title: Pulpal responses to cavity preparation in aged rat molars.
abstract: The dentin-pulp complex is capable of repair after tooth injuries including dental procedures. However, few data are available concerning aged changes in pulpal reactions to such injuries. The present study aimed to clarify the capability of defense in aged pulp by investigating the responses of odontoblasts and cells positive for class II major histocompatibility complex (MHC) to cavity preparation in aged rat molars (300-360 days) and by comparing the results with those in young adult rats (100 days). In untreated control teeth, immunoreactivity for intense heat-shock protein (HSP)-25 and nestin was found in odontoblasts, whereas class-II-MHC-positive cells were densely distributed in the periphery of the pulp. Cavity preparation caused two types of pulpal reactions based on the different extent of damage in the aged rats. In the case of severe damage, destruction of the odontoblast layer was conspicuous at the affected site. By 12 h after cavity preparation, numerous class-II-MHC-positive cells appeared along the pulp-dentin border but subsequently disappeared together with HSP-25-immunopositive cells, and finally newly differentiated odontoblast-like cells took the place of the degenerated odontoblasts and acquired immunoreactivity for HSP-25 and nestin by postoperative day 3. In the case of mild damage, no remarkable changes occurred in odontoblasts after operation, and some survived through the experimental stages. These findings indicate that aged pulp tissue still possesses a defense capacity, and that a variety of reactions can occur depending on the difference in the status of dentinal tubules and/or odontoblast processes in individuals.
authors.affiliation: Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, and Polyclinic Intensive Oral Care Unit, Niigata University Medical and Dental Hospital, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kawagishi
authors.forename: Kuniko
authors.initials: K
authors.lastname: Nakakura-Ohshima
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nomura
authors.forename: Hayato
authors.initials: H
authors.lastname: Ohshima
mesh_terms: D000375:Aging / Q000276:immunology* / Q000473:pathology; D000818:Animals; D002454:Cell Differentiation / Q000276:immunology*; D003782:Dental Pulp / Q000276:immunology* / Q000293:injuries* / Q000473:pathology; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D008963:Molar / Q000276:immunology* / Q000293:injuries* / Q000473:pathology; D009363:Neoplasm Proteins / Q000276:immunology; D009804:Odontoblasts / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration / Q000276:immunology; D013997:Time Factors
chemical_list: D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D000949:Histocompatibility Antigens Class II; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins