Electrical stimulation of tooth pulp in humans. II. Qualities of sensations.

Individual premolar teeth of 22 normal volunteers were stimulated via intradentinal electrodes using brief electrical pulses. Questionnaires were used to determine the qualities of sensations produced by this stimulation. Operationally defined 'innocuous' sensations predominated between 1 and 10 dB SL, and were absent above 30 dB SL. Similarly defined 'painful' sensations were observed throughout the range of suprathreshold intensities but were most common above 20 dB SL. These findings demonstrate that non-painful sensations can arise from electrical tooth pulp excitation in circumstances in which spread of the stimulating current to periodontal and gingival structures is most unlikely. Two interpretations of these results are considered: (1) that tooth pulp afferents may have some unspecified sensory function besides mediation of painful sensations and (2) that they may be specialized in the mediation of nociceptive impulses but may give rise to innocuous sensations under special circumstances.