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

The present study was undertaken to reveal whether S-100 alpha or S-100 beta or both are present in the nerve fibers in the rat molar tooth pulp. No immunoreactivity for S-100 alpha was observed in the molar pulp. In the root pulp, thick smooth-surfaced structures accompanying the blood vessel showed S-100 beta-like immunoreactivity (-LI), and occasionally a very few thin beaded elements exhibited S-100 beta-LI. In the coronal pulp, S-100 beta-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-100 beta-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 mu m into the predentin from the pulp-predentin border. Immunoelectron microscopy revealed that the Schwann cells in the root pulp showed S-100 beta-LI, and that S-100 beta-LI was present in the axoplasm as well as Schwann cells in the coronal pulp. The S-100 beta-IR axons were rarely surrounded by S-100 beta-IR Schwann cells. In the predentin, S-100 beta-IR nerve fibers terminated in a position close to the odontoblast processes. The present findings indicate that S-100 beta, not S-100 alpha, is present in the axon in the dental pulp and predentin as well as in the Schwann cells. (C) 1999 Elsevier Science B.V. All rights reserved.