Multiple-tooth receptive fields of single human periodontal mechanoreceptive afferents.

1. Single-unit impulse activity from 25 mechanoreceptive afferents was recorded in the human inferior alveolar nerve using tungsten microelectrodes. All of these afferents were considered to originate in periodontal receptors because they showed responses to mechanical stimulation of one or more teeth but not to stimulation of the gingiva. 2. For each afferent isolated, forces with "ramp-and-hold"-shaped profiles of similar magnitudes (261 +/- 21 mN, mean +/- SD) were applied to the incisors, the canine, and the first premolar on the recording side, and the contralateral central incisor in four horizontal directions: lingual, labial, mesial, and distal. For a few of the afferents, forces were also applied in the axial directions (up and down). Both static and dynamic response components were analyzed. 3. For about one half of the tested afferents, the receptive fields were restricted to a single tooth. The remainder (52%) responded to stimulation of a group of teeth (on average 3.1 teeth), which typically showed contact between their crowns. 4. Afferents responding to loading of multiple teeth showed their strongest responses to forces applied to a particular tooth, with a gradual decline in the responsiveness to the adjacent teeth. 5. The stimulation directions eliciting the strongest afferent responses for the most sensitive tooth were approximately evenly distributed over the four stimulation directions, except for some bias toward the lingual direction. In contrast, loading of the adjacent teeth most often showed the strongest responses in the mesial or distal directions, in most cases toward the most sensitive tooth.(ABSTRACT TRUNCATED AT 250 WORDS)