title: Odontoblast responses to GaAlAs laser irradiation in rat molars: an experimental study using heat-shock protein-25 immunohistochemistry.
abstract: Pulpal responses to gallium-aluminum-arsenide (GaAlAs) laser irradiation applied to the tooth remains to be elucidated. This study aimed to evaluate the effect of the GaAlAs laser on odontoblasts using immunohistochemistry for heat-shock protein (HSP)-25, which labels mature and newly differentiated odontoblasts. The mesial surface of the upper right first molar of 8-wk-old Wistar rats was lased at an output power of 0.5-1.5 W for 180 s. The animals were perfusion-fixed at intervals of 6 h to 30 d after irradiation. At 6 h to 7 d, the intensity of HSP-25-immunoreactivity was found to be disturbed in the coronal odontoblast-layer in an energy-dependent manner. At 30 d, tertiary dentin with/without bone-like tissue was formed abundantly in the dental pulp. Statistical analysis revealed that the area occupied by the new hard tissues was significantly wider in 1.5 W-lased specimens than in 0.5 W-lased specimens. An intense HSP-25 immunoreactivity was seen in the odontoblasts underlying the tertiary dentin, whereas immunoreactivity was weak around the bone-like tissue. It was concluded that the GaAlAs laser may induce the formation of tertiary dentin by influencing the secretory activity of odontoblasts. However, higher energies may cause irreversible changes to the pulp, often leading to the formation of an intrapulpal bone-like tissue.
authors.affiliation: Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medicine and Dental Sciences, Niigata 951-8514, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tate
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Yoshiba
authors.forename: Nagako
authors.initials: N
authors.lastname: Yoshiba
authors.forename: Masaaki
authors.initials: M
authors.lastname: Iwaku
authors.forename: Takashi
authors.initials: T
authors.lastname: Okiji
authors.forename: Hayato
authors.initials: H
authors.lastname: Ohshima
mesh_terms: D000818:Animals; D003782:Dental Pulp / Q000293:injuries* / Q000378:metabolism; D003809:Dentin, Secondary / Q000254:growth & development* / Q000378:metabolism; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000032:analysis / Q000378:metabolism; D007124:Immunoenzyme Techniques; D007834:Lasers / Q000009:adverse effects*; D009363:Neoplasm Proteins / Q000032:analysis / Q000378:metabolism; D009804:Odontoblasts / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins