Masseter inhibitory periods and sensations upon electrical tooth-pulp stimulation in children and adults

Sensations and masseter inhibitory periods (MIP) evoked by electrical tooth-pulp stimulation were recorded in 5 adults and 10 children. In the adult group there was always a sensation and it was usually associated with a two-phase MIP, with an early and a late component. Sensory detection in teeth with partially formed roots in the younger children (7-9 years old) was markedly reduced, and the MIP was mostly monophasic with a predominantly early component. In the older children with fully formed roots (10-12 years old) sensations did not differ from those in the adults, but the late MIP component occurred in significantly fewer trials (P < 0.01). It is concluded that response to electrical tooth-pulp stimulation develops in the following stages: (1) early, oligosynaptic MIP, (2) sensation, and (3) the late, polysynaptic component of the MIP.