title: Effects of two low-intensity laser therapy protocols on experimental tooth movement.
abstract: OBJECTIVE
  The purpose of this in vivo study was to determine the effect of two low-intensity laser therapy (LILT) protocols on macroscopic and microscopic parameters of experimental tooth movement.
  
  
  METHODS
  To induce experimental tooth movement in rats, 40 cN of orthodontic force was applied to the left first molars. Next, a gallium-aluminum-arsenide (Ga-Al-As) diode laser with a wavelength of 830 nm and power output of 100 mW was applied with fluence of 6000 J/cm(2) on the area around the moved tooth. Two different application protocols were used in the experimental groups: one with daily irradiation and another with irradiation during early stages. Macroscopic and microscopic analyses were performed at days 2 and 7 of tooth movement. The amount of tooth movement was measured with a caliper, and tartrate-resistant acid phosphatase and picrosirius staining were used to enable identification of osteoclasts and immature collagen, respectively.
  
  
  RESULTS
  The amount of tooth movement did not differ between the irradiated and nonirradiated groups on days 2 and 7 of the experiment. On day 2, no difference was observed in the number of osteoclasts or the percentage of immature collagen. On day 7, there was an increase in the number of osteoclasts after daily applications of LILT, while two applications produced no significant difference from control. The amount of immature collagen on the tension side significantly increased in the nonirradiated group and when LILT was applied for only 2 d, whereas it was shown to be inhibited by daily LILT applications (p < 0.05).
  
  
  CONCLUSIONS
  The tested LILT protocols were unable to accelerate tooth movement. Even though the number of osteoclasts increased when LILT was applied daily, the repair at the tension zone was inhibited.
authors.affiliation: Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. marianamarquezan@gmail.com
authors.forename: Mariana
authors.initials: M
authors.lastname: Marquezan
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Bolognese
authors.forename: Mônica Tirre de Souza
authors.initials: MT
authors.lastname: Araújo
mesh_terms: D000818:Animals; D003094:Collagen / Q000502:physiology; D028022:Low-Level Light Therapy; D008297:Male; D008963:Molar / Q000528:radiation effects; D010010:Osteoclasts / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques
chemical_list: D003094:Collagen