title: The effect of laser therapy on the proliferation of oral KB carcinoma cells: an in vitro study.
abstract: OBJECTIVE
  The aim of this study was to assess the proliferative effect of carcinoma cells, strain KB, submitted to laser therapy with wavelengths of lambda685nm (31 mW; Ø; 0.38 cm(2), 4 J/cm(2)) or lambda830nm (34.5 mW; Ø; 0.38 cm(2), 4 J/cm(2)).
  
  
  BACKGROUND
  It is known that the interaction of laser light with living tissues may lead to different results depending upon several factors such as wavelength, dose, potency, and optical properties of the tissue as well as on the condition being treated. The response to the use of laser light may be of stimulation or inhibition. One successful model used to study the effects of laser light on living tissues is the in vitro use of different lineages of cells in culture.
  
  
  METHODS
  Cellular viability was assessed using MTT spectroscopy immediately, and 6, 12, 24, and 72 h after treatment. The irradiations were carried out twice, at 24 h after cell seeding and at 48 h after the first irradiation. The dose of 4 J/cm(2) was given by a lambda685 nm (31 mW, Phi 0.8 cm(2)) or lambda830 nm (34.5 mW, Phi 0.8 cm(2)) diode lasers.
  
  
  RESULTS
  The results demonstrated that the time influenced significantly both control (p = 0.01) and both cultures irradiated with lambda685-nm laser (p = 0.01) or lambda830-nm laser (p = 0.09). The influence of the treatment (laser therapy) was also significant when comparing the results observed in irradiated groups and the control (p = 0.01). The influence of the wavelength in the final result, in other words, in the cellular viability of cultures irradiated with the two wavelengths was also significant (p = 0.01).
  
  
  CONCLUSIONS
  It is concluded that laser therapy had a positive biomodulatory effect on the proliferation of KB cells and that this was influenced by the wavelength.
authors.affiliation: Laser Center, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil.
authors.forename: Jurema Lisboa Freire
authors.initials: JL
authors.lastname: de Castro
authors.forename: Antonio Luiz Barbosa
authors.initials: AL
authors.lastname: Pinheiro
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Werneck
authors.forename: Cristina Pacheco
authors.initials: CP
authors.lastname: Soares
mesh_terms: D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects; D004396:Coloring Agents; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007624:KB Cells; D007834:Lasers; D013778:Tetrazolium Salts; D013844:Thiazoles; D014407:Tumor Cells, Cultured
chemical_list: D004396:Coloring Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; C022616:thiazolyl blue