Journal of Neurophysiology, Vol 62, Issue 4 979-983, Copyright © 1989 by APS
Properties of reinnervated periodontal mechanoreceptors after inferior alveolar nerve injuries in cats
A. R. Loescher and P. P. Robinson
Department of Physiology, Birmingham University Medical School, Birmingham, United Kingdom.
1. The properties of periodontal mechanoreceptors supplying lower canine
teeth in cats have been investigated 12 wk after the crushing or sectioning
of the inferior alveolar nerve. Forces were applied at right angles to the
crown of the tooth and recordings made from filaments dissected from the
nerve central to the injury site. Data obtained from 41 units after nerve
crush and 65 units after nerve section were compared with those from a
series of control animals. 2. The range of directions to which each
receptor was sensitive was significantly smaller after both nerve crush and
nerve section. There were significantly more rapidly adapting units after
both nerve crush (37%) and nerve section (34%) than in the controls (19%).
3. Force thresholds measured at three rates of application (20 N/s, 2 N/s,
and 0.25 N/s) were significantly higher after nerve section but not after
nerve crush. The maximum frequency of discharge was significantly reduced
after both nerve crush and nerve section. 4. Bone was removed from over the
roots of the teeth to localize receptors in the underlying periodontal
ligament. Seventeen receptors were localized in the nerve crush group and
23 in the nerve section group, and their distribution appeared similar to
that found in controls. The conduction velocities of these units were
significantly reduced after nerve section but not after nerve crush. One
unit in the nerve section group appeared to have branched and innervated
receptors in two locations.
