Objective: The expression of vasoactive intestinal peptide (VIP) in dental pulp-dentin complex of human premolar was studied to find out the relationship of distribution and function of VIP positive nerve fibers.
Methods: Fresh health premolars were collected, fixed, decalcified, embedded in paraffin and cut into slices. The slices were treated by immunohistochemical reaction of VIP and quantitative image analysis was then carried out.
Results: VIP positive nerve fibers in dental root were in bundle and branches of the nerve fibers were few. The nerve fibers extended in a radiative way from cervical line to the coronal pulp and branched a lot. A part of branches surrounded blood vessels, some terminated in the dental pulp matrix, the others passed odontoblast layer and ran into the predentin. In the coronal pulp the integral optical density was 12.7400 +/- 1.8070, the volume density was 0.0192 +/- 0.0127, the length density was 0.0046 +/- 0.0028; in predentin the integral optical density was 13.0700 +/- 1.9270, the line length was (19.6000 +/- 8.5970) microns.
Conclusions: VIP-immunoreactive nerve fibers exist in human dental pulp-dentin complex. Some fibers surround blood vessels, some terminate in dental pulp matrix and predentin, which suggest that in addition to relating the action of blood vessels, VIP-immunoreactive nerve fibers might also relate to sense.