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A. Barber, JE. Luger, A. Karpf, Kh. Salame, B. Shlomi, G. Kogan, M. Nissan, M. Alon, and S. Rochkind.

During the last decade, it was discovered that low-power laser irradiation has stimulatory effects on bone cell proliferation and gene expression. The purposes of this review are to analyze the effects of low- power laser irradiation on bone regeneration cells and bone fracture repair, to examine what has been done so far, and to explore the additional works needed in this area. The studies reviewed show how laser therapy can be used to enhance bone regeneration and repair at cell and tissue levels. As noted by researchers, laser properties, the combinations of wavelength and energy dose need to be carefully chosen so as to yield bone regeneration stimulation.

Antonio L.B. Pinheiro1, Marilia G. Oliveira, Pedro Paulo M. Martins, Luciana Maria Pedreira Ramalho, Marcos A. Matos de Oliveira, AurelAcio Novaes Junior, and Renata Amadei Nicolau.

Tissue healing is a complex process that involves local and systemic responses. The use of Low-Level Laser Therapy (LLLT) for wound healing has been shown to be effective in modulating both local and systemic response. Usually, the healing process of bone regeneration is slower than that of soft tissues. The effects of LLLT on bone are still controversial as previous reports show different results. This paper reports recent observations on the effect of LLLT on bone regeneration or healing. The amount of newly formed bone after 830nm laser irradiation of surgical wounds created in the femur of rats was evaluated morphometrically. Forty Wistar rats were divided into four groups: group A (12 sessions, 4.8J/cm2 per session, 28 days); group C (three sessions, 4.8J/cm2 per session, seven days). Groups B and D acted as non-irradiated controls. Forty-eight hours after the surgery, the defects of the laser groups were irradiated transcutaneously with a CW 40mW 830nm diode laser, (f~1mm) with a total dose of 4.8J/cm2. Irradiation was performed three times a week. Computerized morphometry showed a statistically significant difference between the areas of mineralized bone in groups C and D (p=0.017). There was no significant difference between groups A and B (28 days) (p=0.383). In a second investigation, we determined the effects of LLLT on bone healing after the insertion of implants. It is known that dental implants need four and six months period for fixation on the maxillae and on the mandible before receiving loading. Ten male and female dogs were divided into two groups of five animals that received the implant. Two animals of each group acted as controls. The animals were sacrificed 45 and 60 days after surgery. The animals were irradiated three times a week for two weeks in a contact mode with a CW 40mW 830nm diode laser, (f ~1mm) with a total dose per session of 4.8J/cm2 and a dose per point of 1.2J/cm2. The results of the SEM study showed better bone healing after irradiation with the 830nm diode laser. These findings suggest that, under the experimental conditions of the investigation, the use of LLLT at 830nm significantly improves bone healing at early stages. It is concluded that LLLT may increase bone repair at the early stages of healing. Bashardoust Tajali S, MacDermid JC, Houghton P, Grewal R., Department of Physical Therapy, Elborn College, The University of Western Ontario, London, Ontario N6G1H1, Canada. sbashar@uwo.ca
J Orthop Surg Res. 2010 Jan 4;5(1):1 PMID: 20047683 [PubMed]

PURPOSE: The meta-analysis was performed to identify animal research defining the effects of low power laser irradiation on biomechanical indicators of bone and the impact of dosage.

METHODS: We searched five electronic databases (MEDLINE, EMBASE, PubMed, CINAHL, and Cochrane Database of Randomised Clinical Trials) for studies in the area of laser and bone healing published from 1966 to October 2008. Included studies had to investigate fracture healing in an animal model, using any type of low power laser irradiation, and use at least one quantitative biomechanical measures of bone strength. There were 880 abstracts related to laser irradiation and bone issues (healing, surgery, and assessment). Five studies met our inclusion criteria and were critically appraised by two raters independently using a structured tool designed for rating the quality of animal research studies. After full-text review, two articles were deemed ineligible for meta-analysis because of the type of injury method and biomechanical variables used, leaving three studies for meta-analysis. Maximum bone tolerance force before the point of fracture during the biomechanical test, 4 weeks after bone deficiency was our main biomechanical bone properties for the Meta-analysis.

RESULTS: Studies indicate that low power laser irradiation can enhance the biomechanical properties of bone during fracture healing in animal models. Maximum bone tolerance was statistically improved following low-level laser irradiation (average random effect size 0.726, 95% CI 0.08-1.37, p 0.028). While conclusions are limited by the low number of studies, there is concordance across limited evidence that laser improves the strength of bone tissue during the healing process in animal models. Blay A, Blay C C, Groth E B et al.
Laser Med Surg Abstract issue, 2002: 11

The effects of 680 and 830 nm lasers on osseointegration was studied by Blay. 30 adult rats were divided into three groups; two laser groups and one control. The rats in the two laser groups had pure titanium Frialit-2 implants implanted into each proximal metaphysis of their respective tibias, inserted with a 40 Ncm torque. The initial stability was monitored by means of a resonance frequency analyzer. Ten irradiations were performed, 48 hours apart, 4 J/cm2 on two points, starting immediately after surgery. Resonance frequency analysis indicated a significant difference between frequency values at 3 and 6 weeks, as compared to control. At 6 weeks the removal torque in the laser groups was much higher than in the control group. Pires-Oliveira DA, Oliveira RF, Amadei SU, Pacheco-Soares C, Rocha RF.
Osteoporos Int. 2010 Mar 4. [Epub ahead of print] PMID: 20204601 [PubMed – as supplied by publisher]

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 a 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.

J Oral Rehabil. 2008 Dec;35(12):925-33

The interaction between NSAIDs and laser therapy has not been fully evaluated. In this study, selective cyclooxygenase-2 non-steroidal anti-inflammatory drugs were used after surgery for reducing edema and pain. The aim of this study was to evaluate the action of anti-COX-2 selective drug (celecoxib) on bone repair associated with laser therapy. A total of 64 rats underwent surgical bone defects in their tibias and then were assessed to evaluate bone healing. The results suggest that low-level laser therapy is able to improve bone repair in the tibia of rats as a result of an up-regulation for cyclooxygenase-2 expression in bone cells.

J Orthop Surg Res. 2010 Jan 4;5(1):1

This was a meta-analysis performed to identify animal research defining the effects of low power laser irradiation on biomechanical indicators of bone regeneration and the impact of dosage. They looked at a total of 880 studies and picked five studies that met their criteria. They concluded that low power laser irradiation enhanced the biomechanical properties of bone during fracture healing. They concluded that there is concordance that laser improves the strength of bone tissue during the healing process. This is important not only for fractured bone but supports the notion that laser will also be of value with procedures as diverse as tooth implants, osteoporosis, etc.

P204TH. The effects of the low-level laser therapy on tibial bone consolidation in osteopenic rats Renno ACM, Fangel R, Bossini PS, Driusso P, Parizotto N, Oishi J; Federal University of Sao paulo, Santos, Sao Paulo, Brazil, Federal University of Sao Carlos, Sao Carlos, Sao Paulo, Brazil.
IOF World Congress on Osteoporosis December 3-7, 2008 Bangkok, Thailand

Million of fractures occurs every year worldwide due to a reduced bone mass related to osteoporosis. Many of them termed in non-union fractures. 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 significantly 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 Biosilicate® showed higher values of ML compared to the SC group (mean: 0.129).

Conclusion: LLT was effective to improve the callus bone strength of tibial defects in osteopenic rats, in both fluencies used. The results of this work may suggest that laser therapy has an osteogenic effect and it is efficient to accelerate bone consolidation and to increase callus strength in osteopenic rats.

End of Bone Regeneration & Repair Data