Luiz Guilherme P. Soares

Light microscopic description of the effects of laser phototherapy on bone defects grafted with mineral trioxide aggregate, bone morphogenetic proteins, and guided bone regeneration in a rodent model

We carried out a histological analysis on bone defects grafted with mineral trioxide aggregate (MTA) treated or not with laser, bone morphogenetic protein (BMP), and guided bone regeneration (GBR). Benefits of the use of MTA, laser, BMPs, and GBR on bone repair are well known, but there is no report on their association with laser light. Ninety rats were divided into 10 groups each subdivided into 3. Defects on G II and I were filled with the blood clot. G II was further irradiated with LED. G III and IV were filled with MTA; G IV was further irradiated with laser. G V and VI, the defects filled with MTA and covered with a membrane (GBR). G VI was further irradiated with laser. G VII and VIII, BMPs were added to the MTA and group VIII further irradiated with laser. G IX and X, the MTA + BMP graft was covered with a membrane (GBR). G X was further irradiated with laser. Laser light (λ = 850 nm, 150 mW, 4 J/cm(2) ) was applied over the defect at 48-h intervals and repeated for 15 days. Specimens were processed, cut and stained with H&E and Sirius red and underwent histological analysis. Subjects on group X were irradiated. The results showed different tissue response on all groups during the experimental time. Major changes were seen on irradiated subjects and included marked deposition of new bone in advanced maturation. It is concluded that near infrared laser phototherapy improved the results of the use of the MTA on bone defects.

New Bone Formation around Implants Inserted on Autologous and Xenografts Irradiated or not with IR Laser Light: A Histomorphometric Study in Rabbits

Use of biomaterials and light on bone grafts has been widely reported. This work assessed the influence of low-level laser therapy (LLLT) on bone volume (BV) and bone implant contact (BIC) interface around implants inserted in blocks of bovine or autologous bone grafts (autografts), irradiated or not, in rabbit femurs. Twenty-four adult rabbits were divided in 8 groups: AG: autograft; XG: xenograft; AG/L: autograft + laser; XG/L: xenograft + laser; AG/I: autograft + titanium (Ti) implant; XG/I: xenograft + Ti implant; AG/I/L: autograft + Ti implant + laser; and XG/I/L: xenograft + Ti implant + laser. The animals received the Ti implant after incorporation of the grafts. The laser parameters in the groups AG/L and XG/L were λ=780 nm, 70 mW, CW, 21.5 J/cm 2 , while in the groups AG/I/L and XG/I/L the following parameters were used: λ=780 nm, 70 mW, 0.5 cm 2 (spot), 4 J/cm 2 per point (4), 16 J/cm 2 per session, 48 h interval × 12 sessions, CW, contact mode. LLLT was repeated every other day during 2 weeks. To avoid systemic effect, only one limb of each rabbit was double grafted. All animals were sacrificed 9 weeks after implantation. Specimens were routinely stained and histomorphometry carried out. Comparison of non-irradiated and irradiated grafts (AG/L versus AG and XG/L versus XG) showed that irradiation increased significantly BV on both grafts (p=0.05, p=0.001). Comparison between irradiated and non-irradiated grafts (AG/I/L versus AG/I and XG/I/L versus XG/I) showed a significant (p=0.02) increase of the BIC in autografts. The same was seen when xenografts were used, without significant difference. The results of this investigation suggest that the use of LLLT is effective for enhancing new bone formation with consequent increase of bone-implant interface in both autologous grafts and xenografts.

Influence of the Use of Laser Phototherapy (λ660 or 790 nm) on the Survival of Cutaneous Flaps on Diabetic Rats

OBJECTIVE The aim of this study was to assess and compare the effects of laser phototherapy (LPT) on cutaneous flaps on diabetic rats. BACKGROUND Diabetes mellitus is characterized by high blood glucose levels. Its main complications are delayed wound healing, an impaired blood supply, and a decrease in collagen production. Cutaneous flaps are routinely used in several surgical procedures, and most failures are related to poor blood supply. LPT has been studied using several healing models. ANIMALS AND METHODS Twelve Wistar rats were randomized into three groups: group 1 (G1; diabetic animals without treatment), group 2 (G2; diabetic animals irradiated with lambda680 nm), and group 3 (G3; diabetic animals irradiated with lambda790 nm). Diabetes was induced with streptozotocin. A 2- x 8-cm cutaneous flap was raised on the dorsum of each animal, and a plastic sheet was introduced between the flap and the bed to cause poor blood supply. Nonirradiated animals acted as controls. The dose per session was 40 J/cm(2). Laser light was applied transcutaneously and fractioned on 16 contact points at the wound margins (16 x 2.5 J/cm(2)). Animal death occurred on day 8 after surgery. Specimens were taken, processed, cut, stained with eosin (HE) and sirius red, and underwent histological analysis. RESULTS It is shown that accute inflammation was mostly discrete for G3. Chronic inflammation was more evident for G2. Fibroblast number was higher for G3. Angiogenesis was more evident for G3. Necrosis was more evident for G2. Statistical analysis among all groups showed significant differences (p = 0.04) on the level of acute inflammation between G1 and G3, tissue necrosis between G1 and G2 (p = 0.03), chronic inflammation between (p = 0.04), fibroblastic proliferation between G2 and G3 (p = 0.05), and neovascularization between G2 and G3 (p = 0.04). CONCLUSION LPT was effective in increasing angiogenesis as seen on irradiated subjects and was more pronounced when IR laser light was used.

Influence of the λ780nm laser light on the repair of surgical bone defects grafted or not with biphasic synthetic micro-granular hydroxylapatite+Beta-Calcium triphosphate.

The treatment of bone loss due to different etiologic factors is difficult and many techniques aim to improve repair, including a wide range of biomaterials and, recently, photobioengineering. This work aimed to assess, through histological analysis The aim of this study was to assess, by light microscopy, the repair of bone defects grafted or not with biphasic synthetic micro-granular Calcium hydroxyapatite (HA)+Beta-TCP associated or not with Laser phototherapy - LPT (λ780nm). Forty rats were divided into 4 groups each subdivided into 2 subgroups according to the time of sacrifice (15 and 30days). Surgical bone defects were made on femur of each animal with a trephine drill. On animals of Clot group the defect was filled only by blood clot, on Laser group the defect filled with the clot was further irradiated. On animals of Biomaterial and Laser+Biomaterial groups the defect was filled by biomaterial and the last one was further irradiated (λ780nm, 70mW, spot size∼0.4cm(2), 20J/cm(2)-session, 140J/cm(2)-treatment) in four points around the defect at 48-h intervals and repeated for 2weeks. At both 15th and 30th days following sacrifice, samples were taken and analyzed by light microscopy. Many similarities were observed histologically between groups on regards bone reabsorption and neoformation, inflammatory infiltrate and collagen deposition. The criterion degree of maturation, marked by the presence of basophilic lines, indicated that the use of LPT associated with HA+Beta TCP graft, resulted in more advanced stage of bone repair at the end of the experiment.

Raman ratios on the repair of grafted surgical bone defects irradiated or not with laser (λ780 nm) or LED (λ850 nm)

This work aimed to assess biochemical changes associated to mineralization and remodeling of bone defects filled with Hydroxyapatite+Beta-Beta-tricalcium phosphate irradiated or not with 2 light sources. Ratios of intensities, band position and bandwidth of selected Raman peaks of collagen and apatites were used. Sixty male Wistar rats were divided into 6 groups subdivided into 2 subgroups (15th and 30th days). A standard surgical defect was created on one femur of each animal. In 3 groups the defects were filled with blood clot (Clot, Clot+Laser and Clot+LED groups) and in the remaining 3 groups the defects were filled with biomaterial (Biomaterial, Biomaterial+Laser and Biomaterial+LED groups). When indicated, the defects were irradiated with either Laser (λ780 nm, 70 mW, Φ∼0.4 cm(2)) or LED (λ850±10 nm, 150 mW, Φ∼0.5 cm(2)), 20 J/cm(2) each session, at 48 h intervals/2 weeks (140 J/cm(2) treatment). Following sacrifice, bone fragments were analyzed by Raman spectroscopy. Statistical analysis (ANOVA General Linear Model, p<0.05) showed that both grafting and time were the variables that presented significance for the ratios of ∼1660/∼1670 cm(-1) (collagen maturation), ∼1077/∼854 cm(-1) (mineralization), ∼1077/∼1070 cm(-1) (carbonate substitution) and the position of the ∼960 cm(-1) (bone maturation). At 30th day, the ratios indicated an increased deposition of immature collagen for both Clot and Biomaterial groups. Biomaterial group showed increased collagen maturation. Only collagen deposition was significantly dependent upon irradiation independently of the light source, being the amount of collagen I increased in the Clot group at the end of the experimental time. On the other hand, collagen I deposition was reduced in biomaterial irradiated groups. Raman ratios of selected protein matrix and phosphate and carbonate HA indicated that the use of biphasic synthetic micro-granular HA+Beta-TCP graft improved the repair of bone defects, associated or not with Laser or LED light, because of the increasing deposition of HA.

Surgical treatment of oral lymphangiomas with CO2 laser: report of two uncommon cases

This paper reports the treatment of oral lymphangiomas with carbon dioxide CO₂ Laser. Lymphangiomas are rare congenital lymphatic malformations. These lesions are most frequently diagnosed during childhood, are most commonly located in the head and neck region, and are extremely rare in the oral cavity. Oral lymphangiomas are of complex treatment due to the difficulty in performing a complete excision. CO₂ laser is the most often used laser in the oral cavity due to its affinity with water and high absorption by the oral mucosa. Several benefits of the use of CO₂ laser have been reported for surgical oral procedures. The cases reported herein were biopsy-proven lymphangiomas of the oral cavity. The surgical procedures were carried out under local anesthesia and a focused CO₂ laser beam (λ10.600 nm, Φ ~2 mm, CW/RSP) was used. At the end of the surgery, the laser beam was used on a defocused mode to promote better hemostasis. Neither sutures nor dressings were used after surgery. No medication and only mouthwashes were prescribed to all patients on the postoperative period. There were no postsurgical complaints from the patients and no relapses of the conditions were observed after follow-up periods of 12 and 18 months. The use of CO₂ laser was practical, easy to carry out and effective on the treatment of oral lymphangiomas, with no lesion recurrence.

Effects of Laser Photobiomodulation on Cutaneous Wounds Treated with Mitomycin C: A Histomorphometric and Histological Study in a Rodent Model

AIM The aim of the present study was to assess histologically the effect of Laser Photobiomodulation (LPBM) on skin wounds treated with Mitomycin C (MMC). BACKGROUND DATA Wound healing occurs because of a competitive mechanism between the synthesis and lyses of collagen. Therefore, any factor that increases the lyses or reduces the synthesis of collagen may result in changes in the healing process. MMC is an antineoplastic drug that inhibits fibroblast proliferation, collagen synthesis, and neoangiogenesis. LPBM has been shown to stimulate wound healing, increasing the production of collagen, fibroblastic proliferation, and angiogenesis. MATERIALS AND METHODS Forty-eight Wistar rats were randomly distributed into 4 main groups (n = 12): G1--control (G1a--7 d and G1b--14 d); G2--MMC (G2a--7 d and G2b--14 d); G3--MMC + lambda660 nm laser (G3a--7 d and G3b--14 d); and G4--MMC + lambda790 nm laser (G4a--7 d and G4b--14 d). Under general anesthesia, one excisional wound was created on the dorsum of each animal. Two ml of MMC solution was applied to the wound 4 h after surgery for 5 min. LPBM was performed on groups G3 (lambda690 nm; 20 J/cm(2); 30 mW; Phi = 2 mm) and G4 (lambda790 nm; 20 J/cm(2); 40 mW; Phi = 2 mm), starting immediately after the application of the MMC and repeated every other day during the experimental period. Laser light was applied transcutaneously at 4 equidistant points on the wound margin (4 x 5 J/cm(2), 20 J/cm(2)/session). The specimens were routinely cut and processed to wax. The slides were stained with HE and Sirius red. Computerized hystomorphometry was performed. RESULTS LPBM resulted in reduced inflammation and an increase in both fibroblast proliferation and collagen deposition. CONCLUSION The use of LPBM improves wound healing in subjects treated with MMC.

A Feasible Procedure in Dental Practice: The Treatment of Oral Dysplastic Hyperkeratotic Lesions of the Oral Cavity with the CO2 Laser

OBJECTIVES The aim of this work is to report some cases of surgical removal of hyperkeratotic lesions of the oral cavity with the CO(2) laser. BACKGROUND Hyperkeratosis is an abnormal thickening of the stratum corneum caused by increased deposition of keratin, and its histopathologic features show wide variations. These changes are significant because they determine different biologic behavior. Several techniques are used to treat these lesions, including scalpel incision, electrosurgery, cryosurgery, photodynamic therapy, and some drugs. The use of surgical lasers has been proposed as an effective way of treating such lesions safely. The CO(2) laser is the most used laser on the oral cavity because of its affinity for water and high absorption by the oral mucosa. Several benefits of the use of the CO(2) laser are reported in the literature in regard to surgical procedures carried out on the oral cavity. PATIENTS AND METHODS All patients had histopathologic diagnosis of hyperkeratosis and mild epithelial dysplasia and were routinely prepared for surgery under local anesthesia. The surgical procedures were carried out by using a CO(2) laser (Sharplan 20 C; Laser Industries, Tel Aviv, Israel, λ10,600 nm, φ∼2 mm, CW/RSP). The beam was focused to delimit each lesion, and then lesions were excised, and the removed specimens were sent for histopathology. At the end of the surgery, the beam was used in a defocused manner to promote better hemostasis. Neither sutures nor dressings were used after the surgery. No medication but mouthwashes was prescribed to all patients in the postoperative period. CONCLUSIONS The use of the CO(2) laser does not reduce the risk of relapses of the lesion, but it is an easy-to-use technique and results in both a quick surgical procedure and trouble-free postoperative period and may be safely used in dental practice.

Repair of surgical bone defects grafted with hydroxylapatite + β-TCP and irradiated with λ=850 nm LED light.

The treatment of bone loss due to different etiologic factors is difficult and many techniques aim to improve the repair, including a wide range of biomaterials and recently, photobioengineering. This work aimed to assess by histological analysis the repair of bone defects grafted with biphasic synthetic micro-granular HA + β-TCP associated with LED phototherapy. Forty rats were divided into 4 groups (Clot, LED, Biomaterial and LED + Biomaterial) each subdivided into 2 subgroups according to the time of animal death (15 and 30 days). Surgical bone defects were prepared on the femur of each animal with a trephine drill. In animals of the Clot group the defect was filled only by blood clot, in the LED group the defect filled with the clot was further irradiated. In the animals of Biomaterial and LED + Biomaterial groups the defect was filled by biomaterial and the last one was further irradiated (λ = 850 ± 10 nm, 150 mW, Φ ~ 0.5 cm2, 20 J/cm2 - session, 140 J/cm2- treatment) at 48-h intervals for 2 weeks. Following animal death, samples were taken and analyzed by light microscopy. Using the degree of maturation of the bone by assessment of the deposition/organization of the basophilic lines in the newly formed bone tissue, the LED + Biomaterial group was the one in a more advanced stage of bone repair process at the end of the experiment. It may be concluded that the use of LED phototherapy was effective in positively modulating the process of bone repair of bone defects in the femur of rats submitted or not to biomaterial grafting.

Evaluation of Photodynamic Antimicrobial Therapy (PACT) against Trypomastigotes of Trypanosoma cruzi: In Vitro Study

ð Abstract: Policies to combat Chagas disease presents a considerable degree of negligence and is classified at level III by TDR, where the focus of research is based on the improvement and wider dissemination of existing tools and strategies for combating them. The PACT is based on topical or systemic administration of a nontoxic dye sensitive to light, followed by low dose irradiation with visible light of wavelength appropriate. In the presence of oxygen found in the cells, the photosensitizer (FS) enabled may react with molecules in its vicinity by electron transfer or hydrogen, leading to production of free radicals (type I reaction) or by energy transfer to oxygen (type II reaction), leading to production of singlet oxygen. Both paths can lead to cell death and the destruction of diseased tissue. In this work, we verify the effectiveness of PACT associated with a semiconductor laser InGaAlP, a wavelength (λ) equal to 660nm ± 10nm, 30 mW optical power, emitting red light in the visible spectrum, with a dose of 4J/cm 2 in continuous mode, using methylene blue in five differents concentrations on the infective trypomastigote forms of Trypanosoma cruzi. To determine the viability of the parasites, one sample from each treatment group at each concentration was removed and analyzed in a hemocytometer, observing the decrease in the number of live parasites for the solution without treatment. The results demonstrated significant percentage of parasite lysis (up to 86% lethality), what can not be observed in the groups treated with laser or with the FS.