title: Low-level laser therapy influences mouse odontoblast-like cell response in vitro.
abstract: OBJECTIVE
  The purpose of this study was to analyze the influence of two different irradiation times with 85 mW/cm(2) 830 nm laser on the behavior of mouse odontoblast-like cells.
  
  
  BACKGROUND
  The use of low-level laser therapy (LLLT) to stimulate pulp tissue is a reality, but few reports relate odontoblastic responses to irradiation in in vitro models.
  
  
  METHODS
  Odontoblast-like cells (MDPC-23) were cultivated and divided into three groups: control/nonirradiated (group 1); or irradiated with 85 mW/cm(2), 830 nm laser for 10 sec (0.8 J/cm(2)) (group 2); or for 50 sec (4.2 J/cm(2)) (group 3) with a wavelength of 830 nm. After 3, 7, and 10 days, it was analyzed: growth curve and cell viability, total protein content, alkaline phosphatase (ALP) activity, calcified nodules detection and quantification, collagen immunolocalization, vascular endothelial growth factor (VEGF) expression, and real-time polymerase chain reaction (PCR) for DMP1 gene. Data were analyzed by Kruskall-Wallis test (α=0.05).
  
  
  RESULTS
  Cell growth was smaller in group 2 (p<0.01), whereas viability was similar in all groups and at all periods. Total protein content and ALP activity increased on the 10th day with 0.8 J/cm(2) (p<0.01), as well as the detection and quantification of mineralization nodules (p<0.05), collagen, and VEGF expression (p<0.01). The expression of DMP1 increased in all groups (p<0.05) compared with control at 3 days, except for 0.8 J/cm(2) at 3 days and control at 10 days.
  
  
  CONCLUSIONS
  LLLT influenced the behavior of odontoblast-like cells; the shorter time/smallest energy density promoted the expression of odontoblastic phenotype in a more significant way.
authors.affiliation: School of Dentistry of Ribeirão Preto, Cell Culture Laboratory-Department of Morphology, Stomatology and Physiology, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Luciana Batista
authors.initials: LB
authors.lastname: Pereira
authors.forename: Daniela Thomazatti
authors.initials: DT
authors.lastname: Chimello
authors.forename: Maidy Rehder Wimmers
authors.initials: MR
authors.lastname: Ferreira
authors.forename: Luciano
authors.initials: L
authors.lastname: Bachmann
authors.forename: Adalberto Luiz
authors.initials: AL
authors.lastname: Rosa
authors.forename: Karina Fittipaldi
authors.initials: KF
authors.lastname: Bombonato-Prado
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D002478:Cells, Cultured / Q000528:radiation effects; D004797:Enzyme-Linked Immunosorbent Assay; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy / Q000379:methods*; D051379:Mice; D009804:Odontoblasts / Q000502:physiology / Q000528:radiation effects*; D011829:Radiation Dosage; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D012016:Reference Values; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D042461:Vascular Endothelial Growth Factor A