Immunoelectron microscopic study of CGRP nerve terminals in wound healing and dentin bridge formation following rat molar pulpotomy

The purpose of present study was to investigate the relation between the neuropeptide calcination gene-related peptide immunoreactive (CGRP-IR) terminals and the differentiation of odontoblasts during the healing process after a pulpotomy. The maxillary first molars from 56-day-old Wistar rats (n = 24) were obtained. The rats were sacrificed for an immunoelectron microscopic examination at 1, 3, 7, 14, and 28 days postoperatively. By 1 to 3 days postoperatively, numerous degenerated CGRP-IR nerve terminals were observed. By 7 to 14 days postoperatively, regenerated terminals were found to come in contact with the cell bodies of the differentiation odontoblasts and their processes in the residual pulp. By 28 days postoperatively, some CGRP-IR nerve terminals were also seen to come in contact with the odontoblast processes at the odontoblast layer of the dentin bridge. These findings demonstrate strong evidence that CGRP may thus be related to both the proliferation and cytodifferentiation processes, as well as to the active function of the renewed odontoblasts for dentin bridge formation.