Effect of laterotrusive occlusal scheme on chewing duration, external intercostal muscular activity, heart rate, and oxygen saturation.

Objective: To evaluate the effect of the laterotrusive occlusal scheme on chewing duration, external intercostal (EIC) electromyographic (EMG) activity, heart rate (HR), and oxygen saturation (OS) during different tasks in the upright seated position.Methods: Fifty young participants, 25 with canine guidance and 25 with group function, were included. Chewing duration, bilateral EIC EMG activity, HR, and OS were recorded during the following tasks: 1) chewing until swallowing threshold; 2) laterotrusive teeth grinding.Results: Chewing duration, bilateral EIC EMG activity, HR, and OS showed no significant differences between the two laterotrusive occlusal schemes during the tasks studied.Conclusion: These results suggest that chewing duration, EIC muscle activity, HR, and OS were not significantly influenced by the laterotrusive occlusal scheme. Therefore, when a modification of the laterotrusive occlusal scheme is needed during oral rehabilitation or orthodontic treatment, canine guidance or group function should not significantly change EMG activity of EIC muscles.

Enfermedades cardio-metabólicas en el embarazo: revisión sobre diagnóstico, tratamiento y proyección del riesgo cardiovascular a largo plazo / Cardio-metabolic diseases in pregnancy: a review on diagnosis, treatment and projection of long-term cardiovascular risk

Las enfermedades cardiovasculares representan la mayor causa de morbimortalidad a nivel mundial. Si bien presenta un descenso en la población general, en las mujeres tiende a mantenerse estable la prevalencia de enfermedad coronaria. Varios factores propios de la mujer predisponen a que esto ocurra, incluyendo el embarazo, mediado tanto por los cambios hematológicos y cardiovasculares característicos de la gestación; como por patologías asociadas, principalmente trastornos hipertensivos del embarazo y diabetes gestacional. Su presencia se ha asociado fuertemente a la aparición a futuro de otras patologías de alto riesgo cardiovascular como hipertensión crónica, dislipidemia y diabetes mellitus. Dado el impacto que esto representa, se hace imperante la identificación de grupos de alto riesgo y la implementación de medidas preventivas, así como de diagnóstico precoz y tratamientos adecuados con el fin de disminuir complicaciones materno-fetales en las etapas perinatal y posparto.

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Although there is a decrease in general population, the prevalence of coronary heart disease remains stable in women. Several factors typical of womenkind predispose to cardiovascular disease, including pregnancy, mediated by hematological and cardiovascular changes characteristic of it; and by associated pathologies, mainly hypertensive disorders and diabetes. The presence of these diseases has been strongly associated with future presence of other conditions of high cardiovascular risk such as chronic hypertension, dyslipidemia and diabetes mellitus. Given this impact, the identification of high-risk groups and the implementation of preventive measures, as well as early diagnosis and adequate treatment in order to reduce both maternal and fetal complications in perinatal and postpartum stages becomes imperative.

Impacto del uso de edulcorantes no calóricos en la salud cardiometabólica / Impact of the use of calorie-free sweeteners on cardiometabolic health

Resumen Los edulcorantes son sustancias capaces de sustituir el dulzor característico del azúcar y en la actualidad son muy utilizados por su capacidad edulcorante, superior a la de la sacarosa, lo que hace que se requieran menos cantidades de estos en los alimentos. Esta característica ha despertado el interés de muchos investigadores por sus posibles beneficios para pacientes con diabetes y obesidad, entre otras morbilidades. En este artículo se hace una revisión acerca de la relación de los edulcorantes no calóricos con el control del peso, el síndrome metabólico y la aparición de eventos cardiovasculares.

Abstract Sweeteners are substances capable of replacing the characteristic sweetness of sugar. They are currently widely used for their sweetener capacity, which is greater than that of saccharose, and which means lower quantities are required in foods. This characteristic has aroused the interest of many researchers due to their possible benefits in diabetes and obesity, as well as in other disorders. A review is presented in this article on the relationship between calorie-free sweeteners and weight control, metabolic syndrome, and the appearance of cardiovascular events.

Awake teeth grinding in participants with canine guidance or group function: Effect on diaphragm EMG activity, heart rate, and oxygen saturation.

Objective: To compare the effect of canine guidance or group function on diaphragm activity, heart rate, and oxygen saturation during awake teeth grinding at different body positions. Methods: Fifty healthy participants, 25 with canine guidance and 25 with group function, were included. Bilateral electromyographic (EMG) recordings of the diaphragm (DIA) during awake teeth grinding were performed in standing, seated upright, and right lateral decubitus positions. Simultaneously, heart rate and oxygen saturation were measured. Results: EMG activity of the DIA muscle was similar in the working side and non-working side between participants with canine guidance and group function in the different body positions studied. The heart rate and oxygen saturation showed no significant differences between the two groups. Conclusion: EMG activity of the DIA muscle, the heart rate, and oxygen saturation during teeth grinding are not significantly influenced by the type of laterotrusive occlusal scheme.

Effect of breathing type on electromyographic activity of respiratory muscles during tooth clenching at different decubitus positions.

OBJECTIVE: To compare the effect of breathing type on electromyographic (EMG) activity of respiratory muscles during tooth clenching at different decubitus positions. METHODS: Forty young men participants were included, 11 with upper costal, 9 with mixed, and 20 with costo-diaphragmatic breathing type. EMG recordings of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM), and latissimus dorsi (LAT) muscles during tooth clenching in the intercuspal position were performed in dorsal, left lateral, and ventral decubitus positions. RESULTS: DIA EMG activity was higher in subjects with upper costal or mixed than with costodiaphragmatic breathing type (p = 0.006; 0.021, respectively), whereas it was similar between upper costal and mixed breathing types. EIC, SCM, and LAT activity was similar among breathing types. CONCLUSION: Higher DIA activity would be a risk factor to exceed the adaptive capability of healthy subjects with upper costal or mixed breathing type.

Síncope en Urgencias: Aproximación Clínica / Syncope in Emergency Room: Clinical Approach

Resumen El síncope es un síntoma definido como una perdida transitoria de la conciencia de inicio rápido, de corta duración y con recuperación completa y espontánea. Los picos de presentación son en la adolescencia y posterior a la 8va década de la vida. La incidencia de sincope representa del 1% al 3% de los ingresos hospitalarios y se asocia con comorbilidad cardiovascular y farmacoterapia cardiovascular siendo en los adultos mayores una causa importante de morbimortalidad. La incidencia acumulada de síncope en las mujeres es casi el doble que en los hombres. Su aparición está explicada por una disminución en el flujo sanguíneo cerebral producto del descenso del gasto cardiaco ya sea por una caída en la presión arterial sistólica por debajo de 60 mmHg o disminución en la resistencia periférica. El síncope de divide en 3 grupos: 1) Síncope reflejo, en el cual se produce un cambio repentino en la actividad del sistema nervioso autónomo que lleva a la caída en la presión arterial; 2) Síncope secundario a hipotensión ortostática, en donde la actividad simpática eferente no proporciona una suficiente vasoconstricción y 3) Síncope de causa cardiopulmonar, caracterizado por una disminución brusca y repentina del gasto cardiaco producto de arritmias o enfermedades cardiacas estructurales. Dependiendo de la causa del síncope se puede o no presentar pródromo, que más comúnmente se compone de diaforesis, calor y rubor. La verdadera pérdida de la conciencia por lo general dura menos de un minuto, aunque algunos pacientes pueden tardar varios minutos en recuperar plenamente la conciencia. Por ello el diagnóstico está basado en una buena historia clínica con un examen físico completo. El tratamiento depende de la causa y el mecanismo de los episodios sincopales. Adicionalmente se deben tener como objetivos el aliviar los síntomas y mejorar el pronóstico, lo cual implica evitar o reducir las recurrencias.

Abstract Syncope is a symptom defined as a transient loss of consciousness, of rapid onset, of short duration and with complete and spontaneous recovery. Peaks of presentation are in adolescence and after the 8th decade of life. The incidence of syncope represents 1% to 3% of hospital admissions and is associated with cardiovascular comorbidity and cardiovascular pharmacotherapy, being an important cause of morbidity and mortality in the elderly. The accumulative incidence of syncope in women is almost double than in men. Its onset is explained by a decrease in cerebral blood flow due to the decrease in cardiac output, whether due to a drop in systolic blood pressure below 60 mmHg or a decrease in peripheral resistance. The syncope is divides into 3 groups: 1) Reflex syncope, in which there is a sudden change in the autonomic nervous system activity that leads to a drop in blood pressure; 2) Syncope secondary to orthostatic hypotension, where sympathetic efferent activity does not provide sufficient vasoconstriction; and 3) Syncope of cardiopulmonary cause, characterized by an abrupt and sudden decrease in cardiac output due to arrhythmias or structural heart diseases. Depending on the cause of syncope it may or may not present prodrome, which is more commonly composed of diaphoresis, heat and flushing. True loss of consciousness usually lasts less than a minute, although some patients may take several minutes to fully regain consciousness. Therefore, the diagnosis is based on a good medical history with a complete physical examination. Treatment depends on the cause and mechanism of syncopal episodes. In addition, the goals should be to alleviate symptoms and improve prognosis, which means avoiding or reducing recurrences.

Síndrome de Locked-In: Reporte de Caso y Revisión de Literatura / Locked-In Syndrome: Case Report And Review Of Literature

RESUMEN El Síndrome de Locked-In también conocido como Síndrome de Enclaustramiento, de Deseferentización o de Encerramiento, se definió por primera vez en 1966 por Plum y Posner. Las causas pueden agruparse en vasculares y no vasculares, siendo las primeras las más frecuentes. Clínicamente este síndrome se caracteriza porque la conciencia y el estado de vigila están conservados, pero existe cuadriplejía, anartria, disfagia y dificultad para coordinar la mecánica ventilatoria, representando las complicaciones pulmonares la principal causa de muerte. En la mayoría de los casos, el paciente conserva la movilidad ocular vertical, por tanto, el único método de comunicación es por medio de parpadeo ocular y movimientos verticales oculares. A continuación, se hace la presentación de un caso y revisión de la literatura con los aspectos fisiopatológicos, clínicos, diagnósticos y terapéuticos más relevantes.

ABSTRACT Locked-In Syndrome, also known as Enclaustration, Deseferentization, or Enclosure Syndrome, was first defined in 1966 by Plum and Posner. Causes can be grouped into vascular and non-vascular, the former being the most frequent. Clinically this syndrome is characterized by consciousness and the state of watch conserved, but there is quadriplegia, anartria, dysphagia and difficulty to coordinate the ventilatory mechanics, representing pulmonary complications the main cause of death. In most cases, the patient retains vertical eye mobility, so the only method of communication is through eye blinking and vertical eye movements. Next, a case presentation and review of the literature with the most relevant pathophysiological, clinical, diagnostic and therapeutic aspects is done.

Infiltración testicular por leucemia linfoblástica aguda, presentándose como masa testicular: reporte de un caso / Testicular infiltration due to acute lymphoblastic leukemia presented as a testicular mass: a case report

La leucemia linfoblástica aguda es una neoplasia predominante en pediatría, corresponde al 11% de las leucemias. En Colombia hay una incidencia anual en adultos de 1 por cada 100.000 habitantes. La recaída testicular es rara alcanzando solo del 0.9 a 8.8% de todos los casos y representa un signo de recurrencia que puede ser confundida con otros padecimientos testiculares. Se reporta el caso de un paciente masculino de 23 años de edad, con cuadro de 2 meses de evolución consistente en dolor y aumento de tamaño testicular, posterior a trauma, con antecedente de leucemia linfoblástica aguda tratada hace 4 años. Se realiza ecografía testicular que sugiere hidrocele a tensión. Es llevado a cirugía, donde se aprecia testículo con características neoplásicas por lo cual se realiza orquiectomía. Resultado de anatomía patológica concluye masa 12 cm correspondiente a infiltración por leucemia aguda, CD10 y CD34 positivo y Tdt negativo. El testículo es considerado santuario de células leucémicas, sin embargo excepcionalmente puede observarse formación de una masa simulando un tumor testicular

Acute lymphoblastic leukemia is a common pediatric neoplasia, comprising 11% of all leukemias. In Colombia, the annual incidence in adults is 1 out of 100,000 people. Testicular relapse is rare (accounting for only 0.9-8.8% of all cases) and represents a sign of recurrence which can be confused with other testicular conditions. We report the case of a 23-year- old male with testicular pain and swelling for 2 months after a trauma, and a history of acute lymphoblastic leukemia treated 4 years before. A testicular ultrasound suggested tension hydrocele. The patient was taken to surgery where a testis with neoplastic features was observed. Therefore, an orchiectomy was performed. The pathological anatomy revealed a 12-cm mass consisting of infiltration by leukemic cells, showing a positive expression for CD19, CD10, and a negative expression for TdT. The testes are considered a sanctuary site for leukemic cells. However, the formation of a mass that mimic a testicular tumor may exceptionally be observed

Effects of breathing type on electromyographic activity of respiratory muscles at different body positions.

AIM: To compare the effect of breathing type on the activity of respiratory muscles at different body positions. METHODOLOGY: Two groups of 20 subjects each, one with upper costal and the other with costodiaphragmatic breathing, were studied. Electromyographic activity of sternocleidomastoid (SCM), diaphragm (DIA), external intercostal (EIC), and latissimus dorsi (LAT) muscles was recorded at standing and lateral decubitus positions during swallowing and maximal voluntary clenching. RESULTS: All muscles showed higher activity during standing in upper costal breathing subjects except the SCM muscle. EIC activity was higher during standing in the costodiaphragmatic breathing group. Subjects with upper costal breathing showed higher DIA activity than subjects with costodiaphragmatic breathing at both body positions and higher SCM activity at lateral decubitus position, whereas, EIC activity was only higher during swallowing. CONCLUSIONS: Subjects with upper costal breathing presented higher respiratory effort than subjects with costodiaphragmatic breathing, being most prominent at the lateral decubitus position.

Comparison of muscle activity between subjects with or without lip competence: Electromyographic activity of lips, supra- and infrahyoid muscles.

AIM: This study compares the electromyographic (EMG) activity of the muscles from the lips and hyoid bone in subjects with or without lip competence. METHODOLOGY: Two groups of 20 subjects each, with or without lip competence were studied. EMG activity of the superior orbicularis oris (SOO), inferior orbicularis oris (IOO), suprahyoid (SH) and infrahyoid (IH) muscles was recorded with the subject seated in the upright position during the following tasks: (1) at rest; (2) speaking; (3) swallowing; (4) forced deep breathing; (5) maximal voluntary clenching; and (6) chewing. RESULTS: EMG activity was significantly higher in subjects without competent lips than with competent lips in the SOO and IOO muscles during tasks 3 and 4, SOO during task 2 and IOO during task 6. EMG activity was similar in the SOO and IOO muscles during tasks 1 and 5, SOO during task 6 and IOO during task 2. Activity of the SH and IH muscles was similar in both groups for all tasks. CONCLUSIONS: Higher activity in subjects without competent lips implies a higher muscular effort due to the requirement of lip sealing during functional activities. Hyoid muscular activity was not modified by the presence or absence of lip competence.

Eriptosis: mecanismos moleculares y su implicación en la enfermedad aterotrombótica / Eryptosis: molecular mechanisms and their implications in atherothrombotic disease

Introducción: La eriptosis se ha descrito como el proceso de muerte celular programada en el eritrocito antes de la senectud. Puede desencadenarse en situaciones como: el estrés osmótico, el estrés oxidativo, la exposición a metales pesados, entre otros factores. Diversos estudios sugieren que los eritrocitos pueden desempeñar un papel activo en la hemostasia normal o anormal en ciertas condiciones en las que se produce perturbación de la membrana de estas células. Objetivo: Describir los mecanismos involucrados en la eriptosis y su estrecha relación con los procesos de adhesión a la pared vascular que conllevan a la enfermedad trombótica. Método: Se hizo una revisión narrativa a partir de la literatura encontrada en las bases de datos PubMed y Science Direct utilizando las palabras claves. Se seleccionaron 51 artículos originales, 20 revisiones de la literatura y un estudio de casos, que se ajustaban a las exigencias del objetivo. Se revisaron los resúmenes de forma separada e independiente. Seguidamente se buscaron las publicaciones en el texto completo para la revisión. Conclusiones: La eriptosis se caracteriza por la disminución del volumen celular, la vesiculación y la translocación del fosfatidil serina hacia la superficie externa de la membrana plasmática. Las alteraciones en la distribución de los fosfolípidos favorecen los procesos de adhesión celular a la pared vascular, conllevando al deterioro de la microcirculación, lo cual puede ocasionar importantes trastornos a nivel cardiovascular. La comprensión y el esclarecimiento de la eriptosis pueden ser esenciales para la búsqueda de nuevas dianas terapéuticas, encaminadas a ofrecer otras alternativas farmacológicas en el tratamiento de la enfermedad cardiovascular.

Introduction: Eryptosis has been described as programmed process of cellular death in erythrocytes before old age. It can be triggered, among other factors, by situations such as osmotic stress, oxidative stress or exposure to heavy metals. Several studies suggest that erythrocytes can play an active role in normal or abnormal haemostasis in certain conditions where the membrane of these cells is perturbed. Objetive: To describe the mechanisms involved in eryptosis and their close relationship with the processes of adhesion to the vascular wall that entail the thrombotic disease. Methods: A narrative review was carried out from the literature found in data base PubMed and Science Direct by using the key words. 51 original articles, 20 literature reviews and one case study complying with the requirements were selected. Abstracts were reviewed separately and independently. Complete publications were then located for review. Conclusions: Eryptosis is characterised by the decrease in cell volume, the vesiculation and the translocation of phosphatidylserine towards the outer surface of the plasma membrane. Disorders in the distribution of the phospholipids favour processes of cell adhesion to the vascular wall, causing impairment of microcirculation, which can result in important cardiovascular diseases. Understanding and clarifying eryptosis could be essential for finding new therapeutic targets, aimed at offering other pharmacological alternatives for the treatment of cardiovascular diseases.

Natural mediotrusive contact: does it affect the masticatory and neck EMG activity during tooth grinding?

OBJECTIVES: There is scarce knowledge regarding the influence of a natural mediotrusive contact on mandibular and cervical muscular activity. The purpose of this study was to analyze the EMG activity of the anterior temporalis (AT) and sternocleidomastoid (SCM) muscles during awake grinding in healthy subjects with or without a natural mediotrusive occlusal contact. METHOD: Fifteen subjects with natural mediotrusive occlusal contact (Group 1) and 15 subjects without natural mediotrusive occlusal contact (Group 2) participated. Bilateral surface EMG activity of AT and SCM muscles was recorded during unilateral eccentric or concentric tooth grinding tasks. EMG activity was normalized against the activity recorded during maximal voluntary clenching in intercuspal position (IP) for AT muscles and during maximal intentional isometric head-neck rotation to each side, for SCM muscles. RESULTS: EMG activity of AT and SCM muscles showed no statistical difference between groups. EMG activity of AT muscle was higher in the working side (WS) than in the non-WS (NWS) in Group 1 during concentric grinding (0.492 vs 0.331, p = 0.047), whereas no difference was observed in Group 2. EMG activity of SCM was similar between working and NWSs in both groups and tasks. Asymmetry indexes (AIs) were not significantly different between groups. DISCUSSION: These findings in healthy subjects support the assumption that during awake tooth grinding, central nerve control predominates over peripheral inputs, and reinforce the idea of a functional link between the motor-neuron pools that control jaw and neck muscles.

Effect of natural mediotrusive contact on electromyographic activity of jaw and cervical muscles during chewing.

OBJECTIVE: This study evaluated the effect of a natural mediotrusive contact on the electromyographic (EMG) activity of the anterior temporalis and sternocleidomastoid muscles during chewing in healthy subjects. MATERIALS AND METHODS: The study sample included two groups of 15 subjects each (Group 1: with natural mediotrusive contact; Group 2: without natural mediotrusive contact). Bilateral surface EMG activity was recorded on anterior temporalis and sternocleidomastoid muscles during unilateral chewing of a half cookie and unilateral chewing of a piece of apple. Anterior temporalis and sternocleidomastoid muscle activity was normalized against activity recorded during maximal voluntary clenching in intercuspal position and maximal intentional isometric head-neck rotation to each side, respectively. The partial and total asymmetry indexes were also calculated. Data were analyzed using Mann-Whitney, Wilcoxon and unpaired t-test. RESULTS: EMG activity of anterior temporalis and sternocleidomastoid muscles showed no significant difference between the groups. EMG activity of anterior temporalis was similar between working and non-working sides during chewing in both groups. EMG activity of sternocleidomastoid muscle was higher in the working side than in the non-working side in Group 2 subjects. Asymmetry indexes were not significantly different between groups. CONCLUSIONS: The similar EMG pattern and asymmetry indexes observed suggest the predominance of central nervous control over peripheral inputs on anterior temporalis and sternocleidomastoid motor neuron pools.

The effect of a mandibular advancement appliance on cervical lordosis in patients with TMD and cervical pain.

AIMS: A preliminary study to compare cervical lordosis by means of cervical cephalometric analysis, before and after six months of continuous mandibular advancement appliance (MAA) use, and to show how physical therapy posture re-education would improve the cervical lordosis angle. METHODOLOGY: Twenty-two female patients with temporomandibular disorders (TMD) and cervical pain with lordosis <20° were included. Patients had to have a muscle pain history for at least six months, and with an intensity ⩾6, measured by means of a visual analog scale (a horizontal 0-10 numeric rating scale with 0 labeled as 'no pain' and 10 as 'worst imaginable pain'). Patients had to present the angle formed by the posterior tangents to C2 and C7 of equal or less than 20°. Cephalometric and clinical diagnostics were performed initially (baseline) and at the end of the study period (six months). During the third month with MAA treatment, a physical therapist evaluated the postural deficit and performed a program of postural re-education. Angular and linear dimension data presented a normal distribution (P>0·05; Shapiro Wilk Test), so the paired comparison of the cephalometric measurements was made by t-test for dependent samples. RESULTS: Angle 1 (OPT/7CVT); angle 3 (CVT/EVT) and angle 4 (2CL/7CL) showed a significant increase in the cervical lordosis. Angle 2 (MGP/OP), angle 5 (HOR/CVT) and the distances C0-C2 and Pt-VER, presented no significant changes. CONCLUSIONS: The increase in cervical lordosis implies that six months of continuous MAA use, together with a program of postural re-education, promotes the homeostasis of the craniocervical system.

The occlusal appliance effect on myofascial pain.

There are limited studies about the effects of occlusal appliance (OA) after three months of use. This study aimed to compare myofascial pain (MP) according to RDC/TMD, craniocervical relationships (CR) and masseter and temporalis bilateral electromyographic (EMG) activity, before and after three months of occlusal appliance use. Nineteen patients participated in this study. Cephalometric and RDC/TMD diagnostics were performed previously (baseline) and at the end of the study period (three months). EMG recordings at clinical mandibular rest position (MRP), during swallowing of saliva (SW) and during maximum voluntary clenching (MVC) were performed as follows: after one hour of use of an OA; after three months of using the OA for a minimum of 16 hours each day; and immediately after removal from the mouth. MP was relieved in all patients at the end of the study period. CR did not change significantly between baseline and after removal of the OA at the end of the study period. EMG activity during MRP, SW, and MVC decreased in both muscles after one hour using the OA and maintained the same level for the three-month period. When comparing baseline versus final EMG activity without OA, a significant decrease was only observed in the masseter muscle. The results observed in the present study are relevant to clinicians because they imply that the therapeutic effect of OA does not significantly affect the homeostasis of the craniocervical system.

Electromyographic activity during awake tooth grinding tasks at different jaw posture in the sagittal plane.

OBJECTIVE: The goal of this study was to evaluate the electromyographic (EMG) activity of the anterior temporalis, suprahyoid, infrahyoid and trapezius muscles during tooth grinding at different jaw posture tasks. MATERIALS AND METHODS: Participants were 30 healthy subjects with natural dentition, bilateral molar support and incisive protrusive guidance. Bipolar surface electrodes were located on the right side of the subject. EMG recordings were performed in the following tasks: (A) Eccentric grinding from intercuspal position to protrusive edge-to-edge contact position; (B) concentric grinding from protrusive edge-to-edge contact position to intercuspal position; (C) eccentric grinding from intercuspal position to the maximum voluntary retrusive position; and (D) concentric grinding from the maximum voluntary retrusive position to intercuspal position. The results were analyzed statistically by Friedman test and Wilcoxon signed rank-sum test. RESULTS: EMG activity in the anterior temporalis and infrahyoid muscles was significantly higher during task C than the other tasks. EMG activity in the suprahyoid muscles was significantly higher during task C than task D. EMG activity in the trapezius muscle was significantly higher during task C than tasks A and B. CONCLUSIONS: The higher EMG activity recorded in task C could become important when its frequency, duration and magnitude are enough to exceed the adaptation capability of the individual.

Bilateral supra- and infrahyoid EMG activity during eccentric jaw clenching and tooth grinding tasks in subjects with canine guidance or group function.

This study compares the effect of tooth clenching and grinding on supra- and infrahyoid electromyographic (EMG) activity during different laterotrusive jaw posture tasks. The study included 30 healthy subjects with natural dentition and bilateral molar support, 15 with bilateral canine guidance and 15 with bilateral group function. Bipolar surface electrodes were located on the left and right supra- and infrahyoid muscles. EMG activity was recorded during the following tasks: A. eccentric grinding from intercuspal position to the right lateral edge-to-edge contact position; B. clenching in right edge-to-edge lateral contact position; C. concentric grinding from right lateral edge-to-edge contact position to intercuspal position. EMG activity was not significantly different between tasks on the working side, nonworking side, or between both sides, in subjects with canine guidance or group function (Wilcoxon rank-sum test). When comparing EMG activity by occlusal scheme, no significant differences were found either on the working side or the non-working side (Mann-Whitney U test). This result suggests that supra- and infrahyoid EMG activity in its predominant stabilizing role of the hyoid bone is not significantly modified by the type of laterotrusive occlusal scheme.

Anterior temporalis and suprahyoid EMG activity during jaw clenching and tooth grinding.

The aim of this study was to evaluate the anterior temporalis and suprahyoid electromyographic (EMG) activity during jaw clenching and tooth grinding at different jaw posture tasks. The study included 30 healthy subjects with natural dentition and bilateral molar support, incisive protrusive guidance and bilateral laterotrusive canine guidance. Bipolar surface electrodes were located on the right anterior temporalis and suprahyoid muscles. Three EMG recordings in the standing position were performed in the following tasks: C. clenching in the intercuspal position (IP); P1. eccentric grinding from IP to protrusive edge-to-edge contact position; P2. clenching in protrusive edge-to-edge contact position; P3. concentric grinding from protrusive edge-to-edge contact position to IP; L1. eccentric grinding from IP to laterotrusive edge-to-edge contact position; L2. clenching in laterotrusive edge-to-edge contact position; L3. concentric grinding from laterotrusive edge-to-edge contact position to IP. EMG activity during protrusive and laterotrusive tasks was lower than intercuspal position in the anterior temporalis, whereas an opposite EMG pattern was observed in the suprahyoid muscles activity, excepting recorded activity in L2 (mixed model with unstructured covariance matrix). Anterior temporalis activity was higher during P3 than P1 and P2 tasks and during L3 than L1 and L2 tasks, whereas in the suprahyoid muscles, activity was higher during P1 than P2 tasks and during L1 than L2 and L3 tasks. These results could support the idea of a differential modulation of the motor neuron pools of anterior temporalis and suprahyoid muscles of peripheral and/or central origin.

[Olfactory sensory perception]. / Sensopercepción olfatoria: una revisión.

The five senses have had a fundamental importance for survival and socialization of human beings. From an evolutionary point of view the sense of smell is the oldest. This sense has a strong representation within the genome, allowing the existence of many types of receptors that allow us to capture multiple volatile odor producing molecules, sending electrical signals to higher centers to report the outside world. Several cortical areas are activated in the brain, which are interconnected to form an extensive and complex neural network, linking for example, areas involved with memory and emotions, thus giving this sense of perceptual richness. While the concept of flavor is largely related to the sense of taste, smell provides the necessary integration with the rest of the senses and higher functions. Fully understanding the sense of smell is relevant to health professionals. Knowing the characteristics of the receptors, the transduction processes and convergence of information in the higher centers involved, we can properly detect olfactory disorders in our patients.