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The objective of this systematic review is to evaluate the effectiveness of low-level laser therapy in the treatment of herpes labialis. The searches were carried out independently by 2 researchers and the articles were selected through the electronic databases according to the inclusion and exclusion criteria previously established. Initially, 480 articles were found, of which 7 randomized clinical trials and 1 clinical trial were selected. In total, 928 patients were included. In the meta-analysis, the mean healing time for laser use was significant, showing a mean reduction of 1.37 [CI 95% = 0.92 to 1.82] days for tissue healing (p < 0.0001). In the meta-analysis to evaluate the time for crust formation, there was no significant difference between the groups and no significant reduction in the mean time for crust formation (p = 0.150). Only one of the selected studies had a low risk of bias. The use of low-level laser proved to be effective in the treatment of herpes labialis. However, due to the high risk of bias in the included studies, there is a need to carry out new standardized studies to prove the effectiveness of this therapy., (© 2022. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.) more...

Objective: The aim of this study was to evaluate the efficacy of photobiomodulation therapy (PBMT) on the mucosal healing of patients submitted to simple dental extractions after head and neck radiation therapy (HNRT)., Methods: Forty surgical procedures were randomly assigned into two groups: G1: dental extraction + PBMT (n = 19) and G2: dental extraction + sham-PBMT (n = 21). All patients received antibiotic therapy and the surgical alveolotomy to promote primary closure of the surgical site. Group 1 was submitted to PMBT according to the following parameters: 808 nm, 40 mW, 100 J/cm 2 , 70 s, 2.8 J/point, 14 J/session, and area of 0.028cm 2 . The primary outcome was complete mucosal lining at 14 days, and the secondary outcomes were the presence of infection, postoperative pain, and analgesics intake at 7 days. The patients were evaluated every 7 days until 28 days., Results: Alveolar mucosal lining was faster in G1, and at 14 postoperative days, 94.7% patients evolved with complete alveolar mucosal lining compared to no patient from G2 (p < 0.001). Patients from G1 reported postoperative pain less frequently (G1 = 4, 21.1% × G2 = 14, 66.7%, p = 0.005), and also reported lower intake of analgesic pills at D7 (21.1% × 66.7%, p = 0.005%). PBMT had a significant positive impact on both postoperative pain (NNT = 2.192, CI95% = 1.372-5.445) and mucosal healing (NNT = 1.056, CI95% = 0.954-1.181)., Conclusions: This preliminary study strongly supports the use of PMBT to promote surgical alveolar mucosal lining in a shorter time and with less postoperative pain. more...

The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) with different parameters and wavelengths on nitric oxide (NO) release and cell viability. Irradiation was performed with Ga-Al-As laser, continuous mode and wavelengths of 660 and 808 nm at different energy and power densities. For each wavelength, powers of 30, 50, and 100 mW and times of 10, 30, and 60 s were used. NO release was measured using Griess reaction, and cell viability was evaluated by mitochondrial reduction of bromide 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to formazan. LLLT promoted statistically significant changes in NO release and MTT value only at the wavelength of 660 nm (p < 0.05). LLLT also promoted an increase in the NO release and cell viability when the energy densities 64 (p = 0.04) and 214 J/cm 2 (p = 0.012), respectively, were used. LLLT has a significant impact on NO release without affecting cell viability, but the significance of these findings in the inflammatory response needs to be further studied. more...

The aim of this study was to report the effect of laser phototherapy (LPT) on the treatment of burning mouth syndrome (BMS). This prospective clinical study reports on preliminary outcomes of twenty volunteers diagnosed with BMS who have undergone the conventional treatment prior to laser phototherapy. LPT consisted of weekly sessions of LPT (660 nm), for a period of 10 weeks. The laser protocol consisted of the following parameters: 40 mW, 10 J cm(2) and 0.4 J per point, irradiation time of 10 s. In all sessions, the burning intensity was evaluated with a 10 cm Visual Analogue Scale (VAS). The burning intensity evaluation by VAS was performed immediately before and after each LPT session. Nonparametric test of Wilcoxon was used for statistical analysis, considering a significance level of 5%. All volunteers reported reduced burning intensity in all sessions when compared to the previous one and reduction in VAS scores by up to 49% in the last clinical session when compared to the first session. When only the VAS baseline of the first session was compared with the consecutive sessions, there was a statistically significant reduction in VAS scores in almost all sessions. The LPT may be an alternative treatment for the relief of oral burning symptoms in patients with BMS., (© 2015 The American Society of Photobiology.) more...

Low level laser therapy (LLLT) has been used to relieve pain, inflammation, and wound healing processes. Thus, the skin is overexposed to laser and this effect is not completely understood. This study analyzed the effects of the number of laser applications (three, six, and 10) on the intact skin of the masseteric region in mice of strain HRS/J. The animals (n = 30) were equally divided into control (0 J/cm(2)) and irradiated (20 J/cm(2)), and each of these groups was further equally divided according to the number of laser applications (three, six, and 10) and underwent LLLT on alternate days. Samples were analyzed by light microscopy and transmission electron microscope (TEM). The animals receiving applications exhibited open channels more dilated between the keratinocytes and photobiomodulation effect on endothelial cells and fibroblasts by TEM. Under the light microscope after 10 laser applications, the type I collagen decreased (P < 0.05) compared to the three and six applications. Under these experimental conditions, all numbers of applications provided photobiomodulatory effect on the epidermis and dermis, without damage. More studies are needed to standardize the energy density and number of applications recommended for laser therapy to have a better cost-benefit ratio associated with treatment. more...

Low-level laser therapy (LLLT) has been widely used in the treatment of the stomatognathic system dysfunction; however, its biological effect remains poorly understood. This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm(2), 40 mW) on masseter muscle of HRS/J mice after different numbers of laser irradiations (three, six, and ten) for 20 s in alternate days. Three experimental groups were defined according to the number of laser irradiations and three control groups (n=5) were used. On the third day after the last irradiation, all animals were killed and the masseter muscle was removed and processed for the following analysis: (a) transmission electron microscopy, (b) zymography, (c) immunohistochemistry for vascular endothelial growth factor (VEGF) and VEGFR-2. The results showed: (a) with six laser applications, a dilation of T tubules, and sarcoplasmic reticulum cistern, increased pinocytosed vesicles in the endothelium; with ten laser applications, few pinocytic vesicles in the endothelium and condensed mitochondria. (b) Under the conditions of this study, the synthesis of other matrix metalloproteinases was not observed, only the MMP-2 and -9. (c) After ten laser irradiations, immunostaining was observed only for VEGFR-2. We conclude that after six laser applications, ultrastructural changes may facilitate the Ca(+2) transfer to cytosol and increase the fluid transport from one surface to another. The ultrastructural changes and no immunostaining for VEGF with ten applications may decrease the metabolic activity as well as damage the angiogenic process, suggesting that an effective number of laser applications may be less than ten, associating to this therapy a better cost-benefit. more...

Objective: The aim of this study was evaluate the effect of low-level laser therapy (LLLT) in the treatment of burning mouth syndrome (BMS) patients., Background Data: BMS is a clinical condition characterized by a burning sensation in a morphologically normal oral mucosa, without association with systemic disorders., Methods: Ten patients with oral burning sensation were included in the study. After careful evaluation of medical history and oral examination, the diagnosis of BMS was established. All patients were submitted to one weekly session of LLLT for 10 weeks. A continuous wavelength of 660 nm, power 40 mW, 20 J/cm(2), 0.8 J/point, with each point irradiated for 10 sec. In all sessions the burning intensity was evaluated with a 10-cm visual analogue scale (VAS), with 0 indicating no symptoms and 10 indicating the worst burning possible. The burning intensity evaluation by VAS was performed immediately before (VAS baseline) and immediately after each LLLT session. The nonparametric Wilcoxon test was used for statistical analysis, considering significance of 5%., Results: All patients reported improvement in all sessions, with reduction in VAS scores by up to 58% in the tenth session. When only the VAS baseline of the first session was compared with the other sessions, there was a statistically significant reduction in VAS scores in the fourth (p=0.03), fifth (p=0.03), sixth (p=0.009), seventh (p=0.003), eighth, ninth, and tenth (all p=0.002) sessions., Conclusions: LLLT may be an alternative treatment for the relief of oral burning in patients with BMS. more...

Objective: This study aims to analyze the effects of low-level laser therapy (LLLT) on the oxidative activity and the expression/activity of metalloproteinases of the masseter muscle., Background Data: Currently in dentistry LLLT has been used on patients with muscular disorders, such as the temporomandibular disorders (TMDs) but its effect at the cellular level has not been fully elucidated., Methods: Thirty male Wistar rats divided into 6 groups (n=5) received 10 laser irradiations (780 nm, 5 mmW, CW laser, illuminated area 0.04 cm(2), power density 125 mW/cm(2)), with different energy densities (group I-0; group II-0.5; group III-1.0; group IV-2.5; group V-5.0; and group VI-20 J/cm(2)). Muscles were processed for nicotinamide adenine dinucleotide diaphorase (NADH) and sucinate dehydrogenase (SDH) activities and zymography. The photomicrographs were evaluated by the point counting method using a test system and ImageJ software; and by the ANOVA statistical test. The proteinases' secretion/activity was qualitatively analyzed by zymography., Results: LLLT significantly increased (p<0.05) masseter muscle oxidative metabolism shown by the increased area of intermediary fibers in the NADH (groups IV, V, and VI) and SDH (group V) reactions. The same metabolic pattern was observed among the groups in both reactions. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) zymography detected only the MMP-2 expression/activity for the untreated-control group (group I). The exposure to LLLT increased the activity of MPP-2 in group VI and the activity of MMP-9 in all groups exposed to different energy densities of laser irradiation (groups II, III, IV, V, and VI)., Conclusions: Thus, LLLT stimulated the oxidative metabolism and the expression of matrix metalloproteinase (MMPs) of the masseter muscle, which may indicate a matrix remodeling process. However, group VI did not show the best results for oxidative metabolism, probably indicating that the dosage they were given was high for this protocol. more...

It is not well-understood how low-laser therapy affects the skin of the applied area. This study analyzes skin of the masseteric region of mice from the HRS/J strain after three different application regimens (three, six or ten applications per regimen) of low intensity laser at 20 J/cm(2) and 40 mW for 20 sec on alternate days. Three experimental groups according to the number of laser applications (three, six or ten) and three control groups (N = 5 animals for each group) were used. On the third day after the last irradiation, all animals were sacrificed and the skin was removed and processed to analyze the relative occupation of the test area by each epithelial layer and the aspects of neovascularization. Data were submitted to statistical analyzes. The irradiated groups compared to their respective controls at each period of time, showed no significant difference in relative occupation of the test area by the layers and epithelium areas for three and six applications, but for ten applications, a significant decrease (P < 0.05) in the basal and granulosum layers, and epithelium areas were found. From the comparisons of the three irradiated groups together, the group with six laser applications showed statistical difference (P < 0.05) in total epithelium and on the layers. Vascular endothelial growth factor (VEGF) and VEGFR-2 immunoreactivities were similar for the control and irradiated groups. Results suggested a biostimulatory effect with low risks associated with superficial tissues, when the treatment aims the deeper layers after six applications., (Copyright © 2011 Wiley-Liss, Inc.) more...

Objective: This study evaluated with histochemical analysis how the number of laser applications can affect the masseter muscle., Background: In dentistry today, the laser is used in patients with temporomandibular disorders (TMDs), mainly for radiating pain in the masticatory muscles, whose origins may be associated with malocclusion, although the laser effects are not well understood on the cellular level., Materials and Methods: Thirty mice (HRS/J lineage) were randomly distributed into groups according to the number of laser applications (three, six, and 10). For each group of laser applications (experimental, n = 5), it was considered the control group (n = 5), which was not irradiated. All animals inhaled halothane (2-bromo-2-chloro-1, 1, 1-trifluoroethane, minimum 99%, Sigma Aldrich, India) before each laser irradiation performed on the left masseter muscle region, on alternate days with 20 J/cm(2), 40 mW, for 20 sec. The muscle samples were collected for histochemical analysis with succinate dehydrogenase (SDH) enzyme 72 h after the last application., Results: (a) A decrease in area of light fibers type (35.91% ± 6.9%; 32.08% ± 6.3%, and 27.88% ± 6.3%), according to the increase of laser applications (p < 0.05); (b) significant increase (p < 0.05) in the area of intermediate fibers, with an increase of laser application (11.08% ± 3.9%; 16.52% ± 5.7%, and 15.96% ± 3.9%), although the increase with 10 applications was small; (c) area increase of dark fibers in the group with three laser applications (0.16% ± 0.3%) (p < 0.05), and in groups with six and 10 laser applications, respectively (9.68% ± 6.0% and 9.60% ± 4.0%)., Conclusions: The SDH enzyme activity revealed that the number of laser applications increases the metabolic pattern of the muscle fibers. A minimal difference in metabolic activity between six and 10 applications of a laser suggests that further analyses should be done to confirm that six applications are enough to produce the same clinical effects, thereby contributing data to professionals from different fields in regard to the cost-benefit ratio of this therapy. more...