title: Low-level laser therapy on bone repair: is there any effect outside the irradiated field?
abstract: The biological effects of local therapy with laser on bone repair have been well demonstrated; however, this possible effect on bone repair outside the irradiated field has not been evaluated. The aim of this study was to investigate the effect of low-level laser therapy (LLLT) (λ = 830 nm) on repair of surgical bone defects outside the irradiated field, in rats. Sixty Wistar rats were submitted to osteotomy on the left femur and randomly separated into four groups (n = 15): group I, control, bone defect only; group II, laser applied on the right femur (distant dose); group III, laser applied locally on the bone defect and also on the right femur (local and distant doses); and group IV, laser applied locally on the left femur (local dose). Laser groups received applications within a 48-h interval in one point per session of density energy (DE) = 210 J/cm(2), P = 50 mW, t = 120 s, and beam diameter of 0.028 cm. Five animals of each group were euthanized 7, 15, and 21 days after surgery. Histologic analysis in all groups showed new bone formation in the region of interest (ROI) at 7 days. After 15 days, bone remodeling with a decrease of bone neoformation in the marrow area was observed in all groups. After 21 days, advanced bone remodeling with new bone mostly located in the cortical area was observed. The histomorphometric analysis showed at 7 days a significant increase of bone formation in groups III and IV compared to groups I and II. At days 15 and 21, histomorphometric analysis showed no significant differences between them. Laser therapy presented a positive local biostimulative effect in the early stage of bone healing, but the LLLT effect was not observed a long distance from the evaluated area.
authors.affiliation: Oral & Maxillofacial Surgery and Implantology Department, School of Dentistry, University of Uberlândia, Avenida Pará s/no, Campus Umuarama, Bloco 4T, Bairro Umuarama, Uberlândia, Minas Gerais, 38.400-902, Brazil, jonasdantasbat@gmail.com.
authors.forename: Jonas Dantas
authors.initials: JD
authors.lastname: Batista
authors.forename: Sérgio
authors.initials: S
authors.lastname: Sargenti-Neto
authors.forename: Paula
authors.initials: P
authors.lastname: Dechichi
authors.forename: Flaviana Soares
authors.initials: FS
authors.lastname: Rocha
authors.forename: Rogério Miranda
authors.initials: RM
authors.lastname: Pagnoncelli
mesh_terms: D000818:Animals; D001861:Bone Regeneration; D001842:Bone and Bones / Q000473:pathology / Q000528:radiation effects; D005269:Femur / Q000503:physiopathology / Q000528:radiation effects; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D028022:Low-Level Light Therapy; D008297:Male; D017208:Rats, Wistar; D014945:Wound Healing / Q000528:radiation effects