Effects of Nd:YAG laser on wound healing processes: clinical and immunohistochemical findings in rat skin

Evaluation of wound healing and postoperative pain after oral mucosa laser biopsy with the aid of compound with chlorhexidine and sodium hyaluronate: a randomized double blind clinical trial

OBJECTIVES

The aim of this study is to evaluate secondary intention healing process and postoperative pain of oral soft tissues after laser surgery with the use of a compound containing chlorhexidine and sodium hyaluronate.

MATERIALS AND METHODS

This double-blind, randomized clinical study included 56 patients affected by benign oral lesions and subjected to excisional biopsy with diode laser and randomly divided into three groups. Study group (SG) received 0.2% chlorhexidine digluconate and 0.2% sodium hyaluronate treatment; control group (CG) received 0.2% chlorhexidine digluconate; and placebo group (PG) followed the same protocol, taking a neutral solution having the same organoleptic characteristics. Wound healing was evaluated using percentage healing index (PHI). Numeric rating scale (NRS) was used to evaluate postoperative pain.

RESULTS

PHI (T1 = 7 days) was 67.25% for SG, 58.67% for CG, and 54.55% for PG. PHI (T2 = 14 days) was 94.35% for SG, 77.79% for CG, and 78.98% for PG. A statistically significant difference was between the groups for PHI at T2 p = 0.001. No difference was detectable for pain index.

CONCLUSIONS

A solution containing sodium hyaluronate and chlorhexidine is a good support to increase wound healing by secondary intention after laser biopsy, but no differences were in postoperative perception of pain.

CLINICAL RELEVANCE

The use of the tested solution can be recommended after laser oral biopsies, to achieve a healing without suture. About the postoperative pain, the compound has not showed the same results and did not have measurable effects.

Periodontal and peri-implant wound healing following laser therapy

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri-implant treatment, focusing on postoperative wound healing of periodontal and peri-implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports.

Clinical Evaluation of a Device for the Treatment of Cellulite: Triactive

Introduction:

Cellulite has always been a difficult condition for patients and cosmetic physicians to treat. Even if improvement is made in the appearance of cellulite, no machine or topical treatment exists that can provide long-term results in the treatment of cellulite. We evaluated a technique that increases lymphatic drainage and vascular permeation to assist in decreasing the appearance of cellulite.

Materials and Methods:

Sixteen female patients underwent 12 treatments with a device called Triactive, which has a triple-pronged mechanism of action consisting of low-level suction, diode laser, and contact cooling. We measured results by waist, hip, and thigh circumference as well as elasticity, thermography, and blinded photograph evaluations.

Results:

We found a small decrease in hip and thigh circumference as well as an increase in elasticity of the treated cellulite. Evaluation of the photographs yielded an overall 21% average improvement in the appearance of cellulite. There was no change in thermography data after treatments. Results were not present at 1 month.

Discussion:

The Triactive offers a method to temporarily decrease the appearance of cellulite. It appears that treatments must be continued to maintain results. Further study and larger patient groups are needed before this treatment can be recommended above other available treatments.

Technology of Lasers and Their Applications in Oral Surgery: Literature Review

The word “Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation”. Recent advances in laser technology have brought a kind of revolution in dentistry. The purpose of this article is to provide an overview of clinical application of lasers in oral medicine and especially in oral surgery, including their advantages, disadvantages and safety.

Different laser wavelengths comparison in the second-stage implant surgery: an ex vivo study

The implant surgery consists of two distinct techniques, the transmucosal, also known as "one-stage" and the "two-stage" technique. Lasers represent a possible aid in implant dentistry, especially in the two-stage technique and its main characteristics are represented by a decreased trauma to bone and soft tissues, a reduction of pain as well as a reduction of the risk of postoperative infections. The aim of this study was to analyze in an animal model the thermal elevation induced by four different laser wavelengths (diode, Nd:YAG, Er:YAG, KTP) during the implant uncovering. Four pig jaws were used to carry out this study. Five implants were placed in each anatomical specimen for a total of 20 fixtures. Four wavelengths (532, 810, 1,064 and 2,940 nm) were used to uncover the implants. Two thermocouples were used to measure temperature changes during laser irradiation at bone level, peri-implant tissues and on the fixture surface The thermocouples were connected with two probes of 1.5 mm in diameter, in order to simultaneously recording two temperature variations. Surface temperature was also checked during all procedures with a thermal camera (Thermovision A 800, Flyr Systems, Stockolm, Sweden) connected to a PC. The mean temperatures of each specimen (five fixtures) were calculated (TM1, mean temperature at the beginning; TM2, mean peak temperature). Furthermore, a record of the temperature at 1 min after the end of the surgical procedure was taken (mean: TM3). All the recorded values were statistically evaluated by one-way analysis of variance (ANOVA). The thermocouples recorded a lower increase in temperature for Er:YAG and KTP laser; Nd:YAG and diode laser produced similar increases characterized by higher values. The thermo-camera pointed out the lower increase for Er:YAG and higher for diode laser. KTP laser resulted faster in uncovering implants and diode laser was the one that needed more time. This ex vivo study showed that laser utilization with the recommended parameters gives no risks of dangerous thermal elevation to the tissues and implants.

A novel 785-nm laser diode-based system for standardization of cell culture irradiation

OBJECTIVE

The purpose of this study was to develop a novel device that concatenates alignment of infrared lasers and parallel procedure of irradiation. The purpose of this is to seek standardization of in vitro cell irradiation, which allows analysis and credible comparisons between outcomes of different experiments.

BACKGROUND DATA

Experimental data obtained from infrared laser therapies have been strongly dependent upon the irradiation setup. Although further optical alignment is difficult to achieve, in contact irradiation it usually occurs. Moreover, these methods eventually use laser in a serial procedure, extending the time to irradiate experimental samples.

METHODS

A LASERTable (LT) device was designed to provide similar infrared laser irradiation in 12 wells of a 24 well test plate. It irradiated each well by expanding the laser beam until it covers the well bottom, as occurs with unexpanded irradiation. To evaluate the effectiveness of this device, the spatial distribution of radiation was measured, and the heating of plain culture medium was monitored during the LT operation. The irradiation of LT (up to 25 J/cm(2) - 20 mW/cm(2); 1.250 sec) was assessed on odontoblast-like cells adhered to the bottom of wells containing 1 mL of plain culture medium. Cell morphology and metabolism were also evaluated.

RESULTS

Irradiation with LT presented a Gaussian-like profile when the culture medium was not heated >1°C. It was also observed that the LT made it 10 times faster to perform the experiment than did serial laser irradiation. In addition, the data of this study revealed that the odontoblast-like cells exposed to low-level laser therapy (LLLT) using the LT presented higher metabolism and normal morphology.

CONCLUSIONS

The experimental LASERTable assessed in this study provided parameters for standardization of infrared cell irradiation, minimizing the time spent to irradiate all samples. Therefore, this device is a helpful tool that can be effectively used to evaluate experimental LLLT protocols.

Effect of low-level laser therapy on odontoblast-like cells exposed to bleaching agent

The aim of the present study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like MDPC-23 cells exposed to carbamide peroxide (CP 0.01%-2.21 μg/mL of H2O2). The cells were seeded in sterile 24-well plates for 72 h. Eight groups were established according to the exposure or not to the bleaching agents and the laser energy doses tested (0, 4, 10, and 15 J/cm(2)). After exposing the cells to 0.01% CP for 1 h, this bleaching solution was replaced by fresh culture medium. The cells were then irradiated (three sections) with a near-infrared diode laser (InGaAsP-780 ± 3 nm, 40 mW), with intervals of 24 h. The 0.01% CP solution caused statistically significant reductions in cell metabolism and alkaline phosphate (ALP) activity when compared with those of the groups not exposed to the bleaching agent. The LLLT did not modulate cell metabolism; however, the dose of 4 J/cm(2) increased the ALP activity. It was concluded that 0.01% CP reduces the MDPC-23 cell metabolism and ALP activity. The LLLT in the parameters tested did not influence the cell metabolism of the cultured cells; nevertheless, the laser dose of 4 J/cm(2) increases the ALP activity in groups both with and without exposure to the bleaching agent.

Mast cell concentration in the wound healing process of incisions made by different instruments

The aim of this study was to compare the concentration of mast cells (MCs) in the healing process of incisions. Thirty rats were submitted to six linear incisions each, performed in the dorsal skin by carbon dioxide (CO(2)) and diode lasers, electrocautery and conventional scalpel. The animals were euthanized at intervals of 0 h, 24 h, 48 h, 72 h, 7 days and 14 days after the incisions had been made. Histological sections were obtained and stained with toluidine blue for identification of MCs, which were manually counted by conventional microscopy in 20 microscopic fields in the border of the incision, near the granulation tissue, or in the area of new collagen formation, depending on intervals. The concentration of MCs was significantly higher in the wounds made by scalpel than in those made by other techniques at 48 h and 72 h. After 72 h the number of MCs was also significantly higher after electrocautery than after incisions made by 4 W CO(2) laser. On days 7 and 14, there was no significant difference in the MC count among the different types of incisions. In summary, the MC concentration varied after different surgical incisions at early phases of wound healing. At the end of the healing process, however, there were similar MC concentrations around the incisions, suggesting that, in standard incisions in the surgical techniques studied, the wound healing process ultimately occurred in a similar pattern.

An in-vivo experimental evaluation of He-Ne laser photostimulation in healing Achilles tendons

There is no method of treatment that has been proven to accelerate the rate of tendon healing or to improve the quality of the regenerating tendon. Low level laser photostimulation has gained a considerable attention for enhancing tissue repair in a wide spectrum of applications. However, there is controversy regarding the effectiveness of laser photostimulation for improvement of the healing process of surgically repaired tendons. Accordingly, the present study was conducted to evaluate the role of helium-neon (He-Ne) laser photostimulation on the process of healing of surgically repaired Achilles tendons. Thirty unilateral Achilles tendons of 30 Raex rabbits were transected and immediately repaired. Operated Achilles tendons were randomly divided into two equal groups. Tendons at group A were subjected to He-Ne laser (632.8 nm) photostimulation, while tendons at group B served as a control group. Two weeks later, the repaired Achilles tendons were histopathologically and biomechanically evaluated. The histopathological findings suggest the favorable qualitative pattern of the newly synthesized collagen of the regenerating tendons after He-Ne laser photostimulation. The biomechanical results support the same favorable findings from the functional point of view as denoted by the better biomechanical properties of the regenerating tendons after He-Ne laser photostimulation with statistical significance (p <or= 0.01) at most of the biomechanical parameters. He-Ne laser photostimulation reported a great value after surgical repair of ruptured and injured tendons for a better functional outcome. It could be applied safely and effectively in humans, especially with respect to the proposed long-term clinical outcome.

A single center, randomized, comparative, prospective clinical study to determine the efficacy of the VelaSmooth system versus the Triactive system for the treatment of cellulite

BACKGROUND AND OBJECTIVES

One area of cosmetic concern for women of all races is the unsightly appearance of cellulite in the buttocks area and lower extremities. Two modern technological advances claim to improve cellulite and provide reproducible results, TriActive and VelaSmooth. The TriActive laser is intended to reduce the appearance of cellulite through the combination of low-energy diode laser, contact cooling, suction, and massage. The VelaSmooth is based on a combination of two different ranges of electromagnetic energy: infrared light and radio frequency (RF) combined with mechanical manipulation of the skin. This single center study was designed to evaluate the efficacy of the VelaSmooth versus TriActive in the reduction of the appearance of cellulite.

STUDY DESIGN/MATERIALS AND METHODS

Twenty female patients were treated twice a week for 6 weeks with the randomization of TriActive on one side and VelaSmooth on the other side. Patients were evaluated with photographs and circumferential thigh measurements before treatment and after the final treatment.

RESULTS

Although there was improvement in the reduction of cellulite for each device individually, there was no significant difference between VelaSmooth or TriActive devices in the following categories: reduction of thigh circumference, photographic evaluation, and perceived change in before and after photographic grading. There was a statistically significant increase in the incidence of post-treatment bruising with the VelaSmooth compared to TriActive.

CONCLUSIONS

In conclusion, both the TriActive and VelaSmooth provide improvement of cellulite. When comparing differences in efficacy, the average mean percent change calculated was roughly the same for both treatments and showed no statistical difference.

Pilonidal sinus disease treated by depilation using an 800 nm diode laser and review of the literature

BACKGROUND

Pilonidal sinus disease is a debilitating, disfiguring chronic ailment that is often resistant to therapy. Its etiology and treatment remain in question.

OBJECTIVE

To assess the efficacy of an 800 nm diode laser in the treatment of recalcitrant pilonidal sinus disease.

METHODS

Two patients with recalcitrant pilonidal sinus disease were treated in the lower back, buttocks, and perigluteal cleft area with an 800 nm diode laser with a spot size of 9 x 9 mm, fluences of 30 to 48 J/cm2, and pulse widths of 15 to 24 milliseconds.

RESULTS

Long-term relief of pilonidal sinus disease was produced with as few as two treatments 2 months apart to as many as six treatments over a 2-year period. With each successive treatment, fewer pulses were needed and the interval between treatments increased.

CONCLUSION

The 800 nm diode laser may be an effective tool in the treatment of pilonidal sinus disease. By eliminating the source of hair and hair fragments that course along the surface of the lower back and buttocks, interruption of the etiologic source for pilonidal sinus disease can be accomplished.

A Preliminary Report on the Effect of Laser Therapy on the Healing of Cutaneous Surgical Wounds as a Consequence of an Inversely Proportional Relationship between Wavelength and Intensity: Histological Study in Rats

OBJECTIVE

The objective of the present investigation was to assess the histological effects of different wavelengths and intensities on the healing process of cutaneous wounds.

BACKGROUND DATA

Tissue repair is a dynamic interactive process which involves mediators, cells and extra-cellular matrix. Several reports on the use of laser therapy have shown that the healing process is positively affected when the correct parameters are used.

METHODS

Eighteen standardized wounds were surgically created on the dorsum of male and female Wistar rats, which were subsequently divided into two experimental groups according to wavelength used lambda.670 or lambda685 nm) for lasertherapy (LLLT). Each group was divided into three subgroups of three animals according to the intensity of the applied irradiation (2, 15, or 25 mW). Twelve animals were used as untreated controls and were not irradiated. The irradiation was carried out during seven consecutive days. The animals were sacrificed eight days after surgery. The specimens were removed, kept in 4% formaldehyde for 24 h, routinely prepared to wax, stained with H&E, and analyzed under light microscopy.

RESULTS

For both groups, light microscopy showed a substitution repair process; however, when LLLT was used, a positive biomodulatory effect was detectable, chiefly associated with shorter wavelength and low intensity.

CONCLUSIONS

The results of the present study indicate that LLLT improved cutaneous wound repair and that the effect is a result of an inversely proportional relationship between wavelength and intensity, with treatment more effective when combining higher intensity with short wavelength or lower intensity with higher wavelength.

Erbium lasers in dentistry

Erbium hard tissue lasers have the capability to prepare enamel, dentin, caries, cementum, and bone in addition to cutting soft tissue. The ability of hard tissue lasers to reduce or eliminate vibrations, the audible whine of drills, microfractures, and some of the discomfort that many patients fear and commonly associate with high-speed handpieces is impressive. In addition, these lasers can be used with a reduced amount of local anesthetic for many procedures. Today, these instruments have evolved from their initial use for all classes of cavity preparations to their ability for removing soft tissue, their usefulness in the disinfection of bacteria within endodontic canals, and most recently, as an alternative to the high speed handpiece for the removal of bone in oral and maxillofacial surgery. In addition, recent research has centered on the value of the erbium family of laser wavelengths in periodontics, including the removal of calculus.

Can thermal lasers promote skin wound healing?

Lasers are now widely used for treating numerous cutaneous lesions, for scar revision (hypertrophic and keloid scars), for tissue welding, and for skin resurfacing and remodeling (wrinkle removal). In these procedures lasers are used to generate heat. The modulation of the effect (volatilization, coagulation, hyperthermia) of the laser is obtained by using different wavelengths and laser parameters. The heat source obtained by conversion of light into heat can be very superficial, yet intense, if the laser light is well absorbed (far-infrared:CO(2) or Erbium:Yttrium Aluminum Garnet [Er:YAG] lasers), or it can be much deeper and less intense if the laser light is less absorbed by the skin (visible or near-infrared). Lasers transfer energy, in the form of heat, to surrounding tissues and, regardless of the laser used, a 45-50 degrees C temperature gradient will be obtained in the surrounding skin. If a wound healing process exists, it is a result of live cells reacting to this low temperature increase. The generated supraphysiologic level of heat is able to induce a heat shock response (HSR), which can be defined as the temporary changes in cellular metabolism. These changes are rapid and transient, and are characterized by the production of a small family of proteins termed the heat shock proteins (HSP). Recent experimental studies have clearly demonstrated that HSP 70, which is over-expressed following laser irradiation, could play a role with a coordinated expression of other growth factors such as transforming growth factor (TGF)-beta. TGF-beta is known to be a key element in the inflammatory response and the fibrogenic process. In this process, the fibroblasts are the key cells since they produce collagen and extracellular matrix. In conclusion, the analysis of the literature, and the fundamental considerations concerning the healing process when using thermal lasers, are in favor of a modification of the growth factors synthesis after laser irradiation, induced by an HSR. An extensive review of the different techniques and several clinical studies confirm that thermal lasers could effectively promote skin wound healing, if they are used in a controlled manner.

Lasers in plastic surgery

The laser is a relatively new tool in many branches of medicine. In particular, in the field of plastic surgery, lasers have found numerous applications. Laser light is produced by the stimulated emission of photons from the lasing medium. Lasers may be classified according to the lasing medium employed, the wavelength of the emitted light and the pulse duration. One of the main uses of lasers is in the treatment of vascular lesions such as port wine stain (PWS). The 585 nm flashlamp pumped pulsed dye laser (FPPDL) is particularly effective in this role. The principle of selective photothermolysis has allowed highly specific targeting of different tissue components. Newer lasers have been developed to treat pigmented lesions as well as primary and metastatic cutaneous malignancies. In cosmetic surgery, lasers have been developed for skin resurfacing and removal of wrinkles, tattoos and unwanted hair. There has been recent interest in the use of lasers to promote wound healing. Laser therapy is not without complications and the safety of both patient and operator must remain paramount. The future is likely to hold greater advances in this rapidly developing field.

Laser assisted skin closure (LASC) by using a 815-nm diode-laser system accelerates and improves wound healing

BACKGROUND AND OBJECTIVE

This study aimed to evaluate a 815-nm diode-laser system to assist wound closure to accelerate and improve healing process.

STUDY DESIGN/MATERIALS AND METHODS

A total of 25 male hairless rats (mutant OFA Sprague-Dawley rats, IFFA-CREDO, L'Arbresle, France) with four dorsal skin incisions were used for the study. For each wound, the good apposition of the edges was obtained with buried absorbable suture. In the laser group, the laser beam was applied spot by spot through a transparent adhesive dressing along two incisions with the following parameters: 1.5 W; 3 seconds; spot diameter, 2 mm; fluence, 145 J/cm(2). Both control wounds were closed with conventional suture techniques. The duration of the closure procedure was noted for each group. Clinical examination, histologic study, and measurement of tensile strength were performed at 3, 7, 15, and 21 days after surgery. Determination of activation of heat shock protein 70 (Hsp70) through immunocytochemistry was performed at days 1 and 7.

RESULTS

LASC was 4 times faster to process than conventional suture: 1 minute 49 +/- 20.6 seconds vs. 7 minutes 26 +/- 62.2 seconds. In the laser group, healing was accelerated resulting in a more indiscernible scar than in the control groups. Histologic aspect was better with earlier continuous epidermis and dermis and a thinner resulting scar. Tensile strength was 30 to 58% greater than in control groups at 7 and 15 days (P < 0.001). Expression of Hsp70 was markedly induced in skin structures examined after laser exposure.

CONCLUSIONS

This study shows the ability of the 815-nm diode-laser system to assist wound closure leading to an acceleration and an improvement of wound healing with indiscernible resulting scar. The mechanisms of this phenomenon are still unclear but further investigations are in progress to attempt to explain them.

Laser photostimulation of collagen production in healing rabbit Achilles tendons

BACKGROUND AND OBJECTIVE

Low energy laser photostimulation at certain wavelengths can enhance tissue repair by releasing growth factors from fibroblasts and stimulate the healing process. This study was designed to evaluate the influence of laser photostimulation on collagen production in experimentally tenotomized and repaired rabbit Achilles tendons.

STUDY DESIGN/MATERIALS AND METHODS

A total of 24 male New Zealand rabbits, ages 10-12 weeks, were used. Following tenotomy and repair, the surgical hind limbs of the rabbits were immobilized in customized polyurethane casts. The experimental animals were treated with a 632.8 nm He:Ne laser daily at 1.0 J cm(-2) for 14 days. Control animals were sham treated with the laser head. On the fifth day after repair, the casts were removed to allow the animals to bear weight on the lower extremity. The animals were euthanized on the 15th postoperative day, then, the Achilles tendons were excised, processed and analyzed.

RESULTS

Biochemical analyses of the tendons revealed a 26% increase in collagen concentration with laser photostimulation indicating a more rapid healing process in treated tendons compared to controls. Sequential extractions of collagen from regenerating tissues revealed that the laser photostimulated tendons had 32% and 33% greater concentrations of neutral salt soluble collagen and insoluble collagen, respectively, than control tendons suggesting an accelerated production of collagen with laser photostimulation. A significant decrease (9%) in pepsin soluble collagen was observed in laser-treated tendons compared to controls. There were no statistically significant differences recorded in the concentrations of hydroxypyridinium crosslinks and acid soluble collagen between treated and control tendons.

CONCLUSION

This study of laser photostimulation on tendon healing in rabbits suggests that such therapy facilitates collagen production in a manner that enhances tendon healing.

Photodynamic modulation of wound healing with BPD-MA and CASP

BACKGROUND AND OBJECTIVE

Wound healing is an intricate process requiring the orchestration of cells, growth factors, cytokines, and the extracellular matrix. Cytokines, specifically TGF-beta, are believed to be instrumental in sustaining the fibrotic process, which leads to scarring. Photodynamic therapy (PDT) uses potent photosensitizers, which induce a wide range of effects on cells and the extracellular matrix. The influences of PDT on wound healing are not well known.

STUDY DESIGN/MATERIALS AND METHODS

Seven full-thickness incisional wounds were placed on each of 24 hairless Sprague Dawly rats, three wounds on one flank serving as dark controls and four on the contralateral side treated with PDT. Wounds were created two days before, one hour before, or one hour after red light exposure with an argon ion pumped dye laser. Twelve rats were injected with 0.25 mg/kg or 0.5 mg/kg of the PDT drug, BPD-MA, and the other 12 with 5 mg/kg or 10 mg/kg of the PDT drug, CASP, 3 and 24 hours prior to irradiation of light, respectively. At low doses of both photosensitizers, animals were irradiated with 1, 5, 10, and 20 J/cm2. At higher doses of BPD-MA and CASP animals were treated with 10, 20, 50, and 100 J/cm2 of light. Wounds were examined each day for 14 days and noted for edema, erythema, inflammation, necrosis, and quality of scarring. Wounds were also photographed at day 0, 2, 5, 8, and 14 post-irradiation. All animals were sacrificed 14 days after irradiation and the wounds were evaluated by light microscopy.

RESULTS

Grossly, animals treated with 0.25 mg/kg BPD-MA showed no effect with PDT. Animals treated with 0.5 mg/kg BPD, and 5 and 10 mg/kg CASP showed responses that varied with both light and drug dose. Erythema, edema, inflammation, and necrosis attributed to PDT were all observed, but there was no apparent influence of PDT on either the rate or final appearance of wound healing. Histologically, there were no apparent differences between treated and untreated sites, regardless of the drug, dose of light, or time of irradiation.

CONCLUSION

A single PDT treatment given before or after skin wounds does not apparently alter wound healing even when PDT caused brisk inflammatory reactions. PDT may have effects that were not detected. We conclude that PDT does not greatly influence incisional skin wound healing in the rat model.

A preliminary study of healing of superpulsed carbon dioxide laser incisions in the hard palate of monkeys

BACKGROUND AND OBJECTIVE

Prior studies of laser wound healing using different animal models have shown a delayed tissue response after carbon dioxide (CO2) laser application. This article reports on the preliminary findings of healing of superpulsed CO2 laser and scalpel incisions in the hard palate of monkeys.

STUDY DESIGN/MATERIALS AND METHODS

Twelve parallel incisions using a superpulsed, continuous wave CO2 laser and a scalpel were performed in the hard palate of each of two adult monkeys at 3, 7, and 14 days time schedules. Power levels of 2.0, 4.0, and 6.0 Watts were used for the laser incisions. Wounds were harvested, fixed in 10% formalsaline for at least 48 hours and processed routinely. Each specimen was embedded in paraffin wax at 90 degrees to the surface epithelium and 5 microm thick sections prepared for staining with haematoxylin and eosin, Periodic acid Schiff and Masson-trichrome at a step-serial interval of 100 microm. Sections were evaluated independently.

RESULTS

According to the clinical findings we showed a wound closure in all of the wounds (laser and scalpel incisions) at 3, 7, and 14 days of healing. Histologically, we showed that laser incisions at three and seven days demonstrated an increased, power setting-dependent tissue necrosis and marked inflammatory response with minimal organization compared to scalpel incisions. At 14 days both types of incisions exhibited complete wound healing of the epithelium and connective tissue.

DISCUSSION AND CONCLUSIONS

According to these preliminary results, superpulsed CO2 laser tends to produce more pronounced changes (due to tissue thermal damage) with corresponding greater inflammatory reaction and delay in tissue organization only initially.

Nd:YAG laser surgery for the excision of pilonidal cysts: a comparison with traditional techniques

BACKGROUND AND OBJECTIVE

Nd:YAG laser photothermal ablation has been accepted as a treatment modality for hemorrhoidal disease. There is little reported on its use in treating pilonidal disease. We hypothesized that laser would be an excellent tool for pilonidal cystectomy, facilitating improved outcome and patient satisfaction.

STUDY DESIGN/MATERIALS AND METHODS

A 5-year retrospective study was performed comparing Nd:YAG laser to the standard surgical technique. A telephone questionnaire addressing the length of time the cyst was debilitating both preoperatively and postoperatively as well as length of convalescent time before return to work was administered. Pain was assessed by using an analog pain scale.

RESULTS

Operative time for the traditional pilonidal cystectomy was 20 minutes longer than Nd:YAG laser cystectomy. Postoperative hospital stay was similar. Laser patients returned to work an average of 2.4 days earlier, and their postoperative pain was less than those treated traditionally.

CONCLUSION

In an era when the medical consumer makes decisions based on the efficacy of treatment by using criteria such as pain, length of hospitalization, and speed of return to work, Nd:YAG lasers have emerged as a surgical tool that can fulfill these criteria for certain procedures. Patient postoperative satisfaction after laser excision was greater when compared with those who had traditional excisions. Postoperative pain was less, as was the pain experienced during the first week of recovery. Cost for both was comparable.

Longterm comparison of soft palate scars after UPPP made by CO(2), contact Nd-YAG or combined CO (2) and Nd-YAG laser beams

C0(2) laser, contact Nd-YAG laser and Combolaser (combined CO(2) and Nd-YAG laser beam) vary distinctively in the way they interact with target tissue. To study the quality of mature scars produced by these lasers, the ultrastructure and amount of collagen in soft palate scars after 60 uvulopalatopharyngoplasty (UPPP) operations were analysed. The CO(2) laser was used in 19, contact Nd-YAG in 21 and Combolaser in 20 operations. At a clinical follow-up examination carried out, on average, 51 (range 34-74) months postoperatively, a specimen was obtained from the soft palate scar for collagen analysis. Postoperative complaints of the patients were acknowledged. No differences between the laser groups were observed concerning the gross appearance of the scars or the amount and ultrastructure of collagen. Neither the frequency nor the quality of post-operative symptoms showed any differences between the lasers. Although the initial tissue effects are different, long-term remodelling produces nearly identical soft palate scars after the use of CO(2), contact Nd-YAG and Combolaser beams.

The biology of photodynamic therapy

The subcellular, cellular and tissue/tumour interactions with non-toxic photosensitizing chemicals plus non-thermal visible light (photodynamic therapy (PDT) are reviewed. The extent to which endothelium/vasculature is the primary target is discussed, and the biochemical opportunities for manipulating outcome highlighted. The nature of tumour destruction by PDT lends itself to imaging outcome by MRI and PET.

Immediate histological changes in soft palate after uvulopalatopharyngoplasty with CO2, contact Nd:YAG or combined CO2 and Nd:YAG laser beams

CO2, contact Nd:YAG and Combolaser (combined, simultaneous and coaxial CO2 + Nd:YAG laser beam) were used for uvulopalatopharyngoplasty (UPPP). It has been proposed that the combined beam geometry diminishes thermal damage to surrounding tissues when compared with single laser radiation. To study the extent of thermal tissue damage produced by the lasers, tissue samples for light (LM) and transmission electron microscopy (TEM) were taken from the surface of the resected area and 2 and 4 mm below the resection plane. The depth of tissue damage and coagulation was measured. The results showed no consistent differences in the inflammatory reactions or the amount and depth of tissue coagulation observed in samples taken immediately after the operation. The CO2 laser typically produced a carbonized and coagulated wound edge. Combolaser and contact Nd:YAG lasers generated slightly less charring but otherwise resembled each other with coagulated and vacuolized resecate margins. These results indicate that the beam geometry in Combolaser does not diminish thermal damage to surrounding tissues.