title: Laser phototherapy at high energy densities do not stimulate pre-osteoblast growth and differentiation.
abstract: OBJECTIVE
  The aim of this study is to evaluate the effects of red and infrared lasers at high energy densities on pre-osteoblast MC3T3 proliferation and differentiation.
  
  
  BACKGROUND
  The acceleration of bone regeneration by low intensity laser irradiation may hold potential benefits in clinical therapy in orthopedics and dentistry.
  
  
  METHODS
  Cells were irradiated with red (660 nm) and infrared (780 nm) lasers (90 and 150 J/cm2, 40 mW). The control group did not receive irradiation. Cell growth was assessed by a colorimetric test (MTT) (24, 48, 72, 96 h) and cell differentiation was evaluated by alkaline phosphatase (ALP) quantification after growth in osteogenic medium (72, 96 h; 7, 14 days).
  
  
  RESULTS
  None of the irradiation groups had an enhancement in cell growth (p<0.05). The production of ALP was not influenced by irradiation at any period of time (p>0.05).
  
  
  CONCLUSIONS
  The low intensity laser stimulated neither cell growth nor the production of alkaline phosphatase.
authors: Bauru School of Dentistry, Bauru, SP, Brasil.
authors: Pedro Silva
authors: PS
authors: Pacheco
authors: Flávia Amadeu
authors: FA
authors: de Oliveira
authors: Rodrigo Cardoso
authors: RC
authors: Oliveira
authors: Adriana Campos Passanezi
authors: AC
authors: Sant'ana
authors: Maria Lúcia Rubo
authors: ML
authors: de Rezende
authors: Sebastião Luiz Aguiar
authors: SL
authors: Greghi
authors: Carla Andreotti
authors: CA
authors: Damante
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002454:Cell Differentiation / Q000528:radiation effects*; D049109:Cell Proliferation / Q000528:radiation effects*; D006801:Humans; D028022:Low-Level Light Therapy; D010006:Osteoblasts / Q000528:radiation effects*
chemical_list: D000469:Alkaline Phosphatase