The aim of the present study was to determine the action of AsGA laser irradiation on bone repair in the tibia of osteopenic rats. The animals were randomly divided into eight experimental groups according to the presence of ovarian hormone (sham group) or the absence of the hormone (OVX group), as well as being irradiated or non-irradiated. Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.
INTRODUCTION: The development of new techniques to speed the process of bone repair has provided significant advances in the treatment of fractures. Some attention recently focused on the effects of biostimulation on bone.
METHODS: Forty-eight adult rats were randomly divided into eight experimental groups (six animals in each group) according to the presence of ovarian hormone (sham group) or absence of the hormone (ovariectomized (OVX) group) as well as being irradiated or non-irradiated. For the application of low-level laser therapy, the animals were anesthetized with one third of the dose sufficient to immobilize the animal and irradiated with AsGa laser (904 nm, 50 mJ/cm(2) for 2 s, point form and in contact). The control animals received the same type of manipulation as the irradiated animals, but with the laser turned off. Half of the animals were killed 7 days following the confection of the bone defect, and the other half were killed 21 days after the surgery. After complete demineralization, the tibias were cut cross-sectionally in the central region of the bone defect and embedded in paraffin blocks. The blocks were then cut in semi-seriated slices and stained with hematoxylin and eosin.
RESULTS: There was new bone formation in the animals in the OVX group with laser treatment killed after 7 days (p < 0.001). The lowest percentage of bone formation was observed in the OVX without laser killed after 7 days (p > 0.05). All animals killed after 21 days exhibited linear closure of the lesion.
CONCLUSION: Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.
Million of fractures occurs every year worldwide due to a reduced bone mass related to osteoporosis. Many of them termed in non-union fratures. In this context, a lot of methods for treating delayed and non-union fractures have been investigated including low level laser therapy (LLT). Some studies have shown this treatment is able to stimulate the osteogenesis of bone tissue. Therefore, the aim of this study was to investigate the effects of the 830nm laser on tibial bone consolidation in osteopenic rats.
Methodology: It was used 50 female osteopenic rats, divided into 4 groups: standard control (SC), osteopenic fractured control (OC); osteopenic fractured treated with 830nm laser, on the fluence of 60 J/cm2 (OL60); osteopenic fractured treated 830nm laser, on the fluence of 120J/cm2 (OL120). We used a GaAlAs laser, 830 nm, 100 mW, in two different fluencies: 60 and 120 J/cm2. The laser treatment was performed during 12 sessions. On day 14 after the surgery, the animals were euthanized and the right tibias were defleshed and prepared for a biomechanical test (maximum load: ML).
Statistical analysis: data were expressed as mean and statistical differences were determined with the ANOVA test for unpaired data.
Results: The mean ML showed by the control fractured group was statistically significant lower compared to the other groups (mean: 0.006 N). Fractured animals treated with both fluencies of laser presented higher values of ML compared to the fractured controls but the mean ML was lower compared to SC (means: fluence of 60 J/cm2: 0.098; fluence of 120 J/cm2: 0.089). Animals treated with BiosilicateÂ® showed higher values of ML compared to the SC group (mean: 0.129).
Conclusion: LLT was effective to improve callus bone strength of tibial defects in osteopenic rats, in both fluencies used. The results of this work may suggest that the laser therapy has an osteogenic effect and it is efficient to accelerate bone consolidation and to increase callus strength in osteopenic rats.