Low-level laser therapy induces differential expression of osteogenic genes during bone repair in rats.
Fávaro-Pípi E, Ribeiro DA, Ribeiro JU, Bossini P, Oliveira P, Parizotto NA, Tim C, de Araújo HS, Renno AC.
Department of Physiotherapy, Federal University of São Carlos, Brazil.
Photomed Laser Surg. 2011 May;29(5):311-7. doi: 10.1089/pho.2010.2841. Epub 2011 Feb 9. [PMID: 21306231]
Abstract
Objectives: The aim of this study was to measure the temporal pattern of the expression of osteogenic genes after low-level laser therapy during the process of bone healing. We used quantitative real-time polymerase chain reaction (qPCR) along with histology to assess gene expression following laser irradiation on created bone defects in tibias of rats.
Material and methods: The animals were randomly distributed into two groups: control or laser-irradiated group. Noncritical size bone defects were surgically created at the upper third of the tibia. Laser irradiation started 24 h post-surgery and was performed for 3, 6, and 12 sessions, with an interval of 48 h. A 830 nm laser, 50 J/cm(2), 30 mW, was used. On days 7, 13, and 25 post-injury, rats were sacrificed individually by carbon dioxide asphyxia. The tibias were removed for analysis.
Results: The histological results revealed intense new bone formation surrounded by highly vascularized connective tissue presenting slight osteogenic activity, with primary bone deposition in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). The quantitative real-time PCR showed that laser irradiation produced an upregulation of BMP-4 at day 13 post-surgery and an upregulation of BMP4, ALP, and Runx 2 at day 25 after surgery.
Conclusion: Our results indicate that laser therapy improves bone repair in rats as depicted by differential histopathological and osteogenic genes expression, mainly at the late stages of recovery.
Low-level laser therapy enhances the stability of orthodontic mini-implants via bone formation related to BMP-2 expression in a rat model.
Omasa S, Motoyoshi M, Arai Y, Ejima K, Shimizu N.
Department of Orthodontics, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
Photomed Laser Surg. 2012 May;30(5):255-61. Epub 2012 Mar 9. [PMID: 22404559]
Abstract
Objective: The aim of this study was to investigate the stimulatory effects of low-level laser therapy (LLLT) on the stability of mini-implants in rat tibiae.
Background data: In adolescent patients, loosening is a notable complication of mini-implants used to provide anchorage in orthodontic treatments. Previously, the stimulatory effects of LLLT on bone formation were reported; here, it was examined whether LLLT enhanced the stability of mini-implants via peri-implant bone formation.
Materials and methods: Seventy-eight titanium mini-implants were placed into both tibiae of 6-week-old male rats. The mini-implants in the right tibia were subjected to LLLT of gallium-aluminium-arsenide laser (830 nm) once a day during 7 days, and the mini-implants in the left tibia served as nonirradiated controls. At 7 and 35 days after implantation, the stability of the mini-implants was investigated using the diagnostic tool (Periotest). New bone volume around the mini-implants was measured on days 3, 5, and 7 by in vivo microfocus CT. The gene expression of bone morphogenetic protein (BMP)-2 in bone around the mini-implants was also analyzed using real-time reverse-transcription polymerase chain reaction assays. The data were statistically analyzed using Student’s t test.
Results: Periotest values were significantly lower (0.79- to 0.65-fold) and the volume of newly formed bone was significantly higher (1.53-fold) in the LLLT group. LLLT also stimulated significant BMP-2 gene expression in peri-implant bone (1.92-fold).
Conclusions: LLLT enhanced the stability of mini-implants placed in rat tibiae and accelerated peri-implant bone formation by increasing the gene expression of BMP-2 in surrounding cells.
Infrared laser photobiomodulation (lambda 830 nm) on bone tissue around dental implants: a Raman spectroscopy and scanning electronic microscopy study in rabbits.
Lopes CB, Pinheiro AL, Sathaiah S, Da Silva NS, Salgado MA.
Instituto de Pesquisa & Desenvolvimento [Institute for Research & Development] (IP&D), Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, Brazil., Department of Dentistry, UNIVAP, São José dos Campos, Brazil.
Photomed Laser Surg. 2007 Apr;25(2):96-101. [PMID: 17508844]
Abstract
Objective: The aim of this study was to assess, through Raman spectroscopy, the incorporation of calcium hydroxyapatite (CHA; approximately 960 cm(1)), and scanning electron microscopy (SEM), the bone quality on the healing bone around dental implants after laser photobiomodulation (lambda830 nm).
Background data: Laser photobiomodulation has been successfully used to improve bone quality around dental implants, allowing early wearing of prostheses.
Methods: Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with lambda830 nm laser (seven sessions at 48-h intervals, 21.5 J/cm(2) per point, 10 mW, phi approximately 0.0028 cm(2), 86 J per session), and six acted as control. The animals were sacrificed 15, 30, and 45 days after surgery. Specimens were routinely prepared for Raman spectroscopy and SEM. Eight readings were taken on the bone around the implant.
Results: The results showed significant differences on the concentration of CHA on irradiated and control specimens at both 30 and 45 days after surgery (p < 0.001).
Conclusion: It is concluded that infrared laser photobiomodulation does improve bone healing, and this may be safely assessed by Raman spectroscopy or SEM.
Effects of Continuous and Pulsed Infrared Laser Application on Bone Repair Using Different Energy Doses. Study in Rats
Almeida-Lopes1, H. Pretel2, V. Moraes3, P. Jurgens3, L. Ramalho2 and R. Sader3
1 NUPEN, Research, and Education Center for Photo Therapy in Health Sciences, São Carlos, Brazil
2 Morphology Department, UNESP, Araraquara, Brazil
3 Hightech Forschungs Zentrum, Munich, Germany
Abstract
The Laser Therapy effects on the cellular proliferation are extensively searched and widely known. However, there are controversies on the best out put power used in the applications, the ideal fluency and irradiance, better emission mode and the adequate number of sessions in order to obtain the best results. The aim of this paper was to search for the best application fluency and emission mode, using an infrared laser in the repair of bone defects in the rat tibia. Thus, the histological quality of the neo-formed bone was evaluated by analysis using common optic microscopy and polarized light. Application Parameters: 100 mW, 830 nm, spot diameter = 0,06 nm, CW and 10 Hz, 3 sessions with 72 h of interval, energies and respective fluencies: 2 J =70 J/cm 2, 4 J =140 J/cm 2 , 6 J =210 J/cm 2 , 8 J =160 J/cm 2 , 10 J =200 J/cm 2 . Conclusions: Laser Therapy has increased and accelerated the time bone repairing process (in the initial period of 10 days). This laser effect showed to be dose-dependent with the presence of an effective therapeutic window presenting biostimulation of the bone tissue between 4J and 8 J of total energy for both emission mode. The use of the laser with 10 J of energy generated, characterized by the bioinhibition of the tissues (in the initial pe-riod of 10 days). This inhibition took place at the exact irradiation spot).
Effect of lower-level laser therapy on rabbit tibial fracture.
Liu X, Lyon R, Meier HT, Thometz J, Haworth ST.
Musculoskeletal Functional Assessment Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53201, USA. xcliu@mcw.edu
Photomed Laser Surg. 2007 Dec;25(6):487-94. [PMID: 18158750]
Abstract
Objective: The purpose of the study was to demonstrate the biological effects of low-level laser therapy (LLLT) on tibial fractures using radiographic, histological, and bone density examinations.
Methods: Fourteen New Zealand white rabbits with surgically induced mid-tibial osteotomies were included in the study. Seven were assigned to a group receiving LLLT (LLLT-A) and the remaining seven served as a sham-treated control group (LLLT-C). A low-energy laser apparatus with a wavelength of 830 nm, and a sham laser (a similar design without laser diodes) were used for the study. Continuous outflow irradiation with a total energy density of 40 J/cm(2) and a power level of 200 mW/cm(2) was directly delivered to the skin for 50 seconds at four points along the tibial fracture site. Treatment commenced immediately postsurgery and continued once daily for 4 weeks.
Results: Radiographic findings revealed no statistically significant fracture callus thickness difference between the LLLT-A and LLLT-C groups (p > 0.05). However, the fractures in the LLLT-A group showed less callus thickness than those in LLLT-C group 3 weeks after treatment. The average tibial volume was 14.5 mL in the LLLT-A group, and 11.25 mL in the LLLT-C group. The average contralateral normal tibial volume was 7.1 mL. Microscopic changes at 4 weeks revealed an average grade of 5.5 and 5.0 for the LLLT-A group and the LLLT-C group, respectively. The bone mineral density (BMD) as ascertained using a grey scale (graded from 0 to 256) showed darker coloration in the LLLT-A group (138) than in the LLLT-C group (125).
Conclusion: The study suggests that LLLT may accelerate the process of fracture repair or cause increases in callus volume and BMD, especially in the early stages of absorbing the hematoma and bone remodeling. Further study is necessary to quantify these findings.
Effect of low-level laser therapy (GaAlAs) on bone regeneration in midpalatal anterior suture after surgically assisted rapid maxillary expansion.
Angeletti P, Pereira MD, Gomes HC, Hino CT, Ferreira LM.
Division of Plastic Surgery, Federal University of São Paulo, São Paulo, Brazil
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010 Mar;109(3):e38-46. [PMID: 20219584]
Abstract
Objective: The aim of this study was to evaluate the effects of laser therapy on bone regeneration in the midpalatal anterior suture (MPAS) after surgically assisted rapid maxillary expansion (SARME).
Methods: Thirteen patients aged between 18 and 33 years old with maxillary transverse deficiency (> or =7.0 mm) were evaluated. All patients underwent subtotal Le Fort I osteotomy with separation of the pterygomaxillary suture with the use of Hyrax expander, and were divided into 2 groups: control group (n = 6) and laser group (n = 7). A GaAlAs laser (P = 100 mW, lambda = 830 nm, Ø = 0.06 cm(2)) was used. The laser was applied in 8 treatment sessions with intervals of 48 hours. Each treatment session consisted of laser applications, per point (E = 8.4J, ED = 140J/cm(2)), at 3 points on the MPAS, and total dose of E = 25.2 J, ED = 420 J/cm(2). Digital radiographs were taken before the surgical procedure and at 1-, 2-, 3-, 4-, and 7-month follow-up visits. Optical density analysis of the regenerated bone was performed using Adobe Photoshop 8.0 software.
Results: Bone regeneration associated with the use of laser after SARME showed a statistically significant difference. A higher mineralization rate was found in the laser group (26.3%, P < .001) than the control group.
Conclusion: Low-level laser irradiation (GaAlAs) accelerates bone regeneration in MPAS after SARME. However, the optical density measurements after 7 months of follow-up were lower in comparison with the preoperative measurements.
Biomodulatory effects of LLLT on bone regeneration
Antonio L.B. Pinheiro1), Marilia G. Oliveira2), Pedro Paulo M. Martins3), Luciana Maria Pedreira Ramalho4), Marcos A. Matos de Oliveira5), Aurelicio Novaes Júnior, Renata Amadei Nicolau
1) School of Dentistry, Department of Diagnostic and Therapeutics, Universidade Federal da Bahia 2) School of Dentistry, Post-Graduate Program on Oral and Maxillofacial Surgery, Pontificia Universidade Católica do Rio Grande do Sul 3) School of Dentistry, University of Pernambuco 4) School of Dentistry, Laser Center, Universidade Federal da Bahia 5) Lecture, Institute of Research and Development (IP&D) Universidade Vale do Paraíba (UNIVAP)
Abstract
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 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 healing. The amount of newly formed bone after 830nm laser irradiation of surgical wounds created in the femur of rats was evaluated morphometricaly. 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 early stages of healing.