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Biomedical subjects

B Matthews

Publications and source records attributed to B Matthews.

At least 109 records · Page 6Linked to original sources
PubMed1976

Electrical stimulation of teeth.

The technical problems of stimulating intact teeth in clinical diagnosis and in pain research are discussed. Bipolar stimulation has no advantage over monopolar stimulation for most applications. A 100 V constant current stimulator is suitable for monopolar stimulation of healthy teeth with a large electrode at about threshold intensity, but, for monopolar stimulation up to 150 micronA and for bipolar stimulation, very much higher voltages are required and no suitable instrument is available. Circuits are given for isolated 100 V and 1kV constant current stimulators.

Dental Pulp Test↗
PubMed1976

Responses of intradental nerves to chemical and osmotic stimulation of dentine in the cat.

Recordings have been made of the neural responses evoked by stimulation of dentine with solutions of NaCl, NH4Cl and dextrose. Stimulation of the outer dentine produced no response. From the inner dentine, a smaller number of impulses were recorded with solutions of NaCl than with corresponding concentrations of NH4Cl, but a much larger number than with solutions of dextrose. The discharge evoked by a solution increased in mean frequency and decreased in latency as the thickness of dentine was reduced. The responses suggest that the receptors were in the innermost dentine or the pulp and that they were excited by changes in extracellular fluid composition rather than by osmotic effects. The properties of the receptors appear to be different from those involved in pain from dentine in man.

Action Potentials↗
PubMed1974

Evidence on the origin of impulses recorded from dentine in the cat.

1. Recordings have been made from dentine at the tip of the canine teeth of cats using a large Ag/AgCl electrode.2. All-or-none action potentials with complex shapes were recorded when single nerve fibres from the dental pulp were stimulated electrically outside the tooth.3. The wave forms of these action potentials changed when the stimulation rate was increased from 1/sec to 10/sec, when the temperature of the tooth surface was changed between 17 and 42 degrees C, when the thickness of the dentine was reduced, and when local anaesthetic was applied to the dentine. Only a small, monophasic, positive potential remained after transection of the pulp in the crown of the tooth.4. The latency of the action potentials was not affected by these same procedures.5. It is suggested that each wave form represented a compound action potential produced by impulses invading the main branches and terminals of a single nerve in the pulp. Some of the terminals may have penetrated the innermost layers of the dentine.6. There was no spontaneous discharge from pulpal nerves.7. A discharge of impulses was recorded from dentine when 2.5 mol/l. NaCl was applied beneath the electrode at the tip of the tooth. By recording simultaneously from dentine and from single fibres from the tooth pulp, it was shown that impulses recorded from dentine were associated with propagated nerve action potentials.

Action Potentials↗