Low Level Laser Therapy Improves Bone Healing in Rabbit Tibia

Objective: To evaluate histomorphometrically the effects of low level laser therapy (LLLT) on bone regeneration in rabbit tibia.

Methods: Two monocortical surgical defects 8mm deep and 2mm in diameter, separated by approximately 30mm, were created in each tibia of 10 New Zealands rabbits filled with demineralized bovine bone and covered with a collagen membrane. Postsurgically, at day zero, a 830nm diode laser (GaAlAs) was used to irradiate four points arround three of the four defects in each rabbit, leaving one non-irradiated site as control. The first of the three test sites was irradiated again on days 3, 7 and 10; a second site again on days 14 and 17; and a third site yet again on days 21 and 24. Designation of control, first, second and third test sites within each animal was random. The laser was set in contact mode and directed perpendicular to skin. Parameters of exposure were; area of the spot: 0,3cm2; output power: 30mW; dose: 6J/cm2 ; and time of irradiation: 60s per point. On day 40 animals were sacrificed. After the histological processing of the samples new and bovine bone in cortical region of defects were quantified, and sites compared using a non-parametric statistical test ANOVA (p<0.05).

Results: Defects irradiated up to day 17 showed the greatest fraction (76%) of new and bovine bone compared to controls (57%), however, the difference was statistically insignificant.

Conclusions: LLLT stimulated a detectable but statistically insignificant increase in bone formation.