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1.
PLoS One ; 15(12): e0243495, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33320876

RESUMEN

The maintenance of postural balance can be influenced by the lifestyle of a population. This study aimed to determine the electromyographic activity of the masseter and temporalis muscles during mandibular tasks and habitual and non-habitual chewing in indigenous individuals to reveal the differences among white Brazilian individuals. Sixty Brazilians (18 and 28 years) were divided into two groups: 30 Xingu indigenous individuals and 30 white Brazilian individuals, with 20 men and 10 women in each group. The individuals were assessed using the normalized electromyographic activity of mandibular tasks (rest, protrusion, right and left laterality) and electromyographic activity of masticatory cycles in habitual (peanuts and raisins) and non-habitual (Parafilm M) chewing. Data were analyzed using Student's t-test (p < .05). Comparisons between the groups demonstrated significant differences. Indigenous individuals group presented a decrease in the normalized electromyographic activity of the masticatory muscles during mandibular rest [right masseter (p = .002) and left masseter (p = .004) muscles]. There was increase in the normalized electromyographic activity during protrusion [left temporal (p = .03) muscle]. There was increase in the electromyographic activity during chewing: peanuts [right masseter (p = .001), left masseter (p = .001) and right temporal (p = .01) muscles], raisins [right masseter (p = .001), left masseter (p = .002), right temporal (p = .008), left temporal (p = .01) muscles] and Parafilm M [left masseter muscle (p = .05)]. From the findings of this study, we concluded that in the comparison between indigenous and white individuals, positive changes were observed in the electromyographic pattern of the masticatory muscles in the mandibular postural conditions, with greater masticatory efficiency in the indigenous group.


Asunto(s)
Electromiografía , Músculo Masetero/fisiología , Músculo Temporal/fisiología , Adolescente , Adulto , Brasil , Femenino , Humanos , Pueblos Indígenas , Masculino , Masticación/fisiología , Adulto Joven
2.
Sci Rep ; 10(1): 6410, 2020 04 14.
Artículo en Inglés | MEDLINE | ID: mdl-32286442

RESUMEN

Jaw-muscle architecture is a key determinant of jaw movements and bite force. While static length-force and force-velocity relationships are well documented in mammals, architecture dynamics of the chewing muscles and their impact on muscle performance are largely unknown. We provide novel data on how fiber architecture of the superficial anterior temporalis (SAT) varies dynamically during naturalistic feeding in tufted capuchins (Sapajus apella). We collected data on architecture dynamics (changes in muscle shape or the architectural gear ratio) during the gape cycle while subjects fed on foods of different mechanical properties. Architecture of the SAT varied with phases of the gape cycle, but gape distance accounted for the majority of dynamic changes in architecture. In addition, lower gear ratios (low muscle velocity relative to fascicle velocity) were observed when animals chewed on more mechanically resistant foods. At lower gear ratios, fibers rotated less during shortening resulting in smaller pinnation angles, a configuration that favors increased force production. Our results suggest that architectural dynamics may influence jaw-muscle performance by enabling the production of higher bite forces during the occlusal phase of the gape cycle and while processing mechanically challenging foods.


Asunto(s)
Masticación/fisiología , Músculo Temporal/anatomía & histología , Músculo Temporal/fisiología , Animales , Fenómenos Biomecánicos , Cebus , Femenino
3.
Sensors (Basel) ; 20(2)2020 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-31968532

RESUMEN

We present an eating detection algorithm for wearable sensors based on first detecting chewing cycles and subsequently estimating eating phases. We term the corresponding algorithm class as a bottom-up approach. We evaluated the algorithm using electromyographic (EMG) recordings from diet-monitoring eyeglasses in free-living and compared the bottom-up approach against two top-down algorithms. We show that the F1 score was no longer the primary relevant evaluation metric when retrieval rates exceeded approx. 90%. Instead, detection timing errors provided more important insight into detection performance. In 122 hours of free-living EMG data from 10 participants, a total of 44 eating occasions were detected, with a maximum F1 score of 99.2%. Average detection timing errors of the bottom-up algorithm were 2.4 ± 0.4 s and 4.3 ± 0.4 s for the start and end of eating occasions, respectively. Our bottom-up algorithm has the potential to work with different wearable sensors that provide chewing cycle data. We suggest that the research community report timing errors (e.g., using the metrics described in this work).


Asunto(s)
Masticación/fisiología , Monitoreo Fisiológico/instrumentación , Procesamiento de Señales Asistido por Computador/instrumentación , Gafas Inteligentes , Adulto , Algoritmos , Dieta , Electromiografía , Femenino , Humanos , Masculino , Monitoreo Fisiológico/métodos , Músculo Temporal/fisiología
4.
Magn Reson Med Sci ; 19(3): 268-275, 2020 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-31548479

RESUMEN

We analyzed the correlations between the T2 shift and integrated electromyographic (iEMG) values in the masseter and temporal muscles. Six healthy adults engaged in a clenching task over two durations at various bite forces. We evaluated the mean T2 shift per voxel and assessed their correlations with iEMG using a linear mixed model. The regression coefficients were different for each muscle type, similar for the left and right sides, and decreased upon doubling duration.


Asunto(s)
Electromiografía , Imagen por Resonancia Magnética , Músculo Masetero , Relajación Muscular/fisiología , Músculo Temporal , Adulto , Fuerza de la Mordida , Humanos , Músculo Masetero/diagnóstico por imagen , Músculo Masetero/fisiología , Músculo Temporal/diagnóstico por imagen , Músculo Temporal/fisiología
5.
Pain Pract ; 20(2): 147-153, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31538698

RESUMEN

BACKGROUND: Diminished pressure pain thresholds (PPTs) have been found in patients with cluster headache (CH), suggesting the presence of central sensitization. However, it is not known whether sensitization persists over time during the asymptomatic periods. OBJECTIVE: To investigate if men with episodic CH in a long-lasting remission phase exhibit widespread pressure pain hypersensitivity. METHODS: Forty men with episodic CH and 40 matched controls were enrolled. PPTs were assessed bilaterally over 1 trigeminal (temporalis muscle) and 3 extra-trigeminal points (C5/C6 zygapophyseal joint, second metacarpal, tibialis anterior muscle) by a blinded assessor. Patients were assessed in a prolonged remission phase, at least 6 months after their last CH attack and without taking any medication. Depression and anxiety levels were assessed with the Hospital Anxiety and Depression Scale (HADS). For each point, differences in PPTs were evaluated with a multivariate mixed-model analysis of covariance test, with side and group as main factors and depression and anxiety levels as covariates. RESULTS: PPTs were significantly decreased bilaterally over the temporalis muscle (mean difference: 85 to 100 kPa), C5/C6 zygapophyseal joint (mean difference: 65 to 80 kPa), second metacarpal (mean difference: 65 to 90 kPa), and tibialis anterior muscle (mean difference: 135 to 155 kPa) in patients with CH when compared to headache-free subjects (all, P < 0.001). No effect of anxiety or depression levels was found. CONCLUSIONS: Patients with CH exhibited bilateral widespread hypersensitivity to pressure pain during long-lasting remission periods, which was not associated with depression or anxiety. These results support the persistence of central sensitization in episodic CH, even in remote asymptomatic phases.


Asunto(s)
Ansiedad/diagnóstico , Cefalalgia Histamínica/diagnóstico , Depresión/diagnóstico , Dimensión del Dolor/métodos , Dolor/diagnóstico , Presión/efectos adversos , Adulto , Ansiedad/epidemiología , Ansiedad/psicología , Sensibilización del Sistema Nervioso Central/fisiología , Cefalalgia Histamínica/epidemiología , Cefalalgia Histamínica/psicología , Estudios Transversales , Depresión/epidemiología , Depresión/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Dolor/epidemiología , Dolor/psicología , Dimensión del Dolor/psicología , Umbral del Dolor/fisiología , Inducción de Remisión , Músculo Temporal/patología , Músculo Temporal/fisiología
6.
Surg Radiol Anat ; 42(1): 63-67, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31489469

RESUMEN

PURPOSE: Since prehistory, changes of the facial skeleton have been related to the modification of diet. More recent studies have shown changes in the morphology of the mandible and maxilla due to variations of strain during mastication. The temporal muscle (TM) is a strong masticatory muscle, with its insertions extending through the temporal fossa. Our objective is to observe the relations between the TM and the lateral orbital wall (LOW) which could indicate an influence of mastication on the shape of the LOW. METHODS: We conducted a retrospective study using 100 CT scans. The length of the lateral orbital wall (LLOW), the angle between LOW and the medial orbital wall (MOW), the cross-sectional areas of LOW and of the TMs were measured on both sides of each CT scan. The correlation between TMs and other three parameters was studied by Pearson correlations. RESULTS: A correlation was found between TMs and LOWs, a lower with LLOW, and a very weak and negative correlation between LOW/MOW angle. CONCLUSIONS: Anatomical knowledge about TM and investigation of masticatory strains lead us to think that mastication have minimal effect on the morphology of the LOW, only on the frontal process of zygomatic. This may explain, in part, why the LOW is the strongest wall of the orbit.


Asunto(s)
Dieta , Masticación/fisiología , Órbita/diagnóstico por imagen , Órbita/crecimiento & desarrollo , Músculo Temporal/diagnóstico por imagen , Músculo Temporal/fisiología , Anatomía Transversal , Humanos , Músculos Masticadores/diagnóstico por imagen , Músculos Masticadores/fisiología , Órbita/anatomía & histología , Estudios Retrospectivos , Tomografía Computarizada Espiral
7.
J Morphol ; 280(11): 1706-1713, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31513299

RESUMEN

Bite force is a measure of feeding performance used to elucidate links between animal morphology, ecology, and fitness. Obtaining live individuals for in vivo bite-force measurements or freshly deceased specimens for bite force modeling is challenging for many species. Thomason's dry skull method for mammals relies solely on osteological specimens and, therefore, presents an advantageous approach that enables researchers to estimate and compare bite forces across extant and even extinct species. However, how accurately the dry skull method estimates physiological cross-sectional area (PCSA) of the jaw adductor muscles and theoretical bite force has rarely been tested. Here, we use an ontogenetic series of southern sea otters (Enhydra lutris nereis) to test the hypothesis that skeletomuscular traits estimated from the dry skull method accurately predicts test traits derived from dissection-based biomechanical modeling. Although variables from these two methods exhibited strong positive relationships across ontogeny, we found that the dry skull method overestimates PCSA of the masseter and underestimates PCSA of the temporalis. Jaw adductor in-levers for both jaw muscles and overall bite force are overestimated. Surprisingly, we reveal that sexual dimorphism in craniomandibular shape affects temporalis PCSA estimations; the dry skull method predicted female temporalis PCSA well but underestimates male temporalis PCSA across ontogeny. These results highlight the importance of accounting for sexual dimorphism and other intraspecific variation when using the dry skull method. Together, we found the dry skull method provides an underestimation of bite force over ontogeny and that the underlying anatomical components driving bite force may be misrepresented.


Asunto(s)
Fuerza de la Mordida , Maxilares/anatomía & histología , Músculos Masticadores/anatomía & histología , Nutrias/anatomía & histología , Caracteres Sexuales , Animales , Fenómenos Biomecánicos , Femenino , Maxilares/fisiología , Masculino , Músculo Masetero/anatomía & histología , Músculo Masetero/fisiología , Músculos Masticadores/fisiología , Modelos Biológicos , Nutrias/fisiología , Cráneo/anatomía & histología , Cráneo/fisiología , Músculo Temporal/anatomía & histología , Músculo Temporal/fisiología
8.
Neurocirugia (Astur) ; 30(5): 222-227, 2019.
Artículo en Inglés, Español | MEDLINE | ID: mdl-30975560

RESUMEN

INTRODUCTION: There are different techniques for the reconstruction of the temporal muscle (TM) in the pterional approach (PA) in order to avoid and reduce atrophy, it has not been able to avoid it in its entirety. The administration of bupivacaine generates regeneration of muscle fibres. There are no studies in the medical literature that evaluate the time of TM manipulation and the use of bupivacaine for the treatment of atrophy after pterional approach, the present investigation aim is to describe the effects of these variables. PATIENT AND METHODS: Longitudinal study, including patients from 18-80 years old with pterional approach at 2016-2017. We evaluated the effects of the TM manipulation times and the administration of 0.5% bupivacaine on the trophism and function of TM. RESULTS: Twenty-nine patients underwent a PA; 16(55.17%) count with criteria for 0.5% bupivacain infiltration. We found a negative correlation between manipulation times and trophism, with no statistically significance (p>.05). We evaluated presurgical and postsurgical index of Helkimo and Fonseca's index, finding an increase of disfunction with statistically significance (p<.05). In patients who were infiltrated with 0.5% bupivacaine we observed a mean difference in the TM's trophism of 0.275±1.18mm, in contrast with no infiltrated which was 2.39±1.30mm (t[27] = -5.118, p=.0001). CONCLUSIONS: The manipulation of the TM during a pterional approach conditioned an impact on the quality of life according to the disfunction indexes, due to atrophy. This investigation exhibits that de administration of 0.5% bupivacaine during surgery offers a decrease in the TM atrophy.


Asunto(s)
Bupivacaína/uso terapéutico , Atrofia Muscular/prevención & control , Complicaciones Posoperatorias/prevención & control , Regeneración/efectos de los fármacos , Músculo Temporal/efectos de los fármacos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Bupivacaína/administración & dosificación , Bupivacaína/farmacología , Craneotomía/efectos adversos , Difusión , Femenino , Humanos , Inyecciones Intramusculares , Masculino , Persona de Mediana Edad , Fibras Musculares Esqueléticas/efectos de los fármacos , Fibras Musculares Esqueléticas/fisiología , Fagocitos/fisiología , Recuperación de la Función , Colgajos Quirúrgicos , Músculo Temporal/diagnóstico por imagen , Músculo Temporal/fisiología , Músculo Temporal/cirugía , Factores de Tiempo , Tomografía Computarizada por Rayos X , Adulto Joven
9.
Clin Oral Investig ; 23(9): 3445-3455, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30607620

RESUMEN

OBJECTIVES: This study aimed to examine the electromyographic activity of superficial masseter and anterior temporal muscles during chewing gum and gummy jelly mastication in healthy subjects to reveal the difference of neuromuscular control of jaw-closing muscles, according to the food texture. MATERIALS AND METHODS: Electromyographic activity was recorded in 30 adults with Angle Class I occlusion and unimpaired function from the bilateral superficial masseter and anterior temporal muscles during unilateral mastication of two test foods: standardized gummy jelly and color-changeable chewing gum. Differences in normalized electromyographic activity and asymmetry index values between gummy jelly and chewing gum mastication were analyzed during the early, middle, and late phases of mandibular closure. Furthermore, changes among the three closing phases were compared for each test food. RESULTS: High electromyographic activity of both muscles tended to occur bilaterally during the middle and late closing phases during gummy jelly mastication, but increased muscle activity in the late closing phase was not observed during chewing gum mastication. The asymmetry index of the superficial masseter muscle increased significantly from early to late closure, regardless of the food texture, but it tended to decrease for the anterior temporal muscle during gummy jelly mastication. CONCLUSION: The different aspects of the chewing process between the comminution and mixing test measures are necessary to elicit the different human neuromuscular strategies of chewing for different test foods. CLINICAL RELEVANCE: These characteristic EMG activities of the superficial masseter and anterior temporalis muscles may be used as supporting diagnostic information during patient assessments and a reference during evaluation of masticatory system disharmony or dysfunction.


Asunto(s)
Músculo Masetero , Masticación , Músculo Temporal , Adulto , Oclusión Dental , Electromiografía , Voluntarios Sanos , Humanos , Músculo Masetero/fisiología , Músculos Masticadores , Músculo Temporal/fisiología
10.
J Craniofac Surg ; 30(1): 154-157, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30444767

RESUMEN

Mandibular head dislocation and problems with mouth opening may develop after mandibular reconstruction. The authors investigated dislocation of the mandibular head and amount of protrusive sliding (excursion) and their effect on mouth opening. The authors divided 55 mandibular reconstruction patients into 3 groups on the basis of the extent of masticatory muscle and mandibular resection and investigated mandibular head dislocation. On the other hand, the authors focused on mandibular head protrusive excursion as a function of a reconstructed mandible. Protrusive excursion was measured by plain radiography in 29 patients. The extent of mouth opening was measured between the central incisors. Fluoroscopy was performed in 9 patients and the motions of the mandible were analyzed with video-analysis software. Mandibular head dislocation was observed in 15 patients (27.2%) who underwent resection of the mandibular ramus and coronoid process. The extent of mouth opening did not vary significantly among the 3 groups but was lower than that in healthy persons. Mandibular excursion was restricted in patients with conserved temporalis and lateral pterygoid muscles. Protrusive excursion was correlated with the extent of mouth opening. Structural problems involving dislocation of the mandibular head are caused by severing the coronoid process and protrusive excursion disorders are important factors causing mouth opening problems. Physiological sliding and other motions were observed in reconstructed models. The authors believe that when the ramus is resected, there is a greater chance of articular head dislocation. These findings suggest that dislocation of the mandibular head and protrusive excursion disorders arise from imbalances of the remaining masticatory muscles.


Asunto(s)
Luxaciones Articulares/etiología , Reconstrucción Mandibular/efectos adversos , Trastornos de la Articulación Temporomandibular/etiología , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Cóndilo Mandibular/cirugía , Músculos Masticadores/fisiología , Persona de Mediana Edad , Movimiento , Músculos Pterigoideos/fisiología , Rango del Movimiento Articular/fisiología , Estudios Retrospectivos , Músculo Temporal/fisiología , Articulación Temporomandibular/fisiología
11.
Am J Phys Anthropol ; 167(2): 291-310, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-30168867

RESUMEN

OBJECTIVES: Changes to soft- and hard-tissue components of the masticatory complex during development can impact functional performance by altering muscle excursion potential, maximum muscle forces, and the efficiency of force transfer to specific bitepoints. Within Macaca fascicularis, older individuals exploit larger, more mechanically resistant food items and more frequently utilize wide-gape jaw postures. We therefore predict that key architectural and biomechanical variables will scale during ontogeny to maximize bite force and gape potential within older, larger-bodied individuals. MATERIALS AND METHODS: We analyzed 26 specimens of M. fascicularis, representing a full developmental spectrum. The temporalis, superficial masseter, and deep masseter were dissected to determine muscle mass, fiber length, and physiologic cross-sectional area (PCSA). Lever-arm lengths were also measured for each muscle, alongside the height of the temporomandibular joint (TMJ) and basicranial length. These variables were scaled against two biomechanical variables (jaw length and condyle-molar length) to determine relative developmental changes within these parameters. RESULTS: During ontogeny, muscle mass, fiber length, and PCSA scaled with positive allometry relative to jaw length and condyle-molar length within all muscles. TMJ height also scaled with positive allometry, while muscle lever arms scaled with isometry relative to jaw length and with positive allometry (temporalis) or isometry (superficial and deep masseter) relative to condyle-molar length. CONCLUSION: Larger individuals demonstrate adaptations during development towards maximizing gape potential and bite force potential at both an anterior and posterior bitepoint. These data provide anatomical evidence to support field observations of dietary and behavioral differences between juvenile and adult M. fascicularis.


Asunto(s)
Macaca fascicularis , Músculo Masetero , Músculo Temporal , Animales , Antropología Física , Antropometría , Fenómenos Biomecánicos/fisiología , Fuerza de la Mordida , Femenino , Macaca fascicularis/anatomía & histología , Macaca fascicularis/fisiología , Masculino , Músculo Masetero/anatomía & histología , Músculo Masetero/fisiología , Músculo Temporal/anatomía & histología , Músculo Temporal/fisiología
12.
J Nutr Health Aging ; 22(7): 829-836, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30080228

RESUMEN

BACKGROUND: Aging is associated with a decline in masticatory muscles mass and performance. The present study aims to examine the differences in the cross-sectional areas of the masseter, medial and lateral pterygoid muscles in relation to age and the present dental status in a population-based magnetic resonance imaging study. METHODS: This cross sectional study involved 747 subjects aged between 30-89 years (344 male, 403 female) who underwent both a whole body MRI and a full oral examination. The cross-sectional areas of the masseter, medial and lateral pterygoid muscles were measured from MRI images using the software Osirix. Dental and prosthetic status data from the oral examination were classified according to Eichner index. The method of generalized least squares, also called growth curve model, was used to examine the associations between the cross-sectional areas, age and tooth status. RESULTS: The cross-sectional area of the lateral pterygoid muscle decreased substantially with age in women but did not depend on age in men. The medial pterygoid muscle depended on age but an effect modification by gender was uncertain. Masseter muscle was weakly associated with age but strongly associated with the number of teeth in both genders. CONCLUSIONS: Our findings suggest that age has a heterogeneous effect on masticatory muscles. This indicates that age related changes to the masticatory muscles are muscle specific and are not consistent between the different muscles.


Asunto(s)
Envejecimiento/fisiología , Músculo Masetero/fisiología , Músculos Pterigoideos/fisiología , Músculo Temporal/fisiología , Pérdida de Diente/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Estudios Transversales , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Músculos Masticadores/fisiología , Persona de Mediana Edad
13.
J Appl Oral Sci ; 26: e20170214, 2018 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-29768521

RESUMEN

To assess the immediate effects of temporary bite-raising using light-cured orthodontic band cement on the superficial masseter and anterior temporalis electromyography (EMG) activity in healthy adults. Surface EMG signals were recorded bilaterally from the superficial masseter and anterior temporalis muscles of 30 volunteers with a normal occlusion, before and after having temporary bite-raising. The bite-raising was done by adding light-cured orthodontic band cement (3x5x2 mm WxLxH) on the lingual cusps of both upper first molars. The measurements were recorded (i) at rest, (ii) while clenching in centric occluding position and (iii) while chewing on an artificial test food. The EMG activity at rest and during clenching, the maximum voltage, and the duration of the identified EMG signal burst while chewing the artificial test food before and after temporary bite-raising were statistically compared using the paired t-test or the Wilcoxon signed-rank test based on the normality of the variables. The significance level was set at 5%. After temporary bite-raising, we found no significant change in integral EMG activity at rest position for the superficial masseter (mean difference (MD)=7.5 µVs) and for the anterior temporalis muscle (MD=36.8 µVs); however, the integral EMG activity during clenching was significantly reduced for the superficial masseter (MD=201.2 µVs) and for the anterior temporalis muscle (MD=151.8 µVs). During mastication, the maximum voltage of the identified burst was significantly reduced on the preferred chewing side of the superficial masseter and anterior temporalis muscles (MD=127.9 and 47.7 µV, respectively), while no significant change was found for the duration of the identified burst (MD=-34.1 and 3.4 ms, respectively) after temporary bite-raising. The results point to an altered neuromuscular behavior during clenching and chewing immediately after temporary bite-raising with light-cured orthodontic band cement. This information is relevant for orthodontists to inform their patients what will happen to their masticatory muscle activity when this bite-raising method is used.


Asunto(s)
Fuerza de la Mordida , Curación por Luz de Adhesivos Dentales/métodos , Músculo Masetero/fisiología , Cementos de Resina/química , Músculo Temporal/fisiología , Adolescente , Adulto , Electromiografía/métodos , Femenino , Humanos , Masculino , Masticación/fisiología , Soportes Ortodóncicos , Valores de Referencia , Reproducibilidad de los Resultados , Estadísticas no Paramétricas , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven
14.
IEEE Trans Neural Syst Rehabil Eng ; 26(4): 770-779, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29641381

RESUMEN

In this paper, we provide a robust framework to detect anomalous electromyographic (EMG) signals and identify contamination types. As a first step for feature selection, optimally selected Lawton wavelets transform is applied. Robust principal component analysis (rPCA) is then performed on these wavelet coefficients to obtain features in a lower dimension. The rPCA based features are used for constructing a self-organizing map (SOM). Finally, hierarchical clustering is applied on the SOM that separates anomalous signals residing in the smaller clusters and breaks them into logical units for contamination identification. The proposed methodology is tested using synthetic and real world EMG signals. The synthetic EMG signals are generated using a heteroscedastic process mimicking desired experimental setups. A sub-part of these synthetic signals is introduced with anomalies. These results are followed with real EMG signals introduced with synthetic anomalies. Finally, a heterogeneous real world data set is used with known quality issues under an unsupervised setting. The framework provides recall of 90% (± 3.3) and precision of 99%(±0.4).


Asunto(s)
Artefactos , Electromiografía/clasificación , Procesamiento de Señales Asistido por Computador , Algoritmos , Análisis por Conglomerados , Simulación por Computador , Humanos , Movimiento , Reproducibilidad de los Resultados , Relación Señal-Ruido , Músculo Temporal/fisiología , Análisis de Ondículas
15.
Int J Comput Dent ; 21(1): 17-22, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29610777

RESUMEN

The aim of this study was to analyze the effect of occlusal modifications on the muscular activity of the masseter and anterior temporalis muscles. The study included 41 healthy dentate subjects who were examined in relation to the muscle activity of the masseter and anterior temporalis muscles recorded by surface electromyography (EMG) bilaterally in two different sessions. Occlusal plastic strips (thickness: 0.4 or 0.8 mm) were placed on different mandibular teeth to simulate different bite constellations (unilateral, bilateral transversal, and bilateral diagonal). Controlled by visual feedback, the subjects performed submaximum occlusion at 10% and 35% of maximum voluntary contraction (MVC). The activity ratios of the muscles were analyzed by two-way repeated measurement analysis of variance (ANOVA), and the reliability of muscle activity data was determined by intraclass correlation coefficient (ICC) analysis. The activity ratios of the masseter muscles were not significantly different under various biting conditions. In contrast, the anterior temporalis muscles showed significant differences (P < 0.001) between unilateral configurations and the other biting conditions (bilateral transversal or diagonal), in particular during biting at 10% MVC. In general, ICC values revealed low to moderate reliability of the measurements of muscle activity. Under controlled submaximum occlusal loading, the activity behavior of the masseter muscles remained stable, whereas the anterior temporalis muscles reacted differently to distinct occlusal biting configurations. The results support the assumption that the anterior temporalis muscles might operate as fine-tuning muscles when asymmetric bite force distributions occur, for instance during chewing, caused by food fragments between the teeth.


Asunto(s)
Oclusión Dental , Músculo Masetero/fisiología , Músculo Temporal/fisiología , Adulto , Electromiografía , Femenino , Humanos , Masculino , Masticación/fisiología , Adulto Joven
16.
J Plast Reconstr Aesthet Surg ; 71(7): 1051-1057, 2018 07.
Artículo en Inglés | MEDLINE | ID: mdl-29555150

RESUMEN

INTRODUCTION: Masticatory muscles or their nerve supply are options for facial reanimation surgery, but their ability to create spontaneous smile has been questioned. This study assessed the percentage of healthy adults who activate the temporalis and masseter muscles during voluntary and spontaneous smile. METHODS: Healthy volunteer adults underwent electromyography (EMG) studies of the temporalis and masseter muscles during voluntary and spontaneous smile. Responses were repeated three times and recorded as negative, weakly positive, or strongly positive according to the activity observed. The best response was used for analysis. RESULTS: Thirty healthy adults (median age: 34 years, range: 25-69 years) participated. Overall, 92% of the masseter muscles were activated during voluntary smile (22% strong, 70% weak). Seventy-seven percent of the masseter muscles were activated in spontaneous smile (12% strong, 65% weak). The temporalis muscle was activated in 62% of responses in voluntary smile (15% strong, 47% weak) and in 45% of responses in spontaneous smile (13% strong, 32% weak). No significant difference was found for males vs females or closed vs open mouth smiles. There was no significant difference in responses between voluntary and spontaneous smiles for the temporalis and masseter muscles, and their use in voluntary smile did not predict activity in spontaneous smile. CONCLUSIONS: Our study has shown that masseter and temporalis are active in a high proportion of healthy adults during voluntary and spontaneous smiles. Further work is required to determine the relationship between preoperative donor muscle activation and postoperative spontaneous smile, and whether masticatory muscle activity can be upregulated with appropriate training.


Asunto(s)
Electromiografía , Músculo Masetero/fisiología , Sonrisa/fisiología , Músculo Temporal/fisiología , Adulto , Anciano , Estudios de Cohortes , Femenino , Voluntarios Sanos , Humanos , Masculino , Persona de Mediana Edad
17.
Arch Oral Biol ; 90: 113-124, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29597061

RESUMEN

OBJECTIVE: Mammalian mastication serves to improve intra-oral food reduction. Insufficient food reduction creates potential swallowing problems, whereas over-reduction may accelerate tooth wear and increase feeding time. Either extreme has consequences. The study's objectives were: (1) to study the relationship between food reduction, number of chews in a sequence, and chewing rate, (2) to study how controlling the number of chews and chewing rate variability affects food reduction, and (3) to assess how dentoskeletal morphological and electromyographical (EMG) characteristics impact food reduction. DESIGN: Twenty-three healthy, fully-dentate adults chewed a standardized test food under three conditions: (1) no control, (2) number of chews controlled, and (3) number of chews and chewing rate controlled. EMG activity was sampled from masseter and temporalis muscles bilaterally. Demographic, occlusal contact area in maximum intercuspation, and cephalometric data were obtained. RESULTS: In uncontrolled conditions, food reduction and bout duration varied more than expected across subjects. Subjects with poor reduction under controlled conditions were those with poor reduction under uncontrolled conditions. Only occlusal contact area correlated with chewing performance under uncontrolled conditions. Chewing cycle duration, EMG burst duration, and EMG peak onset latency increased when the number of chews was restricted. EMG amplitude, a surrogate for bite force, increased in tasks controlling the number of chews and chewing rate. Chewing rate variability was difficult to diminish below individual-specific levels. CONCLUSIONS: Results: provided evidence that bite force, chewing rate, chewing performance and chewing bout duration reflected individual preferences. Future work will determine whether similar findings occur among other mammals.


Asunto(s)
Masticación/fisiología , Músculos Masticadores/fisiología , Músculo Temporal/fisiología , Adolescente , Adulto , Fuerza de la Mordida , Cefalometría , Oclusión Dental , Electromiografía , Femenino , Alimentos , Voluntarios Sanos , Humanos , Masculino , Músculo Masetero/fisiología , Contracción Muscular/fisiología , Tamaño de la Partícula , Factores de Tiempo , Adulto Joven
18.
Arch Oral Biol ; 89: 37-43, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29438907

RESUMEN

OBJECTIVE: This study sought to examin effects of age and tongue exercise on the posterior digastric (opener) and the temporalis (closer). We hypothesized 1) age would result in differing morphological (cross sectional area) and biochemical (myosin heavy chain isoform) components of these muscles; 2) tongue exercise would result in coactivation of these muscles inducing a decrease in age-related differences between age groups. DESIGN: Young adult (9 months) and old (32 months) Fischer 344 Brown Norway rats were randomized into a tongue exercise or control group. Post-training, posterior digastric and temporalis muscles were harvested and analyzed using: 1) Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) to assess percent myosin heavy chain (MyHC) content; 2) Immunohistochemical staining to determine cross sectional area (CSA). RESULTS: A larger proportion of slowly contracting MyHC isoforms in the posterior digastric and temporalis muscles were found in old. No significant main effects for age or exercise in fiber size were found in posterior digastric muscle. An interaction between age and exercise for temporalis cross sectional area indicated the old exercise group had smaller average cross sectional area than all other groups. CONCLUSIONS FINDINGS: suggest that: 1) Increasing age induces biochemical changes in muscles of the jaw, specifically showing an increase the proportion of slower contracting MyHC isoforms; 2) Increasing age and tongue exercise induce a reduction in muscle fiber cross sectional area in the temporalis muscle only. However, continued study of these cranial muscle systems is warranted to better understand these changes that occur with age and exercise.


Asunto(s)
Envejecimiento/fisiología , Cadenas Pesadas de Miosina/fisiología , Músculos del Cuello/fisiología , Músculo Temporal/fisiología , Lengua/fisiología , Animales , Inmunohistoquímica , Masculino , Fibras Musculares Esqueléticas , Cadenas Pesadas de Miosina/química , Músculos del Cuello/química , Isoformas de Proteínas , Ratas , Ratas Endogámicas F344 , Músculo Temporal/química , Lengua/química
19.
Am J Phys Anthropol ; 166(2): 401-407, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29446440

RESUMEN

OBJECTIVES: Among the diagnostic features of the Neandertal mandible are the broad base of the coronoid process and its straight posterior margin. The adaptive value of these (and other) anatomical features has been linked to the Neandertal's need to cope with a large gape. The present study aims to test this hypothesis with regard to the morphology of the coronoid process. MATERIALS AND METHODS: This admittedly simple, intuitive hypothesis was tested here via a comparative finite-element study of the primitive versus modified state of the coronoid process, using two-dimensional models of the mandible. RESULTS: Our simulations demonstrate that a large gape has an unfavorable effect on the primitive state of the coronoid process: the diagonal, almost horizontal, component of the temporalis muscle resultant (relative to the long axis of the coronoid process) bends the process in the sagittal plane. Furthermore, we show that the modification of the coronoid process morphology alone reduces the process' bending in a wide gape increasing the compression to tension ratio. DISCUSSION: These results provide indirect evidence in support of the hypothesis that the modification of the coronoid process in Neandertals is necessary for enabling their mandible to cope with a large gape.


Asunto(s)
Mandíbula/anatomía & histología , Mandíbula/fisiología , Hombre de Neandertal/anatomía & histología , Hombre de Neandertal/fisiología , Animales , Antropología Física , Antropometría , Análisis de Elementos Finitos , Masticación/fisiología , Músculo Temporal/fisiología
20.
Anat Rec (Hoboken) ; 301(2): 311-324, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29330947

RESUMEN

Analyses of masticatory muscle architecture-specifically fascicle length (FL; a correlate of muscle stretch and contraction speed) and physiological cross-sectional area (PCSA; a correlate of force)-reveal soft-tissue dietary adaptations. For instance, consumers of large, soft foods are expected to have relatively long FL, while consumers of obdurate foods are expected to have relatively high PCSA. Unfortunately, only a few studies have analyzed these variables across large primate samples-an order of particular interest because it is our own. Previous studies found that, in strepsirrhines, force variables (PCSA and muscle masses; MM) scale with isometry or slight positive allometry, while the body size corrected FL residuals correlate with food sizes. However, a study of platyrrhines using different methods (in which the authors physically cut muscles between fascicles) found very different trends: negative allometry for both the stretch and force variables. Here, we apply the methods used in the strepsirrhine study (chemical dissection of fascicles to ensure full length measurements) to reevaluate these trends in platyrrhines and extend this research to include catarrhines. Our results conform to the previous strepsirrhine trends: there is no evidence of negative allometry in platyrrhines. Rather, in primates broadly and catarrhines specifically, MM and PCSA scale with isometry or positive allometry. When examining size-adjusted variables, it is clear that fascicle lengths (especially those of the temporalis muscle) correlate with diet: species that consume soft, larger, foods have longer masticatory fiber lengths which would allow them to open their jaws to wider gape angles. Anat Rec, 301:311-324, 2018. © 2018 Wiley Periodicals, Inc.


Asunto(s)
Dieta , Maxilares/anatomía & histología , Masticación/fisiología , Músculos Masticadores/anatomía & histología , Primates/anatomía & histología , Músculo Temporal/anatomía & histología , Animales , Tamaño Corporal , Maxilares/fisiología , Músculos Masticadores/fisiología , Primates/fisiología , Músculo Temporal/fisiología
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