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1.
Cranio ; 29(4): 255-60, 2011 Oct.
Article in English | MEDLINE | ID: mdl-22128664

ABSTRACT

The clinical observation of the incisors overbite is the most common form used to evaluate the occlusal vertical dimension (OVD); however, this technique offers poor information about the compression state of the TMJ. In order to obtain such information, it is necessary to evaluate the electrical activity of the elevator muscles using surface electromyography (EMG). In case of a compressive irritation of the joint receptors, the trigeminal nucleus returns an inhibitory motor response of the elevator muscles that can be measured. The Learreta's EMG decompression test is done by measuring the EMG response of the masticatory muscles at maximal occlusion in four different OVD positions in such a way that the reduction of the TMJ pressure, and subsequently, relief of the inhibitory motor response can be studied. The aim of this study is to illustrate this technique, its clinical use and its limitations.


Subject(s)
Electromyography/methods , Masticatory Muscles/physiopathology , Temporomandibular Joint Disorders/diagnosis , Vertical Dimension , Biomechanical Phenomena , Bite Force , Electromyography/instrumentation , Humans , Mandible/pathology , Masseter Muscle/innervation , Masseter Muscle/physiology , Masticatory Muscles/innervation , Motor Neurons/physiology , Muscle Contraction/physiology , Muscle Fibers, Skeletal/physiology , Neck Muscles/innervation , Neck Muscles/physiology , Neural Inhibition/physiology , Nociceptors/physiology , Periodontal Ligament/innervation , Periodontal Ligament/physiology , Pressure , Proprioception/physiology , Temporal Muscle/innervation , Temporal Muscle/physiology , Temporomandibular Joint/innervation , Trigeminal Nuclei/physiopathology
2.
Actas odontol ; 2(1): 51-58, ene.-jun. 2005.
Article in Spanish | LILACS | ID: lil-520839

ABSTRACT

Los mecanorreceptores del ligamento periodontal son del tipo SA II, es decir receptores tónicos, de adaptación lenta, que envíanpotenciales de acción tanto en la fase estática como dinámica durante la aplicación de fuerzas sobre los dientes. En el sectoranterior de la arcada dentaria, los receptores involucrados en regular la función de sostener un alimento presentan un comportamientohiperbólico, con máxima capacidad discriminativa en el rango de fuerzas de 0 a 1,2 N. Los receptores involucrados en laregulación del corte de alimentos presentan un comportamiento lineal, respondiendo efectivamente hasta los 22 N, pero conmenor capacidad discriminativa frente a fuerzas de baja intensidad. El sector posterior es la zona de la arcada en la que se ejerceuna mayor fuerza masticatoria. Los mecanorreceptores en esta zona son menos sensibles a la aplicación de la carga. Los dientesanteriores están involucrados en el sostén y corte de los alimentos, mientras que los posteriores están adaptados para la trituración.La ausencia de aferencias sensoriales a partir de los mecanorreceptores periodontales resulta en un control distorsionado delos movimientos masticatorios.


Human periodontal mechanoreceptors are SA II type, tonic or slowly adapting receptors, which fire action potentials during thestatic and dynamic phases of stimulus application. In the anterior teeth, receptors involved in holding fragments of food, displayan hyperbolic stimulus-response curve, with a maximum discriminative capacity in the range of forces between 0 - 1,2 N. Thereceptors involved in splitting food present a lineal stimulus-response curve up to 22 N, but with less discriminative capacity oflow intensity forces. In the posterior teeth, which are loaded with higher forces during masticatory function, mechanoreceptorsare less sensitive to forces. Anterior teeth are involved in holding and splitting of food, while posterior teeth are specialized infragmentation. The loss of sensory afferences from periodontal mechanoreceptors leads to distorted masticatory movements.


Subject(s)
Humans , Periodontal Ligament/innervation , Mechanoreceptors , Dental Stress Analysis , Mastication/physiology
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