Bone Healing

The Effects of Low-Level Laser Therapy on Bone in Diabetic and Nondiabetic Rats.

Photomed Laser Surg. 2009 Aug 21. [Epub ahead of print]

Bayat M, Abdi S, Javadieh F, Mohsenifar Z, Rashid MR.

1 Cellular and Molecular Biology Research Center, Shahid Beheshti University , M.C., Tehran, Iran .

ABSTRACT OBJECTIVE: The aim of the present study was to examine the effects of low-level laser therapy (LLLT) on the tibia of streptozotocin-induced diabetic (STZ-D) rats.

BACKGROUND DATA: LLLT has been found to accelerate fracture healing in animals. Diabetes mellitus decreases bone volume and its biomechanical parameters.

MATERIALS AND METHODS: Twenty rats were divided randomly into four groups. Rats in the first two groups were administrated a single injection of STZ to induce diabetes, while animals in groups 3 and 4 were given a sham injection of distilled water. The right tibia in groups 1 and 2 was treated with a He-Ne laser (632.8 nm, 10 mW) of 28.6 and 382.2 J/cm(2), respectively. LLLT was performed daily for 14 consecutive days. The right tibia of rats in group 3 was treated with LLLT the same as group 2. The right tibia of rats in group 4 was used for based line studies. After 14 d, right tibiae and left tibiae (control bone) were extracted and subjected to the three-point bending test and histological study.

RESULTS: Maximum force (N) was significantly greater in laser-treated bones of groups 2 and 3 compared with their relevant control groups (paired Student t test, p = 0.05 and p = 0.007, respectively). Density of the bone lamella meshwork of compact bone in group 2 was significantly greater in comparison with its control group (paired Student t test, p = 0.005).

CONCLUSION: LLLT on tibia of STZ-D rats increased the bone lamella meshwork density of compact bone and also increased its strength.

PMID: 19698018 [PubMed - as supplied by publisher]

Effect of low-level laser therapy on the fracture healing process.

Kazem Shakouri S, Soleimanpour J, Salekzamani Y, Oskuie MR.

Tabriz University of Medical Sciences, Tabriz, Iran, sk0531ir@yahoo.com.

Lasers Med Sci. 2009 Apr 28. [Epub ahead of print]

Low-level laser therapy (LLLT) is a biophysical form of intervention in the fracture-repair process, which, through several mechanisms, accelerates the healing of fractures and enhances callus formation. The effect of laser on fracture healing is controversial. Some authors affirm that LLLT can accelerate bone formation by increasing osteoblastic activity. The objective of our study was to evaluate the effect of laser therapy on fracture healing. Thirty rabbits were subjected to tibial bone open osteotomies that were stabilized with external fixators. The animals were divided into two study groups: laser group and control group. Callus development and bone mineral density were quantitatively evaluated by CT; the animals were then killed and the fractures were assessed for biomechanical properties. The results demonstrated that the increasing rate of bone mineral density was higher in the laser (L) group than in the control (C) group. CT at 5 weeks revealed a mean callus density of 297 Hounsfield units (HU) for the control group and 691 HU for the L group, which was statistically significant (P = 0.001). In the L group, the mean recorded fracture tension was 190.5 N and 359.3 N for healed and intact bones, respectively, which was statistically significant (P < 0.001). The result of the study showed that the use of laser could enhance callus development in the early stage of the healing process, with doubtful improvement in biomechanical properties of the healing bone; therefore, laser therapy may be recommended as an additional treatment in non-union fractures in humans.

PMID: 19399356 [PubMed - as supplied by publisher]

The effect of low-intensity laser therapy on bone healing around titanium implants: a histometric study in rabbits.

Pereira CL, Sallum EA, Nociti FH Jr, Moreira RW.

Division of Oral and Maxillofacial Surgery, Piracicaba Dental School, Campinas State University, Piracicaba, São Paulo, Brazil.

Int J Oral Maxillofac Implants. 2009 Jan-Feb;24(1):47-51.

PURPOSE: This study aimed to histometrically evaluate the influence of low-intensity laser treatment on bone healing around titanium implants placed in rabbit tibiae.

MATERIALS AND METHODS: Each tibia of 12 adult rabbits received a 3.3 x 6-mm titanium implant. The implants placed in the right tibiae were irradiated with a gallium-aluminum-arsenide diode low-intensity laser every 48 hours for 14 days postoperatively, and the left tibiae were not irradiated. After 3 or 6 weeks, the animals were sacrificed (six animals per period), and nondecalcified sections were obtained and analyzed for bone-to-implant contact (BIC) and bone area within the implant threads. Data were subjected to statistical analysis using analysis of variance (ANOVA) and the Tukey test.

RESULTS: BIC was significantly increased in the laser-treated group at both 3 weeks and 6 weeks. BIC did not increase significantly with time (3 weeks versus 6 weeks). Conversely, bone area within the threads was significantly increased with time (3 weeks versus 6 weeks), regardless of whether the laser was used. Considering bone area within the threads, no significant difference was found for treatment, eg, with or without laser.

CONCLUSION: Low-intensity laser therapy did not affect the area of bone formed within the threads, but it may improve BIC in rabbit tibiae.

PMID: 19344024 [PubMed - indexed for MEDLINE]

Low-level laser therapy improves bone repair in rats treated with anti-inflammatory drugs.

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

Ribeiro DA, Matsumoto MA.

Department of Biosciences, Federal University of Sao Paulo, UNIFESP, Santos, SP, Brazil. daribeiro@unifesp.br

Nowadays, selective cyclooxygenase-2 non-steroidal anti-inflammatory drugs have been largely used in surgical practice for reducing oedema and pain. However, the association between these drugs and laser therapy is not known up to now. Herein, 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, being randomly distributed into four groups: Group 1) negative control; Group 2) animals treated with celecoxib; Group 3) animals treated with low-level power laser and Group 4) animals treated with celecoxib and low-level power laser. The animals were killed after 48 h, 7, 14 and 21 days. The tibias were removed for morphological, morphometric and immunohistochemistry analysis for COX-2. Statistical significant differences (P < 0.05) were observed in the quality of bone repair and quantity of formed bone between groups at 14 days after surgery for Groups 3 and 4. COX-2 immunoreactivity was more intense in bone cells for intermediate periods evaluated in the laser-exposed groups. Taken together, such 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.

PMID: 19090909 [PubMed - indexed for MEDLINE]

Histologic study of the effect of laser therapy on bone repair.

Blaya DS, Guimarães MB, Pozza DH, Weber JB, de Oliveira MG.

Centro Universitário Franciscano, Santa Maria, RS, Brazil.

J Contemp Dent Pract. 2008 Sep 1;9(6):41-8.

AIM: This study used histologic analysis and HE staining to evaluate laser biomodulation of bone repair in cavities made in the femurs of rats that underwent non-ablative laser irradiation.

METHODS AND MATERIALS: Eighteen male Wistar rats weighing 300 to 400 grams were randomly assigned to three groups of six animals each. A surgical defect site was produced with a trephine about 2 mm in diameter under abundant irrigation. In Group I the complete surgical protocol to produce a bone defect was followed but without laser radiation (control). In Group II a continuous wave 830 nm infrared laser was used at 10 J/cm2 and 50 mW at each point of the surgical site. In Group III a continuous wave 685 nm infrared laser at 10J/cm2 and 35 mW was used at each point of surgical site. The animals were irradiated at intervals of 48 hours beginning immediately after the preparation of the defect and were sacrificed on the 15th, 21st, and 30th days. Slides were studied by means of descriptive analysis.

RESULTS: Greater degrees of new bone formation and vertical regeneration were found in the irradiated groups than in the control group.

CONCLUSION: Laser therapy in this study protocol was efficient in promoting bone repair.

CLINICAL SIGNIFICANCE: The use of laser technology has been used to improve the clinical results of bone surgeries and to promote a more comfortable postoperative period and quicker healing.

PMID: 18784858 [PubMed - indexed for MEDLINE]

Effect of soft laser and bioactive glass on bone regeneration in the treatment of bone defects (an experimental study).

AboElsaad NS, Soory M, Gadalla LM, Ragab LI, Dunne S, Zalata KR, Louca C.

Department of Oral Medicine and Periodontology, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

Lasers Med Sci. 2009 Jul;24(4):527-33. Epub 2008 Jul 15.

This study aimed to investigate the influence of low-power gallium-aluminium-arsenide (GaAlAs) laser [830 nm, continuous wave (CW), 40 mW and fluence 4 J/cm(2)] on the healing of surgically created bone defects in rats treated with bioactive glass graft material. Surgical bone defects were created in the mandibles of 36 Wistar rats divided into two groups, each consisting of 18 rats. Group I was treated with bioactive glass plus laser irradiation. Group II was treated with graft material only. The animals were killed at 4 weeks, 8 weeks and 12 weeks postoperatively for histological examination. Laser irradiation had significantly accelerated bone healing at 4 weeks and 8 weeks in comparison with that at the sites not irradiated. However at 12 weeks, complete healing of the defects had occurred with no difference detected. Our results have confirmed the positive effect of soft laser in accelerating bone regeneration.

PMID: 18626570 [PubMed - indexed for MEDLINE]

Effect of soft laser and bioactive glass on bone regeneration in the treatment of infra-bony defects (a clinical study).

AboElsaad NS, Soory M, Gadalla LM, Ragab LI, Dunne S, Zalata KR, Louca C.

Department of Oral Medicine and Periodontology, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

Lasers Med Sci. 2009 May;24(3):387-95. Epub 2008 Jun 26.

This study aimed to investigate the influence of low-power 830 nm gallium-aluminium-arsenide (GaAlAs) laser [continuous wave (CW) 40 mW and fluence 4 J/cm(2), with total energy density of 16 J/cm(2)] on the healing of human infra-bony defects treated with bioactive glass graft material. Twenty patients with chronic periodontitis and bilateral infra-bony defects were included. Using a split mouth design, we treated 20 defects with bioactive glass plus laser irradiation during surgical procedures and on days 3, 5, 7 postoperatively; 20 contra-lateral defects were treated with bioactive glass only. Clinical probing pocket depths, clinical attachment levels and standardized periapical radiographs were recorded at baseline and at 3 months and 6 months postoperatively. At 3 months there was a statistically significant difference between the laser and non-laser sites in the parameters investigated. However, at 6 months, no difference was observed. Our results have confirmed the positive effect of soft laser in accelerating periodontal wound healing.

PMID: 18581160 [PubMed - indexed for MEDLINE]

Bone repair following bone grafting hydroxyapatite guided bone regeneration and infra-red laser photobiomodulation: a histological study in a rodent model.

Pinheiro AL, Martinez Gerbi ME, de Assis Limeira F Jr, Carneiro Ponzi EA, Marques AM, Carvalho CM, de Carneiro Santos R, Oliveira PC, Nóia M, Ramalho LM.

Department of Propedeutica and Clínica Integrada, Laser Center, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil. albp@ufba.br

Lasers Med Sci. 2009 Mar;24(2):234-40. Epub 2008 Apr 17.

The aim of the investigation was to assess histologically the effect of laser photobiomodulation (LPBM) on a repair of defects surgically created in the femurs of rats. Forty-five Wistar rats were divided into four groups: group I (control); group II (LPBM); group III (hydroxyapatite guided bone regeneration; HA GBR); group IV (HA GBR LPBM). The animals in the irradiated groups were subjected to the first irradiation immediately after surgery, and it was repeated every day for 2 weeks. The animals were killed 15 days, 21 days and 30 days after surgery. When the groups irradiated with implant and membrane were compared, it was observed that the repair of the defects submitted to LPBM was also processed faster, starting from the 15th day. At the 30th day, the level of repair of the defects was similar in the irradiated groups and those not irradiated. New bone formation was seen inside the cavity, probably by the osteoconduction of the implant, and, in the irradiated groups, this new bone formation was incremental. The present preliminary data seem to suggest that LPMB therapy might have a positive effect upon early wound healing of bone defects treated with a combination of HA and GBR.

PMID: 18418643 [PubMed - indexed for MEDLINE]

Does the use of laser photobiomodulation, bone morphogenetic proteins, and guided bone regeneration improve the outcome of autologous bone grafts? An in vivo study in a rodent model.

Torres CS, dos Santos JN, Monteiro JS, Amorim PG, Pinheiro AL.

Centro Baiano de Estudos Odontológicos, Especialização em Cirurgia e Traumatologia Bucomaxilofaciais, Universidade Federal da Bahia, Salvador, Brazil.

Photomed Laser Surg. 2008 Aug;26(4):371-7.

OBJECTIVE: The aim of the present investigation was to histologically assess the effect of laser photobiomodulation (LBPM) on the repair of autologous bone grafts in a rodent model.

BACKGROUND DATA: A major problem in modern dentistry is the recovery of bone defects caused by trauma, surgical procedures, or pathologies. Several types of biomaterials have been used to improve the repair of these defects. These materials are often associated with procedures of guided bone regeneration (GBR).

MATERIALS AND METHODS: Twenty four animals were divided into four groups: group I (control); group II (LPBM of the bone graft); group III (bone morphogenetic proteins [BMPs] + bone graft); and group IV (LPBM of the bed and the bone graft + BMPs). When appropriate the bed was filled with lyophilized bovine bone and BMPs used with or without GBR. The animals in the irradiated groups received 10 J/cm(2) per session divided over four points around the defect (4 J/cm(2)), with the first irradiation immediately after surgery, and then repeated seven times every other day. The animals were humanely killed after 40 d.

RESULTS: The results showed that in all treatment groups, new bone formation was greater and qualitatively better than the untreated subjects. Control specimens showed a less advanced repair after 40 d, and this was characterized by the presence of medullary tissue, a small amount of bone trabeculi, and some cortical repair.

CONCLUSION: We conclude that LPBM has a positive biomodulatory effect on the healing of bone defects, and that this effect was more evident when LPBM was performed on the surgical bed intraoperatively, prior to the placement of the autologous bone graft.

PMID: 18647094 [PubMed - indexed for MEDLINE]

Initial effects of low-level laser therapy on growth and differentiation of human osteoblast-like cells.

Stein E, Koehn J, Sutter W, Wendtlandt G, Wanschitz F, Thurnher D, Baghestanian M, Turhani D.

Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Austria.

Wien Klin Wochenschr. 2008;120(3-4):112-7.

Low-level laser therapy is a clinically well established tool for enhancement of wound healing. In vitro studies have also shown that low level laser therapy has a biostimulatory effect on cells of different origin. The aim of this in vitro study was to investigate the initial effect of low-level laser therapy on growth and differentiation of human osteoblast-like cells. SaOS-2 cells were irradiated with laser doses of 1 J/cm2 and 2 J/cm2 using a diode laser with 670 nm wave length and an output power of 400 mW. Untreated cells were used as controls. At 24 h, 48 h and 72 h post irradiation, cells were collected and assayed for viability of attached cells and alkaline phosphatase specific activity. In addition, mRNA expression levels of osteopontin and collagen type I were assessed using semi-quantitative RT-PCR. Over the observation period, cell viability, alkaline phosphatase activity and the expression of osteopontin and collagen type I mRNA were slightly enhanced in cells irradiated with 1 J/cm2 compared with untreated control cells. Increasing the laser dose to 2 J/cm2 reduced cell viability during the first 48 h and resulted in persistently lower alkaline phosphatase activity compared with the other two groups. The expression of osteopontin and collagen type I mRNA slightly decreased with time in untreated controls and cells irradiated with 1 J/cm2, but their expression was increased by treatment with 2 J/cm2 after 72 h. These results indicate that low-level laser therapy has a biostimulatory effect on human osteoblast-like cells during the first 72 h after irradiation. Further studies are needed to determine the potential of low-level laser therapy as new treatment concept in bone regeneration.

PMID: 18322773 [PubMed - indexed for MEDLINE]

Infrared laser light further improves bone healing when associated with bone morphogenic proteins: an in vivo study in a rodent model.

Gerbi ME, Marques AM, Ramalho LM, Ponzi EA, Carvalho CM, Santos Rde C, Oliveira PC, Nóia M, Pinheiro AL.

School of Dentistry, Federal University of Pernambuco, Recife, PE, Salvador.

Photomed Laser Surg. 2008 Feb;26(1):55-60.

OBJECTIVE: This study assessed histologically the effect of laser photobiomodulation (LPBM) on the repair of surgical defects created in the femurs of Wistar rats treated or not treated with bone morphogenic proteins (BMPs) and organic bovine bone graft.

BACKGROUND DATA: This paper is part of an ongoing series of works in which biomaterials are used in association with LPBM. Several previous reports by our group have shown that the use of laser photobiomodulation improves the treatment of bone defects.

MATERIALS AND METHODS: Forty-eight adult male Wistar rats were divided into four randomized groups: group I (control, n = 12); group II (LPBM, n = 12); group III (BMPs + organic bovine bone graft, n = 12); and group IV (BMPs + organic bovine bone graft + LPBM, n = 12). The irradiated groups received seven irradiations every 48 h, beginning immediately after the surgical procedure. The laser therapy (lambda = 830 nm, 40 mW CW, varphi = 0.6 mm) consisted of 16 J/cm(2) per session divided equally over four points (4 J/cm(2) each) around the defect. The subjects were sacrificed after 15, 21, and 30 d, and the specimens were routinely embedded in wax, stained with hematoxylin and eosin and sirius red, and analyzed under light microscopy.

RESULTS: The results showed histological evidence of increased deposition of collagen fibers (at 15 and 21 d), as well as an increased amount of well-organized bone trabeculae at the end of the experimental period (30 d) in the irradiated animals versus the non-irradiated controls.

CONCLUSION: The use of LPBM with BMPs and organic bovine bone grafts increases the positive biomodulating effects of laser light.

PMID: 18248162 [PubMed - indexed for MEDLINE]

Effect of IR laser photobiomodulation on the repair of bone defects grafted with organic bovine bone.

Márquez Martínez ME, Pinheiro AL, Ramalho LM.

School of Dentistry, Pernambuco University, Camaragibe, Pernambuco, Brazil.

Lasers Med Sci. 2008 Jul;23(3):313-7. Epub 2007 Sep 20.

A major problem on modern dentistry is the recovery of bone defects of different etiologies. Biomaterials are used to improve the repair of these defects. Previous studies have shown positive effects of Laser Photobiomodulation (LPBM) on the repair of both soft and bone tissues. This study assessed histologically the effect of LPBM on the repair of surgical defects on the femur of rats filled with lyophilized bovine bone. The animals were divided into three groups: group I (control); group II (graft); group III (graft + LPBM). The animals on the irradiated groups received 16 J/cm(2) per session divided into four points around the defect being the first irradiation immediately after surgery and repeated at every 48 h during 2 weeks. Animal death occurred 15, 21, and 30 days after surgery. The specimens were routinely processed and stained with H/E and Sirius red and analyzed by light microscopy. There was histological evidence of improved collagen fiber deposition at early stages of the healing; increased amount of well-organized bone trabeculae at the end of the experimental period on irradiated animals. It is concluded that LPBM has positive biomodulative effect on the healing process bone defects.

PMID: 17882467 [PubMed - indexed for MEDLINE]

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.

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.

PMID: 18158750 [PubMed - indexed for MEDLINE]

Histologic comparison of light emitting diode phototherapy-treated hydroxyapatite-grafted extraction sockets: a same-mouth case study.

Brawn PR, Kwong-Hing A.

343 Railway Street, Vancouver, British Columbia, Canada. brawn_peter@yahoo.ca

Implant Dent. 2007 Jun;16(2):204-11.

BACKGROUND: The stimulating effect of red and near-infrared (NIR) laser phototherapy on bone regeneration and growth has been shown in a number of in vitro and animal studies. However, the effect of NIR phototherapy on the bone regeneration of hydroxyapatite (HA) -treated extraction sockets has not been previously demonstrated.

MATERIALS AND METHODS: An investigational Biolux extraoral light emitting diode phototherapy device was used daily for 21 days postextraction and socket grafting with HA (Osteograf LD300) unilaterally. Bone regeneration of the phototherapy-treated and nontreated side was compared in same-mouth extraction sockets.

RESULTS: Histologic evaluations showed enhanced bone formation and faster particle resorption associated with the phototherapy-treated socket graft compared with the non-phototherapy-treated socket.

CONCLUSIONS: The accelerated bone healing in the phototherapy-treated HA socket graft may provide faster implant placement compared to non-phototherapy-treated socket grafts.

PMID: 17563511 [PubMed - indexed for MEDLINE]

The therapeutic effect of low-level laser on repair of osteochondral defects in rabbit knee.

Kamali F, Bayat M, Torkaman G, Ebrahimi E, Salavati M.

Department of Physical Therapy, University of Social Welfare and Rehabilitation, Tehran, Iran. fahimehkamali@hotmail.com

J Photochem Photobiol B. 2007 Jul 27;88(1):11-5. Epub 2007 May 1.

INTRODUCTION: Low level laser therapy (LLLT) has been shown to enhance collagen production and wound healing but its effect on cartilage repair from biomechanical point of view is not known yet. The aim of present study was to evaluate the biomechanical behaviour of repairing osteochondral defect in rabbits which received a pulsed low-level gallium-arsenide (Ga-As) laser irradiation.

MATERIALS AND METHODS: Osteochondral defects with 5mm diameter and 4mm in depth induced by drilling in right femoral patellar grooves of 41 adolescent male rabbits. They were divided into experimental and control groups. Experimental group received pulsed Ga-As (890nm) laser irradiation with energy density of 4.8J/cm(2). The rabbits in control group received placebo LLLT with shut-down equipment. The control defects were allowed to heal spontaneously. Each group were divided into three subgroups: A, B and C. Subgroups A, B and C were sacrificed on 4, 8, and 16 weeks after surgery. The knee joint were removed, and the defects were examined biomechanically by in situ-indentation method. The thickness, instantaneous and equilibrium indentation stiffness was measured during the test. Data were analysed using ANOVA and independent sample t-test.

RESULT: While no difference was observed in the repaired cartilage biomechanical properties among 4th, 8th, 16th weeks in study groups. The equilibrium indentation stiffness of experimental group was significantly higher in 8th week in comparison with control group.

CONCLUSION: LLLT significantly enhances the stiffness of repairing tissue in the 8th week post injury in osteochondral defects in rabbits.

PMID: 17555980 [PubMed - indexed for MEDLINE]

Effects of two types of low-level laser wave lengths (850 and 630 nm) on the orthodontic tooth movements in rabbits.

Seifi M, Shafeei HA, Daneshdoost S, Mir M.

Faculty of Dentistry, Orthodontics Department, Shaheed Beheshti University of Medical Science, Evin, Tehran, Iran. seifimassoud@gmail.com

Lasers Med Sci. 2007 Nov;22(4):261-4. Epub 2007 Mar 3.

The effects of low-level lasers on bone cellular activity, bone structures, bone healing, fibroblasts activity and inflammation process have already been investigated. Considering orthodontic tooth movement, which is a complicated inflammatory process involving simultaneous bone apposition and resorption, the aim of this controlled study is to investigate the quantitative effects of a pulsed 850 nm laser (Optodan) and a continuous 630 nm laser (KLO3) on the orthodontic tooth movement in rabbits. This experimental study was conducted on 18 male albino rabbits divided into three equal groups of control, Optodan and KLO3. In all the groups, NiTi-closed coil springs were used on the first mandibular molars with 4-oz tension. The control group was not irradiated by laser, but the teeth in the laser groups were irradiated 9 days according to the periodontal therapeutic protocols. After 16 days, samples were sacrificed. The distance between the distal surface of the first molar and the mesial surface of the second molar was measured with 0.05-mm accuracy. The data were subjected to the statistical tests of Kolmogrov Smirnov and variance analysis. The mean orthodontic tooth movements of the first mandibular molars were 1.7 +/- 0.16 mm in control group, 0.69 +/- 0.16 mm in Optodan group and 0.86 +/- 0.13 mm in KLO3 group. There were statistically significant difference between the control and the two other laser-irradiated groups (P < 0.001). The findings of the present study imply that the amounts of orthodontic tooth movement, after low-level laser therapy, are diminished. It could not be concluded that any low-level laser will reduce the speed of teeth movement in orthodontic treatments, and further studies with less or more energies may show different results.

PMID: 17334676 [PubMed - indexed for MEDLINE]

Low-level laser effect on mandibular distraction osteogenesis.

Miloro M, Miller JJ, Stoner JA.

Section of Oral and Maxillofacial Surgery, University of Nebraska Medical Center, Omaha, NE 68198-5180, USA. mmiloro@unmc.edu

J Oral Maxillofac Surg. 2007 Feb;65(2):168-76.

PURPOSE: The purpose of this study was to determine whether low-level laser (LLL) application during distraction osteogenesis could accelerate bone regeneration and decrease the length of the consolidation phase and thereby reduce potential patient morbidity.

MATERIALS AND METHODS: Nine adult female New Zealand white rabbits underwent bilateral mandibular corticotomies and placement of unidirectional distraction devices (KLS-Martin LP, Jacksonville, FL). Each rabbit served as its own internal control. After a latency of 1 day, distraction progressed bilaterally at 1 mm per day for 10 days. Immediately after each device activation, the experimental side, chosen randomly, was treated with real LLL (Laser Medical Systems, Hedehusene, Denmark) of 6.0 J x 6 transmucosal sites in the area of the distraction gap. Radiographs were taken presurgically, immediately postsurgically, and weekly until sacrifice, and the bone was analyzed using a semiquantitative 4-point scale (Bone Healing Score [BHS]). Three animals each were sacrificed at 2, 4, and 6 weeks postdistraction, and each hemimandible was prepared for histologic examination in a blinded fashion.

RESULTS: Ten millimeters of distraction was achieved in each rabbit bilaterally. Radiographically, the BHS was higher for the LLL-treated group at all time periods. Histologically, the area of new bone trabeculation and ossification was more advanced for the LLL-treated group, with less intervening fibrovascular intermediate zone in the bony regenerate, at all time periods. The formation of a complete inferior border occurred sooner in the treatment group than in the controls.

CONCLUSIONS: LLL accelerates the process of bone regeneration during the consolidation phase after distraction osteogenesis. The adjunctive use of LLL may allow a shortened period of consolidation and therefore permit earlier device removal, with the avoidance of morbidity associated with prolonged device retention.

PMID: 17236917 [PubMed - indexed for MEDLINE]

A preliminary study of healing of diode laser versus scalpel incisions in rat oral tissue: a comparison of clinical, histological, and immunohistochemical results.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Jun;103(6):764-73. Epub 2006 Nov 7.

D'Arcangelo C, Di Nardo Di Maio F, Prosperi GD, Conte E, Baldi M, Caputi S.

University G. D'Annunzio, Faculty of Medicine, Department of Oral Science, Unit of Restorative Dentistry, Chieti, Italy.

OBJECTIVE: The aim of this preliminary study was to compare wound healing of rat oral tissues after surgical procedure with diode laser or scalpel. Healing was evaluated histologically, immunohistochemically, and by measurement of 2 nitric oxide synthase isoforms (eNOS and iNOS) as intracellular messenger molecules with important immune functions. The instruments were also evaluated for performance and ease of use.

STUDY DESIGN: Twenty-four standardized incisions were performed in the hard palate of 12 male Wistar rats. Each rat received 2 incisions on the opposite sides of the palate by using a steel scalpel (control group) and a diode laser (808 nm) at a power output of 4 W and 6 W (test group). Histological and immunohistochemical analyses were performed on tissue samples after 7 and 14 days. The expression of eNOS and iNOS was confirmed by RT-PCR (reverse transcriptase-polymerase chain reaction) and Western blot analysis.

RESULTS: Scalpel repair was found to be equivalent to or better than laser repair at the intervals measured. Histological analysis showed that incision wound repair after laser surgical procedure was related to parameters and beam characteristics. Diode laser at a power output of 6 W showed the worst results of tissue repair, especially after 7 days. On the contrary, the extent of epithelial damage lateral to the wound edge and the extent of collagen denaturation were near equal with scalpel incision and laser irradiation at 4 W after 14 days. Biochemical analysis of RT-PCR and Western blots also confirmed histological results with a greater concentration of eNOS and iNOS after 7 days of laser surgical procedure.

CONCLUSIONS: Clinical and histological findings change over time for different treatments. Diode laser tends to produce more pronounced changes than conventional scalpel surgical procedure (due to tissue thermal damage), with corresponding greater inflammatory reaction and delay in tissue organization only at the initial stage. Thus, long-term histology is critical for predicting treatment results. The clinical use of low-level diode laser for tissue welding of oral mucosa should be investigated further, since it appears to be a good alternative to scalpel incision and suture repair.

PMID: 17095269 [PubMed - indexed for MEDLINE]

Effect of low intensity laser irradiation on surgically created bony defects in rats.

Nissan J, Assif D, Gross MD, Yaffe A, Binderman I.

J Oral Rehabil. 2006 Aug;33(8):619-924.

Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. nissandr@post.tau.ac.il

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.

Comparative study of how low-level laser therapy and low-intensity pulsed ultrasound affect bone repair in rats.

Lirani-Galvão AP, Jorgetti V, da Silva OL.

Bioengineering Department, University of São Paulo, São Paulo, Brazil. analirani@hotmail.com

Photomed Laser Surg. 2006 Dec;24(6):735-40.

OBJECTIVE: This study aimed to compare the consequences of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on bone repair.

BACKGROUND DATA: Many studies have assessed the effects of LLLT and LIPUS on bone repair, but a comparison of them is rare.

METHODS: Male Wistar rats (n = 48) with tibial bone osteotomy were used. One group had the osteotomized limb treated with LLLT (GaAlAs laser, 780 nm, 30 mW, 112.5 J/cm(2)) and the second group with LIPUS (1.5 MHz, 30 mW/cm(2)), both for 12 sessions (five times per week); a third group was the control. After 20 days, rats were sacrificed and had their tibias submitted to a bending test or histomorphometric analysis.

RESULTS: In the bending test, maximum load at failure of LLLT group was significantly higher (p < 0.05). Bone histomorphometry revealed a significant increase in osteoblast number and surface, and osteoid volume in the LLLT group, and a significant increase in eroded and osteoclast surfaces in the LIPUS group.

CONCLUSION: LIPUS enhanced bone repair by promoting bone resorption in the osteotomy area, while LLLT accelerated this process through bone formation.

PMID: 17199474 [PubMed - indexed for MEDLINE]

Effect of low intensity laser irradiation on surgically created bony defects in rats.

Nissan J, Assif D, Gross MD, Yaffe A, Binderman I.

Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. nissandr@post.tau.ac.il

J Oral Rehabil. 2006 Aug;33(8):619-924.

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.

PMID: 16856960 [PubMed - indexed for MEDLINE]

Photoengineering of bone repair processes.

Pinheiro AL, Gerbi ME.

Laser Center, School of Dentistry, Department of Propedêutica and Clínica Integrada, Universidade Federal da Bahia, Canela Salvador, BA, Salvador, Brazil. albp@ufba.br

Photomed Laser Surg. 2006 Apr;24(2):169-78.

OBJECTIVE: This paper aims to report the state of the art with respect to photoengineering of bone repair using laser therapy.

BACKGROUND DATA: Laser therapy has been reported as an important tool to positively stimulate bone both in vivo and in vitro. These results indicate that photophysical and photochemical properties of some wavelengths are primarily responsible for the tissue responses. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect in healing bone.

METHODS: A series of papers reporting the effects of laser therapy on bone cells and tissue are presented, and new and promising protocols developed by our group are presented.

RESULTS: The results of our studies and others indicate that bone irradiated mostly with infrared (IR) wavelengths shows increased osteoblastic proliferation, collagen deposition, and bone neorformation when compared to nonirradiated bone. Further, the effect of laser therapy is more effective if the treatment is carried out at early stages when high cellular proliferation occurs. Vascular responses to laser therapy were also suggested as one of the possible mechanisms responsible for the positive clinical results observed following laser therapy. It still remains uncertain if bone stimulation by laser light is a general effect or if the isolate stimulation of osteoblasts is possible.

CONCLUSION: It is possible that the laser therapy effect on bone regeneration depends not only on the total dose of irradiation, but also on the irradiation time and the irradiation mode. The threshold parameter energy density and intensity are biologically independent of one another. This independence accounts for the success and the failure of laser therapy achieved at low-energy density levels.

PMID: 16706695 [PubMed - indexed for MEDLINE]

Repair of bone defects treated with autogenous bone graft and low-power laser.

J Craniofac Surg. 2006 Mar;17(2):297-301.

da Silva RV, Camilli JA.

Department of Anatomy, Institute of Biology, State University of Campinas, UNICAMP, São Paulo, Brazil.

Because bone healing at the graft site is similar to a fracture repair, the purpose of the present study was to evaluate the effects of low-power laser irradiation on the repair of rat skull defects treated with autogenous bone graft. A defect measuring 3 mm in diameter was produced in the left parietal bone and filled with an autogenous bone graft obtained from the right parietal bone. The animals were divided into 3 groups of 20 rats each: nonirradiated control, irradiated with 5.1 J/cm, and irradiated with 10.2 J/cm. The laser (2.4 mW, 735 nm, 3.4 x 10 W/cm, 3-mm spot size) was applied three times per week for 4 weeks. Greater volume of newly formed bone was observed in the irradiated group with 10.2 J/cm. In both irradiated groups, a greater volume of newly formed bone occurred only in the first 2 weeks. The results demonstrated that laser irradiation at the grafted site stimulated osteogenesis during the initial stages of the healing process in a skull defect of the rat and that this effect was dose dependent.

Periodontal tissue healing following flap surgery using an Er:YAG laser in dogs.

Lasers Surg Med. 2006 Apr;38(4):314-24.

Mizutani K, Aoki A, Takasaki AA, Kinoshita A, Hayashi C, Oda S, Ishikawa I.

Periodontology, Department of Hard Tissue Engineering, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. mizutani.peri@tmd.ac.jp

BACKGROUND AND OBJECTIVES: The purpose of this study was to compare periodontal tissue healing following flap surgery using an Er:YAG laser with that of conventional surgery.

STUDY DESIGN/MATERIALS AND METHODS: Bilateral premolars with experimentally induced periodontitis in six dogs were treated by periodontal flap surgery. Degranulation and root debridement in the furcation were performed using an Er:YAG laser or curet. At 3 months postsurgery, animals were sacrificed and decalcified specimens were prepared for histological and histometric analysis.

RESULTS: Degranulation and root debridement were effectively performed with an Er:YAG laser without major thermal damage and significantly faster than with a curet. Histologically, the amount of newly formed bone was significantly greater in the laser group than in the curet group, although both groups showed similar amounts of cementum formation and connective tissue attachment.

CONCLUSIONS: The Er:YAG laser irradiation can be safely and effectively utilized in periodontal flap surgery, and has the potential to promote new bone formation. Copyright 2006 Wiley-Liss, Inc.

PMID: 16568444 [PubMed - indexed for MEDLINE]

Assessment of bone repair associated with the use of organic bovine bone and membrane irradiated at 830 nm.

Gerbi ME, Pinheiro AL, Marzola C, Limeira Junior Fde A, Ramalho LM, Ponzi EA, Soares AO, Carvalho LC, Lima HV, Goncalves TO.

School of Dentistry, Federal University of Bahia, Salvador, Brazil.

Photomed Laser Surg. 2005 Aug;23(4):382-8.

OBJECTIVE: The aim of the present investigation was to assess histologically the effect of LLLT (GaAIAs, 830 nm, 40 mW, CW, (Phi) approximately 0.6 mm, 16 J/cm(2) per session) on the repair of surgical defects created in the femur of the Wistar Albinus rat. The defects were filled to lyophilized bovine bone (Gen-ox), organic matrix) associated or not to GTR (Gen-derm).

Background Data: A major problem on modern Dentistry is the recovery of bone defects caused by trauma, surgical procedures or pathologies. Several types of biomaterials have been used in order to improve the repair of these defects. These materials are often associated to procedures of GTR. Previous studies have shown positive effects of LLLT on the repair of soft tissue wounds, but there are a few on its effects on bone healing.

Methods: Surgical bone defects were created in 42 animals divided into five groups: Group I (control, 6 animals); Group II (Gen-ox, 9 animals); Group III (Gen-ox + Laser, 9 animals); Group IV (Gen-ox + Gen-derm, 9 animals); Group V (Gen-ox + Gen-derm + Laser, 9 animals). The animals on the irradiated group received 16 J/cm(2) per session divided into four points around the defect (4 J/cm(2)) being the first irradiation immediately after surgery and repeated seven times at every 48 h. The animals were humanly killed after 15, 21, and 30 days.

Results: The results of the present investigation showed histological evidence of improved amount of collagen fibers at early stages of the bone healing (15 days) and increased amount of well organized bone trabeculae at the end of the experimental period (30 days) on irradiated animals compared to non irradiated ones.

Conclusions: It is concluded that a positive biomodulative effect on the healing process of one defect associated or not to the use of organic lyophilized bone and biological bovine lyophilized membrane on the femur of the rat.

Low-level laser irradiation promotes proliferation and differentiation of human osteoblasts in vitro.

Stein A, Benayahu D, Maltz L, Oron U.

Department of Zoology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.

Photomed Laser Surg. 2005 Apr;23(2):161-6

OBJECTIVES: The aim of the present study was to investigate the effect of low-level laser irradiation on proliferation and differentiation of a human osteoblast cell line.

BACKGROUND DATA: It was previously found that low-level laser therapy (LLLT) enhances bone repair in experimental models.

MATERIALS AND METHODS: Cultured osteoblast cells were irradiated using He-Ne laser irradiation (632 nm; 10 mW power output). On the second and third day after seeding the osteoblasts were exposed to laser irradiation. The effect of irradiation on osteoblast proliferation was quantified by cell count and colorimetric MTT (dimethylthiazol tetrazolium bromide) assay 24 and 48 h after second irradiation.

RESULTS: A significant 31-58% increase in cell survival (MTT assay) and higher cell count in the once-irradiated as compared to nonirradiated cells was monitored. Differentiation and maturation of the cells was followed by osteogenic markers: alkaline phosphatase (ALP), osteopontin (OP), and bone sialoprotein (BSP). A two-fold enhancement of ALP activity and expression of OP and BSP was much higher in the irradiated cells as compared to non-irradiated osteoblasts.

CONCLUSION: We conclude that LLLT promotes proliferation and maturation of human osteoblasts in vitro. These results may have clinical implications.

Enhancement of bone formation in rat calvarial bone defects using low-level laser therapy.

Khadra M, Kasem N, Haanaes HR, Ellingsen JE, Lyngstadaas SP.

Department of Oral Surgery and Oral Medicine, University of Oslo, Norway. maawan@odont.uio.no

Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004 Jun;97(6):693-700.

OBJECTIVE: To evaluate the effect of low-level laser therapy (LLLT), using a GaAlAs diode laser device, on bone healing and growth in rat calvarial bone defects.

STUDY DESIGN: An animal trial of 4 weeks' duration was conducted using a randomized blind, placebo-controlled design. Standardized round osseous defects of 2.7 mm diameter were made in each parietal bone of 20 rats (n=40 defects). The animals were randomly divided into an experimental and a control group of 10 animals each. In the experimental group, a GaAlAs diode laser was applied immediately after surgery and then daily for 6 consecutive days. The control group received the same handling and treatment, but with the laser turned off. Five rats from each group were killed on day 14 and the remainder on day 28 postoperatively. From each animal, tissue samples from one defect were prepared for histochemistry and samples from the contralateral defect for histology. Levels of calcium, phosphorus, and protein were determined by using atomic absorption spectrometry, colorimetry, and photometry, respectively. Student t-test and Mann-Whitney were used for statistical analyses.

RESULTS: At both time points the tissue samples from the experimental animals contained significantly more calcium, phosphorus, and protein than the controls. Similarly, histological analyses disclosed more pronounced angiogenesis and connective tissue formation, and more advanced bone formation in the experimental group than in the controls.

CONCLUSION: LLLT may enhance bone formation in rat calvarial bone defects.

Effects of pulse frequency of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells.

Ueda Y, Shimizu N.

Department of Orthodontics, Nihon University School of Dentistry at Matsudo Chiba, Japan.

J Clin Laser Med Surg. 2003 Oct;21(5):271-7.

OBJECTIVE: The purpose of this study was to determine the effect of pulse frequencies of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells in vitro.

BACKGROUND DATA: Various photo-biostimulatory effects of LLLT, including bone formation, were affected by some irradiation factors such as total energy dose, irradiation phase, laser spectrum, and power density. However, the effects of pulse frequencies used during laser irradiation on bone formation have not been elucidated.

MATERIALS AND METHODS: Osteoblast-like cells isolated from fetal rat calvariae were irradiated once with a low-energy Ga-Al-As laser (830 nm, 500 mW, 0.48-3.84 J/cm2) in four different irradiation modes: continuous irradiation (CI), and 1-, 2-, and 8-Hz pulsed irradiation (PI-1, PI-2, PI-8). We then investigated the effects on cellular proliferation, bone nodule formation, alkaline phosphatase (ALP) activity, and ALP gene expression.

RESULTS: Laser irradiation in all four groups significantly stimulated cellular proliferation, bone nodule formation, ALP activity, and ALP gene expression, as compared with the non-irradiation group. Notably, PI-1 and -2 irradiation markedly stimulated these factors, when compared with the CI and PI-8 groups, and PI-2 irradiation was the best approach for bone nodule formation in the present experimental conditions.

CONCLUSION: Since low-frequency pulsed laser irradiation significantly stimulates bone formation in vitro, it is most likely that the pulse frequency of LLLT an important factor affecting biological responses in bone formation.

Effect of low-power GaAlAs laser (660 nm) on bone structure and cell activity: an experimental animal study.

Nicola RA, Jorgetti V, Rigau J, Pacheco MT, dos Reis LM, Zangaro RA.

Vale of Paraiba University, Sao Jose dos Campos, SP, Brazil.

Lasers Med Sci. 2003;18(2):89-94.

Low-level laser therapy (LLLT) is increasingly being used in the regeneration of soft tissue. In the regeneration of hard tissue, it has already been shown that the biomodulation effect of lasers repairs bones more quickly. We studied the activity in bone cells after LLLT close to the site of the bone injury. The femurs of 48 rats were perforated (24 in the irradiated group and 24 in the control group) and the irradiated group was treated with a GaAlAs laser of 660 nm, 10 J/cm2 of radiant exposure on the 2nd, 4th, 6th and 8th days after surgery (DAS). We carried out histomorphometry analysis of the bone. We found that activity was higher in the irradiated group than in the control group: (a) bone volume at 5 DAS (p=0.035); (b) osteoblast surface at 15 DAS (p=0.0002); (c) mineral apposition rate at 15 and 25 DAS (p=0.0008 and 0.006); (d) osteoclast surface at 5 DAS and 25 DAS (p=0.049 and p=0.0028); and (e) eroded surface ( p=0.0032). We concluded that LLLT increases the activity in bone cells (resorption and formation) around the site of the repair without changing the bone structure.

Laser stimulation on bone defect healing: an in vitro study.

Guzzardella GA, Fini M, Torricelli P, Giavaresi G, Giardino R.

Department of Experimental Surgery, Codivilla-Putti Research Institute/Rizzoli Orthopaedic Institute, Italy. gaetanoantonio.guzzardella@ior.it

Lasers Med Sci. 2002;17(3):216-20.

The aim of this in vitro study was to evaluate whether low-power laser (LPL) stimulation can accelerate bone healing. Bone defects of a standard area were created in the distal epiphysis of 12 femora explanted from six rats, and they were cultured in BGJb medium for 21 days. Six defects were treated daily with Ga-Al-As, 780 nm LPL for 10 consecutive days (lased group, LG), while the remainder were sham-treated (control group, CG). Alkaline phosphatase/total protein (ALP/TP), calcium (Ca), and nitric oxide (NO) were tested on days 7, 14 and 21 to monitor the metabolism of cultured bone. The percentage of healing of the defect area was determined by histomorphometric analysis. After 21 days significant increases were observed in ALP/TP in LG versus CG (p<0.001), in NO in the LG versus CG ( p<0.0005) and in Ca in CG versus LG ( p<0.001). The healing rate of the defect area in the LG was higher than in the CG ( p=0.007). These in vitro results suggest that Ga-Al-As LPL treatment may play a positive role in bone defect healing.

Laser therapy improves healing of bone defects submitted to autologous bone graft.

Weber JB, Pinheiro AL, de Oliveira MG, Oliveira FA, Ramalho LM.

School of Dentistry, Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Brazil.

Photomed Laser Surg. 2006 Feb;24(1):38-44.

OBJECTIVE: The aim of the present study was to assess histologically the effect of low-level laser thrapy (LLLT) (lambda 830 nm) on the healing of bone defects associated with autologous bone graft.

BACKGROUND DATA: LLLT has been used on the modulation of bone healing because of the photo-physical and photochemical properties of some wavelengths. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect on the healing bone.

METHODS: Sixty male Wistar rats were divided into four groups: G1 (control), G2 (LLLT on the surgical bed), G3 (LLLT on the graft), and G4 (LLLT on both the graft and the surgical bed). The dose per session was 10 J/cm(2), and it was applied to the surgical bed (G2/G4) and on the bone graft (G3/G4). LLLT was carried out every other day for 15 days (lambda 830 nm, phi = 0.5 cm(2), 50 Mw, 10 J/cm(2)). The dose was fractioned in four points. The animals were sacrificed 15, 21, and 30 days after surgery; specimens were taken and routinely processed (wax, cut, and stain with H&E and Sirius red stains). Light microscopic analysis was performed by a pathologist.

RESULTS: In the groups in which the LLLT was used trans-operatively on the surgical bed (G2/G4), bone remodeling was both quantitatively and qualitatively more evident when compared to subjects of groups G1 and G3.

CONCLUSION: The present study indicates that the use of LLLT trans-operatively resulted in a positive biomodulative effect on the healing of bone defects associated with autologous bone grafts.