Antimicrobial Photodynamic Therapy (AmPDT) is an alternative to conventional treatments of local infections such as the use of antibiotics, which may lead to the development of resistance. AmPDT in addition of requiring the use of a photosensitizer it also needs a light source executed. In search of an efficient and cheap procedure, we aimed to assess the efficacy of using 1,9-dimethylmethylene blue (DMMB) as photosensitizer associated with the use of either Laser (λ660 nm), LED (λ632 ± 2 nm) or a multispectral polarized light (λ400 – 2000 nm) using different energy densities to kill E. faecalis (Laser or LED) or S. aureus (PL) in vitro. For this, 300 (S. aureus) or 3.32 ηg/ml (E. faecalis) of DMBB and energy densities of 5 (PL) or 18 J/cm2 (Laser/LED) were used. Five minutes of pre-incubation time was used. CFU count (S. aureus) or the most probable number method (MPN) (E. faecalis) were used as assessment methods. The results showed a 99.97 % reduction on CFU counts of S. aureus and 99.999998 % reduction on E. faecalis (using both light sources). It is concluded that AmPDT carried out with 1,9-dimethylmethylene blue associated with either Laser, LED or Polarized light was efficacious on the reduction, in vitro, of the counts of aerobes and aerotolerant anaerobes Gram-positive bacteria.
Bacterial resistance to antibiotics is reality and need for alternative treatments is urgent. The aim of this work was to evaluate, in vitro, the effect of LED photochemotherapy on Staphylococcus aureus (ATCC 23529) using 25 μg / mL of phenothiazine compound combined with LED light (λ632 ± 2ηm) using 12 J/cm2 energy density. The experiments were carried out in triplicate and the samples were divided into groups: Control, Irradiated (treated only with light), Photosensitizer (treated only in the presence of the dye), LED-Photochemotherapy (treatment with light associated with dye). Counts of the colony forming units and the data obtained were statistically analyzed (ANOVA, Tukey’s test, p<0.05). The present study demonstrated that the efficacy of LED-Photochemotherapy as the use of 25 μg/mL x 12 J/cm2 caused 91.57 % of inhibition of bacterial growth. It is concluded that using energy density of 12 J/cm2 associated to 25 μg/mL caused high in vitro inhibition of S. aureus.
The aim of this study is to evaluate the Antimicrobial Photodynamic Therapy (AmPDT) of microorganisms mediated by red LED (λ640 ± 5 ηm, 120 mW, spot of 0.785 cm2) associated with Photogem. Microorganisms of the posterior dorsal region of the tongue and oral mucosa were collected and inoculated in 8 mL of TSB medium overnight followed by inverse homogenization. Culture plates with 24 wells were used for the irradiated and non-irradiated species. Each well received 400 μL of the suspension containing the microorganisms. In eight wells no Photogem was used and they were the irradiated and non-irradiated controls. The remain of the wells had Photogem applied with a pre-irradiation time of 5 min in concentrations of 40, 20, 10, 5 e 2.5 μg/mL. LED was applied for 5 min and 45 sec (50 J/cm2). After agitation, 200 μL were withdrawn from each well and colorimetric measurements were immediately taken. Other 200 μL were withdrawn from the wells after 1 hour in bacteriological incubator for a second measurement. The best results found were for 40 μg/mL of Photogem associated with LED irradiation and immediate (36.7%) and for 5 μg/mL with LED irradiation with measurements one hour after incubation (42.8%). This study suggests that antimicrobial photodynamic therapy with Photogem associated to red LED can be a potential mechanism of control of oral microorganisms.
The use of curcumin as antimicrobial agent has been suggested and this effect may be potentialized by appropriate light.
This study evaluated the effect of PACT using blue LED (λ450ηm ± 5ηm, 220mW and spot of 0.785 cm2) associated to
Curcumin at different concentrations (75, 37.5, 18.75, 9.37 and 4.68 μg /mL). Microorganisms from the oral mucosa and
the posterior region of the tongue were collected and inoculated into test tubes containing 8mL of TSB medium. For
these assays were performed 16 readings. In the assays were used culture plate of 24 wells. To each well was added 400
μL of the suspension containing the microorganisms. Suspensions without curcumin were placed in eight wells.
Elsewhere, curcumin was applied varying concentrations with pre-irradiation time of 5 min. After stirring, 200 μL
aliquot was taken from each well and the readings were immediately carried out by a spectrophotometer (SPECTRA
MAX). Assessments of turbidity were performed following CLSI standard methods. After 1 hour of incubation in a
bacteriological oven, 200 μL aliquot was removed from the remaining wells for a second reading. The results showed a
decrease of total microorganisms in the most of test groups. The best result of the PACT was with 75 μg/mL, showing
81% of inhibition. It is concluded that PACT with blue LED associated to Curcumin could be a potential mechanism for
controlling microorganism proliferation on the oral cavity.
Antimicrobial Photodynamic therapy is a technique in which microorganisms are exposed to a photosensitizing drug and then irradiated with low-intensity visible light of the appropriate wavelength. The resulting photochemical reaction generates cytotoxic reactive oxygen species, such as singlet oxygen and free radicals, which are able to exert bactericidal effect. Much is already known about the photodynamic inactivation of microorganisms: both antibiotic-sensitive and - resistant strains can be successfully photo inactivated, and there is the additional advantage that repeated photosensitization of bacterial cells does not induce a selection of resistant strains. Recently, a series of studies have shown that it is possible to kill bacteria with a light source after the microorganisms have been sensitized with low concentration of dye, such as phenothiazines. 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 red-orange LED. Experimental groups: Control Group (L-F-), Phenothiazine group (L-F+) LED group (L+F-), Photodynamic therapy group (L+F+). The tests presented in this study were carried out in triplicate. This study demonstrated that AmPDT is able to increase about twice the phagocytic ability of macrophages; however, the bactericidal capacity of these cells did not show a substantial improvement, probably because the oxidative burst was less intense.
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 Staphylococcusaureus (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 Staphylococcusaureus.
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 Staphylococcusaureus (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.
Prospective studies are based on the analysis of patent documents and aims to assess the both technological history and development providing innovation opportunities. This study was a technological prospection mapping aiming to identify breakthrough in PDT and the new possibilities of the technology. Therefore, research in the bank patent 'Spacenet Patent Search' was performed using determinants descriptors associated with the theme: 'A61K41', 'A61N5 / 06'. Were analyzed in this study 326 documents. In evaluating these patents, it was possible to observe an increase in the number of deposits over time, with peak between 1990 and 2000. The highest number of inventors of this area are part of the private sector and the US appear as main producer of technology. It was also observed that blue light, porphyrins and their derivatives are the main topics. It may be concluded that PDT still offers a large opportunity for growth as several wavelengths, and photosensitizers that may be used in the technique.
The aim of this study was to evaluate the effect of photodynamic antimicrobial chemotherapy (PACT) using
phenothiazinium dyes - PTZ irradiated with red laser (λ660nm) or red-orange LED (λ632±2nm) on Staphylococcus aureus in vitro. triplicate tests were performed in 10 groups: control, Laser (L1+P- and L2+P-) bacterial suspensions were
irradiated only with laser energy 2.4 and 4.8 J/cm2 respectively, (Led1+P- and Led2+P-) irradiated only with LED energy
2.4 and 4.8 J/cm2 respectively, (L1+P+ and L2+P+) irradiated with laser in the presence of 1μg/ml of photosensitizer,
(Led1+P+ and Led2+P+) irradiated with LED in the presence of 1μg/ml of photosensitizer and finally (L-P+) only in the
presence of PTZ dye. Bactericidal effect of the PACT was assessed by counting colony-forming units. The results
showed no significant difference on regards different energy densities on group PACT for both lights. PACT groups
(L2+P+ and Led2+P+) compared to the Control showed significant reduction of CFUs. LED/Laser groups (L2+P- and
Led2+P-) compared to control and PTZ groups showed also significant differences as groups LED/Laser (4.8J/cm2)
increased the average of CFUs. Although the results of this study have shown a reduction in average number of colonyforming
units by the appropriate Laser or LED-dye treatment combination, it this topic requires further investigation.
Candidiasis is caused by Candida species found on the skin, gastrointestinal tract and mucous cavities of the humans and
may be acute, chronic, localized or systemic. Alhough C. albicans is the species most often identified as responsible for
this type of infection C. Tropicalis has been considered an emerging cause. The effect of the association of phenothiazine
- PTZ and laser on fluconazole-resistant C.tropicalis growth was tested. 2.5 x 106 CFU/mL 100mg/mL of phenothiazine with the pre-irradiation time of 10 min were irradiated with laser light (660 nm; 4.8 and 12 J/cm2 (L1 and L2 respectively) 40 mW) followed by incubation in RPMI for 24h. The following conditions were tested: control (control),
laser (L1 and L2), phenothiazine (F1 and F2), and PACT (F1L1 and F2L2). Statistically significant diferences were seen
between groups (L-F +) and (F + L +) for both conditions of the laser, with a growth inhibition of the yeast around 67
and 51%, respectively, however, when using only the laser there was an increase of 18% in the survival of these cells.
PACT's efficacy on fluconazole-resistant C. tropicalis depended on both the time of pre-irradiation and concentration of
the PTZ.
Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.
In Brazil solar incidence is high and continuous throughout the year. Body exposure to sunlight may be a key point in the
rates of individuals affected by melanoma and other types of skin cancer in many countries. Brazil already occupies the
15th place in the ranking of melanoma cases and the limitations presented by drugs used in the therapy of this cancer,
new approaches are being used in an attempt to decrease the mortality of this malignancy. The aim of this study was to
evaluate the effects of phenothiazinium dyes (PD) associated with laser light on murine melanoma (B16F10) in vitro by
measuring cell growth using colorimetric assay before and after photodynamic therapy. We used a diode laser (λ660nm,
2.4 J/cm2, 40 mW, 60 s, CW) associated with PD at 12.5 μg/mL, time pre-irradiation of 30 minutes). The following
groups were tested: control (LF-), PD (L-F+), Laser (L+F-), Laser + PD (L+F+). The results showed a significant
reduction in cell growth in the group treated by the photodynamic therapy compared to the control at 24 and 48 h (p <
0.001). Were showing at 30 min PD has a dose-dependent response on B16F10 cells, but at 24 h did not demonstrated
this response.
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.
The objective of this study was to contribute to PDT development by researching alternative light sources using redorange LED light at doses of 2.4 e 4.8 J/cm2 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 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 demonstrated that comparing the LED group (L2 + P-) with negative control group, LED group (L1+ P-) and photosensitizer group there was a statistically significant (p<0.0001, p<0.01 and p<0.001, respectively) that the group treated only with LED (energy density of 4.8J/cm2) increased the average of CFU counts. The negative control group when compared to the groups submitted to PDT only showed a statistically significant reduction (p<0.01) relative to the group (L2+P+) 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 LED-dye treatment combination, it needs further investigation.
Dental bleaching is a much requested procedure in clinical dental practice and widely related to dental esthetics. The literature is contradictory regarding the effects of bleaching agents on the morphology and demineralization of enamel after bleaching. The aim of this study was to analyze in vitro by scanning electron microscopy (SEM) the effect of hydrogen peroxide at 20% at neutral pH, cured by the green LED, to evaluate the action of these substances on dental enamel. We selected 15 pre-molars, lingual surfaces were sectioned and previously marked with a central groove to take the experimental and control groups on the same specimen. The groups were divided as follows. The mesial hemi-faces were the experimental group and distal ones as controls. For morphological analysis were performed 75 electron micrographs SEM with an increase of X 43, X 220 and X 1000 and its images were evaluated by tree observers. Was also performed quantitative analysis of the determination of the surface atomic composition of the samples through microanalysis with the aid of scanning electron microscopy. The use of hydrogen peroxide at a concentration of 20% at photoactivated green LED showed no significant changes in mineral composition of the samples or the dental morphological structure of the same when compared to their controls, according to the study protocol.
Maria de Fátima Lima Ferreira, Fabiola Bastos de Carvalho, Susana C. P. S. de Oliveira, Juliana Monteiro, Gustavo Santos, Maria Gesteira, Tereza Cristina Teixeira Maia, Antônio Pinheiro
The aim of this study was to evaluate the efficacy of the laser photobiomodulation (FBML) in prevention and treatment
of oral mucositis induced by chemotherapy protocols CMF (cyclophosphamide, methotrexate, 5-Fluouracil) and FAC (5
Fluouracil + Adriamycin + Cyclophosphamide) in cancer patients breast. We selected 28 patients treated at the Center
for High Complexity (CACON), who underwent 6 cycles of 21 days of treatment, with diagnosis of infiltrating ductal
carcinoma (ICD C50.9). Were randomly divided into three groups: Group A - eight patients (Protocol FAC + Dental
protocol of CACON + Laser), Group B - 6 patients (Protocol CMF + Dental protocol of CACON + Laser), Group C - was divided into two sub-groups: Group C1 with 8 patients (Control Group 1: FAC + Dental protocol o CACON) and
group C2 with 6 patients (control group 2: Protocol CMF + Dental protocol of CACON). Patients in Group A and B
were use of preventive FBML 24 hours before the start of chemotherapy cycle, then every 48 hours and was extended up to one week following completion of chemotherapy. The groups A and B, presented oral mucositis grade 0 (64.29%) p = 0.07, grade I (7.14%), grade II (14.29%), grade III (7.14 %), grade IV (7.14%) compared to group C, who presented mucositis grade 0 (35.71%) in the initial evaluation with p = 0.10, grade I (21.43%), grade II (28.57%), grade III
(14.29%), grade IV (0.00%), patients who used the FBML as a preventive and therapeutic showed a reduction and pain
relief in 42.86%. It is concluded that the low power laser when used preventively or as therapy and showed immediate
relief of pain and accelerate tissue repair.
The present studied evaluated the in vitro effects of PDT on Leishmania (Leishmania) amazonensis promastigotes. For
this examination L. amazonensis promastigotes, stain Josefa, were used and maintained in Warren media supplement
with fetal bovine serum at 26°C for 96 hours. A viability curve was accomplished using different concentrations of
methylene blue photosensitizer associated to red laser light in order to obtain the most effective interaction to inhibit the
parasite's growth. Two pre-irradiation periods, 5 and 30 minutes, were evaluated and the promastigotes were counted by
colorimetry. On fluorescence microscopy the autophagic processes and reactive oxygen species were detected.
Promastigotes treated with Photodynamic Therapy (PDT) by concentrations of 5 and 0,315ug/mL, presented cellular
proliferation inhibition when compared to the control. In the first condition, the cells had structural alterations such as
truncated cells, cells with two flagella, bleb formation and cells body deformation, while none of these modifications
could be visualized in the control group. When analyzed through fluorescence microscopy, the promastigotes treated
were positives for free radicals immediately after light application and also 1 hour after treatment presenting signs of
autophagia. PDT on L. (L.) amazonensis is effective causing alterations that can help elucidate the mechanisms of the
parasite's death when treated with methilene
Cristiane Becher Rosa, Susana Oliveira Sampaio, Juliana Monteiro, Maria Ferreira, Fátima Zanini, Jean Santos, Maria Cristina Cangussú, Antonio Pinheiro
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.
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.
Aim: The aim of the present investigation was to compare, using the MTT Assay, the effects of a polarized light system
(λ400-2000nm, 40mW, φ5cm, 9.6J/cm2) on cellular cultures of human laryngeal carcinoma (H.Ep.2) and in a fibroblast
lineage (L929-CLLINCTC clone 929). Summary Background Data: Recently there has been increased interest in the
propagation of polarized light in randomly scattering media, such as biological tissues, because their high potential of
applications, particularly in biomedical area. Materials and Methods: The illuminations were performed at the
following times: T0 (24 hours after handling the cells) and T48 (equivalent to 48 hours after the first illumination). The
cellular viability was assessed using MTT essay at the following times T0, T6, T12, T24, T48, T72. The results were
analyzed using the Graphpad Prism®
software. Results: The results showed that time had influenced on the cellular
viability of L929 on both control (P=0.0014) and illuminated cultures (P=0.0035). Significant difference between control
(P=0.0001) and illuminated H.Ep.2 cells (P=0.0001) was observed. There was a significant difference between the two
used types of cells illuminated when compared to their controls: H.Ep.2 (P=0.0001) and L929 (P=0.0002). Conclusion:
The use of polarized light on H.Ep.2 and L929 cells resulted on photobiological effects that need further investigation of
the mechanisms involved as this is the first study using this methodology.
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.
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