemorrhagic stroke; with right side of the affected body (n = 12) and without the neurological disorder (n = 12). Maximum molar bite force was verified using a digital dynamometer. Muscle thickness was measured using ultrasound images obtained at rest and during maximal voluntary contraction of the masseter and temporalis muscles. Thermographic camera was used to record the thermographic patterns of the masseter and temporalis muscles. Data were subjected to Student's t-test (P < .05). RESULTS: The maximum molar bite force showed significant differences in the right (P = .04) and left (P = .03) sides, with a reduction in force in the post-hemorrhagic stroke group on the affected and unaffected sides. There was a significant difference (P < .05) in the thickness of the left temporal muscle at mandibular rest (P = .01) between groups. The post-hemorrhagic stroke group clinically presented greater muscle thickness in almost 100% of the muscles evaluated in both clinical conditions. There were no significant differences in skin temperature in the masseter and temporal muscles between the groups. CONCLUSIONS: Our results suggest functional changes in the stomatognathic system of subjects after a hemorrhagic stroke, especially concerning molar bite force and masticatory muscle thickness in the temporal muscle (unaffected side).

Relación entre contactos mediotrusivos con la articulación temporomandibular y la oclusión / Relationship between mediotrusive contacs, the temporomandibular joint and occlusion

Los contactos mediotrusivos son aquellos contactos oclusales que se encuentran entre las vertientes in- ternas de las cúspides linguales maxilares y las inter- nas de las cúspides bucales mandibulares del lado de no trabajo durante los movimientos de lateralidad. Estos contactos mediotrusivos podría desencadenar trastornos temporomandibulares, afectando la oclu- sión y la articulación temporomandibular. El objetivo de este estudio es analizar las caracterís- ticas y la relación entre los contactos mediotrusivos con la articulación temporomandibular y la oclusión en pacientes que consultan al Servicio de Oclusión y ATM del Hospital Odontológico de la Facultad de Odontología de la Universidad Nacional del Nordeste (AU)

Mediotrusive contacts are those occlusal contacts that are found between the internal slopes of the maxillary lingual cusps and the internal slopes of the mandibular buccal cusps on the non-working side during laterality movements. These mediotrusive contacts could trigger temporomandibular disorders affecting occlusion and temporomandibular joint. The objective of this study was to analyze the characteristics and relationship of mediotrusive contacts with occlusion and the temporomandibular joint, in patients who consult the Occlusion and TMJ Service of the Dental Hospital of the Faculty of Dentistry of the National University of the Northeast (AU)

Ultra-Low Frequency Transcutaneous Electrical Nerve Stimulation on Pain Modulation in a Rat Model with Myogenous Temporomandibular Dysfunction.

Masticatory myofascial pain (MMP) is one of the most common causes of chronic orofacial pain in patients with temporomandibular disorders. To explore the antinociceptive effects of ultra-low frequency transcutaneous electrical nerve stimulation (ULF-TENS) on alterations of pain-related biochemicals, electrophysiology and jaw-opening movement in an animal model with MMP, a total of 40 rats were randomly and equally assigned to four groups; i.e., animals with MMP receiving either ULF-TENS or sham treatment, as well as those with sham-MMP receiving either ULF-TENS or sham treatment. MMP was induced by electrically stimulated repetitive tetanic contraction of masticatory muscle for 14 days. ULF-TENS was then performed at myofascial trigger points of masticatory muscles for seven days. Measurable outcomes included maximum jaw-opening distance, prevalence of endplate noise (EPN), and immunohistochemistry for substance P (SP) and µ-opiate receptors (MOR) in parabrachial nucleus and c-Fos in rostral ventromedial medulla. There were significant improvements in maximum jaw-opening distance and EPN prevalence after ULF-TENS in animals with MMP. ULF-TENS also significantly reduced SP overexpression, increased MOR expression in parabrachial nucleus, and increased c-Fos expression in rostral ventromedial medulla. ULF-TENS may represent a novel and applicable therapeutic approach for improvement of orofacial pain induced by MMP.

Vitamin D and Temporomandibular Disorders: What Do We Know So Far?

BACKGROUND AND AIMS: Vitamin D is synthesized in the skin with the aid of ultraviolet-B radiation, playing a variety of roles in the body. Temporomandibular disorders (TMDs) are a group of pathological conditions involving the temporomandibular joints as well as the masticatory muscles and othersurrounding tissues. In the present narrative review, we investigated the potential role of vitamin D in the etiology of temporomandibular disorders in order todetermine whether the current knowledge supports 25-hidroxyvitamin D (25-OHD) supplementation in temporomandibular disorders associated with insufficient or deficient levels of vitamin D. METHODS: A literature research was performed in PubMed, Scopus, Science Direct, and Google Scholar databases, and a total of 10 articles were included for analysis. RESULTS: Among the observational studies published to date, investigating the role for vitamin D in the etiology of TMDs, six of them suggest that there is a connection between the two aspects. In this context, patients suffering from TMD, with deficient levels of vitamin D (<30 ng/mL), are most likely to benefit from supplementation, whereas individuals with vitamin D level >50ng/mL probably have little benefit from supplementation. CONCLUSION: Vitamin D might be a safe, simple, and potentially beneficial way to prevent TMDs or to reduce pain; however, more randomized and placebo-controlled trials are required before any firm conclusions can be drawn.

Análise de diferentes tarefas para normalização do sinal elétrico do músculo orbicular da boca pela contração voluntária máxima: estudo piloto / Analysis of different tasks to normalize the electrical signal of the orbicularis oris muscle by maximum voluntary contraction: pilot study

RESUMO Objetivo pesquisar a atividade elétrica do músculo orbicular da boca em quatro diferentes tarefas isométricas e indicar a mais apropriada para utilização como referência na normalização do sinal elétrico do músculo orbicular da boca pela contração voluntária máxima. Métodos participaram do estudo 22 indivíduos, sendo dez do sexo masculino e 12 do feminino, com idades entre 20 e 33 anos. A atividade elétrica das porções superior e inferior do músculo orbicular da boca foi registrada durante a realização das seguintes tarefas isométricas: protrusão labial com fechamento, protrusão labial sem fechamento, contrarresistência com a placa de resistência labial e preensão de lábios. A ordem de realização das tarefas foi randomizada entre os participantes. Os dados foram comparados entre as tarefas, para cada seguimento labial. Resultados no segmento marginal superior, a tarefa com maior média e mediana de amplitude foi preensão labial, embora sem diferença significativa entre tarefas. O menor coeficiente de variação foi obtido na tarefa de contrarresistência com a placa de resistência labial. No segmento marginal inferior, a tarefa com maior média e mediana de amplitude foi protrusão labial com fechamento, que também teve o menor coeficiente de variação e diferença significativa entre as tarefas protrusão labial com fechamento e preensão, sendo os maiores valores obtidos na primeira. Conclusão indica-se como referência para a normalização do sinal elétrico do músculo orbicular da boca, pela contração voluntária máxima, a tarefa de protrusão labial com fechamento.

ABSTRACT Purpose To verify the electrical activity of the orbicularis oris in four different isometric tasks and to indicate the most appropriate task for use as a reference in the normalization of the electrical signal of the orbicularis oris muscle by maximum voluntary contraction. Methods Twenty-two individuals participated in the study, of which 10 were male and 12 were female, with ages ranging from 20 to 33 years. The electrical activity of the upper and lower parts of orbicularis oris muscle was recorded during the following isometric tasks: lip protrusion with bilabial closure; lip protrusion without bilabial closure; the counter resistance using the plate of labial resistance and lips prehension. The order of the tasks was randomized among participants. Data were compared between tasks for each lip part. Results in the upper marginal segment, the task with the highest mean and median amplitude was lip prehension, although there was no significant difference between tasks. The lowest coefficient of variation was obtained in the counter resistance task with the plate of labial resistance. In the lower marginal segment, the task with the highest mean and median amplitude was labial protrusion with lips closure, which also had the lowest coefficient of variation. In this segment, there was a significant difference between labial protrusion with lips closure and prehension, with the highest values obtained in the first task. Conclusion lip protrusion with bilabial closure is suggested as reference for the normalization of the electrical signal of the orbicularis oris muscle, by maximum voluntary contraction.

Osteoartrosis de ATM: recuperar la función / TMJ Osteoarthrosis: recover function

Objetivo: evaluar la rehabilitación funcional de la ATM en pacientes con osteoartrosis, con abordaje neuromuscular. La osteoartrosis se caracteriza por la degeneración del cartílago articular y la cortical ósea, que conduce a dolor e inmovilidad. Se incluyó a 8 mujeres entre 20 y 42 años de edad con dolor en la región orofacial, signos de oclusión disfuncional e imágenes compatibles con trastornos degenerativos en ATM. Clínicamente se evaluó el dolor y la oclusión y, mediante tecnología electrónica, se obtuvieron datos objetivos de los movimientos de apertura-cierre y lateralidades, la velocidad de apertura-cierre mandibulares y de los ruidos articulares. Las mediciones fueron realizadas al inicio y al finalizar el tratamiento de estabilización mandibular con una ortosis neuromuscular. Para determinar la significación estadística se utilizaron el Student`s test de comparaciones múltiples y el análisis de varianza, ANOVA, de un factor. Las diferencias entre medias se consideraron significativas con p <0.05. Los resultados demostraron ausencia de dolor en el 100% de los casos al primer mes de tratamiento. Se incrementaron la apertura bucal (6,73 mm promedio), ambas lateralidades (P=0.0023), velocidad en apertura y en cierre (no estadísticamente significativo). Después de estabilizar la mandíbula se redujo la frecuencia de los ruidos. En conclusión, la oclusión dental disfuncional es el principal factor etiológico de la artrosis de la ATM. El establecimiento de una oclusión fisiológica produce la descompresión de la ATM, aumenta el rango de los movimientos mandibulares y disminuye significativamente el dolor (AU)

Objective: to evaluate the functional rehabilitation of the TMJ in patients with osteoarthritis, with a neuromuscular approach. Osteoarthrosis is characterized by degeneration of articular cartilage and bone cortex, which leads to pain and immobility. Eight women between 20 and 42 years of age with pain in the orofacial region, signs of dysfunctional occlusion, and images consistent with degenerative TMJ disorders were included. Clinically, pain and occlusion were evaluated and, using electronic technology, objective data were obtained on the opening-closing movements and lateralities, the opening-closing speed of the jaws and joint noises. Measurements were made before and at the end of the mandibular stabilization treatment with a neuromuscular orthosis. To determine the statistical significance, the Student`s multiple comparisons test and the analysis of variance, ANOVA, of one factor were used. The differences between means were considered significant with p <0.05. The results showed absence of pain pain in 100% of cases in the first month of treatment. Mouth opening (6.73 mm average), both lateralities (P = 0.0023), opening and closing speed (not statistically significant) were increased. After stabilizing the jaw the noise frequency value was reduced. In conclusion, dysfunctional dental occlusion is the main etiologic factor of TMJ osteoarthritis. Establishing a physiological occlusion causes TMJ decompression, increases the range of mandibular movements, and significantly decreases pain (AU)

Alternativas de tratamiento para pacientes jóvenes con pérdida de estructura dentaria. Parte 2: caso clínico / Treatment alternatives for young patients with loss of dental structure. Part 2: a clinical case

El objetivo de este artículo es presentar una alternativa de tratamiento rehabilitador para pacientes jóvenes con gran pérdida de estructura dental, vinculada a lesiones de origen no bacteriano. Se presenta el caso clínico de un paciente de sexo masculino, de 39 años de edad, que acudió a la Cátedra de Odontología Integral Adultos de la Facultad de Odontología de la Universidad de Buenos Aires (FOUBA) relatando síntomas compatibles con hipersensibilidad dentaria y fatiga de los músculos masticadores. Al mismo tiempo, manifestó disconformidad con el aspecto estético de su sonrisa. Teniendo en cuenta la gran pérdida de sustancia en sus piezas dentarias producida por hábitos parafuncionales (bruxismo), se realizó una rehabilitación oral adhesiva con cerámicas utilizando el protocolo de abordaje terapéutico sugerido por la Cátedra. En pacientes que presentan severos desgastes (AU)

Physiotherapy in hypomobility of temporomandibular joints.

INTRODUCTION: Temporomandibular disorders (TMD) are the second most common cause of chronic pain in the human musculoskeletal system. The triad of symptoms of TMD includes: pain within the temporomandibular joint (TMJ), limitation of its mobility and capitations. The aim of the study was to present the methods of physiotherapy and to assess its effectiveness in patients with hypomobility of temporomandibular joints. MATERIAL AND METHODS: 44 patients (40.2 ± 10.6 years) were examined for signs of TMD using the Manual Functional Analysis of masticatory system (MFA) questionnaire due to DC/TMD. In the above group, 20 patients showed hypomobility of TMJs and myofascial pain. They underwent a 3-week physiotherapy consisting of manual therapy and exercises. In the study group, linear measurements of TMJs mobility and palpation of selected masticatory muscles were performed. Pain was assessed before and after 3 weeks of therapy according to Numerical Rating Scale (NRS). Statistical processing of the data was done with STATISTICA 13 and was conducted considering significance at a p-value <0.05. RESULTS: Significant improvement in TMJ's mobility, which increased on average by 6.6 mm (p = 0.0005) and reducing of pain, a decrease of 3 points on average on the NRS Scale (p = 0.00002) were achieved. CONCLUSIONS: The applied physiotherapy algorithm, including manual therapy and exercises of masticatory muscles, is effective in the case of improvement TMJ's range of motion and reduction of pain in patients with hypomobility of TMJ's.

Muscular pattern in patients with temporomandibular joint disc displacement with reduction: an electromyographical assessment.

OBJECTIVE: Surface Electromyography of masticatory muscles (sEMG) is used as a tool to support diagnosis and treatment of Temporomandibular disorders (TMDs). The study aimed at examining jaw muscles pattern in individuals with temporomandibular joint disc displacement with reduction (TMJ/DDR). This sort of subjects was supposed to have a different muscular pattern compared to the control group. MATERIALS AND METHODS: Sixty-four women with unilateral TMJ/DDR and forty TMD-free women underwent a sEMG assessment of masticatory muscles. Descriptive statistics were performed. Student T-Test assessed differences between the two groups. Statistical significance was set at ρ < 0.05. RESULT: The t-test showed statistically significant results only in BAR and SMI scores (ρ value < 0,0001). The other measurements did not differ between the two groups. BAR index values of all healthy subjects were within the reference range. Almost the entire TMJ/DDR group had BAR index out of reference range and anteriorly placed. CONCLUSION: Women with TMJ/DDR showed an altered recruitment of the jaw muscles, with significant difference between the activity of the couple of temporalis and the one of masseters, compared to the control group. A lower chewing efficiency was found in the DDR group compared to the control one.

Effects of 4-Week Diacutaneous Fibrolysis on Myalgia, Mouth Opening, and Level of Functional Severity in Women With Temporomandibular Disorders: A Randomized Controlled Trial.

OBJECTIVE: The purpose of this study was to assess the effects of 4-week protocol of diacutaneous fibrolysis (DF) compared with simulated DF (sham-DF) on myalgia and mouth opening. METHODS: In a sham randomized controlled trial, 34 women with temporomandibular disorders and myofascial pain were randomly divided as intervention group (IG) and sham-DF group (SG). The IG received 4 weeks of real DF, and the SG received sham. Pain was assessed through the visual analog scale and pressure pain thresholds (PPTs) on the temporomandibular joint (TMJ), and over the temporal and masseter muscles. The Mandibular Function Impairment Questionnaire was used to classify the participants regarding to the severity of the functional limitation related to TMD. RESULTS: Pain scores decreased for both groups, but the IG showed lower values at week 4, with between-group differences. Bilateral temporal PPT showed higher values at week 4, with between-group differences. The SG had lower PPTs but the IG had higher PPTs, both compared to baseline results. The time-by-group interaction and the frequency of participants above 40 mm of mouth opening showed a significant difference for the IG over time with higher results at the 4-week assessment compared to its own baseline. Both groups showed lower MFIQ scores from baseline to 4-week assessment. There was a lower frequency of a moderate level of severity for the IG. No differences were observed for TMJ or for the masseter muscles PPT. CONCLUSION: Improvements were observed for visual analog scale scores and PPTs on temporal muscles. There was a group-by-time interaction in the IG, suggesting a possible potential use of DF for mouth opening.

Electromyography as a Means of Assessing Masticatory Muscle Activity in Patients with Pain-Related Temporomandibular Disorders.

Aim: The aim of this study was to evaluate masticatory muscle electrical activity in patients with pain-related and pain-free temporomandibular disorders (TMDs) as well as in subjects with no TMD. Methods: Ninety children with mixed dentition were recruited to the study. Of this total, 30 subjects were diagnosed with pain-related TMD (TMD-P), 30 with pain-free TMD (TMD-PF), and 30 without TMD. We used Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD) to assess the presence of TMD in the examined children. The electromyographical (EMG) potentials of the temporalis and masseter muscles were measured with a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) at rest and during maximum voluntary clenching (MVC). Results: An analysis of the EMG recordings showed statistically significant intergroup differences in masticatory muscle electrical activity at rest and during MVC. Significantly higher rest temporalis muscle activity was noted in pain-related TMD subjects compared with that children from the pain-free TMD and non-TMD groups, as well as in TMD-PF children in relation to those without TMD. The EMG potentials of the temporalis muscle during MVC were much lower in patients with TMD-P than in pain-free TMD and non-TMD subjects. Masseter muscle activity at rest in the TMD-pain group was significantly greater, and masseter muscle EMG potentials during clenching were markedly lower than in patients with no TMD diagnosis. Conclusion: The use of electromyography to assess masticatory muscle function revealed alterations in the pattern of temporalis and masseter muscle activity in patients with pain-related TMD compared with the pain-free subjects.

The mechanism of beneficial effect of radiofrequency therapy on masticatory muscles in temporomandibular disorders - a literature review.

Temporomandibular disorders (TMD) is one of the most common problem in contemporary dentistry. It is a term covering dysfunction of the masticatory muscles and the temporomandibular joints. Patients are suffering from severe pain, followed by limited mandibular opening and sounds in the temporomandibular joints during jaw movement. TMD influences the quality of life because the symptoms can become chronic and difficult to manage. Radiofrequency waves (RF) are electromagnetic waves with low energy and high frequency. They provide pain relief without causing significant damage to the nervous tissue. The RF therapy is commonly used for physiotherapeutic treatment of skeletal muscle relaxation, as a supportive therapy. The rehabilitation effect of these waves is based on diathermy by means of high-voltage quick alternating current. RF has also found application in physical therapy, as a therapeutic tool for various types of chronic pain syndromes. The aim of this literature review is to show the beneficial effect of radiofrequency waves on the pain of the masticatory muscles in the course of TMD.

Effects of Neuromuscular Electrical Stimulation Synchronized with Chewing Exercises on Bite Force and Masseter Muscle Thickness in Community-Dwelling Older Adults in South Korea: A Randomized Controlled Trial.

This study is aimed at investigating the effects of synchronized neuromuscular electrical stimulation (NMES) and chewing exercises on bite force and the masseter muscle thickness in community-dwelling older adults. Material and methods: Forty older adults were enrolled in South Korea and randomly assigned to either an experimental or control group. The experimental group performed chewing exercises using the No-Sick Exerciser equipment synchronized with NMES applied to the bilateral masseter muscles, while the control group performed only chewing exercises. Both groups received interventions for 20 min/day, 5 days/week, for 6 weeks. Bite force was measured using the OCCLUZER device, and masseter muscle thickness was measured using a portable ultrasound. Results: Both groups showed a significant increase in bite force and masseter muscle thickness compared to baseline measurements (p < 0.05). The experimental group showed a significantly higher increase in bite force and masseter muscle thickness than the control group after combined intervention (p < 0.05). Conclusion: This study demonstrates that NMES synchronized with chewing exercises is more efficient in increasing bite force and masseter muscle thickness than chewing exercises alone in community-dwelling older adults.

The key role of the mandible in modulating airflow amplitude during sleep.

RATIONALE: Mandibular position and motion during sleep rely on the balance between mandibular elevators and depressors. We hypothesized that vertical mandibular position (VMP) modulates airflow amplitude during sleep. METHODS: VMP, tidal nasal flow pressure (NFP) and concurrent surface electromyographic activity of the masseters (sEMG-m) were recorded and processed by a customized algorithm from 100 polysomnographic fragments including a micro-arousal (25 obstructive sleep apnea patients). The relationship between mandibular position and changes in airflow was analysed. RESULT: Concurrent VMP and sEMG-m activity changes routinely occurred before a new steady state of airflow documented by NFP. Vertical mandible depression was associated with a median (95% CI) reduction in NFP of 40.9% (14.6%-71.3%, p = 0.007) while vertical mandible elevation and mouth closure were associated with a median (95% CI) relative increase in NFP after arousal of 52.6% (17.9%-56.2%, p = 0.001). CONCLUSION: Elevation and lowering of the mandible were associated with changes in masseteric EMG activity modulating airflow amplitude during sleep.

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.

The effectiveness of stabilization appliance therapy among patients with myalgia.

BACKGROUND: The efficacy of stabilization appliance therapy for masticatory muscle pain is debated. Therefore, there are currently no clear usage standards. We analyzed patient factors influencing its efficacy and characterized masticatory muscle pain subtypes to determine appropriate therapy candidates. METHODS: This case series study recruited patients diagnosed with local myalgia or myofascial pain and used variables related to temporomandibular disorders in the analysis. We used temporary appliance to screen patients for sleep bruxism for 2 weeks. Afterwards, we initiated therapy with stabilization appliances. Efficacy was evaluated via tenderness intensity during muscle palpation and the treatment satisfaction score after 2 months of treatment. RESULTS: We analyzed 62 (91%) patients. Tenderness upon muscle palpation was mitigated in 27 patients. Mitigated tenderness odds ratios were 0.035 for myofascial pain, 0.804 for 15-item Patient Health Questionnaire scores, and 1.915 for facet length. Thirty-nine patients expressed satisfaction; satisfaction odds ratios were 0.855 for 9-item Patient Health Questionnaire scores, 1.606 for facet length, and 4.023 for awake bruxism awareness. CONCLUSIONS: Stabilization appliance therapy is most effective for patients with awake bruxism awareness, local myalgia, long facets, and no psychosocial risk factors.

Paramyotonia Congenita with Persistent Distal and Facial Muscle Weakness: A Case Report with Literature Review.

BACKGROUND: Paramyotonia congenita (PC; OMIM 168300) is a non-dystrophic myotonia caused by mutations in the SCN4A gene. Transient muscle stiffness, usually induced by exposure to cold and aggravated by exercise, is the predominant clinical symptom, and interictal persistent weakness is uncommon. CASE REPORT: We report a family with a history of PC accompanied by persistent hand muscle weakness with masticatory muscle involvement. Persistent weakness was exacerbated with age, and MR analysis showed marked atrophy of temporal, masseter, and finger flexor muscles with fatty replacement. The PC causative mutation T1313M in the SCN4A gene was prevalent in the family. Administration of acetazolamide chloride improved clinical symptoms and the results of cold and short exercise tests. Phenotypic variation within the family was remarkable, as the two younger affected patients did not present with persistent weakness or muscle atrophy. CONCLUSIONS: PC associated with the T1313M mutation is a possible cause of persistent distal hand weakness.