title: Pulp responses after CO(2) laser irradiation of rat dentin.
abstract: OBJECTIVE
  The purpose of this study was to investigate pulp responses after CO(2) laser irradiation of rat molars using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical methods.
  
  
  BACKGROUND
  Many kinds of lasers have been used for the treatment of dentin hypersensitivity. However, the immunohistochemical details of the responses of dentin-pulp complex cells after CO(2) laser irradiation through the dentin are still not clear.
  
  
  METHODS
  Adult male Sprague-Dawley rats were used in this study. A CO(2) laser (wavelength of 10.6 μm, 2 W in the super pulse mode, pulse 0.6 ms) and total laser energy of 4 J (density, 203.84 J/cm(2)) was used. The temperature change in the pulp was measured using a super fine sheath thermocouple.
  
  
  RESULTS
  The temperature at the pulp side after the CO(2) laser irradiation increased 22.5°C. The expression of tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-1-α mRNAs was significantly higher at 6, 12, and 24 h after laser irradiation than in the control group (p<0.05). Histologically, a slight degeneration of the pulp tissue was observed immediately after the laser irradiation. Immunohistochemically, heat shock protein (HSP)-70-positive cells in the pulp horn were observed immediately after irradiation and cells positive for vascular endothelial growth factor (VEGF) in the subodontoblast layer were observed after 5 days. There were no nestin-positive cells immediately, but after 5 days nestin-positive cells were recognized in the deeper pulp cells. Immediately after irradiation, neurofilament protein (NFP)-positive nerve fibers were observed but they disappeared in the pulp horn after 5 days.
  
  
  CONCLUSIONS
  These results suggest that 203.84 J/cm(2) CO(2) laser irradiation of pulp tissue through the dentin, such as is used in the clinic, induces inflammatory and pathological cytokine pathways to repair the damaged pulp tissue.
authors: Department of Clinical Pathophysiology, Tokyo Dental College, Chiba, Japan.
authors: Dong-Ho
authors: DH
authors: Lee
authors: Satoshi
authors: S
authors: Murakami
authors: Sultan Zeb
authors: SZ
authors: Khan
authors: Kenichi
authors: K
authors: Matsuzaka
authors: Takashi
authors: T
authors: Inoue
mesh_terms: D000818:Animals; D003782:Dental Pulp / Q000737:chemistry / Q000528:radiation effects*; D003804:Dentin / Q000528:radiation effects*; D007150:Immunohistochemistry; D054020:Lasers, Gas; D008297:Male; D064231:Nestin / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D064231:Nestin; D016900:Neurofilament Proteins