Effects of low energy laser on wound healing in a porcine model

Effects of Buprenorphine, Chlorhexidine, and Low-level Laser Therapy on Wound Healing in Mice

Systemic buprenorphine and topical antiseptics such as chlorhexidine are frequently used in research animals to aid in pain control and to reduce infection, respectively. These therapeutics are controversial, especially when used in wound healing studies, due to conflicting data suggesting that they delay wound healing. Low-level laser therapy (LLLT) has been used to aid in wound healing without exerting the systemic effects of therapies such as buprenorphine. We conducted 2 studies to investigate the effects of these common treatment modalities on the rate of wound healing in mice. The first study used models of punch biopsy and dermal abrasion to assess whether buprenorphine HCl or 0.12% chlorhexidine delayed wound healing. The second study investigated the effects of sustained-released buprenorphine, 0.05% chlorhexidine, and LLLT on excisional wound healing. The rate of wound healing was assessed by obtaining photographs on days 0, 2, 4, 7, and 9 for the punch biopsy model in study 1, days 0, 1, 2, 4, 6, 8, 11, and 13 for the dermal abrasion model in study 1, and days 0, 3, 6, and 10 for the mice in study 2. Image J software was used to analyze the photographed wounds to determine the wound area. When comparing the wound area on the above days to the original wound area, no significant differences in healing were observed for any of the treatment groups at any time period for either study. Given the results of these studies, we believe that systemic buprenorphine, topical chlorhexidine, and LLLT can be used without impairing or delaying wound healing in mice.

Laser parameters for efficient biomedical stimulation: A study to increase cognitive response rate

BACKGROUND:

The laser is able to irradiate the exact amount of stimulation to an area by a non contact method, and has the advantage of being able to stimulate the local target area.

OBJECTIVE:

This study examined an efficient method of laser tactile stimulation using laser parameter combinations.

METHODS:

The laser parameters that could cause an increase in the cognitive response rate of human subjects were examined without increasing the amount of total laser energy.

RESULTS:

As a result, the appropriate matching parameters such as duty ratio, pulse frequency, and exposure time of laser pulses showed a dominant influence in effectively increasing the tactile response rate of subjects with limited amount of total laser energy.

CONCLUSIONS:

This study can be applied to neurophysiology, cognitive research, and clinical laser application.

Low-level laser therapy: an experimental design for wound management: a case-controlled study in rabbit model

Background:

There is a wide array of articles in medical literature for and against the laser effect on wound healing but without discrete effect determination or conclusion. This experimental study aims to evaluate the efficacy of low-level laser therapy on wound healing.

Materials and Methods:

Thirty-four rabbits were randomly enrolled in two groups after creating a full thickness of 3 × 3 cm wound. The intervention group received low density laser exposure (4 J/cm²) on days 0, 3 and 6 with diode helium-neon low-intensity laser device (wl = 808 nm) and in control group moist wound dressing applied. Finally, wound-healing process was evaluated by both gross and pathological assessment.

Results:

Fibrin formation was the same in the two groups (P = 0.4) but epithelialisation was much more in laser group (P = 0.02). Wound inflammation of the laser group was smaller than that of the control groups but statistical significance was not shown (P = 0.09). Although more smooth muscle actin was found in the wounds of the laser group but it was not statistically significant (P = 0.3). Wound diameter showed significant decrease in wound area in laser group (P = 0.003).

Conclusion:

According to our study, it seems that low-level laser therapy accelerates wound healing at least in some phases of healing process. So, we can conclude that our study also shows some hopes for low level laser therapy effect on wound healing at least in animal model.

Laser biomodulation of normal and neoplastic cells

This study was designed to determine the laser dose for the stimulation, zero-bioactivation, and inhibition of normal and neoplastic cells in vitro. The medical use of laser biomodulation has been occurring for decades in the area of tissue healing and inflammatory conditions. The potential to modulate the regeneration and differentiation of early cellular precursors by laser photons is a valuable endeavor searching for novel and efficient methods. A 35-mW HeNe (632.8-nm) laser and power density of 1.25 mW/cm(2) was used to irradiate tissue culture dishes seeded with 400 cells/dish of normal cells (CHO, CCL-226, 3 T3, and HSF) and neoplastic cells (EMT-6 and RIF-1). All cell lines were cultured using DMEM supplemented with 10% and 5% FBS, 2 mM glutamine and 100 U pen-strep antibiotic. Irradiation times of 16, 32, 48, 64, 80, 96, 112, 128, 144, and 160 s for three consecutive days to deliver cumulative doses of 60, 120, 180, 240, 300, 360, 420, 480, 540, and 600 mJ/cm(2) were done, respectively. Cell cultures were stained and colony-forming efficiency was determined. Data analysis was done using Student's t test, α = 0.05. A trend of stimulation, zero-bioactivation, and inhibition in all cell lines was observed except for CCL-226 which gave a pattern of inhibition, zero-bioactivation, and inhibition. The optimum biostimulatory dose was at 180 mJ/cm(2) and bioinhibitory doses were from 420-600 mJ/cm(2) cumulative doses. This study established the dose-dependency of cell growth to laser treatments, that the extent of cellular proliferation is influenced by the type of cells involved, and the risk when laser irradiation is performed on patients with undiagnosed neoplasms and during pregnancy. On the other hand, the ability of laser irradiation to regulate embryonic fibroblasts and human skin fibroblast in vitro suggests possible laser biomodulatory effects on embryonic and adult stem cells directed for tissue regeneration. Studies on the effects of light treatments exploring different laser parameters for the clonal expansion and differentiation of stem cells are recommended.

Analysis of the systemic effect of red and infrared laser therapy on wound repair

OBJECTIVE

To evaluate, using histological analysis, the systemic action and repair process of wounds produced on the back of rats and treated with red, infrared, or both lasers applied directly or indirectly to the wounds.

BACKGROUND DATA

Skin tissue repair and wound healing are complex processes that involve a series of dynamic events. Many benefits are associated with biomodulation using laser therapy.

METHODS

Thirty-six male Wistar rats were divided into four groups: control (without laser), red laser (aluminium gallium indium phosphide (AlGaInP); lambda=685 nm; phi=0.0314 cm2; CW; P=30 mW; D=20 J, time of irradiation=667 sec), infrared laser (gallium-aluminum-arsenide (GaAlAs): lambda=830 nm; phi=0.0314 cm2; CW; P=50 mW; D=20 J, time of irradiation=401 sec), and both lasers (infrared laser: GaAlAs; lambda=830 nm; phi=0.0314 cm2; CW; P=50 mW; D=10 J, time of irradiation=201 sec+red laser: AlGaInP; lambda=685 nm; phi=0.0314 cm2; CW; P=30 mW; D=10 J, time of irradiation=334 sec; total dose=20 J). Three subgroups were formed according to observation time points. Three wounds were produced on the back of each animal. Only the wound closest to the head was irradiated in the experimental groups. For the evaluation of skin reaction and wound healing, three animals of each group were killed at 3, 5, and 7 days postoperatively. The irradiation protocol established 48-hour intervals between applications, with the first application immediately after the surgical procedure.

RESULTS

In the red and infrared laser group, healing was more advanced in the wound located furthest from the point of laser application. The most effective healing of a proximal wound was verified in the control group on the 7th postoperative day.

CONCLUSION

The combined application of red and infrared lasers resulted in the most evident systemic effect on the repair of skin wounds produced in rats.

Effects of a polarized light source (400-2000 nm) on Hep.2 and L929 cell lines: a spectroscopic in vitro study

OBJECTIVE

The aim of this study was to evaluate the effects on Hep.2 cells originating from laryngeal carcinomas, and L929 cells originating from a fibroblast line, subjected to polarized light at a wavelength of 400-2000 nm.

BACKGROUND DATA

Recently there has been increased interest in the propagation of polarized light in randomly scattering media such as biological tissues, because of its potential applications in medicine.

MATERIALS AND METHODS

Irradiation was performed at two time points: T0 (24 h after cell culture) and T48 (48 h after the first irradiation). Cellular viability was assessed using an MTT assay at the following times: T0 (first irradiation), T6 (6 h after the first irradiation), T12 (12 h after the first irradiation), T24 (24 h after the first irradiation), T48 (48 h after the first irradiation), and T72 (72 h after the first irradiation). The results were analyzed using Graphpad Prism software.

RESULTS

The results showed that time influenced the cellular viability of L929 cells of both control (p = 0.0014) and illuminated cultures (p = 0.0035). Significant differences between control cells (p = 0.0001) and illuminated Hep.2 cells (p = 0.0001) were observed. There was a significant difference between the proliferation of the two types of cells illuminated compared to their controls: Hep.2 (p = 0.0001) and L929 (p = 0.0002).

CONCLUSION

The use of polarized light on Hep.2 and L929 cells resulted in photobiological effects that need further investigation, as this is the first study using this methodology.

The light revival: does phototherapy promote wound healing? A review

BACKGROUND

Throughout history, light has been recognised as a potential source of healing. The introduction of lasers made it possible to modify and control light for optimum therapeutic use.

AIM

This paper reviews recent clinical trials that test phototherapy on human models in order to assess the value of phototherapy in routine wound care.

METHOD

A literature search was undertaken using a variety of sources including online databases.

RESULTS

The results of numerous in vitro and animal investigations suggest that phototherapy may stimulate cell activity and promote tissue repair. Reports of human clinical trials are relatively few. There is inconsistency of selected treatment parameters amongst studies testing the effect of phototherapy on wound healing. Clinical trials using human models do not provide sufficient evidence to establish the usefulness of phototherapy as an effective tool in wound care regimes.

CONCLUSION

Further well designed research trials are required to determine the true value of phototherapy in routine wound care.

The use of light photobiomodulation on the treatment of second-degree burns: a histological study of a rodent model

OBJECTIVE

The aim of this investigation was to compare, by light microscopy, the effects of the use of laser photobiomodulation (LPBM) and polarized light (PL) on second-degree burns on rodents.

BACKGROUND DATA

Burns are severe injuries that result in the loss of tissue fluids, destruction of tissues, infection, and shock. With severe and widespread third-degree burns death may occur. Several light sources have been suggested as being effective for improving wound healing.

MATERIALS AND METHODS

Forty five rats were used in this study. A second-degree burn was created on the dorsum of each animal, and the animals were divided into four groups: PL (400-2000 nm, 40 mW, 2.4 J/cm(2)/min); LPBM-1 (780 nm, 35/40 mW, theta approximately 2 mm, 4 x 5 J/cm(2)); LPBM-2 (660 nm, 35/40 mW, theta approximately 2 mm, 4 x 5 J/cm(2)); and untreated animals acted as controls. The treatment was started immediately post-burn at four points around the burned area (laser: 5 J/cm(2) per site). The illumination with PL was performed according to the manufacturer's instructions. Treatments were repeated at 24-h intervals for 7 d. The animals were sacrifice at 3, 5, and 7 d post-burn. The specimens were routinely cut and stained and analyzed by light microscopy using hematoxylin and eosin and Sirius red.

RESULTS

The analysis of the results demonstrated that the damaged tissue was able to efficiently absorb and process the light at all tested wavelengths. LPBM at 660 nm showed better results at early stages of wound healing. However, the use of 780-nm laser light had beneficial effects throughout the experimental period, with the animals growing newly-formed tissue similar to normal dermis.

CONCLUSION

Despite our findings that the use of both types of light energy improved the healing of second-degree burns at the early stages, long-term assessment is needed to verify if this improvement will influence the final results of treatment.

Efficacy of low-level laser therapy for chronic cutaneous ulceration in humans: a review and discussion

Chronic wounds, particularly venous ulcerations, are notoriously difficult to heal. Because current therapies are variable in their ability to induce complete healing, there remains a need to develop adjunctive treatments that can improve or accelerate the healing process. The use of low-energy lasers to stimulate wound healing has been pursued over many decades in studies of varying quality. This form of treatment has had high appeal due to its novelty, relative ease, and low morbidity profile. The authors reviewed the available published literature on low-level laser technology in an attempt to provide cumulative insight on the effect of this treatment for wound healing.

The effects of topical tripeptide copper complex and helium-neon laser on wound healing in rabbits

The aim of this study was to compare the clinical and histopathological effects of tripeptide copper complex (TCC) and two different doses of laser application (helium-neon laser, 1 and 3 J cm(-2)) on wound healing with untreated control wounds. Experimental wounds were created on a total of 24 New Zealand white rabbits and topical TCC or laser was applied for 28 days. The wounds were observed daily, and planimetry was performed on days 7, 14, 21 and 28 to measure the unhealed wound area and percentage of total wound healing. Biopsies were taken weekly to evaluate the inflammatory response and the level of neovascularization. The median time for the first observable granulation tissue was shorter (P < 0.05) in the low and high dose laser groups than in the control group (3 and 2.66 vs. 4.5 days), but was not different between the TCC and control groups (4.16 vs. 4.5 days). Filling of the open wound to skin level with granulation tissue was faster (P < 0.05) in the TCC and high dose laser groups than in the control group (14 and 16 vs. 25 days), but was not different between the low dose laser and control groups (23 vs. 25 days). The average time for healing was shorter (P < 0.05) in the TCC and high dose laser groups (29.8 and 30.2 vs. 34.6 days), but was not different between the low dose laser and control groups (33.8 vs. 34.6 days). Histopathologically, wound healing was characterized by a decrease in the neutrophil counts and an increase in neovascularization. The TCC and high dose laser groups had greater neutrophil and vessel counts than in the control group, suggesting a more beneficial effect for wound healing.

The Effect of Low Reactive-Level Laser Therapy (LLLT) with Helium-Neon Laser on Operative Wound Healing in a Rat Model

The effect of low reactive-level laser therapy (LLLT) with a He-Ne laser on operative wound healing was investigated in a rat model. 10-millimeter surgical wounds were created on the backs of Sprague Dawley rats, and animals were assigned to one of eleven groups (n=5). Ten groups received either 8.5 mW or 17.0 mW irradiation of 15 seconds LLLT a day with one of five different irradiation frequencies, i.e. daily (from the 1st to 6th day following surgery), every other day (the 1st, 3rd, and 5th day), on only the 1st day, on only the 3rd day, and on only the 5th day; the 1st day was the day following the surgery. The control group received no irradiation. A skin specimen was harvested from the dorsal thoracic region on the 7th day to measure the rupture strength. The control group had the lowest rupture strength (5.01 N), and the 17.0 mW every other day irradiation group had the highest rupture strength (13.01 N). Statistical differences were demonstrated in the 8.5 mW irradiation setting between the every other day irradiation group and the control group (p<0.05); and in 17.0 mW irradiation setting between the every day irradiation, the every other day, and the 1st day only groups vs. the control group (p<0.01). Histological examination demonstrated that wound healing in the 17.0 mW every other day irradiation group was promoted most significantly such as the prevention of excessive inflammation, increased formation of collagen fibers, and recovery in continuity of tissues. The control group showed poor wound healing and the other experimental groups showed intermediate healing. Thus LLLT with a He-Ne laser was found to promote the healing of operative wounds in the present rat model, in which the most favorable application of LLLT was the 17.0 mW setting of 15 seconds a day with a frequency of every other day.

Low-Level Laser Therapy for Wound Healing: Mechanism and Efficacy

BACKGROUND

Given the recent interest in light-emitting diode (LED) photomodulation and minimally invasive nonablative laser therapies, it is timely to investigate reports that low-level laser therapy (LLLT) may have utility in wound healing.

OBJECTIVES

To critically evaluate reported in vitro models and in vivo animal and human studies and to assess the qualitative and quantitative sufficiency of evidence for the efficacy of LLLT in promoting wound healing.

METHOD

Literature review, 1965 to 2003.

RESULTS

In examining the effects of LLLT on cell cultures in vitro, some articles report an increase in cell proliferation and collagen production using specific and somewhat arbitrary laser settings with the helium neon (HeNe) and gallium arsenide lasers, but none of the available studies address the mechanism, whether photothermal, photochemical, or photomechanical, whereby LLLT may be exerting its effect. Some studies, especially those using HeNe lasers, report improvements in surgical wound healing in a rodent model; however, these results have not been duplicated in animals such as pigs, which have skin that more closely resembles that of humans. In humans, beneficial effects on superficial wound healing found in small case series have not been replicated in larger studies.

CONCLUSION

To better understand the utility of LLLT in cutaneous wound healing, good clinical studies that correlate cellular effects and biologic processes are needed. Future studies should be well-controlled investigations with rational selection of lasers and treatment parameters. In the absence of such studies, the literature does not appear to support widespread use of LLLT in wound healing at this time. Although applications of high-energy (10-100 W) lasers are well established with significant supportive literature and widespread use, conflicting studies in the literature have limited low-level laser therapy (LLLT) use in the United States to investigational use only. Yet LLLT is used clinically in many other areas, including Canada, Europe, and Asia, for the treatment of various neurologic, chiropractic, dental, and dermatologic disorders. To understand this discrepancy, it is useful to review the studies on LLLT that have, to date, precluded Food and Drug Administration approval of many such technologies in the United States. The fundamental question is whether there is sufficient evidence to support the use of LLLT.

Polarized Light (400–2000 nm) and Non-ablative Laser (685 nm): A Description of the Wound Healing Process Using Immunohistochemical Analysis

OBJECTIVE

This study aimed to describe, through morphologic and cytochemical analysis, the healing process of wounds submitted (or not) to laser therapy (lambda685 nm) or polarized light (lambda400-2000 nm).

BACKGROUND DATA

There are many reports on different effects of several types of phototherapies on the treatment of distinct conditions, amongst them, on wound healing. Laser therapy and the use of polarized light are still controversial despite successive reports on their positive effects on several biological processes.

METHODS

Thirty male Wistar rats, approximately 4 months old, were used, and standardized excisional wounds were created on their dorsum. The wounds were irradiated in four equidistant points with laser light or illuminated with polarized light, both with doses of 20 or 40 J/cm2. Group 1 acted as untreated controls. Animals were irradiated every 48 h during 7 days, starting immediately after surgery, and were humanely killed on the 8th post-operative day. Specimens were taken and routinely processed and stained with H&E, and for descriptive analysis of myofibroblasts and collagen fibers, the specimens were imunnomarked by smooth muscle alpha-actin and picrosirius stain.

RESULTS

Control specimens showed the presence of ulceration, hyperemia, discrete edema, intense, and diffuse inflammation, collagen deposition was irregular, and myofibroblasts were seen parallel to the wound margins. Wounds treated by laser therapy with a dose of 20 J/cm2 showed mild hyperemia, inflammation varied from moderate to intense, the number of fibroblasts was large, and the distribution of collagen fibers was more regular. Increasing the dose to 40 J/cm2 evidenced exuberant neovascularization, severe hyperemia, moderate to severe inflammation, large collagen deposition, and fewer myofibroblasts. On subjects illuminated with polarized light with a dose of 20 J/cm2, mild to moderate hyperemia was detectable, and collagen matrix was expressive and unevenly distributed; a larger number of myofibroblasts was present and no re-epithelialization was seen. Increasing the dose resulted in mild to moderate hyperemia, no re-epithelialization was seen, edema was discrete, and inflammation was moderate.

CONCLUSION

The use of 685-nm laser light or polarized light with a dose of 20 J/cm2 resulted in increased collagen deposition and better organization on healing wounds, and the number of myofibroblast was increased when polarized light is used.

Burn healing with a diode laser: 670 nm at different doses as compared to a placebo group

OBJECTIVE

A study on burn healing in rats was initiated using a diode laser at varied doses for determination of optimum dosimetry and treatment schedule.

MATERIALS AND METHODS

A number of male Sprague-Dawley rats were randomly assigned to several groups. Anesthesia (a mixture of ketamine HCl and Xylocaine) was administered intraperitoneally. Burn on both flanks was created using a preheated metal probe and measured daily using a caliper. The right side of the treated rats was irradiated five times and three times per week. Slopes from the actual burn areas were obtained and compared against the control with the healing rate calculated and expressed in percent.

RESULTS

In reference to the control group, no significant difference in healing was observed. In comparing both treatment schedules, there was likewise no significant difference at any day in both age-groups. Notably in younger rats, accelerated healing was observed with the highest rate in the lower range of doses (1 and 5 J/cm2), 12.4% and 11.6%, respectively.

CONCLUSION

This experiment affirms that the beneficial effect on burn healing in rats is indeed affected by an interplay of several factors.

Assessment of Bone Repair Associated with the Use of Organic Bovine Bone and Membrane Irradiated at 830 nm

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.

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.

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.

Effect of 830-nm laser light on the repair of bone defects grafted with inorganic bovine bone and decalcified cortical osseus membrane

OBJECTIVE

The aim of this study was to histologically assess the effect of low-level laser therapy (LLLT) (lambda830 nm) on the repair of standardized bone defects of the femur of Wistar albinus rats grafted with inorganic bovine bone and associated (or not) with decalcified bovine cortical bone membrane.

BACKGROUND DATA

Bone loss may be a result of pathology, trauma, or surgical procedure. Extensive studies on the process of bone repair have been undertaken, and several techniques for the correction of bone defects have been proposed. Amongst them is the use of several types of grafts, the use of membranes, and the combination of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone healing is not completely understood.

MATERIALS AND METHODS

Five randomized groups were studied: group I (control); group IIA (Gen-ox); group IIB (Gen-ox + LLLT); group IIIA (Gen-ox + Gen-derm); and group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur and were treated according to the group. The animals of irradiated groups were irradiated every 48 h for 15 days; the first irradiation was performed immediately after the procedure. The animals were irradiated transcutaneuosly at four points around the defect. At each point, a dose of 4 J/cm2 was given (phi approximately equal to 0.6 mm, 40 mW), and the total dose per session was 16 J/cm2. The animals were humanely killed at 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, stained with H&E and Picrosirius stains, and analyzed under light microscopy.

RESULTS

The results showed more advanced repair of the irradiated groups when compared to the non-irradiated ones. The repair of the irradiated group was characterized by both increased bone formation and on the amount of collagen fibers around the graft within the cavity, as early as the 15th day after surgery, considering the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION

It is concluded that LLLT had a positive effect on the repair of bone defect by graft associated or not with the use of biological membrane.

Effect of 830-nm Laser Light on the Repair of Bone Defects Grafted with Inorganic Bovine Bone and Decalcified Cortical Osseous Membrane

OBJECTIVE

The aim of this study was to assess histologically the effect of LLLT (lambda830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats grafted with inorganic bovine bone and associated or not to decalcified bovine cortical bone membrane.

BACKGROUND DATA

Bone loss may be a result of several pathologies, trauma or a consequence of surgical procedures. This led to extensive studies on the process of bone repair and development of techniques for the correction of bone defects, including the use of several types of grafts, membranes and the association of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone is not completely understood.

MATERIALS AND METHODS

Five randomized groups were studied: Group I (Control); Group IIA (Gen-ox); Group IIB (Gen-ox + LLLT); Group IIIA (Gen-ox + Gen-derm) and Group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur of the animals and were treated according to the group. The animals of the irradiated groups were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the surgical procedure. The animals were irradiated transcutaneously in four points around the defect. At each point a dose of 4 J/cm2 was given (phi approximately 0.6 mm, 40 mW) and the total dose per session was 16 J/cm2. The animals were humanely killed 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, and stained with H&E and Picrosirius stains and analyzed under light microscopy.

RESULTS

The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity since the 15th day after surgery, through analysis of the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION

It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft.

Lasers in periodontics

Publicity about the use of lasers in dentistry has generated considerable interest in both professional and lay audiences. The purpose of this report is to provide information for members of the dental profession about the current and potential application of laser technology to periodontal practice. This report was prepared by the Research, Science and Therapy Committee of the American Academy of Periodontology.

MMPs and TIMP-1 are differentially expressed between acute murine excisional and laser wounds

BACKGROUND AND OBJECTIVES

Matrix metalloproteinases (MMPs) and their physiological inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) play significant roles in wound repair. The aim of this study was to determine whether MMP and TIMP-1 mRNA is differentially expressed between laser-created and excisional skin wounds.

STUDY DESIGN/MATERIALS AND METHODS

Full-thickness wounds were created on the dorsal surface of Balb/c mice by either excision of the skin or with a CO2 laser. Animals were sacrificed at days 1, 3, 5, 7, 10, and 13, and their wounds processed for RNA isolation or histology and immunohistochemistry.

RESULTS

Northern hybridization for MMP-3, -10, -13, and TIMP-1 mRNA demonstrated higher expression on days 1, 3, and 5 in the laser wounds as compared to the excisional wounds. Histological evaluation revealed a two day delay in the resurfacing of laser wounds as compared to excisional wounds. Immunohistochemistry of Day 5 and 7 excisional and laser wounds showed MMP-3 within the epidermal compartment and the neo-dermis. No remarkable differences were noted in the spatial distribution patterns of MMP-3 between wound types.

CONCLUSIONS

Our findings demonstrate that MMPs and TIMP-1 mRNA expression is higher on days 1-5 post injury in full thickness laser-created wounds than in comparable same day excisional wounds.

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.

The influence of photodynamic therapy on the wound healing process in rats

In photodynamic therapy (PDT), photosensitisers (PS) are used along with lasers for the treatment of tumors. The combined effect of photosensitisers and lasers on the wound healing process is studied using delta-aminolevulinic acid (ALA) (5 mg/kg) and hematoporphyrin derivative (HPD) (5 mg/kg) as photosensitisers in the open excision wounds of rats. The lasers used were He-Ne laser (3 J/cm2) and Nd:YAG laser (30 J/cm2). This study is important for understanding the healing process involved after PDT. Open excision wounds treated with He-Ne lasers in animals that received ALA as photosensitiser showed complete wound closure at the earliest by 13 +/- 1 days, and with results obtained for HPD and the combination of lasers with complete closing by 14 +/- 1 days. However, the control group of animals that received ALS or HPD with no laser treatment showed wound healing on the twentieth and eighteenth days with a deviation of one day and two days, respectively. ALA with the combination of Nd:YAG and He-Ne lasers and HPD with He-Ne laser alone does not show quicker wound healing effects. Histopathological results also gave similar results. Tensile strength measurements do not vary significantly from control group to the test group. ALA along with He-Ne laser of HPD along with the combination of He-Ne and low power Nd-YAG lasers are found to be ideal methods for quickening the wound healing process in rat.

Helium-neon laser irradiation is not a stressful treatment: a study on heat-shock protein (HSP70) level

BACKGROUND AND OBJECTIVE

Helium-neon (He-Ne) laser irradiation has been clinically used to reduce chemotherapy-induced mucositis. This work was designed to find out if this treatment is stressful at the cellular level by studying its effects on the level of the stress-inducible heat shock proteins.

STUDY DESIGN/MATERIALS AND METHODS

Human desmodontal and mouse L929 fibroblasts were irradiated using a 60 mW laser by a single application of 1.5 and 3J/cm2 in continuous mode. Heat shock protein level was studied by gel electrophoresis and Western blotting using monoclonal antibodies.

RESULTS

He-Ne treatment does not induce heat shock protein synthesis in human desmodontal nor in mouse fibroblasts at the energy densities used in this study.

CONCLUSIONS

These results indicate that the treatment is not stressful at the cellular level.

Helium-neon laser irradiation at fluences of 1, 2, and 4 J/cm2 failed to accelerate wound healing as assessed by both wound contracture rate and tensile strength

BACKGROUND AND OBJECTIVE

Reports in the literature indicate that low energy laser irradiation has a biostimulatory effect on wound healing; however, no mechanism of this effect has been elucidated.

STUDY DESIGN/MATERIALS AND METHODS

We attempted to establish a model from which to study the mechanism of biostimulation. The effects of low energy helium-neon irradiation on wound healing were observed in two rat models. In the first model, 1.5 cm diameter full thickness excisional skin defects were created in the dorsal midline of rats (n = 32). All animals were anesthetized and all eschars were debrided daily. Wound area was determined by caliper measurements for 2 weeks postoperatively. Rats that received a treatment of 1 J/cm2 had two defects in the dorsal skin. One wound was treated and the second was used as its own control. These measurements were not blinded. Rats that received 2 J/cm2, 4 J/cm2, or anesthesia alone had one defect on the dorsal skin. Caliper measurements of these wounds were blinded. We were unable to demonstrate any difference in the rate of wound contracture in rats that received a daily dose of 1 J/cm2, 2 J/cm2, 4 J/cm2, or anesthesia alone (P > 0.8 by student's t-test). In the second model, a single 2 cm longitudinal full thickness skin incision was created in the dorsal midline of each rat (n = 24). No difference was found between rats that received anesthesia alone and those treated daily with 2 J/cm2 as assessed by tensile strength measurements on postoperative days 7 and 14 (P > 0.8 by student's t-test between groups at both time points). These determinations were blinded.

RESULTS

Despite our intentions of studying the mechanism of low energy HeNe biostimulation, we were unable to demonstrate a beneficial effect.

CONCLUSION

In this study, helium-neon laser irradiation produced no measurable benefit on wound healing.

Effects of photostimulation on wound healing in diabetic mice

BACKGROUND AND OBJECTIVE

Low-level laser irradiation at certain fluences and wavelengths can enhance the release of growth factors from fibroblasts and stimulate cell proliferation in vitro. We evaluated whether low-level laser irradiation can improve wound healing in diabetes mellitus.

STUDY DESIGN/MATERIALS AND METHODS

Genetically diabetic mice (C57BL/Ksj/db/db) were used as the animal model for this wound healing study. The experimental animals were divided among four groups: negative control, positive control (topical basic fibroblast growth factor [bFGF] on wound), laser therapy group; and a combination group of laser therapy and topical bFGF. An argon dye laser (Lexel Auora Model 600) at a wavelength of 630 nm and an output of 20 m W/cm2 was used as the light source. The speed of wound closure and histological evaluation were used to analyze the experimental results.

RESULTS

Laser irradiation enhanced the percentage of wound closure over time as compared to the negative control group (58.4 +/- 2.6 vs. 40.8 +/- 3.4 at day 10 and 95.7 +/- 2 vs. 82.3 +/- 3.6 at day 20, P < .01). Histological evaluation showed that laser irradiation improved wound epithelialization, cellular content, granulation tissue formation, and collagen deposition in laser-treated wounds as compared to the negative control group (6.4 +/- 0.16 vs. 3.8 +/- 0.13 at day 10 and 12 +/- 0.21 vs. 8.2 +/- 0.31, P < .01).

CONCLUSION

This study of laser biostimulation on wound healing in diabetic mice suggests that such therapy may be of great benefit in the treatment of chronic wounds that occur as a complication of diabetes mellitus.

Healing of burns after treatment with 670-nanometer low-power laser light

Recent investigations have reported contradictory results on the influence of low-power laser light on wound healing. Low-power laser with a power output of 250 mW and an emitted laser light of 670 nm have been insufficiently investigated to date. The effect of a 250-mW/670-nm laser light on the healing of burning wounds in rats was investigated. Thirty rats were burned on both flanks. One wound was irradiated with 670-nm laser light (2 J/cm2), whereas the other side remained untreated. Macroscopic evaluation of the wounds was performed daily; 10, 20, and 30 days after burning, 10 rats were killed and the wounds histologically evaluated. Neither macroscopic nor histologic examination of the irradiated wound showed accelerated wound healing when compared with control wounds. In the present study, irradiation of burns with a 250-mW/670-nm laser light produced no beneficial effects on wound-healing processes.

Using lasers in diabetic wound healing

Lasers are a treatment choice that appeals to patients. Early research suggests that laser therapy may have a role in hastening wound healing. Attempts have been made to use helium neon, CO2, and KTP lasers in encouraging wound healing in diabetics. We will review the English literature related to laser use in diabetic wound healing and discuss the concept of the use of nondestructive lasers for biostimulation. Further research is needed to assess effectiveness of biostimulation for diabetic wound healing.

The use of low energy photon therapy (LEPT) in venous leg ulcers: a double-blind, placebo-controlled study

BACKGROUND

Venous ulcers are estimated to be present in 0.2 to 0.4% of the population. Although new therapies have significant promise, nonhealing ulcers still represent a significant problem.

OBJECTIVE

To evaluate the efficacy of low energy photon therapy (LEPT) in the treatment of venous leg ulcers.

METHODS

A placebo-controlled, double-blind study using low energy photon therapy was performed in nine patients with 12 venous ulcers. Treatment was given three times a week for 10 weeks, using two monochromatic optical sources. One source provided a wavelength (lambda) of 660 nm (red) while the second source delivered a wavelength of 880 nm (infrared). Two optical probes were used, one consisted of an array of 22 monochromatic sources, operating at a wavelength of 660 nm and covering an area 6 x 10 cm2. The second probe had seven infrared sources, operating at a wavelength of 880 nm and covering an area of 4 cm2. The above configuration of optical probes was selected to cover the majority of the ulcer area being treated. The patients who were randomized to placebo treatment received sham therapy from an identical-appearing light source from the same delivery system.

RESULTS

Nine patients with 12 venous ulcers were randomized to receive LEPT or placebo therapy. At the conclusion of the study, the percentage of the initial ulcer area remaining unhealed in the LEPT and placebo groups was 24.4% and 84.7%, respectively (P = 0.0008). The decrease in ulcer area (compared to baseline) observed in the LEPT and placebo groups was 193.0 mm2 and 14.7 mm2, respectively (P = 0.0002). One patient dropped out of the study, complaining of lack of treatment efficacy; he was found to be randomized to the placebo group. There were no adverse effects.

CONCLUSION

In this placebo-controlled, double-blind study LEPT was an effective modality for the treatment of venous leg ulcers.

Photomodulation of oxidative metabolism and electron chain enzymes in rat liver mitochondria

Low-level laser irradiation has been applied in a variety of laboratory studies and clinical trials for photobiostimulation over the last three decades. Considerable skepticism exists regarding the concept of photostimulation within the medical community. One of the major difficulties with photoirradiation research is that it lacks experimentally supportable mechanisms for the alleged photobiostimulatory effects. This study was undertaken to determine whether oxidative metabolism and electron chain enzymes in rat liver mitochondria can be modulated by photoirradiation. Oxygen consumption, phosphate potential, and energy charge of rat liver mitochondria were determined following photoirradiation. Activities of mitochondrial enzymes were analyzed to assess the specific enzymes that are directly involved with the photostimulatory process. An argon-dye laser at a wave-length of 660 nm and at a power density of 10 mW/cm2 was used as a photon source. Photoirradiation significantly increased oxygen consumption (0.6 J/cm2 and 1.2 J/cm2, P < 0.05), phosphate potential, and the energy charge (1.8 J/cm2 and 2.4 J/cm2, P < 0.05) of rat liver mitochondria and enhanced the activities of NADH: ubiquinone oxidoreductase, ubiquinol: ferricytochrome C oxidoreductase and ferrocytochrome C: oxygen oxidoreductase (0.6 J/cm2, 1.2 J/cm2, 2.4 J/cm2 and 4.8 J/cm2, P < 0.05). The activities of succinate ubiquinone oxidoreductase, ATPase, and lactate dehydrogenase were not affected by photoirradiation.

A preliminary study of the effects of laser radiation on collagen metabolism in cell culture

A low power Ga-As pulse laser was used to stimulate cultured human embryonic fibroblast cells. Energy fluencies varied from 0-1 J/cm2 over a period of 1-4 days. Fibroblast procollagen production was monitored by the synthesis of [3H] hydroxyproline, and DNA replication was assessed by [3H] thymidine incorporation. Following laser treatment, controlled pepsin digestion measured the increase in cell biostimulation. Maximum increase in collagen production and cell biostimulation occurred after 4 episodes of laser treatment at 24-hour intervals. Laser doses between 0.099 and 0.522 J/cm2 had the most significant stimulatory effects on fibroblast function. Clinical efficacy of the low power Ga-As pulse laser may be related to enhanced connective tissue repair.

Biostimulation of wound healing by low-energy laser irradiation. A review

This paper reviews studies on the basic principles of biostimulation of wound healing by various low-energy lasers. It looks at the mechanism of action of biostimulation as well as the laser's effect on cell proliferation, collagen synthesis, and would healing.

The effects of low level laser treatment on recovery of nerve conduction and motor function after compression injury in the rat sciatic nerve

An animal study is presented examining the effect of low level laser (LLL) treatment on nerve regeneration following axonotmesis. Twenty animals received a standardised injury to the right sciatic nerve using a time, load and length sequence (10 min, 150 N, 5 mm) known to cause extensive axonal degeneration of the rat sciatic nerve. The LLL treatment was administered using a hand-held laser probe in light contact with the skin on the dorsal aspect of the hind leg overlying the site of the axonotmesis injury to the sciatic nerve. A group of 10 animals were treated with 6J of LLL (GaAlAs 830 nm) daily for a period of 28 d. Ten more animals were treated daily with a sham exposure setting and served as controls. Nerve function was assessed by a recognised method of walking tract print analysis; the "Sciatic Functional Index" (SFI), and nerve regeneration was assessed by recording the evoked compound action potentials (cAP) in the common peroneal nerve. At 21 d post-injury, the laser-treated group had a significantly lower median SFI than the sham laser-treated group, indicating that the real laser treatment had improved functional recovery in the nerve. However, no differences were found between the evoked cAP parameters that were measured in the laser-treated and sham laser-treated groups. Histological examination reiterated the lack of difference between the two groups. Consequently, the effects of LLL on recovery must have occurred more peripherally to the point measured.