The tissue response to laser therapy appears to vary by dose. Low-intensity laser therapy appears to reduce the severity of mucositis, at least in part, by reducing COX-2 levels and associated inhibition of the inflammatory response.

The diode laser energy delivered into small to median hemorrhoidal piles caused little pain and led to a partial to complete resolution within a short time compared to open hemorrhoidectomy. Some adjustments must be made to prevent burning lesions and residual plicoma. Although it is not a good method for big piles, this technique opens new possibilities for surgical treatment of hemorrhoidal disease.

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The aim of this study was to investigate the effect of low-level laser therapy (LLLT) on bone repair in femoral fractures. Sixty adult Wistar rats were randomly assigned into one of two groups: group A (ostectomy + LLLT) or group B (ostectomy + sham laser). An experimental model of complete bone fracture was surgically created by removing a 2-mm fragment from the middle third of the femoral shaft. Data were analyzed on days 8, 13, and 18 after the fracture (subgroups 1, 2, and 3). Samples were assessed for changes in inflammatory infiltration; trabecular bone matrix, periosteal, and new bone formations; and changes in the expression of particular osteogenic-related proteins (osteocalcin, osteopontin, and osteonectin). Microscopic analysis revealed a significant decrease in inflammatory infiltration, intense trabecular bone matrix and periosteal formation, and an increase in newly formed bone after laser irradiation. We also found an increase in the expression of bone matrix proteins with LLLT, with a significant difference measured for osteocalcin in the LLLT group at day 8 (p = 0.007). We show that LLLT plays an important role in augmenting bone tissue formation, which is relevant to fracture healing. LLLT may therefore be indicated as an adjunct therapeutic tool in clinical practice for the treatment or recovery of nonunion injuries.

This study supports two mechanisms of action for LLLT in reducing mucositis severity. The increase in collagen organization in response to the 35 mW laser indicates that LLLT promotes wound healing. In addition, LLLT also appears to have an anti-inflammatory effect, as evidenced by the reduction in neutrophil infiltrate.

Therapeutic approaches to chronic actinic cheilitis focus on the removal or destruction of diseased epithelium. The CO(2) laser has become an important therapeutic alternative, achieving clinical resolution in around 90% of patients. Although many laser physical parameters have been reported, some are known for their low potential for scar induction without compromising the success of the results. The aim of this clinicohistological study was to compare the therapeutic responses to two low-morbidity protocols involving a single laser pass. A total of 40 patients with chronic multicentric and microscopically proven disease were randomly submitted to two conservative CO(2) laser protocols using a bilateral comparative model. The degree of histological atypia of the epithelium was determined in 26 patients both pre- and postoperatively for both protocols. Other histological phenomena were assessed in addition to this central analysis parameter. Clinical recurrence occurred in 12.5% of patients for each protocol, together with a significant reduction in the degree of epithelial atypia (p < 0.001), which was occasionally complete. However, no difference was found between the protocols (p > 0.05). Using these morphological parameters it was not possible to determine whether postoperative epithelial atypias in part of the sample were reactive or residual in nature. A few patients may show minor postoperative lesions. Due to their potential to achieve clinical and importantly microscopic resolution, the studied protocols may be used for mild through moderate dysplastic epithelium and clinically diffuse disease.

To evaluate the modulation of proinflammatory (interleukin-6, IL-6; tumor necrosis factor-α, TNF-α; and interferon-γ, IFN-γ) and anti-inflammatory cytokines (transforming growth factor-β1, TGF-β1) in the inflammation processes in vivo with low-level laser action, 50 isogenic mice were randomly distributed into three groups: control (no surgical procedure, n = 10), sham (surgical procedure with three standard cutaneous incisions, followed by an abdominal muscle incision and suture, n = 20), and laser (same procedure followed by laser exposure, n = 20). The sham group was divided into three subgroups: sham I (euthanasia and evaluation, 36 h after surgical procedure), sham II (euthanasia and evaluation, 60 h after surgical procedure), and sham III (euthanasia and evaluation, 84 h after surgical procedure). The laser group was also divided in three subgroups: laser I (a single laser session, 12 h after surgery), laser II (two laser sessions, 12 and 36 h after surgery), and laser III (three laser sessions, 12, 36, and 60 h after surgery). All animals in the laser groups received three points per session of continuous infrared laser (wavelength of 780 nm, power of 20 mW, fluency of 10 J/cm(2), exposure time of 20 s per point, and energy of 0.4 J). After euthanasia, spleen mononuclear cells were isolated and cultured for 48 h. Concentrations of IL-6, TNF-α, IFN-γ, and TGF-β1 were obtained by enzyme-linked immunosorbent assay method. There was a significant difference between the IL-6 and TNF-α concentrations in the 60-and 84-h evaluations when the laser and sham groups were compared to the control group (p < 0.05), except for laser II in the TNF-α analysis (p > 0.05). The IFN-γ concentration analysis showed a significant difference only in sham II when compared to the control group (p < 0.05). Thus, there was a modulatory effect of TNF-α and IFN-γ in the laser group, particularly in the 60-h postoperative evaluation. There was no significant difference between the laser, sham, and control groups for TGF-β1 analysis (p > 0.05). The low-level laser application decreased the TNF-α and IFN-γ release in vivo of spleen mononuclear cells in mice, especially after two exposure sessions. However, there was no modulation of the IL-6 and TGF-β1 release.

Laser discectomy or nucleotomy is an increasingly important method for less invasive procedures of column, but the ideal kind of laser is still not established. As the wavelength is an important parameter for water absorption, this study was performed to investigate the action of the laser emission in the near infrared (808 to 1908 nm) region in the context of surgical procedures for percutaneous intervertebral disc decompression (nucleotomy). Forty intervertebral discs from pigs lumbar spines were irradiated with laser (λ = 808, 980, 1470 and 1908 nm), 1-s on/off time cycles, for 120 cycles and 10 W of power (808, 980, and 1470 nm) or 240 cycles and 5 W of power (1908 nm), with total power of 1200 J, and subjected to microscopic evaluation through hematoxylin-eosin (HE) staining in order to measure the ablation lesions and the residual thermal injury. Ten other discs were not irradiated and worked as controls. The ablation lesions were measured (in mm) at 1.08 ± 1.25, 1.70 ± 0.63, 2.23 ± 1.02, 1.37 ± 0.39, and 0.94 ± 0.41 (median ± SD) for the control, 808, 980, 1470, and 1908 nm groups, respectively. The difference between 1908 nm and all the other groups was statistically significant (p < 0.05). The residual thermal injury was less evident in 1908 nm laser and sharper in 980 nm laser wavelengths. The laser at a wavelength of 1908 nm was considered the most efficient for the vaporization of the nucleus pulposus, followed by the laser wavelengths of 1470, 808, and 980 nm, and proved to be useful for laser nucleotomy procedure.