title: Cellular effect of low-level laser therapy on the rate and quality of bone formation in mandibular distraction osteogenesis.
abstract: OBJECTIVE
  Therapeutic lasers have been shown to influence bone physiology and repair. The aim of the present investigation was to evaluate the use of a GaAlAs (λ:810 nm) laser in distraction osteogenesis.
  
  
  BACKGROUND
  To reduce problems associated with distraction osteogenesis and shorten the time required for treatment, it is desirable to accelerate the process of bone formation.
  
  
  METHODS
  Eighteen male rabbits underwent corticotomy of mandibular body, and customized distraction devices were inserted. After a 5-day latency period, the mandibles were lengthened by 0.5 mm/day for 10 days. The rabbits were divided into two groups. A GaAlAs (λ: 810 nm) laser beam with the parameters power (P), 200 mW; energy density (ED), 3 J/cm(2); time (T), 7.5 sec; power density (PD) 400 mW/cm(2); energy (E) 1.5 J and spot diameter, 0.8 mm was directed medially and laterally in the study group; the control group received no laser treatment. The exposure continued with six more doses every other day. Three rabbits from each of the two groups were euthanized on the 10th, 20th, and 40th days post-distraction (consolidation) period.
  
  
  RESULTS
  Both light microscopy and scanning electron microscopic (SEM) analysis showed significant improvement in new bone formation in the study group at the 10th and 20th days compared with the control group, but the difference was more prominent on the 10th day. By the 40th day, there were no significant differences between the two groups.
  
  
  CONCLUSIONS
  This study shows that a low-level GaAlAs (λ:810 nm; P, 200 mW) laser hastens new bone formation only in the early stages of the consolidation period in distraction osteogenesis, and has no significant effect in later stages.
authors.affiliation: 1 Oral and Maxillofacial Surgery Department, Dental Faculty, AJA University of Medical Sciences , Tehran, Iran .
authors.forename: Farzad
authors.initials: F
authors.lastname: Fazilat
authors.forename: Mahdi
authors.initials: M
authors.lastname: Ghoreishian
authors.forename: Reza
authors.initials: R
authors.lastname: Fekrazad
authors.forename: Katayoun A M
authors.initials: KA
authors.lastname: Kalhori
authors.forename: Sara Dehghan
authors.initials: SD
authors.lastname: Khalili
authors.forename: Antonio Luiz Barbosa
authors.initials: AL
authors.lastname: Pinheiro
mesh_terms: D000818:Animals; D028022:Low-Level Light Therapy; D008297:Male; D008334:Mandible; D010012:Osteogenesis / Q000528:radiation effects*; D019857:Osteogenesis, Distraction / Q000379:methods*; D011817:Rabbits