An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth.

Background: To investigate the effect of restoration of lost vertical by centric stabilizing splint on electromyographic (EMG) activity of masseter and anterior temporalis muscles bilaterally in patients with generalized attrition of teeth. Materials and Methods: EMG activity of anterior temporalis and masseter muscle was recorded bilaterally for 10 patients whose vertical was restored with centric stabilizing splint. The recording was done at postural rest position and in maximum voluntary clenching for each subject before the start of treatment, immediately after placement of splint and at subsequent recall visits, with splint and without the splint. Results: The EMG activity at postural rest position (PRP) and maximum voluntary clench (MVC) decreased till 1 month for both the muscles. In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint. At MVC in the third month, the muscle activity without splint decreased significantly as compared to pretreatment values for anterior temporalis and masseter, while with the splint an increase was seen beyond the pretreatment values. Conclusion: A definite response of anterior temporalis and masseter muscle was observed over a period of 3 months. This is suggestive that the reversible increase in vertical prior to irreversible intervention must be carried out for a minimum of 3 months to achieve neuromuscular deprogramming. This allows the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.

Temporal branch of facial nerve: a normative study of nerve conduction / Ramo temporal do nervo facial: um estudo normativo da condução nervosa

The temporal branch of the facial nerve is particularly vulnerable to traumatic injuries during surgical procedures. It may also be affected in clinical conditions. Electrodiagnostic studies may add additional information about the type and severity of injuries, thus allowing prognostic inferences. The objective of the present study was to develop and standardize an electrophysiological technique to specifically evaluate the temporal branch of the facial nerve. METHOD: Healthy volunteers (n=115) underwent stimulation of two points along the nerve trajectory, on both sides of the face. The stimulated points were distal (on the temple, over the temporal branch) and proximal (in retro-auricular region). Activities were recorded on the ipsilateral frontalis muscle. The following variables were studied: amplitude (A), distal motor latency (DML) and conduction velocity (NCV). RESULTS: Differences between the sides were not significant. The proposed reference values were: A >0.4 mV, DML <3.9 ms and NCV >40 m/s. Variation between hemifaces should account for less than 60 percent for amplitudes and latency, and should be inferior to 20 percent for conduction velocity. CONCLUSION: These measurements are an adequate way for proposing normative values for the electrophysiological evaluation of the temporal branch.

O ramo temporal do nervo facial é particularmente vulnerável a lesões traumáticas nos procedimentos cirúrgicos. Também pode ser acometido em várias condições clínicas. Estudos eletrodiagnósticos podem acrescentar informações quanto ao tipo e severidade das lesões. A pesquisa visa aperfeiçoar técnica eletrofisiológica para avaliação específica daquele ramo. MÉTODO: Voluntários (n=115) foram submetidos a estimulação eletroneurográfica em dois pontos, nas duas hemifaces. Estímulo distal na têmpora, estímulo proximal na região retroauricular. Foram registradas distâncias dos pontos de estímulo até pontos anatômicos da face; assim como variáveis relacionadas com o potencial de ação resultante. RESULTADOS: Houve grande variabilidade nas amplitudes, porém a diferença entre as hemifaces não foi significativa. Valores de referência propostos foram: amplitude (A) >0.4mV, latência motora distal (LMD) <3.9ms e velocidade de condução (VCN) >40m/s. Variabilidade aceitável entre os lados: LMD e A <60 por cento e VCN <20 por cento. CONCLUSÃO: Este estudo pode ser a ferramenta inicial para aplicações futuras no diagnóstico e seguimento de pacientes com lesões no ramo temporal.

Estudio radiográfico y electromiográfico de los músculos masetero y temporal anterior en individuos con maloclusión tipo II, 1 de angle y controles / Radiographic and electromiographic study of masseter and temporal anterior muscles in subjects with angle II, I malloclusion and controls

El objetivo de este estudio fue comparar la actividad electromiográfica (EMG) de los músculos Masetero (Ms) y Temporal anterior (Ta) de sujetos portadores de maloclusión Angle II, 1 y controles. Se seleccionaron 19 sujetos estudiantes universitarios con características antropométricas similares (edad, peso, talla e IMC). Clínica y radiográficamente se dividieron en dos grupos: Grupo Control (GC) individuos portadores de neutroclusión y Grupo Disto (GD) con individuos portadores de maloclusión Tipo II, 1 de Angle. Se les realizó una electromiografía de superficie (EMG) de acuerdo a la técnica de Ferrario et al. (1993) y se analizaron los datos a partir de Root Mean Square (RMS). A partir de este registro se analizaron la amplitud media de voltaje (mV), la relación Ms/Ta y la distribución de las clases de voltaje, determinadas por los potenciales de acción de unidades motoras (PAUM). De la telerradiografía se analizaron los siguientes datos: ANB, SNA, SNB según Steiner (1992), relación molar, ángulo alfa de inclinación del Ms y brazo de palanca de acuerdo al modelo de Throkcmorton et al. (1980). Se utilizó Test "t" Student para evaluar significancia estadística (p<0,05) entre los grupos. La amplitud de voltaje fue mayor en el GD para todos los músculos estudiados (p<0,05). La relación Ms/Ta fue mayor en el GC. El ángulo alfa fue mayor en GD, también el brazo de palanca. La distribución de PAUM fue mayor en GC (79,0 por ciento), que en GD (57,8 por ciento) (p<0,05). GD presenta mayor amplitud de voltaje que GC, probablemente por presentar menos aferencias inhibitorias periodontales. También GD presenta una menor variedad de PAUM lo que implica que tiene menos reserva funcional que GC.

The of this study is compare the electromiographic activity (EMG) of the Masseter (Ms) and Temporal Anterior (Ta) muscles in subjects with malocclusion Angle II, I and controls. This study involving 19 young adults with similar anthropometric characteristics (Age, weight, hight, BMI). We evaluate clinical and radiographicaly this subject and divided it in to groups: Control Group CG with neutrocclusion and Distal Group (DG) with Angle II, I malocclusion. The both groups was submit a surface EMG according to Ferrario et al. (1993). We used the root mean square (RMS) math operation to calculate the mean voltage amplitude for each muscle. Furthermore we calculate the ratio Ms/Ta and the distribution of voltage class determinate for motor units actions potentials (MUAP). The Rx examination included SNA, SNB and ANB angles according to Steiner (1992), alfa angle and lever arm of Ms according the Throckmorton et al. (1980) mandibular model. The Stundent "t" Test was used to determine whether there were significant differences (p<0.05) between CG and DG parameters. The voltage amplitude was more higher in DG than CG. The ratio Ms/Ta showed protagonism of Ms in CG. The alfa angle and lever arm of Ms were more greater in DG than CG. DG presents a poor number of voltage class (57.8 percent) respect to CG (79.0 percent). DG presents a greater voltage amplitude in relation to CG, probably because the feedback inhibitory periodontal tissue plays an important role. Moreover DG presents a low voltage classes distribution of MUAP that suggest that have minus functional reserve.

Fenómenos autónomos referidos por punto gatillo miofacial en el músculo temporal como una respuesta neuropática / Autonomus referred phenomena by myofacial trigger point in temporalis muscle as a neuropathic response

Los puntos gatillo miofaciales (Pgs) son puntos hiperirritables en un músculo esquelético asociado a un nódulo palpable causado por una banda muscular tensa. Los Pgs miofaciales presentan dentro de sus signos y síntomas alteraciones motoras, sensoriales y autonómicas. En este artículo reportamos un caso en el que se presenta un fenómeno autónomo referido a partir de un punto gatillo miofacial y se plantean las vías neuroanatómicas involucradas en esta respuesta, analizando la hipótesis que las respuestas autónomas referidas asociadas al dolor pueden considerarse eventos neuropáticos del sistema nervioso autónomo.

Myofascial trigger points (MTP) are hyperirritable points in skeletal muscle associated with a palpable lump caused by a strained muscle band. MTP presented within signs and symptoms of motor, sensory and autonomic impairment. In this article we report a case in which an autonomous referred phenomena from a myofascial trigger point and raises the neuroanatomical pathways involved in this response, considering the hypothesis that self-related responses associated with neuropathic pain can be regarded as events of the autonomic nervous system. Clinical and experimental evidence discussed in this article indicates that myofascial trigger point pain is an autonomic phenomena associated, that can be systemic and localized, and must be considered in evaluating patients with these diagnosis.