The biomedical effects of laser application

Effect of laser therapy on attachment, proliferation and differentiation of human osteoblast-like cells cultured on titanium implant material

The aim of this in vitro study was to investigate the effect of low-level laser therapy (LLLT) on the attachment, proliferation, differentiation and production of transforming growth factor-ss(1) (TGF-beta(1)) by human osteoblast-like cells (HOB). Cells derived from human mandibular bone were exposed to GaAlAs diode laser at dosages of 1.5 or 3 J/cm(2) and then seeded onto titanium discs. Non-irradiated cultures served as controls. After 1, 3 and 24h, cells were stained and the attached cells were counted under a light microscope. In order to investigate the effect of LLLT on cell proliferation after 48, 72 and 96 h, cells were cultured on titanium specimens for 24h and then exposed to laser irradiation for three consecutive days. Specific alkaline phosphatase activity and the ability of the cells to synthesize osteocalcin after 10 days were investigated using p-nitrophenylphosphate as a substrate and the ELSA-OST-NAT immunoradiometric kit, respectively. Cellular production of TGF-beta(1) was measured by an enzyme-linked immunosorbent assay (ELISA), using commercially available kits. LLLT significantly enhanced cellular attachment (P<0.05). Greater cell proliferation in the irradiated groups was observed first after 96 h. Osteocalcin synthesis and TGF-beta(1) production were significantly greater (P<0.05) on the samples exposed to 3 J/cm(2). However, alkaline phosphatase activity did not differ significantly among the three groups. These results showed that in response to LLLT, HOB cultured on titanium implant material had a tendency towards increased cellular attachment, proliferation, differentiation and production of TGF-beta(1), indicating that in vitro LLLT can modulate the activity of cells and tissues surrounding implant material.

Effect of LLLT Ga-Al-As (685 nm) on LPS-induced inflammation of the airway and lung in the rat

The purpose of this study was to investigate the effect of low level laser therapy (LLLT) on male Wistar rat trachea hyperreactivity (RTHR), bronchoalveolar lavage (BAL) and lung neutrophils influx after Gram-negative bacterial lipopolyssacharide (LPS) intravenous injection. The RTHR, BAL and lung neutrophils influx were measured over different intervals of time (90 min, 6 h, 24 h and 48 h). The energy density (ED) that produced an anti-inflammatory effect was 2.5 J/cm(2), reducing the maximal contractile response and the sensibility of trachea rings to methacholine after LPS. The same ED produced an anti-inflammatory effect on BAL and lung neutrophils influx. The Celecoxib COX-2 inhibitor reduced RTHR and the number of cells in BAL and lung neutrophils influx of rats treated with LPS. Celecoxib and LLLT reduced the PGE(2) and TXA(2) levels in the BAL of LPS-treated rats. Our results demonstrate that LLLT produced anti-inflammatory effects on RTHR, BAL and lung neutrophils influx in association with inhibition of COX-2-derived metabolites.

Spontaneous Ultraweak Photon Emission from Biological Systems and the Endogenous Light Field

Still one of the most astonishing biological electromagnetic phenomena is the ultraweak photon emission (UPE) from living systems. Organisms and tissues spontaneously emit measurable intensities of light, i.e. photons in the visible part of the electromagnetic spectrum (380-780 nm), in the range from 1 to 1,000 photons x s-1 x cm-2, depending on their condition and vitality. It is important not to confuse UPE from living systems with other biogenic light emitting processes such as bioluminescence or chemiluminescence. This article examines with basic considerations from physics on the quantum nature of photons the empirical phenomenon of UPE. This leads to the description of the non-thermal origin of this radiation. This is in good correspondence with the modern understanding of life phenomena as dissipative processes far from thermodynamic equilibrium. UPE also supports the understanding of life sustaining processes as basically driven by electromagnetic fields. The basic features of UPE, like intensity and spectral distribution, are known in principle for many experimental situations. The UPE of human leukocytes contributes to an endogenous light field of about 1011 photons x s-1 which can be influenced by certain factors. Further research is needed to reveal the statistical properties of UPE and in consequence to answer questions about the underlying mechanics of the biological system. In principle, statistical properties of UPE allow to reconstruct phase-space dynamics of the light emitting structures. Many open questions remain until a proper understanding of the electromagnetic interaction of the human organism can be achieved: which structures act as receptors and emitters for electromagnetic radiation? How is electromagnetic information received and processed within cells?

Effect of Low Intensity Helium-Neon (He-Ne) Laser Irradiation on Diabetic Wound Healing Dynamics

OBJECTIVE

The aim of this study was to determine the effect of low-energy He-Ne laser treatment on wound healing dynamics (histological and biochemical) in diabetic rats.

BACKGROUND DATA

Low-energy laser photostimulation at certain wavelengths can enhance tissue repair by releasing growth factors from fibroblasts and can facilitate the healing process of diabetic wounds.

MATERIALS AND METHODS

A circular 4 cm2 excisional wound was created on the dorsum of the experimentally (Alloxan)-induced diabetic rats. In the study group (N = 24) the wound was treated with He-Ne laser (632.8 nm wavelength) at a dose of 4.8 J/cm2 for 5 days a week until the wound healed completely. The control group (N = 24) was sham-irradiated. The results were statistically analyzed by an independent t test for biochemical analysis and the nonparametric Mann-Whitney U test for histopathological parameters.

RESULTS

The analysis of the biochemical parameters and histopathological parameters of the wounds showed that the laser-treated group healed faster and better as compared to the control group (p < 0.0001). The laser-treated group healed on average by the 18th day whereas, the control group healed on average by the 59th day.

CONCLUSION

Laser photostimulation promotes the tissue repair process of diabetic wounds.

The use of polarized polychromatic non-coherent light as therapy for acute tennis elbow/lateral epicondylalgia: a pilot study

OBJECTIVE

The aim of this study was to assess the efficacy of polarized, polychromatic, non-coherent, low energy light (Bioptron 2, Bioptron AG, Switzerland) in the treatment of acute tennis elbow.

BACKGROUND

Tennis elbow, or lateral epicondylitis, is one of the most common lesions affecting the arm. A plethora of treatment regimes have been described for this condition, but no specific therapy has emerged as a gold standard.

METHODS

A pilot study was carried out with 25 patients who had acute tennis elbow. Bioptron 2 device was applied over lateral epicondyle three times per week for 4 weeks. Pain on VAS, function on VAS, and painfree grip strength were measured at the beginning (week 0) and at the end of the study (week 4).

RESULTS

The pain on VAS was reduced at the end of treatment (t(24) = 3.84, p = 0.001). Function on VAS was increased at the end of treatment (t(24) = 4.23, p < 0.001). Pain-free grip strength was increased at the end of treatment (t(24) = 4.23, p < 0.004).

CONCLUSION

Although the results suggested that the Bioptron 2 could reduce patients' symptoms with acute tennis elbow, future controlled studies are needed to establish the relative and absolute effectiveness of Bioptron 2.

Combined treatment of therapeutic laser and herbal application improves the strength of repairing ligament

The present study investigated the effects of combined therapeutic laser and herbal medication protocols on injured medial collateral ligaments (MCLs) of rat knees. Fully 36 rats were evenly divided into 9 groups. Right MCLs of groups 1 to 6 and 8 were transected, while that of groups 7 and 9 remained intact. After surgery, group 1 was treated with 1 session of high-dosed laser; group 2 with 9 sessions of low-dosed laser; group 3 with an herbal plaster; groups 4 and 5 received combined treatments of groups 1 and ss and 2, and 3 respectively; groups 6 and 7 received only bandaging; groups 8 and 9 received placebo laser and no treatment, respectively. All MCLs were subjected to biomechanical testing at 3 weeks postsurgery. Results revealed significant differences among groups in ultimate tensile strength (UTS) and stiffness (p < 0.01). Combination of multiple low-dosed laser treatment with herbal treatment (group 5) resulted in higher UTS than either no treatment (groups 6 and 8), single high-dosed laser treatment (group 1), multiple low-dosed laser treatment (group 2), or herbal treatment (group 2) alone. We concluded that combined applications of laser and herb can enhance further biomechanical properties of repairing rat MCLs than separate applications at 3 weeks postinjury.

He-Ne laser effects on blood microcirculation during wound healing: A method of in vivo study through laser Doppler flowmetry

BACKGROUND AND OBJECTIVES

Low-intensity laser therapy (LILT) is widely used for wound healing promotion and its mechanism of action may be due to an enhancement of blood supply. The aim of this study was to evaluate blood flow alterations in a wound healing model, using laser Doppler flowmetry (LDF) associated with a normalized perfusion parameter.

STUDY DESIGN/MATERIALS AND METHODS

An injury was provoked in 15 rats and blood flow was measured periodically over a period of 21 days. Control groups were established to evaluate LDF and He-Ne laser effects on microcirculation. A 1 J/cm(2) dose was utilized, with 6 mW/cm(2) irradiance.

RESULTS

The results demonstrated flow alterations provoked by lesion, and inflammatory response (P < 0.05). There were no statistical differences between groups.

CONCLUSIONS

The results did not show a significant sustained effect on microcirculation with this He-Ne dose.

Ablation of temporomandibular joint structures of a pig with a fibre-guided 308nm excimer laser light—an in vitro investigation

PURPOSE

The present in vitro investigation was carried out to assess the efficacy of treatment with 308 nm excimer laser radiation applied to the structures of the temporomandibular joint of a pig. Laser parameters suitable to ensure adequate clinical efficiency with only minor thermal damage to the surrounding tissues were to be determined.

MATERIAL AND METHODS

Tissue structures of the temporomandibular joint (cortical and cancellous bone, cartilage, disc and muscle) were extracted from freshly killed pigs and served as specimens. The specimens were embedded in polymethylmethacrylate. The laser light was applied after horizontal sectioning and measurement of thickness. The number of impulses that were necessary to perforate the specimen was counted and the rate of ablation determined. In addition, the irradiated surface was investigated histologically and the degree of tissue alteration was evaluated.

RESULTS

The lowest energy threshold for ablation was found at an energy density of 0.8 J/cm2. Depending on the type of tissue, the maximum rate of ablation was evaluated as 1.7-6.3 microm/pulse. The depth of the thermal alteration to the surrounding tissue was about 30-70 microm.

CONCLUSION

The guidable 308 nm excimer laser light offers a combination of precise tissue ablation with only minimal thermal damage to the surrounding tissue.

Evaluation of the use of low level laser and photosensitizer drugs in healing

BACKGROUND AND OBJECTIVES

In the last decade, many different kinds of therapies have emerged as a consequence of advances in the field of applied technology. It is known that low level laser therapy contributes to tissue healing; however, the use of photodynamic therapy (PDT) in healing and the scar formation processes has not been fully explored. The present study analyses the effect of low level laser InGaAIP (685 nm), radiation, either alone or combined with a phthalocyanine-derived photosensitizer (PS) in a gel base delivery (GB) system, on the healing process of cutaneous wounds in rats.

STUDY DESIGN/MATERIALS AND METHODS

The rats were divided into six groups: control (untreated) (CG), gel base (GB), photosensitizer (PS), laser (LG), laser+photosensitizer (LPS), and laser+photosensitizer in a GB (LPSG). Standardized circular wounds were made on the dorsum of each rat with a skin punch biopsy instrument. After wounding, treatment was performed once daily and the animals were killed at day 8. Tissue specimens containing the whole wound area were removed and processed for histological analysis using conventional techniques. Serial cross-sections were analyzed to evaluate the organization of the dermis and epidermis as well as collagen deposition.

RESULTS

The animals of groups LG, PS, LPS, and LPSG presented higher collagen content and enhanced re-epithelialization as compared to CG (control) and GB rats. Connective tissue remodeling was more evident in groups LPS and LPSG.

CONCLUSIONS

The results clearly indicated a synergetic effect of light+photosensitizer+delivery drug on tissue healing. PDT did not cause any healing inhibition or tissue damage during the healing process.

Photohemolysis of erythrocytes by He-Ne laser irradiation: the effect of power density

The effects of He-Ne laser irradiation on erythrocyte hemolysis were studied. Erythrocytes are prone to be easily damaged with hemolysis under laser irradiation. It was found that the power density (PD) of laser irradiation, but not the total irradiation power, is the crucial parameter for the hemolysis. Under irradiation with a PD of 5.41 mW/microm(2), erythrocytes were photohemolyzed within a few seconds, while at a PD of 0.52 mW/microm(2) the average tolerance duration (TD; from the start of irradiation to hemolysis) of erythrocytes was 110 s. The TDs of erythrocytes were also individual erythrocyte-dependent, which may be due to their different ages. The average TDs of erythrocyte samples from different donors were different, reflecting individual variations.

The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study

OBJECTIVE

We used statistical meta-analysis to determine the overall treatment effects of laser phototherapy on tissue repair and pain relief.

BACKGROUND DATA

Low-power laser devices were first used as a form of therapy more than 30 years ago. However, their efficacy in reducing pain or promoting tissue repair remains questionable.

METHODS

Following a literature search, studies meeting our inclusion criteria were identified and coded. Then, the effect size of laser treatment, that is, Cohen's d, was calculated from each study using standard meta-analysis procedures.

RESULTS

Thirty-four peer-reviewed papers on tissue repair met our inclusion criteria and were used to calculate 46 treatment effect sizes. Nine peer-reviewed papers on pain control met the inclusion criteria and were used to calculate nine effect sizes. Meta-analysis revealed a positive effect of laser phototherapy on tissue repair (d = +1.81; n = 46) and pain control (d = +1.11; n = 9). The positive effect of treatment on specific indices of tissue repair was evident in the treatment effect sizes determined as follows: collagen formation (d = +2.78), rate of healing (d = +1.57), tensile strength (d = +2.13), time needed for wound closure (d = +0.76), tensile stress (d = +2.65), number and rate of degranulation of mast cells (d = +1.87), and flap survival (d = +1.95). Further, analysis revealed the positive effects of various wavelengths of laser light on tissue repair, with 632.8 nm having the highest treatment effect (d = +2.44) and 780 nm the least (d = 0.60). The overall treatment effect for pain control was positive as well (d = +1.11). The fail-safe number-that is, the number of studies in which laser phototherapy has negative or no effect-needed to nullify the overall outcome of this analysis was 370 for tissue repair and 41 for pain control.

CONCLUSIONS

These findings mandate the conclusion that laser phototherapy is a highly effective therapeutic armamentarium for tissue repair and pain relief.

Ultrastructural comparison of medial collateral ligament repair after single or multiple applications of GaAlAs laser in rats

BACKGROUND AND OBJECTIVES

To examine single versus multiple applications of a gallium aluminum arsenide (GaAlAs) laser on the ultrastructural morphology of surgically injured medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen rats were studied with 12 receiving right MCL transection and 4 receiving sham injury. Group 1 (n = 4) received one session of laser (31.6 J/cm(2)) immediately after injury. Group 2 (n = 4) received 9 doses of transcutaneous laser (3.5 J/cm(2)). The controls (Group 3, n = 4) received one session of placebo laser, while the sham Group 4 (n = 4) received no treatment. Ultrastructural analyses were done with electron microscopy at 3 weeks.

RESULTS

The mass-averaged diameters of collagen fibril in the core and periphery of MCLs treated with multiple laser were larger than the control and those with single laser treatment (P < 0.05). However, the sham injured group had larger fibrils than all other groups (P < 0.05).

CONCLUSIONS

The repairing MCLs had smaller collagen fibrils than the sham injured ligaments. Multiple laser treatments enhanced the collagen growth in the repairing MCLs at 3 weeks after injury, which are superior to a single treatment with similar dosage.

A histologic assessment of the influence of low-intensity laser therapy on wound healing in steroid-treated animals

OBJECTIVE

The aim of the present study was to evaluate the effect of low-intensity laser therapy on the wound healing process treated with steroid.

BACKGROUND DATA

Various biological effects have been associated with low-level laser therapy (LLLT).

MATERIALS AND METHODS

Forty-eight rats were used, and after execution of a wound on the dorsal region of each animal, they were divided into 4 groups (n = 12), receiving the following treatments: G1 (control), wounds and animals received no treatment; G2, wounds were treated with LLLT; G3, animals received an intraperitoneal injection of steroid dosage (2 mg/kg of body weight); G4, animals received steroid and wounds were treated with LLLT. The laser emission device used was a GaAIAs (904 nm), in a contact mode, with 2.75 mW gated with 2.900 Hz during 120 sec (33 J/cm(2)). After the period of 3, 7, and 14 days, the animals were sacrificed and the parts sent to histological processing and dyed using hematoxylin and eosin (HE) and Masson trichromium (MT) techniques.

RESULTS

The results have shown that the wounds treated with steroid had a delay in healing, while LLLT accelerated the wound healing process. Also, wounds treated with laser in the animals treated with steroid presented a differentiated healing process with a larger collagen deposition and also a decrease in both the inflammatory infiltrated and the delay on the wound healing process.

CONCLUSION

LLLT accelerated healing, caused by the steroid, acting as a biostimulative coadjutant agent, balancing the undesirable effects of cortisone on the tissue healing process.

The efficacy of laser therapy in wound repair: a meta-analysis of the literature

OBJECTIVE

We determined the overall effects of laser therapy on tissue healing by aggregating the literature and subjecting studies meeting the inclusion and exclusion criteria to statistical meta-analysis.

BACKGROUND DATA

Low-level laser therapy (LLLT) devices have been in use since the mid sixties, but their therapeutic value remains doubtful, as the literature seems replete with conflicting findings.

MATERIALS AND METHODS

Pertinent original research papers were gathered from library sources, online databases and secondary sources. The papers were screened and coded; those meeting every inclusion and exclusion criterion were subjected to meta-analysis, using Cohen's d. statistic to determine the treatment effect size of each study.

RESULTS

Twenty-four studies with 31 effect sizes met the stringent inclusion and exclusion criteria. The overall mean effect of laser therapy on wound healing was highly significant (d = +2.22). Sub-analyses of the data revealed significant positive effects on wound healing in animal experiments (d = +1.97) as well as human clinical studies (d = +0.54). The analysis further revealed significant positive effects on specific indices of healing, for example, acceleration of inflammation (d = +4.45); augmentation of collagen synthesis (d = +1.80); increased tensile strength (d = +2.37), reduced healing time (d = +3.24); and diminution of wound size (d = +0.55). The Fail-Safe number associated with the overall effect of laser therapy was 509; a high number representing the number of additional studies-in which laser therapy has negative or no effect on wound healing-required to negate the overall large effect size of +2.22. The corresponding Fail-Safe number for clinical studies was 22.

CONCLUSION

We conclude that laser therapy is an effective tool for promoting wound repair.

Low-level laser therapy in dentistry

Low-level laser therapy (LLLT) is a newly developing technique in dentistry, although it has been used among medical, dental, physiotherapy, and veterinary professions in some parts of the world for decades. LLLT can offer tremendous therapeutic benefits to patients, such as accelerated wound healing and pain relief. There is much to be learned about the mechanisms, recognition of the therapeutic window, and how to properly use these cellular phenomena to reach the treatment goals.

The use of polarized light in aesthetic surgery

This article presents a clinical investigation of polarized light therapy after aesthetic surgery procedures. The study included patients who the authors underwent face-lifts, blepharoplasties, and various facial ancillary procedures, at center during the past 2 1/2 years. One side of the surgically treated area was managed with polarized light, whereas the other side served as a control. The results were compared using clinical examination only including signs of recovery such as resolution of swelling and bruises. The results in most cases showed a significant difference between the treated and untreated sides.

Photobiomodulation Improves Cutaneous Wound Healing in an Animal Model of Type II Diabetes

OBJECTIVE

We investigated the effects of photobiomodulation (PBM) on cutaneous wound healing in an animal model of type II diabetes, Psammomys obesus (Sand Rats).

BACKGROUND DATA

632-nm light has been established as the most effective wavelength for treatment of cutaneous wounds; however, the inconsistent efficacy of PBM may be due to inadequate treatment parameter selection.

METHODS

Using 632-nm light, an initial series of experiments were done to establish optimal treatment parameters for this model. Following creation of bilateral full-thickness skin wounds, non-diabetic Sand Rats were treated with PBM of differing dosages. Wound healing was assessed according to wound closure and histological characteristics of healing. Optimal treatment parameters were then used to treat type II diabetic Sand Rats while a diabetic control group received no irradiation. In order to elucidate the mechanism behind an improvement in wound healing, expression of basic fibroblast growth factor (bFGF) was assessed.

RESULTS

Significant improvement in wound healing histology and wound closure were found following treatment with 4 J/cm(2) (16 mW, 250-sec treatments for 4 consecutive days; p < 0.05). The 4 J/cm(2) dosage significantly improved histology and closure of wounds in the diabetic group in comparison to the non-irradiated diabetic group. Quantitative analysis of bFGF expression at 36 h post-injury revealed a threefold increase in the diabetic and non-diabetic Sand Rats after PBM.

CONCLUSIONS

The results demonstrate that PBM at an energy density of 4 J/cm(2) is effective in improving the healing of cutaneous wounds in an animal model of type II diabetes, suggesting that PBM (632 nm, 4 J/cm(2)) would be effective in treating chronic cutaneous wounds in diabetic patients.

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

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.

Comparison of single and multiple applications of GaAlAs laser on rat medial collateral ligament repair

BACKGROUND AND OBJECTIVES

To examine single versus multiple applications of the gallium aluminum arsenide (GaAlAs) laser on the healing of surgically injured medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen rats were studied, with 12 receiving surgical transection to their right MCL and 4 receiving a sham injury. Group 1 (n = 4) received a single dose of GaAlAs laser therapy (wavelength 660 nm, average power 8.8 mW, pulse 10 kHz, dosage 31.6 J/cm(2)) directly to their MCL during surgery. Group 2 (n = 4) received 9 doses of GaAlAs laser therapy applied transcutaneously on alternate days (wavelength 660 nm, average power 8.8 mW, pulse 10 kHz, dosage 3.5 J/cm(2)). The controls (Group 3, n = 4) received one session of placebo laser at the time of surgery, with the laser equipment shut down, while the sham injured Group 4 (n = 4) received no treatment. Biomechanical tests for structural stiffness, ultimate tensile strength (UTS), and load-relaxation were done at 3 weeks after injury. The stiffness and UTS data were normalized by expressing as a percentage of the left side of each animal before statistical analysis.

RESULTS

The load-relaxation data did not show any differences between the groups (P = 0.18). The normalized stiffness levels of Groups 2 (81.08+/-11.28%) and 4 (92.66+/-13.19%) were significantly higher (P = 0.025) than that of the control Group 3 (58.99+/-15.91%). The normalized UTS of Groups 2 (81.38+/-5.68%) and 4 (90.18+/-8.82%) were also significantly higher (P = 0.012) than that of the control (64.49+/-9.26%). Although, Group 1 had higher mean stiffness and UTS values than the control, no statistically significant difference was found between these two groups.

CONCLUSIONS

Multiple laser therapy improves the normalized strength and stiffness of repairing rat MCLs at 3 weeks after injury. The multiple treatments seem to be superior to a single treatment when the cumulative dosages are comparable between the two modes of application.

Clinical evaluation of the effects of low-intensity laser (GaAlAs) on wound healing after gingivoplasty in humans

Low-intensity laser therapy aims at pain suppression, edema reduction and acceleration of wound healing. The main goal of this study was to clinically evaluate the effects of Aluminum Gallium Arsenate laser - 670nm in wound healing after gingivoplasty in 11 patients. Surgery was performed in anterior superior and/or inferior regions. The right side of the patient (test group) received a laser energy density of 4J/cm², in a 48-hour interval, during one week, totalizing four sessions. The irradiation was punctual in a contact mode in three points. The left side did not receive irradiation (control group). Clinical evaluation was performed by five specialists in periodontology through photography of the treated areas at post-surgical periods of 7, 15, 21,30,60 days. The observers pointed the best healed side. The Sign test was used for statistical analysis with a confidence level of 5% (P<0.05). The examiners found a better pattern of healing sometimes in the test and sometimes in the control group until 21 days after surgery. After this period there was no apparent difference between them. There was no statistical difference between the sides (p>0.05). These results have shown that low-intensity laser therapy did not accelerate oral mucosa healing after gingivoplasty.

Effects of different protocol doses of low power gallium–aluminum–arsenate (Ga–Al–As) laser radiation (650 nm) on carrageenan induced rat paw ooedema

The purpose of the present study was to investigate the effect of the low power laser therapy on the acute inflammatory process. Male Wistar rats were used. The rat paw oedema was induced by sub-plantar injection of carrageenan, the paw volume was measured before and 1, 2, 3 and 4 h after the injection using a hydroplethysmometer. To investigate the mechanism action of the Ga-Al-As laser on inflammatory oedema, parallel studies were performed using adrenallectomized rats or rats treated with sodium diclofenac. Different laser irradiation protocols were employed for specific energy densities (EDs), exposure times and repetition rates. The rats were irradiated with the Ga-Al-As laser during 80 s each hour. The ED that produced an anti-inflammatory effect were 1 and 2.5 J/cm(2), reducing the oedema by 27% (P<0.05) and 45.4% (P<0.01), respectively. The ED of 2.5 J/cm(2) produced anti-inflammatory effects similar to those produced by the cyclooxigenase inhibitor sodium diclofenac at a dose of 1 mg/kg. In adrenalectomized animals, the laser irradiation failed to inhibit the oedema. Our results suggest that low power laser irradiation possibly exerts its anti-inflammatory effects by stimulating the release of adrenal corticosteroid hormones.

Low-Level Laser Treatment Can Reduce Edema in Second Degree Ankle Sprains

OBJECTIVE

Low-level laser therapy (LLLT) has been used for the last few years to treat sports injuries. The purpose of this study was to compare three therapeutic protocols in treating edema in second degree ankle sprains that did not require immobilization with a splint, under placebo-controlled conditions.

MATERIALS AND METHODS

Forty-seven soccer players with second degree ankle sprains, selected at random, were divided into the following groups: The first group (n = 16) was treated with the conventional initial treatment (RICE, rest, ice, compression, elevation), the second group (n = 16) was treated with the RICE method plus placebo laser, and the third group (n = 15) was treated with the RICE method plus an 820-nm GaA1As diode laser with a radiant power output of 40 mW at 16 Hz. Before the treatment, and 24, 48, and 72 h later, the volume of the edema was measured.

RESULTS

A three by three repeated measures ANOVA with a follow up post hoc test revealed that the group treated with the RICE and an 820-nm GaA1As diode laser presented a statistically significant reduction in the volume of the edema after 24 h (40.3 +/- 2.4 mL, p < 0.01), 48 h (56.4 +/- 3.1 mL, p < 0.002), and 72 h (65.1 +/- 4.4 mL, p < 0.001).

CONCLUSIONS

LLLT combined with RICE can reduce edema in second-degree ankle sprains.

Effects of low power Er:YAG laser on the tooth pulp-evoked jaw-opening reflex

BACKGROUND AND OBJECTIVES

Analgesic properties of laser irradiation have been of great interest in the field of dentistry. This study aimed at evaluating the analgesic effects of the Er:YAG laser system in rats during and after laser irradiation.

STUDY DESIGN/MATERIALS AND METHODS

A pulsed Er:YAG laser was applied to the oral mucosa of the mandibular incisor at an energy density of approximately 0.1 J/cm(2)/pulse for 10 minutes at 10 Hz, and the integrated digastric muscle electromyogram in tooth pulp-evoked jaw-opening reflex was used as an index of the nociceptive response.

RESULTS

Significant reflex suppression was observed 10 minutes after laser irradiation. The reflex amplitude started to return to its original level about 45 minutes after cessation of laser irradiation.

CONCLUSIONS

The Er:YAG laser used at low output levels presented inhibitory effects on the tooth pulp-evoked jaw-opening reflex, suggesting that this laser system may be of use for pain control during various dental treatments.

A comparative study of 632.8 and 532 nm laser irradiation on some rheological factors in human blood in vitro

The effects of laser irradiation with 632.8 and 532 nm on rheological properties of blood were comparatively studied in vitro. Under the irradiation condition of 30 mW, laser irradiation of blood samples using a spot diameter of 5 mm with each laser, showed promising results in the modulation of hemorheological properties. When blood samples from patients with abnormally high values of erythrocyte sedimentation rate (ESR) were irradiated, the values of ESR were lowered statistically by either of the 632.8 or 532 nm lasers. The laser irradiation reduced blood viscosities at different shear rates (10-110 S(-1)) for the hyper-viscosity blood samples. Laser irradiation increased the electrophoretic mobility (EPM) of erythrocytes when the values of the sample's EPM were abnormally slow. The erythrocyte deformability was enhanced by laser irradiation when the deformability of the sample from the patients was originally poor. For verifying the improvement of laser irradiation on erythrocyte deformability, the typical erythrocyte samples with poor deformability were produced by the pre-treatment of the erythrocytes with Ca(2+). The deformability of these erythrocyte samples was also improved after laser irradiation. These results suggest that membrane-bound hemoglobin (Hbm) might be the initial site of the interaction, since Hbm is the main cause of poor deformability when erythrocytes were treated with Ca(2+). In all experiments including ESR, blood viscosity, EPM and erythrocyte deformability, the 532 nm laser demonstrated more efficient effects on modulating rheological properties than 632.8 nm laser. This wavelength effect is consistent with the absorption spectrum of hemoglobin, reflecting that hemoglobin may be one of the action targets under laser irradiation.

Phototherapy in the treatment of acne vulgaris: what is its role?

Acne vulgaris is a common dermatosis affecting 80% of the population. To date, different treatments have been used to manage this condition. Antibacterials and retinoids are currently the mainstay of treatment for acne, but their success rate varies. Phototherapy is emerging as an alternative option to treat acne vulgaris. Studies examining the role of different wavelengths and methods of light treatment have shown that phototherapy with visible light, specifically blue light, has a marked effect on inflammatory acne lesions and seems sufficient for the treatment of acne. In addition, the combination of blue-red light radiation seems to be superior to blue light alone, with minimal adverse effects. Photodynamic therapy has also been used, even in nodular and cystic acne, and had excellent therapeutic outcomes, although with significant adverse effects. Recently, low energy pulsed dye laser therapy has been used, and seems to be a promising alternative that would allow the simultaneous treatment of active acne and acne scarring. Further studies are needed to clarify the role of phototherapy as a monotherapy or an adjuvant treatment in the current management of acne vulgaris.

Effect of low-power He-Ne laser irradiation on rabbit articular chondrocytes in vitro

BACKGROUND AND OBJECTIVES

In the orthopaedic field, the repair of articular cartilage is still a difficult problem, because of the physiological characters of cartilaginous tissues and chondrocytes. To find an effective method of stimulating their regeneration, this in vitro study focuses on the biostimulation of rabbit articular chondrocytes by low-power He-Ne laser.

STUDY DESIGN/MATERIALS AND METHODS

The articular chondrocytes isolated from the cartilage of the medial condyle of the femur of the rabbit were incubated in DMEM/HamF(12) medium. The second passage culture were spread on 24 petri dishes and were irradiated with laser at power output of 2-12 mW for 6.5 minutes, corresponding to the energy density of 1-6 J/cm(2). Laser treatment was performed three times at a 24-hour interval. After lasering, incubation was continued for 24 hours. Non-irradiated cells were kept under the same conditions as the irradiated ones. The cell proliferation activity was evaluated with a XTT colorimetric method and the cell secretion activity was analyzed by metachromasia and immunocytochemistry.

RESULTS

Irradiation of 4-6 J/cm(2) increased the cell numbers and revealed a considerably higher cell proliferation activity comparing to control cultures. Thereinto, the energy density of 4 and 5 J/cm(2) remarkably increased cell growth, with positive effect on synthesis and secretion of extracellular matrix.

CONCLUSIONS

The present study showed that a particular laser irradiation stimulates articular chondrocytes proliferation and secretion. These findings might be clinically relevant, indicating that low-power laser irradiation treatment is likely to achieve the repair of articular cartilage in clinic.

Histomorphometric study of the healing of human oral mucosa after gingivoplasty and low-level laser therapy

BACKGROUND AND OBJECTIVES

The aim of the present study was to analyze the effects of diode laser irradiation on the healing of human oral mucosa.

MATERIALS AND METHODS

After gingivoplasty, the right hemi-arch (test group) of 16 patients was irradiated with a diode laser. The left side (control group) was not irradiated. Incisional biopsies were performed on both sides at 7, 14, 21, and 60 days after surgery and morphometrically analyzed by light microscopy.

RESULTS

Epithelium width ranged from 260.6 to 393.5 microm. Volume densities of basal (20.2%), prickle cell (55.6%), and cornified (24.2%) layers remained stable. The peak number of neutrophils were 6 cells/mm(2) and the mononuclear cells were 44 cells/mm(2). Collagen fibers (80%) and fibroblasts (14%) occupied the main volume of connective tissue. The one-way ANOVA and the paired Student's t-test were used for statistical analysis (P < 0.05).

CONCLUSION

Low-level laser therapy did not accelerate the healing of oral mucosa after gingivoplasty.

Comparison of the photostimulatory effects of visible He-Ne and infrared Ga-As lasers on healing impaired diabetic rat wounds

BACKGROUND AND OBJECTIVES

In this study, the ability of photostimulation to promote healing of impaired wounds was investigated using a Ga-As laser in rats with experimental diabetes and the results were compared with previously reported findings of the effects of a He-Ne laser on the repair of healing-impaired diabetic rat wounds 1.

STUDY DESIGN/MATERIALS AND METHODS

Diabetes was induced in male rats by streptozotocin injection following which two full thickness punch wounds of 6-mm diameter were created in the skin, one on either side of the spine of each animal. The left wound of each animal was treated with infrared radiation at 904 nm produced by a Ga-As laser at an energy density of 1.0 J/cm(2). The right wound of each animal served as the control. The wounds were treated with a laser 5 days a week for 3 weeks. Following animal sacrifice, the strips of skin containing the wound sites were collected and analyzed.

RESULTS

The results from the biomechanical analysis indicated that the Ga-As laser used in this study significantly increased wound tensile strain and toughness compared to the control wounds. Marginal increases in wound tensile strength (9%) and stress (7%) were observed in the Ga-As laser-treated wounds compared to the controls. No significant changes were found in Young's modulus and energy absorption capacity between the control and laser-treated wounds. Analysis of wound collagen revealed a significant increases in total collagen (14%), salt soluble collagen (31%), acid soluble (14%), and insoluble collagen (50%) with simultaneous decrease in pepsin soluble collagen (19%) in the Ga-As laser-treated wounds compared to controls. Comparisons of these results with the earlier findings revealed that the He-Ne laser appears to be superior to the Ga-As laser, at the parameters of treatment tested, in promoting the wound healing in diabetic rats.

CONCLUSIONS

The differences in stimulatory effects noted between the He-Ne and Ga-As lasers suggest that the photochemical response the cells for each laser may depend on the wavelength and coherent properties of the electromagnetic radiation.

A preliminary investigation into light-modulated replication of nanobacteria and heart disease

OBJECTIVE

The purpose of this preliminary study is to evaluate the effect of various wavelengths of light on nanobacteria (NB).

BACKGROUND DATA

NB and mitochondria use light for biological processes. NB have been described as multifunctional primordial nanovesicles with the potential to utilize solar energy for replication. NB produce slime, a process common to living bacteria. Slime release is an evolutionary important stress-dependent phenomenon increasing the survival chance of individual bacteria in a colony. In the cardiovascular system, stress-induced bacterial colony formation may lead to a deposition of plaque.

METHODS

Cultured NB were irradiated with NASA-LEDs at different wavelengths of light: 670, 728 and 880 nm. Light intensities were about 500k Wm(-2), and energy density was 1 x 10(4) J m(-2).

RESULTS

Monochromatic light clearly affected replication of NB. Maximum replication was achieved at 670 nm.

CONCLUSIONS

The results indicate that suitable wavelengths of light could be instrumental in elevating the vitality level of NB, preventing the production of NB-mediated slime, and simultaneously increasing the vitality level of mitochondria. The finding could stimulate the design of cooperative therapy concepts that could reduce death caused by myocardial infarcts.

Living nanovesicles--chemical and physical survival strategies of primordial biosystems

Life on Earth and Mars could have started with self-assembled nanovesicles similar to the present nanobacteria (NB). To resist extreme environmental stress situations and periods of nutritional deprivation, nanovesicles would have had a chemical composition protected by a closed mineralized compartment, facilitating their development in a primordial soup, or other early wet environment. Their survivability would have been enhanced if they had mechanisms for metabolic communication, and an ability to collect primordially available energy forms. Here, we establish an irreducible model system for life formation starting with NB.

Spectral response for laser enhancement in hepatic regeneration for hepatectomized rats

BACKGROUND AND OBJECTIVES

The low intensity laser therapy (LILT) has been widely used in all medical fields due to its therapeutic effects in reparative process, pain relief, and biostimulation. Even though there is a therapeutic window of wavelengths for clinical application, little has been done concerning the frequency spectrum response to biological effects. In this work, we investigate the dependence of different wavelengths irradiation in the enhancement of the tissue regeneration after partial hepatectomy in Wistar rats.

STUDY DESIGN/MATERIALS AND METHODS

The proliferating cell nuclear antigen (PCNA) labeling index and the respiratory control (oxygen consumption in extracted mitochondria) were the tests used to evaluate the liver regeneration after laser irradiation with different wavelengths.

RESULTS AND CONCLUSIONS

The results show a correlated spectral response that can be explained based on the combined effect of light penetration on biological tissues and the biomolecular excitation efficiency for each wavelength used.

cDNA microarray analysis of gene expression profiles in human fibroblast cells irradiated with red light

In this paper, the cDNA microarray technique was used to investigate the gene expression profiles of human fibroblasts irradiated by low-intensity red light. Proliferation assays showed that the fibroblast HS27 cells responded with a curve effect to different doses of low-intensity red light irradiation at a wavelength of 628 nm. An optimal dose of 0.88 J per cm2 was chosen for subsequent cDNA microarray experiments. The gene expression profiles revealed that 111 genes were regulated by the red light irradiation and can be grouped into 10 functional categories. Most of these genes directly or indirectly play roles in the enhancement of cell proliferation and the suppression of apoptosis. Two signaling pathways, the p38 mitogen-activated protein kinase signaling pathway and the platelet-derived growth factor signaling pathway, were found to be involved in cell growth induced by irradiation of low-intensity red light. Several genes related to antioxidation and mitochondria energy metabolism were also found to express differentially upon irradiation. This study provides insight into the molecular mechanisms associated with the beneficial effects of red light irradiation in accelerating wound healing.

The use of polarised polychromatic non-coherent light alone as a therapy for venous leg ulceration

OBJECTIVE

This study assessed the effectiveness of polarised, polychromatic, non-coherent light therapy in the treatment of venous leg ulcers. Investigators in previous studies have advocated the use of light as an adjunct to other proven therapies or on its own.

METHOD

This was a pilot prospective case-series study. We enrolled 25 patients with venous leg ulcers. All were treated with light only. Phototherapy (light therapy) treatments were given once a day over four weeks.

RESULTS

All ulcers except one (99%) had a positive value for the change in healing area at the end of the four weeks. The total number of 73 leg ulcers recorded at the beginning of the study was reduced to 51 at the end of the four weeks (p < 0.01). The decrease in wound surface area following the treatment was statistically significant (mean: 57.15%; SD: 31.87%; p < 0.01).

CONCLUSION

Polarised, polychromatic light therapy applied as a monotherapy was associated with positive healing rates in patients with venous leg ulcers. It is a simple and non-invasive treatment. However, a well-designed randomised controlled study is needed to confirm the efficacy of this form of phototherapy and to objectively evaluate recommendations for its routine use in clinical practice.

Contraindications in noninvasive laser therapy: truth and fiction

OBJECTIVE

Noninvasive laser therapy is a treatment method employed in many disciplines. This review article points out instances when it appears to be effective to administer such therapy.

MATERIALS AND METHODS

Noninvasive laser therapy has a number of suitable applications that cause minimal damage to the patient. Many patients are not sent to institutions equipped with relevant instruments, since physicians are burdened by a number of contraindications, many of which are incorrect. The purpose of this article was to divide these contraindications into the following three groups: correct indications, indications doubtful under certain conditions, and incorrect indications.

DISCUSSION

We consider the following contraindications as correct: history of a histologically demonstrated malignant carcinoma; irradiation of the neck region in hyperthyreosis; epilepsy; exposure of the retina; and exposure of the abdomen during pregnancy. The contraindications that are doubtful under certain conditions are as follows: fever and infectious diseases; certain blood diseases; heavy blood losses; neuropathies; and irradiation in the region of gonads. The other contraindications reported in the literature are considered to be incorrect.

Does low output laser stimulation enhance the healing of crural ulceration? Some critical remarks

The objective of the experiment was to evaluate the impact of laser stimulation on crural ulceration healing. Three groups were established at random from patients with crural ulceration: A, B and C. Group A included 21 patients, group B included 22 patients and group C, 22 patients. Patients in all groups were treated with pharmaceuticals and with compressive therapy. The ulcers in group A were additionally irradiated with laser light of wavelength 810 nm, so that a dose of 4 J/cm2 was applied in each procedure. Patients in group B were additionally subjected to a blind test (with placebo in the form of quasi-laser therapy). At the end of the treatment a statistically significant reduction of the area and volume of the ulcers was found in all groups. No statistically significant difference was found between the groups in terms of average rate of change per week of the relative area of ulceration and average rate of change per week of the relative volume of ulceration. Reduction of infected area was observed in all groups, but a significant change was only observed in group C. No significant impact of laser light (lambda=810 nm, P=65 mW, p=4 J/cm2) on any of the stages of ulceration healing was observed.

Therapeutic low energy laser improves the mechanical strength of repairing medial collateral ligament

BACKGROUND AND OBJECTIVES

Low energy laser therapy has been shown to enhance collagen production but its effect on tissue strength is not well reported. We tested the effects of therapeutic laser on the strength of healing medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-four rats received surgical transection to their right MCL and eight received sham operation. After surgery, 16 received a single dose of gallium aluminum arsenide laser to their transected MCL for 7.5 minutes (n = 8) or 15 minutes (n = 8) and eight served as control with placebo laser, while the sham group didn't receive any treatment. The MCLs were biomechanically tested at either 3 or 6 weeks post-operation.

RESULTS

The normalized ultimate tensile strength (UTS) and stiffness of laser and sham groups were larger than control (P < 0.001). The UTS of laser and sham groups were comparable. Laser and sham groups had improved in stiffness from 3 to 6 weeks (P < 0.001).

CONCLUSIONS

A single dose of low energy laser therapy improves the UTS and stiffness of repairing MCL at 3 and 6 weeks after injury.

Improvement of macromolecular clearance via lymph flow in hamster gingiva by low-power carbon dioxide laser-irradiation

BACKGROUND AND OBJECTIVE

Although therapeutic effects of low-power laser-irradiation on periodontal disease have been reported, little is known about the biological effects of laser-irradiation in the gingiva. Recently we reported that topical warming stimulated macromolecular clearance via lymph flow in hamster gingiva. This study was conducted to investigate whether low-power laser-irradiation affects macromolecular clearance via the lymph flow in the gingiva.

STUDY DESIGN/MATERIALS AND METHODS

We injected 14C-methylated albumin into the mandibular gingiva of anesthetized hamsters followed by topical carbon dioxide (CO2) laser-irradiation (30 seconds, 0.5-1.5 W). We measured the clearance of radiolabeled albumin from the gingiva and its drainage into submandibular lymph nodes during 10 minutes.

RESULTS

The clearance of the radiolabeled albumin from the gingiva and the influx into the submandibular lymph nodes were increased by CO2 laser-irradiation.

CONCLUSION

Low-power CO2 laser-irradiation improves macromolecular clearance via the lymph flow in hamster gingiva.

Carpal tunnel syndrome pain treated with low-level laser and microamperes transcutaneous electric nerve stimulation: A controlled study

OBJECTIVE

To investigate whether real or sham low-level laser therapy (LLLT) plus microamperes transcutaneous electric nerve stimulation (TENS) applied to acupuncture points significantly reduces pain in carpal tunnel syndrome (CTS).

DESIGN

Randomized, double-blind, placebo-control, crossover trial. Patients and staff administered outcome measures blinded.

SETTING

Outpatient, university-affiliated Department of Veterans Affairs medical center.

PARTICIPANTS

Eleven mild to moderate CTS cases (nerve conduction study, clinical examination) who failed standard medical or surgical treatment for 3 to 30 months.

INTERVENTION

Patients received real and sham treatment series (each for 3-4wk), in a randomized order. Real treatments used red-beam laser (continuous wave, 15mW, 632.8nm) on shallow acupuncture points on the affected hand, infrared laser (pulsed, 9.4W, 904nm) on deeper points on upper extremity and cervical paraspinal areas, and microamps TENS on the affected wrist. Devices were painless, noninvasive, and produced no sensation whether they were real or sham. The hand was treated behind a hanging black curtain without the patient knowing if devices were on (real) or off (sham).

MAIN OUTCOME MEASURES

McGill Pain Questionnaire (MPQ) score, sensory and motor latencies, and Phalen and Tinel signs.

RESULTS

Significant decreases in MPQ score, median nerve sensory latency, and Phalen and Tinel signs after the real treatment series but not after the sham treatment series. Patients could perform their previous work (computer typist, handyman) and were stable for 1 to 3 years.

CONCLUSIONS

This new, conservative treatment was effective in treating CTS pain; larger studies are recommended.

A conservative approach for deep dermal burn wounds using polarised-light therapy

This article reports a clinical study investigating the role of polarised-light therapy in the conservative treatment of deep dermal burn wounds. In 22 out of 67 patients with deep dermal burn wounds, clinical evaluation revealed only a very limited potential for spontaneous healing, and, despite the fact that the majority of the surgeons (four out of six) would have recommended surgery, these patients were treated conservatively with polarised-light therapy (400-2000 nm, 40 m W cm(-2), 2.4 J cm(-2)) until complete closure. Evaluation by a panel of four surgeons, all experts in burn surgery, revealed that conservative treatment of these deep dermal wounds with polarised-light irradiation resulted in a significantly shorter healing time, with almost no hypertrophic scarring, and optimal aesthetic and functional results at long-term follow-up. No extension of the hospital stay was required. Polarised-light therapy may be a valuable way of avoiding surgery in patients with deep dermal burns.

Computerized morphometric assessment of the effect of low-level laser therapy on bone repair: an experimental animal study

OBJECTIVE

The aim of this study was to evaluate morphometrically the amount of newly formed bone after GaAlAs laser irradiation of surgical wounds created in the femur of rats.

BACKGROUND DATA

Low-level laser therapy (LLLT) has been used in several medical specialties because of its biomodulatory effects on different biological tissues. However, LLLT is still controversial because of contradictory reports. This is a direct result of the different methodologies used in these works.

MATERIALS AND METHODS

In this study, 40 Wistar rats were divided into four groups of 10 animals each: group A (12 sessions, 4.8 J/cm2 per session, observation time of 28 days); group C (three sessions, 4.8 J/cm2 per session, observation time of 7 days). Groups B and D acted as nonirradiated controls. The specimens were routinely processed to wax and cut at 6-microm thickness and stained with H&E. For computerized morphometry, Imagelab software was used.

RESULTS

Computerized morphometry showed a significant difference between the areas of mineralized bone in groups C and D (p = 0.017). There was no difference between groups A and B (28 days; p = 0.383).

CONCLUSION

It is concluded that, under this experimental condition, LLLT increased bone repair at early bone healing.

Effect of Gallium-Aluminum-Arsenide Triple-Diode Laser Irradiation on Evoked Motor and Sensory Action Potentials of the Median Nerve

Purpose:

to measure the effects of gallium-aluminum-arsenide (GaAlAs) triple-diode laser irradiation (830 nm, 90 mW) on neural transmission in the median nerve and to determine whether location of treatment influences effectiveness of treatment.

Participants:

42 healthy, adult volunteers, each assigned to 1 GaAlAs or placebo laser group and 1 wrist or forearm treatment group under randomized, double-blinded conditions.

Method:

Nerve-conduction studies were performed on each subject’s nondominant arm before and 10 minutes after treatment. Peak-to-peak amplitudes of both evoked motor and sensory action potentials (APs) were recorded.

Results:

A 2-way ANOVA indicated no significant differences among the amplitudes associated with placebo and GaAlAs laser irradiation. Amplitudes of sensory APs associated with location (wrist or forearm) were, however, significantly different both before and after treatment. No significant interaction was observed between laser and location after treatment, indicating that GaAlAs laser irradiation did not affect median-nerve APs.

Low intensity laser therapy (830nm) in the management of minor postsurgical wounds: a controlled clinical study

BACKGROUND AND OBJECTIVE

The stimulatory effects of low intensity laser therapy (LILT) have been widely published for the treatment of chronic ulceration. In contrast to this previous work, the current study investigated its potential efficacy (by using a dosage of 9 J/cm2) in the management of acute wounds. For this purpose, uncomplicated postoperative wounds after minor podiatric surgery were examined.

STUDY DESIGN/MATERIALS AND METHODS

The study was designed as a controlled group study. Ethical approval was granted by the University of Ulster's Research Ethics Committee. Patients (n = 9) presenting with a total of 12 wounds after minor surgical procedures (partial/total nail avulsions/electrosurgery) were recruited from the Podiatry Teaching Clinic, Northern Ireland. Patients attended the clinic once per week for assessment and treatment. Weekly irradiation was performed by using a CBM Master 3 (CB Medico, Copenhagen, Denmark) diode laser (GaAlAs). The physical parameters of the output of this unit were as follows: wavelength, 830 nm; average power output, 30 mW; spot size, 0.1 cm2; irradiance, 300 mW/cm2; continuous wave output. Wound assessment and recording of pain levels were conducted weekly. Wound measurement was completed by using planimetry and digitising methods.

RESULTS

Current findings indicated no statistically significant differences between Laser and Control groups for wound closure (P = 0.28 digitising; P = 0.49 planimetry) nor for pain levels reported (P = 0.88).

CONCLUSION

It would seem that LILT provides no advantages in the management of minor postoperative wounds over current practice. Despite no apparent benefit of infrared laser at this dosage in the management of acute stage wounds, further research is required to determine its potential efficacy in the management of other wound types.