Archives of oral biology
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Archives of oral biology · Apr 2002
The effect of pulpward pressure on the response to 50% lidocaine (lignocaine) applied to exposed dentine in cats.
The responses of intradental nerves can be blocked by 50% lidocaine applied to exposed, etched dentine. The aim here was to analyse electrophysiologically the contribution of pulpward pressure to the anaesthetic effect of lidocaine applied to exposed dentine. In 17 adult cats with intact lower canines, approximately 1mm of the coronal tip of the canine was removed and the exposed dentine acid-etched. ⋯ Applying 10.0 kPa pressure to the lidocaine solution blocked all the pulpal nerve responses (n=5) to both stimulation modes. The amplitude of the antidromic compound action potential was significantly decreased when the applied pressure was increased. These results suggest that increased pulpward pressure may effectively force anaesthetic solution more rapidly through the dentinal tubules into the pulp.
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Archives of oral biology · Aug 2001
Fatigue and pain in human jaw muscles during a sustained, low-intensity clenching task.
Fatigue, pain and changes in the electromyographic (EMG) activity of the jaw-closing muscles are well documented during short, high-intensity tooth-clenching tasks but less so during sustained, low-intensity tasks. In this study, 11 healthy men clenched on a bite-force meter for 60 min at 10% of the maximal voluntary contraction (MVC) and scored the intensity of fatigue and pain on separate 10 cm visual analogue scales (VAS). Surface EMG activity from the masseter and anterior temporalis muscles was recorded in 10 s epochs every 5 min throughout the task. ⋯ The mean frequency of the EMG activity decreased in all muscles during the task (95.7 vs. 46.6 Hz;P<0.001), and the root mean squares increased (53.2 vs. 154 microV, P<0.001). The changes in EMG activity were more strongly correlated with the sensation of fatigue than pain. These findings demonstrate that a sustained, low-intensity clenching task can induce subjective and electrophysiological indications of fatigue.
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Archives of oral biology · May 2001
Excitatory actions of experimental muscle pain on early and late components of human jaw stretch reflexes.
It has recently been shown that a slow stretch evokes a short-latency (probably monosynaptic) and a long-latency (polysynaptic) reflex response in human jaw-closing muscles. The effect of nociceptive muscle input on the fusimotor system has not been investigated in detail. In order to investigate the effect of sustained muscle pain on the jaw stretch reflex, two main experiments were performed. ⋯ These results indicate that experimental jaw-muscle pain in humans facilitates the early as well as the late component of the jaw stretch reflex response as revealed by both sEMG and imEMG. This effect appears to be independent of the level of excitation of the muscle and not related to volume effects of the injected saline. A change in the sensitivity of the fusimotor system during muscle pain is suggested as an explanation.
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Archives of oral biology · Jul 2000
Comparative StudyEffect of the sensory neuropeptide antagonists h-CGRP((8-37)) and SR 140.33 on pulpal and gingival blood flow in ferrets.
In a previous study, it was concluded that the neuropeptides calcitonin gene-related peptide (CGRP) and substance P are released during resting conditions in the (exposed) ferret dental pulp, contributing to a basal vasodilator tone in the pulpal vessels. In order to exclude the possibility that the method used elicited axon reflexes, which might be responsible for neuropeptide release, the present study was designed without pulp exposure. Non-invasive laser-Doppler flowmetry was used to measure the effects of intra-arterial infusions of the antagonists h-CGRP((8-37)) and SR 140.33 (neurokinin 1-receptor antagonist) on pulpal and gingival blood flow before, during and after electrical tooth stimulation. ⋯ Infusion of h-CGRP((8-37)) greatly reduced this electrically induced vasodilatation, indicating that CGRP is the principal factor responsible for the vasodilatation observed after tooth stimulation. This study confirms the previous finding that a resting vasodilator tone due to the release of CGRP and SP exists in the ferret dental pulp. It is concluded that spontaneous, basal release of the neuropeptides CGRP and substance P exists both in dental pulp and gingiva in the ferret.
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Archives of oral biology · Aug 1999
Mandibular posture during sleep in patients with obstructive sleep apnoea.
Vertical mandibular posture is thought to be related to narrowing of the upper airway, because mouth opening is associated with an inferior-posterior movement of the mandible and the tongue which influences pharyngeal airway patency. To test whether the mandibular posture is related to the occurrence and/or termination of obstructive sleep apnoea (OSA), the vertical mandibular position was recorded intraorally using a magnet sensor during a standard sleep study in seven patients with OSA. Measurements were recorded during sleep both in the supine and lateral recumbent positions. ⋯ In non-rapid eye-movement sleep, mandibular opening increased progressively during apnoeic episodes and decreased at the termination of apnoeic episodes. In contrast, no significant change in mandibular posture occurred in apnoeic episodes during rapid eye-movement sleep. It was concluded that the vertical mandibular posture is more open during sleep in patients with OSA than in healthy adults and that mandibular opening increases progressively during apnoeic episodes and decreases at the termination of those episodes.