Selective stimulation of human tooth-pulp with a new stable method: responses and validation.

Introduction: The aims of this study were to establish a safe technique for selective stimulation of nerves in human tooth-pulp during long experiments and to validate its use even with stimuli of high intensities.

Methods: A custom-made veneer containing 2 silver wire-conductive cream electrodes was attached with cement to the labial surface of an upper central incisor tooth. A variety of stimulus intensities were applied, and sensory and reflex responses from jaw-closing muscles were recorded.

Forces, movements and reflexes produced by pushing human teeth.

Pushing a tooth results in movement of the tooth and reflex inhibition of activity in jaw-closing muscles. The aims of this study were to determine how much tooth movement is required to elicit such reflexes and whether this is dependent on the point of force application to the tooth. Eight experiments were performed on six volunteer subjects.

Quantification of jaw reflexes evoked by natural tooth contact in human subjects.

Inhibitory jaw reflexes are believed to be important for protecting the teeth and temporo-mandibular structures from damage during sudden or forceful biting or mastication. Accordingly, alterations in these reflexes are sometimes implicated in aetiologies proposed for oro-facial pain syndromes, although the association is not well-established. We now aim to develop a method for quantifying objectively inhibitory jaw reflexes evoked by natural tooth contact.

The inhibitory effect of a chewing task on a human jaw reflex.

This study was undertaken to investigate whether an inhibitory jaw reflex could be modulated by experimentally controlled conditions that mimicked symptoms of temporomandibular disorders. Reflecting on previous work, we anticipated that these conditions might suppress the reflex. Electromyographic recordings were made from a masseter muscle in 18 subjects, while electrical stimuli were applied to the upper lip.

Mastication and swallowing: 2. control.

Unlabelled: In recent years, it has become clear that the neural mechanisms controlling chewing and swallowing emanate from centres in the brainstem. However, these activities may be modulated by conscious processes and by feedback from peripheral nerves.This review relates this knowledge to clinical dentistry and, in particular, to the possible relationship between craniomandibular dysfunctions and impaired control of the masticatory system.

Mastication and swallowing: 1. Functions, performance and mechanisms.

Unlabelled: The process of mastication involves movements of the tongue, lips and cheeks as well as the more obvious actions of the teeth and jaws. In recent years there have been significant advances in our knowledge of the relationships between these movements in human beings and of how the processes of mastication are related to the associated events of swallowing. In this, the first of two papers, we review the role of mastication in food processing and nutrition and the effect of tooth loss on masticatory performance.

Differences between inhibitory jaw reflexes evoked by stimulation of tooth pulp and across the adjacent alveolar process in man.

Objective: In humans, stimulation of nerves in or around teeth can evoke inhibitory jaw reflexes. Previous studies had suggested that there may be subtle differences in the timings of the responses. The aim of the present study was to investigate this by comparing reflexes evoked by electrical stimulation of a tooth and of the adjacent tissues in individual subjects.

Modulation of an inhibitory jaw reflex by remote noxious stimulation: effects of spatial conditioning factors.

In humans, inhibitory jaw reflexes can be depressed by painful stimulation of remote parts of the body. The underlying mechanisms may involve diffuse noxious inhibitory controls (DNIC). Animal experiments have shown that the neurons which may mediate DNIC show spatial encoding (i.

Dissociation of nociceptive modulation of a human jaw reflex from the influence of stress.

In human beings, inhibitory jaw reflexes can be depressed by painful stimulation of remote parts of the body. Since similar effects can be produced by the stress of anticipating pain, we wished to investigate whether the effects of remote painful stimuli are dependent on stress. EMG recordings were made from a masseter muscle while subjects maintained activity in the muscle at approximately 12.

Functional roles of oral reflexes in chewing and biting: phase-, task- and site-dependent reflex sensitivity.

Because loading during chewing is not totally predictable and jaw-closing muscles are strong and act over short distances, feedback from oral receptors is important in the control of mastication. Information on such feedback can be obtained by studying reflexes in jaw muscle EMGs. This review will deal with the contribution of reflex mechanisms to modifying motor neuron activity during chewing, and the dependency of reflex sensitivity on motor task, phase of movement, and site of stimulation.

Modulation of human jaw reflexes: heterotopic stimuli and stress.

The inhibitory reflexes in jaw elevator muscles, which are the predominant muscle responses to stimuli in or around the human mouth, are subject to modulation by nociceptive stimulation of remote parts of the body. The evidence for, and nature of, these modulatory effects are reviewed with particular emphasis on the reflex inhibition of masseteric activity evoked by electrical stimulation of the upper lip. This reflex is markedly reduced in magnitude by noxious stimulation of remote parts of the body surface or deeper tissues.

Differentiation of nociceptive- from stress-induced modulatory influences on human reflexes.

This paper describes a new protocol that addresses the question of whether, in human experiments, modulatory effects of remote nociceptive conditioning stimuli on reflex responses are mediated by the stress induced by the conditioning stimuli. The protocol has been illustrated by a study into the effect of a remote nociceptive conditioning stimulus on an inhibitory jaw reflex. Electromyograms were recorded from an active masseter muscle and inhibitory reflexes were evoked by applying electrical stimuli to the upper lip.

Remote noxious stimuli modulate jaw reflexes evoked by activation of periodontal ligament mechanoreceptors in man.

The purpose of the study was to investigate whether jaw reflexes evoked by selective stimulation of periodontal ligament me canoreceptors are susceptible to modulation by remote noxious stimulation. Experiments were performed on 10 volunteer subjects. Skin surface recordings were made from the jaw-closing masseter muscle.

Topical review: modulation of trigeminal sensory input in humans: mechanisms and clinical implications.

In this review, the modulatory effects of tooth and implant loading, orofacial pain, and psychological factors on somatosensory and jaw-motor function in humans are assessed. Experimental studies on the control of jaw actions have revealed that patients with prostheses supported by osseointegrated implants show an impairment of fine motor control of the mandible. One possibility is that this may be related to the loss of afferent information from periodontal ligament mechanoreceptors, which results in considerably higher and more variable forces to hold and manipulate food between the teeth.