Effects Of Low-energy Laser Irradiation Research Articles

Effects of Low-Energy Laser Irradiation on Sperm Cells Dynamics of Rabbit (Oryctolagus Cuniculus)

Infertility is a world disease in which a couple is unable to achieve pregnancy. There are numerous parameters to determinate fertility; nevertheless, sperm motility is by consensus one of the most important attributes to evaluate male fertility. Contributions to a better understanding of this crucial parameter are imperative; hence, the aim of this investigation was to assess the effect of low-energy laser irradiation on sperm cell dynamics in thawed samples that were cryopreserved. We used a 405 nm blue laser beam to irradiate spermatic cells from rabbit inside a temperature-controlled dispersion chamber at 37 °C; then, we applied an image recognizing system to calculate individual sperm trajectories and velocities. We found that sperms raise its motility after irradiation suggesting that λ=405 nm is an optimal wavelength for spermatic photo-stimulation.

Effect of low-energy laser irradiation and antioxidant supplementation on cell apoptosis during skeletal muscle post-injury regeneration in pigs.

The aim of this study was to evaluate the effect of low-energy laser irradiation, coenzyme Q10 and vitamin E supplementation on the apoptosis of macrophages and muscle precursor cells during skeletal muscle regeneration after bupivacaine-induced injury. The experiment was conducted on 75 gilts, divided into 5 experimental groups: I--control, II--low-energy laser irradiation, III--coenzyme Q10, IV--coenzyme Q10 and vitamin E, V--vitamin E. Muscle necrosis was induced by injection of 0.5% bupivacaine hydrochloride. The animals were euthanized on subsequent days after injury. Samples were formalin fixed and processed routinely for histopathology. Apoptosis was detected using the TUNEL method. The obtained results indicate that low-energy laser irradiation has a beneficial effect on macrophages and muscle precursor cell activity during muscle post-injury regeneration and protects these cells against apoptosis. Vitamin E has a slightly lower protective effect, limited mainly to the macrophages. Coenzyme Q10 co-supplemented with vitamin E increases the activity of macrophages and muscle precursor cells, myotube and young muscle formation. Importantly, muscle precursor cells seem to be more sensitive to apoptosis than macrophages in the environment of regenerating damaged muscle.

Molecular effects of low-energy laser irradiation during orthodontic tooth movement

Since orthodontic treatments usually take around 2–3 years, it can be a great burden for both patients and providers. Therefore, shortening the duration of treatment is both desirable and beneficial to the orthodontists as long treatment duration is associated with increased risks of gingival inflammation, decalcification, dental caries, and root resorption. Several novel modalities have been reported to accelerate orthodontic tooth movement including low-level laser therapy, pulsed electromagnetic fields, electrical currents, corticotomy, distraction osteogenesis, and mechanical vibration. Low-level laser therapy (LLLT) is an effective method to prompt wound healing, bone repair, and modeling after surgery. These biostimulatory effects of LLLT have been related to increased fibroblast and osteoblast activities. Similarly, LLLT has been suggested to play a role in accelerated tooth movement. In vivo rat studies have demonstrated that low-level laser irradiation (LLLI) increases osteoclastogenesis on the compression side via stimulation of the receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL) and the c-fms/macrophage colony-stimulating factor (M-CSF) during experimental tooth movement. On the tension side, LLLI stimulates bone formation and has been associated with increased expression of type I collagen (COL1), fibronectin (FN), and osteopontin (OPN). Furthermore, In vivo studies have shown that LLLI induces differentiation and activation of osteoblasts and osteoclasts. Therefore, LLLI facilitates the turnover of connective tissues and accelerates the bone remodeling process by stimulating osteoblast and osteoclast proliferation and function during orthodontic tooth movement. This article reviews the current knowledge of the biological effects of laser irradiation and its molecular effect on orthodontic tooth movement. Since orthodontic treatments usually take around 2–3 years, it can be a great burden for both patients and providers. Therefore, shortening the duration of treatment is both desirable and beneficial to the orthodontists as long treatment duration is associated with increased risks of gingival inflammation, decalcification, dental caries, and root resorption. Several novel modalities have been reported to accelerate orthodontic tooth movement including low-level laser therapy, pulsed electromagnetic fields, electrical currents, corticotomy, distraction osteogenesis, and mechanical vibration. Low-level laser therapy (LLLT) is an effective method to prompt wound healing, bone repair, and modeling after surgery. These biostimulatory effects of LLLT have been related to increased fibroblast and osteoblast activities. Similarly, LLLT has been suggested to play a role in accelerated tooth movement. In vivo rat studies have demonstrated that low-level laser irradiation (LLLI) increases osteoclastogenesis on the compression side via stimulation of the receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL) and the c-fms/macrophage colony-stimulating factor (M-CSF) during experimental tooth movement. On the tension side, LLLI stimulates bone formation and has been associated with increased expression of type I collagen (COL1), fibronectin (FN), and osteopontin (OPN). Furthermore, In vivo studies have shown that LLLI induces differentiation and activation of osteoblasts and osteoclasts. Therefore, LLLI facilitates the turnover of connective tissues and accelerates the bone remodeling process by stimulating osteoblast and osteoclast proliferation and function during orthodontic tooth movement. This article reviews the current knowledge of the biological effects of laser irradiation and its molecular effect on orthodontic tooth movement.

Periodontal effects with self ligating appliances and laser biostimulation.

Background:Recently, various biostimulation's effects of low energy laser irradiation have been reported. The present study was designed to examine the effects of low-energy laser irradiation on alveolar bone remodelling during orthodontic tooth movement and finally on formation of new keratinized gingiva.Materials and Methods:22 patients and 27 teeth in vestibular mucosal without keratinized gingiva were selected. Every patient was treated with self ligating appliances. In every orthodontic session the patient was treated with Diode laser biostimulation. At the moment of debonding, 27 teeth involved in the research were evaluated in terms of quality and quantity of attached gingiva. BOP and CAL loss were investigated.Results:Every tooth considered at the end of orthodontic treatment showed an attached gingiva around the crown: The average of keratinized gingiva at the end of the study was 3.10 mm and the mean increasing at each month was 0,49 mm.Conclusions:The combination between self ligating appliances and laser's biostimulation could improve the differentiation of periodontal ligaments stem cells in fibroblasts, able to promote attached gingiva around the crown of the teeth erupted in oral vestibular mucosa.

In vitro Study of the Survival, Reproduction and Morphology of Daphnia pulicaria irradiated with a Low Energy Laser

Daphnia is a genus of crustaceans that is representative of freshwater communities. The species exhibit a high sensitivity to a wide range of toxic compounds so that they have been used internationally as biomonitors in toxicity tests to evaluate ecosystem conditions such as water quality. It is also a model genus in genetics, epigenetics and reproductive ecology. In this work, we used Daphnia pulicaria as a model to measure the effects of low-energy laser irradiation on survival, reproduction, and morphology variables of parental organisms and their offspring. We used (1) a single clone line of organisms to eliminate interindividual genetic variability; (2) individuals from more than 50 generations after the clone line was established, and offspring from the third brood onwards to dissipate maternal and epigenetic effects, and (3) neonates, those individuals of the species that have less than 48 hours of life, because they are the most sensitive stage to optical stimuli. We analyzed number of deaths, longevity, age at first reproduction, number of offspring per week, number of total offspring during all their life cycle, body size, size of the antennules, and length of the apical spine of the 4th and 5th brood of the irradiated individuals, who were exposed to a blue laser stimulus of 405 nm for 25 minutes with a power of 40 mW at a distance of 50 cm, compared to those of the control (non-irradiated) group.

The effect of low-energy laser irradiation on apoptotic factors following experimentally induced transient cerebral ischemia

Apoptosis, or programmed cell death, resulting from cerebral ischemia may be related to decreased levels of anti-apoptotic factors, such as serine/threonine kinase (Akt), phosphorylated Akt (pAkt), pBAD, and Bcl-2, and increased levels of pro-apoptotic factors, such as BAD, caspase 9, and caspase 3 activities. In this study, we investigated the effects of low-energy laser (660 nm) irradiation (LLI) on the levels and activity of various anti- and pro-apoptotic factors following ischemia. Transient cerebral ischemia was induced in Sprague-Dawley rats by unilateral occlusion of the middle cerebral artery for 1 h, followed by reperfusion. LLI was then directed on the cerebrum for varying lengths of duration (1, 5, or 10 min at an energy density of 2.64 J/cm², 13.2 J/cm², and 24.6 J/cm², respectively). The expression levels of Akt, pAkt, BAD, pBAD, Bcl-2, caspase 9, and caspase 3 activities were measured 4 days after injury. The levels of Akt, pAkt, Bcl-2, and pBAD were significantly increased following laser irradiation. In addition, LLI significantly decreased caspase 9 and caspase 3 activities caused by ischemia-reperfusion. LLI may protect the brain by upregulating Akt, pAkt, pBAD, and Bcl-2 expression and downregulating caspase 9 and caspase 3 expression following transient cerebral ischemia. This modality is a promising protective therapeutic intervention after strokes or other ischemic events.

Low-energy laser irradiation facilitates the velocity of tooth movement and the expressions of matrix metalloproteinase-9, cathepsin K, and alpha(v) beta(3) integrin in rats

It has previously been reported that low-energy laser irradiation stimulated the velocity of tooth movement via the receptor activator of nuclear factor kappa B (RANK)/RANK ligand and the macrophage colony-stimulating factor/its receptor (c-Fms) systems. Matrix metalloproteinase (MMP)-9, cathepsin K, and alpha(v) beta(3) [alpha(v)beta3] integrin are essential for osteoclastogenesis; therefore, the present study was designed to examine the effects of low-energy laser irradiation on the expression of MMP-9, cathepsin K, and alpha(v)beta3 integrin during experimental tooth movement. Fifty male, 6-week-old Wistar strain rats were used in the experiment. A total force of 10g was applied to the rat molars to induce tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moving tooth and, after 7 days, the amount of tooth movement was measured. To determine the amount of tooth movement, plaster models of the maxillae were made using a silicone impression material before (day 0) and after tooth movement (days 1, 2, 3, 4, and 7). The models were scanned using a contact-type three-dimensional (3-D) measurement apparatus. Immunohistochemical staining for MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 was performed. Intergroup comparisons of the average values were conducted with a Mann-Whitney U-test for tooth movement and the number of tartrate-resistant acid phosphatase (TRAP), MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3-positive cells. In the laser-irradiated group, the amount of tooth movement was significantly greater than that in the non-irradiated group at the end of the experiment (P < 0.05). Cells positively stained with TRAP, MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 were found to be significantly increased in the irradiated group on days 2-7 compared with those in the non-irradiated group (P < 0.05). These findings suggest that low-energy laser irradiation facilitates the velocity of tooth movement and MMP-9, cathepsin K, and integrin subunits of alpha(v)beta3 expression in rats.

ヘリウムネオンレーザーによる低エネルギーレーザー照射が腫瘍細胞に及ぼす影響

ヘリウムネオンレーザーによる低エネルギーレーザー照射が腫瘍細胞に及ぼす影響

レーザーと生体応答―病理学の立場から―

Since the laser was developed in 1960,its applying to optical communication and medical practice has been investigated well. There are many kinds of dental laser and more than twelve of them are used in Japan. High-energy lasers are useful in producing coagulation necrosis in target tissue with a subsequent reaction in the surrounding tissue. Various biostimulatory effects of low-energy laser irradiation have been reported that it acts on regeneration healing, fibroblast and chondral proliferation, collagen synthesis, nerve regeneration. It is used in odontotherapy for diseases of hard tissue and soft tissue, periodontitis and peri-implantitis. The usage rate of a dental laser is 30% of dental clinics in Japan and 60% of them use a laser with carbon dioxide gas. In this paper, we describe the carbon dioxide whether promote the wound healing or not. The laser is used for a lot of medical treatments now. Moreover, the laser is used for not only the treatment; its usage also has been increased for diagnosis and prevention of the disease. Especially, its research and development progress rapidly due to applying to the odontology for medical treatment.

Low‐energy laser stimulates tooth movement velocity via expression of RANK and RANKL

Recent studies have demonstrated that low-energy laser irradiation stimulates bone formation in vitro and in vivo. However, very little is known about the effects of laser irradiation on osteoclastogenesis. The receptor activator of the nuclear factor-kB (RANK) / RANK ligand (RANKL) / osteoprotegerin (OPG) system is essential and sufficient for osteoclastogenesis. The present study was designed to examine the effects of low-energy laser irradiation on expressions of RANK, RANKL, and OPG during experimental tooth movement. To induce experimental tooth movement in rats, 10 g of orthodontic force was applied to the molars. Next, a Ga-Al-As diode laser was used to irradiate the area around the moved tooth and the amount of tooth movement was measured for 7 days. Immunohistochemical staining with RANK, RANKL, and OPG was performed. Real time PCR was also performed to elucidate the expression of RANK in irradiated rat osteoclast precursor cells in vitro. In the irradiation group, the amount of tooth movement was significantly greater than in the non-irradiation group by the end of the experimental period. Cells that showed positive immunoreactions to the primary antibodies of RANKL and RANK were significantly increased in the irradiation group on day 2 and 3, compared with the non-irradiation group. In contrast, the expression of OPG was not changed. Further, RANK expression in osteoclast precursor cells was detected at an early stage (day 2 and 3) in the irradiation group. These findings suggest that low-energy laser irradiation stimulates the velocity of tooth movement via induction of RANK and RANKL.

Low-energy laser irradiation stimulates the tooth movement velocity via expression of M-CSF and c-fms

Recent studies have demonstrated that low-energy laser irradiation stimulates bone formation in vitro and in vivo. However, very little is known about the effects of laser irradiation on osteoclastogenesis. Macrophage colony-stimulating factor (M-CSF) is essential and sufficient for osteoclastogenesis. The present study was designed to examine the effects of low-energy laser irradiation on expressions of M-CSF and c-fms during experimental tooth movement. A total of 10 g of orthodontic force was applied to rat molars to cause experimental tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moved tooth and the amount of tooth movement was measured for 7 days. Immunohistochemical staining with M-CSF and c-fms was performed. RT-PCR was also performed to elucidate the expression of c-fms from irradiated rat osteoclast precursor cells. In the irradiation group, the amount of tooth movement was significantly greater than that of the non-irradiation group at the end of the experiment. Cells positively stained with M-CSF and c-fms were found to be significantly increased in the irradiation group on days 2 and 3 as compared with the non-irradiation group. Further, c-fms expression in osteoclast precursor cells was detected at an early stage (days 2 and 3) in the irradiation group. These findings suggest that low-energy laser irradiation stimulates the velocity of tooth movement via the expressions of M-CSF and c-fms.

Biostimulation of Na,K-ATPase by low-energy laser irradiation (685 nm, 35 mW): Comparative effects in membrane, solubilized and DPPC:DPPE-liposome reconstituted enzyme

Objective The aim of the present work was to investigate the effect of low-energy laser irradiation (685 nm, 35 mW) on the ATPase activity of the different forms of the Na,K-ATPase. Methods Membrane-bound and solubilized (αβ) 2 form of Na,K-ATPase was obtained from the dark red outer medulla of the kidney and proteoliposomes of DPPC:DPPE and Na,K-ATPase was prepared by the co-solubilization method. Irradiations were carried out at 685 nm using an InGaAIP diode laser. Results The ATPase activity of the membrane fraction was not altered with exposition to irradiation doses between 4 and 24 J/cm 2. However, with irradiation doses ranging from 32 to 40 J/cm 2, a 28% increase on the ATPase activity was observed while when using up to 50 J/cm 2 no additional enhancement was observed. When biostimulation was done using the solubilized and purified enzyme or the DPPC:DPPE-liposome reconstituted enzyme, an increase of about 36–40% on the ATPase activity was observed using only 4–8 J/cm 2. With irradiation above these values (24 J/cm 2) no additional increase in the activity was observed. These studies revealed that the biostimulation of ATPase activity from different forms of the Na,K-ATPase is dose dependent in different ranges of irradiation exposure. The stimulation promoted by visible laser doses was modulated and the process was reverted after 2 h for the enzyme present in the membrane and after about 5 h for the solubilized or the reconstituted in DPPC:DPPE-liposomes.

A Histopathological and Immunohistochemical Study of Wound Healing Mechanism and Biological Effect of Low-Energy Laser Irradiation in Type 2 Diabetic Model Mice

Diabetes mellitus (DM) is a typical life style related disease, in which hyperglycemia is caused by an absolute defect (type 1 DM) or relative defect (type 2 DM) of insulin. Specifically, type 2 DM is considered a life style related disease. DM is known to cause a capillary vessel disorder due to the hyperglycemia and often brings about delayed wound healing ; however, the mechanism behind this delayed wound healing is uncertain and the effect of laser irradiation using a mouse model is insufficient. Thus, this paper studies histopathological and immunohistochemical changes using the db/db mouse model in order to investigate the wound healing mechanism in type 2 DM as well as the biological effects of wound healing by low-energy laser irradiation. This DM model mice (db/db) were compared with a normal mice (m+/m+). The different levels of inflammatory cell infiltration in the wound site, capillary dilatation and regeneration, and proliferation of fibroblasts and collagen fibers were observed over time, and delayed wound healing was studied histopathologically. Moreover, db/db of laser irradiation was compared with db/db of non laser irradiation, finding capillary dilatation and regeneration, the proliferation of fibroblasts and collagen fibers prominent. Mast cells seen by metachromasia in toluidine blue pH 2.5 staining were observed in the dermis around the margin on the wound site of m+/m+ and db/db of non laser irradiation, capillary dilatation and regeneration, and proliferation of the fibroblasts and collagen fibers surroundings. The number of mast cells over time was lower in db/db of non laser irradiation than in m+/m+, however, more degranulation was seen in db/db of laser irradiation than in db/db of non laser irradiation. According to immunohistochemical findings, HSP70 was positively immunoreactive in neutrophils, macrophages, vascular endothelial cells, fibroblasts and epidermis. Moreover, the appearance of HSP70 was lower in db/db of non laser irradiation than in m+/m+. The appearance level of HSP70 in vascular endothelial cells was higher in db/db of laser irradiation than in db/db of non laser irradiation. NOS2 kept positively high in vascular endothelial cells continuously until 7 days post-operatively in db/db of the non laser irradiation compared with m+/m+. On the other hand, the level of NOS2 was low in macrophages and vascular endothelial cells in db/db of laser irradiation. Moreover, while the appearance of FGF2 was identified on 2 days in neutrophils in m+/m+, it was seen by 5 days in db/db of non laser irradiation, suggesting a delayed appearance time. The positive appearance of FGF2 was high in vascular endothelial cells and fibroblasts in db/db of laser irradiation. These findings suggest a delayed wound healing process in db/db of non laser irradiation by the decrease in the mast cell number and mast cell degranulation, decreased expression of HSP70 and FGF2, and increased expression of NOS2. It is speculated that low-energy laser irradiation improves the above findings and delayed wound healing process in db/db of non laser irradiation.

Optimal Low-Energy Laser Irradiation Causes Temporal G2/M Arrest on Rat Calvarial Osteoblasts

Low-energy laser irradiation (LELI) accelerates wound healing and is thought to accelerate bone formation. However, the mechanism of laser healing is not clear. To clarify the biological mechanism of LELI healing, we investigated the effects of LELI on rat osteoblasts in vitro. Osteoblastic cells from 3-day-old Wistar rat calvaria were irradiated using a low-energy gallium-aluminum-arsenide (Ga-Al-As) diode laser. Bone formation, osteoblast differentiation, and cell proliferation were evaluated by von Kossa staining, reverse-transcription polymerase chain reaction, alkaline phosphatase (ALP) staining, 5-bromo-2'-deoxyuridine (BrdU) uptake, and fluorescence-activated cell sorter (FACS) analysis. At 21 days after LELI, the greatest bone formation was observed with irradiation energy of 3.75 J/cm2 and the first week after seeding. LELI (3.75 J/cm2) induced an increased number of cells at day 3. LELI-stimulated differentiation in osteoblastic cells was demonstrated by the increases of Runx2 expression and ALP-positive colonies. By contrast, at 1 day after laser irradiation, the number of cells in the irradiation group was significantly lower than that in the control group. BrdU uptake indicated lower proliferation 12 and 24 hours after irradiation compared with the control. Furthermore, FACS data demonstrated a higher proportion of cells in the G2/M phase of the cell cycle 12 hours after irradiation compared with the control. G2/M arrest was confirmed by the appearance of G2/M arrest marker 14-3-3-sigma or phospho-p53. These results demonstrate that LELI induces not only acceleration of bone formation but also initial G2/M arrest, which may cause wound healing like tissue repair.

Effect of Low-Intensity Laser Irradiation on the Process of Bone Repair

The effect of low-intensity laser (GaAsAl) irradiation on bone repair in the femurs of mice was investigated. An experimental model of hole injury with surgery drills was used in 20 mouse femurs followed by a study of the effect of low-energy laser irradiation on bone repair. The experimental model was divided into two groups. The first (10 left femurs) received laser irradiation immediately after injury and was followed for different time intervals (24, 48, and 72 h). The right femurs (control group) underwent hole injury but no laser irradiation. The rats were sacrificed after 14 days and the results were analyzed using a quantitative histometrical method. The Mann-Whitney test was used to perform the statistical analysis. Histometrical analysis revealed a more rapid accumulation of reparative new bone in the hole injury of the laser-irradiated legs. We conclude that GaAsAl laser irradiation after injury was effective on bone repair when compared to results in the control group.

Effect of low-energy laser irradiation on the area of experimental myocardial infarction, lipid peroxidation, and hemoglobin affinity for oxygen.

The mechanism of antiischemic effect of low-energy laser radiation was studied in rats with experimental myocardial infarction taking into consideration the effect of laser on hemoglobin affinity for oxygen and intensity of lipid peroxidation. Low-energy laser irradiation for 15 min in vitro decreased the area of myocardial infarction, slightly reduced hemoglobin affinity for oxygen, and inhibited lipid peroxidation. Short-term low-energy laser irradiation did not reduce the area of necrosis, initiated lipid peroxidation, and increased superoxide dismutase activity.

Effect of low-power laser irradiation on bony implant sites.

This study was designed to examine the effects of low-energy laser irradiation on osteocytes and bone resorption at bony implant sites. Five male baboons with a mean age of 6.5 years were used in the study. Four holes for accommodating implants were drilled in each iliac crest. Sites on the left side were irradiated with a 100 mW low-energy laser (690 nm) for 1 min (6 Joule) immediately after drilling and insertion of four sandblasted and etched (Frialit-2 Synchro) implants. Five days later, the bone was removed en bloc and was evaluated histomorphometrically. The mean osteocyte count per unit area was 109.8 cells in the irradiated group vs. 94.8 cells in the control group. As intra-individual cell counts varied substantially, osteocyte viability was used for evaluation. In the irradiated group, viable osteocytes were found in 41.7% of the lacuna vs. 34.4% in the non-irradiated group. This difference was statistically significant at P < 0.027. The total resorption area, eroded surface, was found to be 24.9% in the control group vs. 24.6% in the irradiated group. This difference was not statistically significant. This study showed that osteocyte viability was significantly higher in the samples that were subjected to laser irradiation immediately after implant site drilling and implant insertion, in comparison to control sites. This may have positive effects on the integration of implants. The bone resorption rate, in contrast, was not affected by laser irradiation.

Laser irradiation inhibition of open gingival embrasure space after orthodontic treatment

Abstract The purpose of this study was to investigate the inhibitory effect of low-energy laser irradiation on an incidence of open gingival embrasure space after orthodontic treatment. The patient was a 20-year, 7-month-old Japanese female with an Angle Class I malocclusion and crowding in the mandible. Treatment consisted of extraction of maxillary and mandibular first premolars and use of the Edgewise technique. A Ga-Al-As diode laser was used to irradiate an area of 0.5 cm2 at the labial and lingual gingival papilla between the canines. The time of exposure was 6 minutes for 3 days, carried out between the relevelling and en masse stages of movement. The total energy corresponding to 6 minutes of exposure varied from 1.90 J/cm2. There was no further evidence of open gingival embrasure space, except at the mandibular central incisor. Further: an improvement in the gingival inflammation caused by a periodontal disease was observed, and periodontal pocket depth was maintained. These results suggest that low-energy laser irradiation may inhibit the incidence of open gingival embrasure space after orthodontic treatment.

Inhibition of interleukin-1beta production and gene expression in human gingival fibroblasts by low-energy laser irradiation.

Human gingival fibroblast (hGF) cells reside in gingival tissues which are challenged frequently by oral bacteria. Lipopolysaccharide (LPS) from periodontal pathogens can penetrate gingival tissues and stimulate the production of interleukin-1beta (IL-1beta), which has been implicated in inflammation and bone resorption. The anti-inflammatory effects of low-energy laser irradiation have been reported, but the mechanisms of this biostimulatory effect have not been fully elucidated. Primary cultured hGF cells were challenged with LPS isolated from Campylobacter rectus, a known periodontal disease-associated pathogen, and irradiated by a Ga-Al-As diode low-energy laser (830 nm, 3.95-7.90 J/cm2). The hGF cells cultured medium showed a marked elevation of IL-1beta production by LPS, which was significantly inhibited by laser irradiation in a dose-dependent manner. By reverse transcription-polymerase chain reaction (RT-PCR) analysis, this inhibitory effect was involved in the reduction of IL-1beta mRNA levels but not that of the IL-1beta converting enzyme.

Effects of low-energy laser irradiation on bone remodeling during experimental tooth movement in rats.

Low-energy laser irradiation has many anabolic effects such as the acceleration of bone formation. However, its effects on tooth movement, performed by bone resorption and formation, have not been well characterized. A total of 10 g of orthodontic force was applied to rat molars to cause experimental tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moved tooth, and after 12 days, the amount of tooth movement was measured. Calcein was injected subcutaneously to label the newly formed alveolar bone for quantitative analysis. Immunohistochemical staining of proliferating cell nuclear antigen was performed to evaluate cellular proliferation. TRAPase staining was also performed to facilitate the identification of osteoclasts. In the laser irradiation group, the amount of tooth movement was significantly greater (1. 3-fold) than that of the nonirradiation group in the end of the experiment. The amount of bone formation and rate of cellular proliferation in the tension side and the number of osteoclasts in the pressure side were all significantly increased in the irradiation group when compared with the nonirradiation group (P < 0. 01). These findings suggest that low-energy laser irradiation can accelerate tooth movement accompanied with alveolar bone remodeling.