title: Effects of CO2 Lasers on Dental Pulp Biology in Rats.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effects of CO2 lasers on the proliferation and differentiation of dental pulp cells, and their latent self-recovery in connection with their stemness using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry.
  
  
  METHODS
  The first molars from male Sprague-Dawley rats, each weighing ∼150-200 g, were used for this study. The upper first molars were irradiated with a 10,600 nm wavelength CO2 laser under identical parameters (2 W CO2 laser, energy 4J, energy density 203.84 J/cm(2) for 8.8 sec) through the dentin of the occlusal surface. The molars were extracted immediately, or at 1, 3 or 5 days after the laser irradiation. RT-PCR analysis using primers specific for heat shock protein 70 (Hsp70), adenosine triphosphate (ATP)-binding cassette transporter G2 (ABCG2), dentin sialophosphoprotein (DSPP), and dentin matrix protein 1 (DMP1), and immunohistochemistry using antibodies specific for proliferating cell nuclear antigen (PCNA), ABCG2, CD34, and CD44 were performed.
  
  
  RESULTS
  RT-PCR analysis revealed that Hsp70 mRNA expression in the immediate group and ABCG2 mRNA expression at day 1 were the highest. DSPP and DMP1 mRNA expression in the laser-irradiated groups increased gradually, reaching its peak on the 5th day of the experiment, although no significant difference found among groups with regard to DMP1 expression. Immunohistochemically, PCNA-positive cells were observed at all times after the laser irradiation; however, they were most evident on day 3. CD44-positive cells were observed strongly on day 1 and day 3, while ABCG2-positive cells were the most evident on day 3.
  
  
  CONCLUSIONS
  These results demonstrate that CO2 laser irradiation induces degeneration in the pulp tissue, which is then repaired by newly formed odontoblast-like cells.
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .
authors.forename: Tungalag
authors.initials: T
authors.lastname: Ser-Od
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yasumoto
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .
authors.forename: Akram
authors.initials: A
authors.lastname: Al-Wahabi
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .|2 Oral Health Science Center, Tokyo Dental College , Tokyo, Japan .
authors.forename: Kei
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .
authors.forename: Satoshi
authors.initials: S
authors.lastname: Murakami
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .|2 Oral Health Science Center, Tokyo Dental College , Tokyo, Japan .
authors.forename: Kenichi
authors.initials: K
authors.lastname: Matsuzaka
authors.affiliation: 1 Department of Clinical Pathophysiology, Tokyo Dental College , Tokyo, Japan .|2 Oral Health Science Center, Tokyo Dental College , Tokyo, Japan .
authors.forename: Takashi
authors.initials: T
authors.lastname: Inoue
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D003782:Dental Pulp / Q000166:cytology* / Q000528:radiation effects; D054020:Lasers, Gas; D008297:Male; D059630:Mesenchymal Stem Cells / Q000528:radiation effects*; D023421:Models, Animal; D009804:Odontoblasts / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley