Immunohistochemical localization of S-100β in the dental pulp of the rat molar

Abstract

The present study was undertaken to reveal whether S-100α or S-100β or both are present in the nerve fibers in the rat molar tooth pulp. No immunoreactivity for S-100α was observed in the molar pulp. In the root pulp, thick smooth-surfaced structures accompanying the blood vessel showed S-100β-like immunoreactivity (-LI), and occasionally a very few thin beaded elements exhibited S-100β-LI. In the coronal pulp, S-100β-like immunoreactive (-IR) structures arborized repeatedly and extensively; they had a predominantly thick, smooth-surfaced appearance, though parts appeared thin and beaded. Numerous thin varicose S-100β-IR structures ran through the odontoblast cell layer, and further penetrated into the predentin alongside the dentinal tubules. They could be traced for approximately 10–20 μm into the predentin from the pulp-predentin border. Immunoelectron microscopy revealed that the Schwann cells in the root pulp showed S-100β-LI, and that S-100β-LI was present in the axoplasm as well as Schwann cells in the coronal pulp. The S-100β-IR axons were rarely surrounded by S-100β-IR Schwann cells. In the predentin, S-100β-IR nerve fibers terminated in a position close to the odontoblast processes. The present findings indicate that S-100β, not S-100α, is present in the axon in the dental pulp and predentin as well as in the Schwann cells.