Juliana S. C. Monteiro

Does the Use of Laser Photobiomodulation, Bone Morphogenetic Proteins, and Guided Bone Regeneration Improve the Outcome of Autologous Bone Grafts? An in Vivo Study in a Rodent Model

OBJECTIVE The aim of the present investigation was to histologically assess the effect of laser photobiomodulation (LBPM) on the repair of autologous bone grafts in a rodent model. BACKGROUND DATA A major problem in modern dentistry is the recovery of bone defects caused by trauma, surgical procedures, or pathologies. Several types of biomaterials have been used to improve the repair of these defects. These materials are often associated with procedures of guided bone regeneration (GBR). MATERIALS AND METHODS Twenty four animals were divided into four groups: group I (control); group II (LPBM of the bone graft); group III (bone morphogenetic proteins [BMPs] + bone graft); and group IV (LPBM of the bed and the bone graft + BMPs). When appropriate the bed was filled with lyophilized bovine bone and BMPs used with or without GBR. The animals in the irradiated groups received 10 J/cm(2) per session divided over four points around the defect (4 J/cm(2)), with the first irradiation immediately after surgery, and then repeated seven times every other day. The animals were humanely killed after 40 d. RESULTS The results showed that in all treatment groups, new bone formation was greater and qualitatively better than the untreated subjects. Control specimens showed a less advanced repair after 40 d, and this was characterized by the presence of medullary tissue, a small amount of bone trabeculi, and some cortical repair. CONCLUSION We conclude that LPBM has a positive biomodulatory effect on the healing of bone defects, and that this effect was more evident when LPBM was performed on the surgical bed intraoperatively, prior to the placement of the autologous bone graft.

Influence of Laser Phototherapy (λ660 nm) on the Outcome of Oral Chemical Carcinogenesis on the Hamster Cheek Pouch Model: Histological Study

PURPOSE This study aimed to evaluate, histologically, the effect of low-level laser therapy (LLLT) (λ660 nm) on DMBA chemically induced lesions of the oral mucosa of hamsters. BACKGROUND DATA Squamous cell carcinoma (SCC) is the most common neoplasm of the oral cavity. It is aggressive, highly proliferative, invasive, and metastatic. There is evidence that LLLT similarly affects neoplasic and non-neoplasic cells. METHODS Cancerous lesions were induced on the cheek pouch of 15 golden Syrian hamsters by using DMBA 3 times a week for 8 weeks. At the end of the cancer induction (8 weeks), animals in G1 were killed and the presence of tumors confirmed. Animals in G3 were irradiated (λ660 nm, 30 mW, CW, Ø=3 mm, area: 0.07 cm(2), 424 mW/cm(2), 133 sec, 56.4(2)J/ cm(2), 4J) at every other day for 4 weeks. G2 received no interventions for the same period. Samples were taken and underwent histological analysis by light microscopy. RESULTS GI showed 100% well-differentiated SCC. G2 showed 20% moderately differentiated and 80% well-differentiated SCC. G3 showed 40% well-differentiated, 40% poorly differentiated, and 20% moderately differentiated SCC. Significant differences (p=0.02) in the amount of well-differentiated SCC were seen between G1 and G3 and between G3 and G2 (p=0.04). Significant difference was also seen between G3 and G1 and G2 with regard to the amount of poorly differentiated tumors (p=0.04). CONCLUSIONS It is concluded that LLLT, within the parameters used in the present study, caused a significant progression of the severity of SCC in the oral cavity of hamsters.

Effect of LED Red and IR Photobiomodulation in Tongue Mast Cells in Wistar Rats: Histological Study

OBJECTIVE This article aimed to study the effect of LED Phototherapy (LED-PHT) (?630?nm or ?850?nm) on mast cells on the dorsum of the tongue of rodents. BACKGROUND DATA Vasodilatation is one of the reported effects of laser light on tissues. Laser light is able to induce the release of mediators responsible for vasodilatation, such as those produced by mast cells. Mast cells are also related to some diseases such as hay fever. METHODS Sixty Wistar rats were divided into three groups: I, Control; II, IR-LED (?850?nm, 21.9?J/cm(2), 73 sec; and III, red-LED (?630?nm, 21.9?J/cm(2), 73?sec). The specimens were taken after, 20, 45, and 60?min following irradiation. The specimens were routinely processed; stained with toluidine blue; and then total, degranulated, and non-degranulated mast cells were counted and statistical analysis performed. RESULTS Both LED irradiated subjects showed significant difference when compared to the control subjects on the total number mast cells (p<0.001, ANOVA), degranulated mast cells (p<0.001, ANOVA), and non-degranulated mast cells (p<0.001, ANOVA). Comparing the two groups of LED irradiated subjects, significant difference was observed regarding the total number of cells (p<0.001, paired t-test) and degranulated mast cells (p<0.001, paired t-test) with a greater number of these cells noted in the IR-LED group. On the other hand, Red-LED irradiated subjects showed a significantly greater number of non-degranulated mast cells (p=0.001, paired t-test). CONCLUSIONS Our results lead us to conclude that both red and IR-LED light caused increased mast cell degranulation and that IR-LED light resulted in a greater number of mast cells.

LED antimicrobial photodynamic therapy with phenothiazinium dye against Staphylococcus aureus: An in vitro study

The objective of this study was to evaluate, in vitro, the bactericidal effect of AmPDT on Staphylococcus aureus (ATCC 25923) using different concentrations (100, 50, 25, 12.5 and 6.25μg/mL) of phenothiazine compound combined with LED light (λ632±2nm) using varied energy densities (12, 9.6, 7.2, 4.8 and 2.4J/cm2). The experiments were carried out in triplicate and the samples were divided into groups: Control, Irradiated (treated only with light at different energy densities), Photosensitizer (treated only in the presence of the dye), AmPDT (treatment with light associated with dye). Counts of the colony forming units and the data obtained were statistically analyzed (ANOVA, Tukeys test, p<0.05). The results showed no difference between irradiated and Control groups. However, using the photosensitizer alone caused significant increased cytotoxicity and consequent reduction on the CFU counts (12.5μg/mL (p<0.001), 25μg/mL, 50μg/mL and 100μg/mL (p<0.0001). When AmPDT was used significant inhibition above 70% were detected for all concentrations of the photosensitize (p<0.0001) except for 6.25μg/mL. The results indicate a dose-response dependent when the photosensitizer is used alone but not for the sole use of the light is used. It is concluded that, a single application of AmPDT, using energy density of 12J/cm2 associated either to 12.5 (81.52%) or 25μg/mL (91.57%) resulted in higher in vitro inhibition of S. aureus.

Photodynamic antimicrobial chemotherapy (PACT) using phenothiazines derivatives associated with the red-orange LED against staphylococcus aureus

The objective of this study was to evaluate the bactericidal effect of photodynamic antimicrobial chemotherapy (PACT) using phenothiazinium dye (Toluidine blue O and methylene blue) at a low concentration of 1μg/mL irradiated with the red laser at doses of 2.4 e 4.8 J/cm² on strain of Staphylococcus aureus (ATCC 23529) in vitro. For this research, tests were performed in triplicate and the samples were distributed into six test groups: (L-P-) Negative control (L1+P-) and (L2+P-) bacterial suspensions were irradiated with laser energy 2.4 and 4.8 J/cm2 respectively in the absence of photosensitizer; (L1+P+) and (L2+P+) bacterial suspensions were irradiated with laser in the presence of 1μg/ml of photosensitizer and finally (L-P+) bacterial suspensions only in the presence of phenothiazinium dye. Therefore, were analyzed the potential bactericidal PACT by counting of colony-forming units and analyzed statistically (ANOVA, Tukey test, p<0.05). The results showed that the negative control group when compared with laser group (L2+P-) it was observed a statistically significant increase (p<0.01) which L2+P- showed a higher number of CFU, on the other hand when compared to L1+P- no statistically significant difference was found, relation to the groups submitted to PACT, only showed a statistically significant reduction relative to the group irradiated L2+P+ (p<0.01) that showed a decrease in the number of CFU. There was no statistically significant difference between the groups submitted to PDT (L1+P+ and L2+P+). Although the results of this study have shown a reduction in average number of colony forming units by the appropriate laser-dye treatment combination, it needs further investigation.

Influence of laser and LED irradiation on mast cells of cutaneous wounds of rats with iron deficiency anemia

This work aimed to study histologically the effect of Laser or LED phototherapy on mast cells on cutaneous wounds of rats with iron deficiency. 18 rats were used and fed with special peleted iron-free diet. An excisional wound was created on the dorsum of each animal which were divided into: Group I - Control with anemia + no treatment; Group II - Anemia + Laser; Group III - Anemia + LED; Group IV - Healthy + no treatment; Group V - Healthy + Laser; Group VI - Healthy + LED. Irradiation was performed using a diode Laser (λ660nm, 40mW, CW, total dose of 10J/cm2, 4X2.5J/cm2) or a RED-LED ( λ700nm, 15mW, CW, total dose of 10J/cm2). Histological specimens were routinely processed, cut and stained with toluidine blue and mast cell counts performed. No significant statistic difference was found between groups as to the number of degranulated, non-degradulated or total mast cells. Greater mean values were found for degranulated mast cells in the Anemia + LED. LED irradiation on healthy specimens resulted in a smaller number of degranulated mast cells. Our results leads to conclude that there are no significant differences in the number of mast cells seven days after irradiation following Laser or LED phototherapy.

Evaluation of the effect of laser radiation on fibroblast proliferation in repair of skin wounds of rats with iron deficiency anemia

The aim of this study was to assess the effect of low- level laser therapy (LLLT) on fibroblast proliferation on wound repair of rats with Iron deficiency anemia since there is no reports on literature about this subject. Iron deficiency anemia was induced on 36 newborn rats then an excisional wound was created on the dorsum of the animals which were divided into four groups: (I) - non-anemic, (II) - Anemic, (III) - non-anemic + LLLT, (IV) Anemic+ LLLT. The animals in each group were sacrificed at 7, 14 and 21 days. Laser irradiation was performed on each group (λ660nm,40Mw,CW) by contact mode with a dose of 2,5J/ cm2 in four points on the area of the wound and total of 10J/cm2 per session. Data were evaluated by analysis of variance (ANOVA) followed by Paired t-test. The results showed LLLT was able to stimulate fibroblastic proliferation in rats with iron deficiency anemia at the 21st day while at control group (III) no statistically significant differences was found.

Effects of visible or IR Laser light on the progression of chemo-induced oral dysplasia: In vivo study on the hamster cheek pouch model

Oral Epithelial dysplasia may be a white, red or mixed patch that may affect several sites of the mouth. Chemo-induced precancerous lesions are standard model to study cancer on the oral cavity. The use of Laser photobiomodulation on the oral care is a standard procedure these days and it is known that it proliferative effects on both cells and tissues depending on dose, wavelengths and other parameters. The aim of this study was to assess the effect of laser light on the evolution of chemo-induced epithelial dysplasia on the hamster cheek pouch model. Sixteen animals were divided into four groups: Control (n=8), Laser λ660nm (n=4), and Laser λ790nm (n=4). DMBA induction was carried out three times a week. All animals presented epithelial dysplasia seven days after first induction. When appropriate, laser (λ660nm or λ790nm, 30/40mW, Φ ~ 3mm, 4J/cm2) was used at 48 h interval during two weeks. Chemo-induction continued during all experimental period (6 weeks). Following animal death, specimens were taken, routinely process to wax, cut and stained with H.E. Slides were analyzed under light microscopy by an oral pathologist using WHO (2005) criteria for epithelial dysplasia. At the end of the experiment, 100% of control specimens showed mild epithelial dysplasia. On laser irradiated animals, 75% of the specimens showed mild epithelial dysplasia and 25% showed moderate ones extending beyond the medium third of the epithelium. It was concluded that the use of both wavelength and a dose of 4J/cm2 may increase the severity of oral epithelial dysplasia.

Effectiveness of Antimicrobial Photodynamic Therapy on Staphylococcus aureus using Phenothiazinium Dye with Red Laser.

The aim of this study was to evaluate in vitro the bactericidal effect of Antimicrobial Photodynamic Therapy - AmPDT using a phenothiazinium compound (toluidine blue O and methylene blue, 12.5 μg/mL) on Staphylococcus aureus (ATCC 23529) irradiated or not with the red laser (λ 660 nm, 12J/cm2). All tests were performed in triplicate and samples distributed into the following groups: Negative control, Laser, Photosensitizer, and AmPDT. Bactericidal effect of the Antimicrobial Photodynamic Therapy was assessed by counting of colony-forming units and analyzed statistically (ANOVA, Tukey test, p<0.05). The results showed, comparing the Laser group with Negative control, a statistically significant increase of counting on the Laser group (p = 0.003). The use of the photosensitizer alone reduced the mean number of CFU (64.8%) and its association with the Laser light resulted in 84.2% of inhibition. The results are indicative that the use of Antimicrobial Photodynamic Therapy presented in vitro bactericidal effect on Staphylococcus aureus.

Evaluation of the efficacy of photodynamic antimicrobial therapy using a phenothiazine compound and LED (red-orange) on the interface: macrophage vs S . aureus

Nowadays photodynamic inactivation has been proposed as an alternative treatment for localized bacterial infections as a response to the problem of antibiotic resistance. Much is already known about the photodynamic inactivation of microorganisms: both antibiotic-sensitive and -resistant strains can be successfully photoinactivated and there is the additional advantage that repeated photosensitization of bacterial cells does not induce a selection of resistant strains. Staphylococcus spp. are opportunistic microorganisms known for their capacity to develop resistance against antimicrobial agents. The emergence of resistant strains of bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) poses a major challenge to healthcare. MRSA is a major cause of hospital-acquired infection throughout the world and is now also prevalent in the community as well as nursing and residential homes. The aim of this study was to evaluate the phagocytic function of macrophages J774 against S. aureus in the presence and absence of AmPDT with phenothiazine compound (12.5 μg/mL) and low level laser (λ=660nm, 12 J/cm²). Experimental groups: Control group (L-P-), Phenothiazine group (L-P+) Laser group (L+P-), AmPDT group (L+P+).The tests presented in this study were performed in triplicate. This study showed that AmPDT induced bacterial death in about 80% as well as increasing phagocytic capacity of macrophages by approximately 20% and enhanced the antimicrobial activity by approximately 50% compared to the control group and enabling more intense oxidative burst.