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The current international guidelines identify tumescent ablative techniques such as laser thermal ablation (EVLA) and radiofrequency (RFA) to be the gold standard in varicose vein surgery. New-generation lasers have been introduced, which have high wavelengths (1940 and 2000 nm) and therefore with a greater affinity for water than the old generation (980- and 1470-nm lasers). The purpose of the study was to evaluate the biological effect and the temperatures produced during the use of lasers with different wavelengths (980, 1470, and 1940 nm) and with optical fibers with different emission (radial diverging at 60° and radial with cylindrical mono-ring) on in vitro model. Porcine liver was used as an in vitro model. The laser control units used had 3 different wavelengths: 980, 1470, and 1940 nm. The optical fibers used were 2: the Corona 360 fiber (mono-ring radial fiber) and the infinite fiber (cylindrical mono-ring fiber). The laser operating parameters used included the delivery of 6 W in continuous wave (CW) mode with a standard 10 s/cm pull-back. Eleven measurements were made for each fiber and for each laser, for a total of 66 measurements. We performed measurements of the maximum transverse diameter produced with laser irradiation to evaluate the biological effectiveness of the treatment. During laser irradiation, we performed measurements of both of the temperatures reached on the external surface of the porcine tissue, near the tip of the laser catheter, and the temperatures reached inside the irradiated tissue by using a digital laser infrared thermometer with apposite probe. The calculation of the statistical significance (p-value) was obtained with the ANOVA method with two between factors. The comparison study of the maximum transverse diameter (DTM) of the lesion produced on the target tissue demonstrated the absence of statistically significant differences between the 1470-nm laser and the 1940-nm laser regardless of the type of fiber used. It was not possible to perform measurements of the maximum transverse diameter produced with the 980-nm laser as this produced no visible effect on the model. The comparison study of the temperatures developed during and immediately after the treatment instead showed higher maximum surface temperatures (TSM) and a higher thermal increase (IT) regardless of the type of fiber used in a statistically significant way (respectively, p 0.002 and 0.012) when using the 980-nm laser versus the 1940-nm laser. Comparing instead the 980-nm laser with 1470 nm, there were no differences in TI recorded during the procedure but a significantly higher VTI (p 0.029). The experiment conducted with the new generation laser, compared with those of the first and second generation, shows how this works overall at lower temperatures with the same effectiveness., (© 2023. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

The safety and efficacy of laser hair removal have been well established through many clinical studies and through clinical use over the past 25 years. A laser hair removal device that protects the epidermis by utilizing cryogen spray cooling (CSC) is widely used internationally. In darker skin types, post-inflammatory hyperpigmentation (PIH) can occur after laser hair removal. In particular, laser hair removal with CSC is known to cause crescent-shaped or ring-shaped PIH. In this experiment, we report a visualization of this PIH mechanism. The laser used in this experiment is a 755-nm-long-pulsed alexandrite laser. Graph paper was treated with this laser to assess for thermal damage. We investigated changes in thermal damage due to differences in laser spot size, fluence output, and laser beam angle in relation to the graph paper. When using a spot size of 18 mm, we observed that higher fluences caused crescent-shaped thermal damage on the margins of the treated graph paper. It was also confirmed that when the hand piece is not held perpendicular to the skin, the laser-treated area is expanded and the CSC range is narrowed. These factors caused the area of thermal damage to widen. This widening causes ring-shaped thermal injury, leading to PIH. We treated graph paper using a hair removal laser with CSC to investigate the mechanism of crescent or ring-shaped thermal damage. Laser treatment on graph paper is effective as a test for defects in the CSC device. Factors that cause inadequate cooling, which leads to PIH, are large spot size, high fluence, not holding the laser hand piece perpendicular to the skin, and malfunctioning of CSC device. [ABSTRACT FROM AUTHOR]

We investigated the influence of femtosecond laser irradiation on the growth of the two most common infectious bacterial pathogens in wounds; Staphylococcus aureus and Pseudomonas aeruginosa as an attempt to validate optimum parameters for a laser-based bactericidal modality to be used clinically. Bacterial cultures were exposed to femtosecond laser irradiation at different wavelengths, exposure times, and laser powers. The source of femtosecond laser was INSPIRE HF100 laser system, Spectra-Physics, which is pumped by a mode-locked femtosecond Ti: sapphire laser MAI TAI HP, Spectra-Physics. After irradiation, bacterial cells' survival was monitored by observing the clear zones of inhibition in cultured agar plates. Results for all strains indicated that the exposure to femtosecond laser irradiation with a wavelength ranging from ultraviolet (λ > 350 nm) to blue laser light (λ < 480 nm), for a period above 20 min and with a power density of ≈ 0.063 W/cm 2 , was enough to inhibit both bacterial pathogens with the results maintained for 1 week following irradiation.

The effects of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser and silicon carbide (SiC) paper on the surface micro-topography of titanium-6 aluminium-4 vanadium (Ti6Al4V) alloy were examined in relation to the response of bone cells. The study was performed in three distinct stages: (1) after surface treatment of samples by laser and SiC paper, the surface hardness, surface roughness, corrosion resistance and surface tension were evaluated; (2) the growth of mouse connective tissue fibroblast cells (L-929) on untreated and treated samples was assessed in vitro; (3) the response of goat osteoblast cells to untreated and treated implanted samples was assessed in vivo. The surface roughness varied between 7 +/- 0.02 for laser-treated samples (LTSs) at 140 J cm(-2) and 21.8 +/- 0.05 for mechanically treated samples (MTSs). The surface hardness was found to vary from 377 Vickers hardness number (VHN) for MTSs to 850 VHN for LTSs. A corrosion potential of -0.21V was achieved for the LTSs compared with -0.51V for the MTSs. The LTSs exhibited a more hydrophilic behaviour (i.e. wettability) than did the MTSs. No cytotoxicity effect, unlike for the MTSs, was observed for the LTSs. The results of in vivo tests indicated longitudinal growth of osteoblast cells along the grooves on the samples formed by the SiC paper, and multidirectional spreading of the cells on the LTSs. [ABSTRACT FROM AUTHOR]

This paper introduces a novel application of the laser speckle technique in dentistry, focusing on assessing the efficiency of dental excavation methods used to remove decayed tooth structure. The aim is to evaluate the efficiency of two chemo-mechanical agents and the high-speed drill using the laser speckle technique, which offers objective, non-invasive, and real-time evaluation capabilities. Extracted human primary molars with active occlusal carious lesions were sectioned into three parts, with each part allocated to one of three groups: Group 1 (Brix3000 ® ), Group 2 (Papacarie DUO ® ), and Group 3 (High-speed drill mechanical caries removal). Caries removal was performed using the designated agent or method for each group. After caries excavation, speckle imaging using a 632.8 nm laser was conducted. Additionally, SEM was used to acquire micro-photographs of the surface morphology of the treated samples. The findings reveal insights into the comparative efficiency of the three dental excavation agents and methods using the laser speckle technique. The speckle parameters extracted from speckle patterns generated by treated teeth provide valuable information for evaluating the performance of the excavation methods. The scanning electron microscopy images also offer detailed visual evidence to support the analysis. This paper demonstrates the potential of the laser speckle technique for assessing the efficiency of dental excavation methods. The objective, non-invasive, and real-time evaluation provided offers advantages over subjective visual assessment and manual measurements., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Low-level light therapy (LLLT), also known as photo biomodulation (PBM), is a type of optical therapy that uses red or near-infrared lasers or light-emitting diodes (LEDs) for medical treatment. The laser wavelengths involved in PBM typically range between 600-700 nm and 780-1100 nm, with power densities ranging between 5 mW/cm 2 and 5 W/cm 2 . PBM is a series of biochemical cascades exhibited by biological tissues after absorbing a certain amount of energy from light. PBM has been widely used in clinical practice in the past 20 years, and numerous clinical trials have demonstrated its biological efficacy. However, the underlying mechanisms have not yet been fully explored. In this paper, we have summarized the research into PBM over the past two decades, to identify the important mechanisms of the biological effects of PBM from the perspective of molecular mechanisms, cellular levels, and tissue changes. We hope our study provide a theoretical basis for future investigations into the underlying mechanisms., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Vital pulp therapy (VPT) is primarily intended to preserve the vitality of pulp tissues, which have been exposed for any reason. Various materials and techniques have been proposed to improve treatment outcomes, including the use of lasers. This study aimed to review the histological results of different dental lasers including low-level lasers, carbon dioxide (CO2), erbium-doped yttrium aluminum garnet laser (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, and diode lasers for VPT. This focused review included a comprehensive electronic search of Scopus, MEDLINE, Web of Science, and Google Scholar databases from 2000 to 2022 by two independent investigators. Different combinations of keywords were used, and reference mining of related papers was done. The review included studies related to histologic evaluation of laser-assisted vital pulp therapy that stated the laser parameters that were used. Articles with radiographic or clinical assessments or articles lacking necessary data were excluded. Non-English articles were excluded unless their abstract was in English and encompassed the necessary data. Most studies indicated the efficacy of lasers for reduction of inflammation, acceleration of healing, and increasing the thickness of dentinal bridge. According to the evidence, lasers used in combination with pulp capping agents are beneficial to enhance the success rate of VPT. [ABSTRACT FROM AUTHOR]

Aim: The aim of the present study was to evaluate the efficacy of 30°-angled Er:YAG laser tip and different periodontal instruments on root surface roughness and morphology in vitro. Methods: Eighteen bovine teeth root without carious lesion were decoronated from the cementoenamel junction and seperated longitidunally. A total of 36 obtained blocks were mounted in resin blocks and polished with silicon carbide papers under water irrigation. These blocks were randomly assigned into 3 treatment groups. In Group 1, 30°-angled Er:YAG laser (2.94 μm) tip was applied onto the blocks with a 20 Hz, 120 mJ energy output under water irrigation for 20 s. In Groups 2 and 3, the same treatment was applied to the blocks with new generation ultrasonic tip and conventional curette apico-coronally for 20 s with a sweeping motion. Surface roughness and morphology were evaluated before and after instrumentation with a profilometer and SEM, respectively. Results: After instrumentation, profilometric analysis revealed significantly higher roughness values compared to baseline in all treatment groups(p < 0.05). Laser group revealed the roughest surface morphology followed by conventional curette and new generation ultrasonic tip treatment groups (p < 0.05). In SEM analysis, irregular surfaces and crater defects were seen more frequently in the laser group. Conclusion: Results of the study showed that the use of new generation ultrasonic tip was associated with smoother surface morphology compared to 30°-angled Er-YAG laser tip and conventional curette. Further in vitro and in vivo studies with an increased sample size are necessary to support the present study findings. [ABSTRACT FROM AUTHOR]

Keywords: Public Health; Quantum Electronics; Nonlinear Optic; Hard Tissue; Ablation Efficacy EN Public Health Quantum Electronics Nonlinear Optic Hard Tissue Ablation Efficacy 1 1 1 12/09/22 20221202 NES 221202 This article was retracted by the Editors, as the paper was originally published by Mersini I Makropoulou and Eirini I Papagiakoumou (2004) Lasers and hard-tissue interactions. Public Health, Quantum Electronics, Nonlinear Optic, Ablation Efficacy, Hard Tissue. [Extracted from the article]

In this paper, a closed-form analytical solution of hyperbolic Pennes bioheat equation is obtained for spatial evolution of temperature distributions during moving laser thermotherapy of the skin and kidney tissues. The three-dimensional cubic homogeneous perfused biological tissue is adopted as a media and the Gaussian distributed function in surface and exponentially distributed in depth is used for modeling of laser moving heat source. The solution procedure is Eigen value method which leads to a closed form solution. The effect of moving velocity, perfusion rate, laser intensity, absorption and scattering coefficients, and thermal relaxation time on temperature profiles and tissue thermal damage are investigated. Results are illustrated that the moving velocity and the perfusion rate of the tissues are the main important parameters in produced temperatures under moving heat source. The higher perfusion rate of kidney compared with skin may lead to lower induced temperature amplitude in moving path of laser due to the convective role of the perfusion term. Furthermore, the analytical solution can be a powerful tool for analysis and optimization of practical treatment in the clinical setting and laser procedure therapeutic applications and can be used for verification of other numerical heating models.

Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical technique with numerous advantages such as rapidity, multi-elemental analysis, no specific sample preparation requirements, non-destructiveness, and versatility. It has been proven to be a robust elemental analysis tool attracting interest because of being applied to a wide range of materials including biomaterials. In this paper, we have performed spectroscopic studies on gallstones which are heterogeneous in nature using LIBS and wavelength dispersive X-ray fluorescence (WD-XRF) techniques. It has been observed that the presence and relative concentrations of trace elements in different kind of gallstones (cholesterol and pigment gallstones) can easily be determined using LIBS technique. From the experiments carried out on gallstones for trace elemental mapping and detection, it was found that LIBS is a robust tool for such biomedical applications. The stone samples studied in the present paper were classified using the Fourier transform infrared (FTIR) spectroscopy. WD-XRF spectroscopy has been applied for the qualitative and quantitative analysis of major and trace elements present in the gallstone which was compared with the LIBS data. The results obtained in the present paper show interesting prospects for LIBS and WD-XRF to study cholelithiasis better. [ABSTRACT FROM AUTHOR]

We performed a narrative review with the focus on laser settings and surgical procedure with thulium laser. Our primary goal was to define the most valid settings of each surgical procedure to overcome the inconsistency about nomenclature of thulium surgery and to ensure comparability of future publications. A literature search of articles on thulium laser treatment of benign prostatic hyperplasia (BPH) was conducted between 2009 and 2019. We proposed a new classification standard for laser settings and associated surgical procedure. Each article was analyzed and categorized as concordant or discordant referring to the new classification. In total, 74 papers were included in this narrative review. Overall, 43% and 42% of included studies reported discordant laser parameters and surgical description, respectively. Most of the studies on vaporization were categorized as discordant because they reported a medium/low laser setting instead of high power. Conversely, 93.3% of studies on enucleation were deemed as discordant for laser setting because they reported high power parameters instead of medium-low power setting. Most of the studies on laser enucleation and vapo/enucleation were considered discordant for surgical procedure since authors did not mention the use of mechanical vs. laser method for enucleation. The current literature lacks a uniform definition and standardization of the terminology of thulium laser settings and surgical techniques to guarantee comparability between different approaches. We found a huge heterogeneity in 10 years of surgery with thulium laser. We proposed a new classification of laser setting and procedural description for categorization of thulium laser surgery for BPH. [ABSTRACT FROM AUTHOR]

Optically tunable gold nanoparticles have been widely used in research with near-infrared light as a means to enhance laser-induced thermal therapy since it capitalizes on nanoparticles' plasmonic heating properties. There have been several studies published on numerical models replicating this therapy in such conditions. However, there are several limitations on some of the models which can render the model unfaithful to therapy simulations. In this paper, two techniques of simulating laser-induced thermal therapy with a high-absorbing localized region of interest inside a phantom are compared. To validate these models, we conducted an experiment of an agar-agar phantom with an inclusion reproducing it with both models. The phantom was optically characterized by absorption and total attenuation. The first model is based on the macroperspective solution of the radiative transfer equation given by the diffusion equation, which is then coupled with the Pennes bioheat equation to obtain the temperature. The second is a Monte Carlo model that considers a stochastic solution of the same equation and is also considered as input to the Pennes bioheat transfer equation which is then computed. The Monte Carlo is in good agreement with the experimental data having an average percentage difference of 4.5% and a correlation factor of 0.98, while the diffusion method comparison with experimental data is 61% and 0.95 respectively. The optical characterization of the phantom and its inclusion were also validated indirectly since the Monte Carlo, which used those parameters, was also validated. While knowing the temperature in all points inside a body during photothermal therapy is important, one has to be mindful of the model which fits the conditions and properties. There are several reasons to justify the discrepancy of the diffusion method: low-scattering conditions, absorption, and reduced scattering are comparable. The error bars that are normally associated when characterizing an optical phantom can justify also a part of that uncertainty. For low-size tumors in depth, one may have to increase the light dosage in photothermal therapies to have a more effective treatment.

This paper aims to develop a method for laser speckle image segmentation of tooth surfaces for diagnosis of early stages caries. The method, applied directly to a raw image obtained by digital photography, is based on the difference between the speckle pattern of a carious lesion tooth surface area and that of a sound area. Each image is divided into blocks which are identified in a working matrix by their χ 2 distance between block histograms of the analyzed image and the reference histograms previously obtained by K-means from healthy (h&#95;Sound) and lesioned (h&#95;Decay) areas, separately. If the χ 2 distance between a block histogram and h&#95;Sound is greater than the distance to h&#95;Decay, this block is marked as decayed. The experiments showed that the method can provide effective segmentation for initial lesions. We used 64 images to test the algorithm and we achieved 100% accuracy in segmentation. Differences between the speckle pattern of a sound tooth surface region and a carious region, even in the early stage, can be evidenced by the χ 2 distance between histograms. This method proves to be more effective for segmenting the laser speckle image, which enhances the contrast between sound and lesioned tissues. The results were obtained with low computational cost. The method has the potential for early diagnosis in a clinical environment, through the development of low-cost portable equipment.

This study aimed to compare the effects of (HNLT) and (ILT) on diabetic foot ulcer. Sixty-five patients with diabetic foot ulcer (51 males and 14 females) aged 50-60 years. The participants were classified randomly to two groups, groups I and II. Group I received helium-neon laser therapy (HNLT) and conventional therapy with and group II received infrared laser therapy (ILT) and conventional therapy with for 8 weeks. Ulcer surface area was assessed using a sheet of cellophane paper at the beginning of the study, after 4 weeks, and after 8 weeks at the end of the study. At the beginning of the study, baseline clinical characteristics showed non-significant differences between the two groups (p > 0.05). After 4 weeks intervention, there were significant improvements in ulcer surface area in the two groups (p < 0.05). At the end of the study, after 8 weeks intervention, there were higher reduction in ulcer area in HNLT group more than ILT group, but this difference was statistically non- significant between the two groups (p > 0.05). The present study demonstrates that HNLT and ILT have similar effects to control diabetic foot ulcer in a short-term (up to 8 weeks). Eight weeks of laser therapy have beneficial impacts in diabetic foot ulcer. [ABSTRACT FROM AUTHOR]

Infrared neural stimulation (INS) is a new and developing approach for neural repair, with the advantages of being non-contact, spatially precise, and artifact-free. However, the disadvantage of infrared light is that it is difficult to stimulate deep tissue because of its weak penetrating power. Therefore, this paper introduces an improved method using near-infrared laser to stimulate bullfrog sciatic nerves because of its strong penetrating power. Meanwhile, gold nanorods (Au NRs) are injected into the nerve to increase the absorption of light. The mechanism is the instantaneous temperature rise caused by the absorption of infrared light by Au NRs. The compound muscle action potential (CMAP) associated with the irradiated sciatic nerve is recorded by a multi-channel physiological signal instrument. The peak to peak amplitude (Vpp) of CMAP for sciatic nerves injected with Au NRs increases significantly compared to the CMAP for control nerves without Au NRs. These results demonstrate INS by labeling nerves with nanoparticle exhibiting latent capacity to increase the efficiency, spatial resolution, and the neural responsivity, and especially, can increase the penetration depth and reduce the requisite radiant exposure level. [ABSTRACT FROM AUTHOR]

Optical neural stimulation in the cochlea has been presented as an alternative technique to the electrical stimulation due to its potential in spatially selectivity enhancement. So far, few studies have selected the near-infrared (NIR) laser in cochlear neural stimulation and limited optical parameter space has been examined. This paper focused on investigating the optical parameter effect on NIR stimulation of auditory neurons, especially under shorter pulse durations. The spiral ganglion neurons in the cochlea of deafened guinea pigs were stimulated with a pulsed 810-nm NIR laser in vivo. The laser radiation was delivered by an optical fiber and irradiated towards the modiolus. Optically evoked auditory brainstem responses (OABRs) with various optical parameters were recorded and investigated. The OABRs could be elicited with the cochlear deafened animals by using the 810-nm laser in a wide pulse duration ranged from 20 to 1000 μs. Results showed that the OABR intensity increased along with the increasing laser radiant exposure of limited range at each specific pulse duration. In addition, for the pulse durations from 20 to 300 μs, the OABR intensity increased monotonically along with the pulse duration broadening. While for pulse durations above 300 μs, the OABR intensity basically kept stable with the increasing pulse duration. The 810-nm NIR laser could be an effective stimulus in evoking the cochlear neuron response. Our experimental data provided evidence to optimize the pulse duration range, and the results suggested that the pulse durations from 20 to 300 μs could be the optimized range in cochlear neural activation with the 810-nm-wavelength laser.

B Correction to: Lasers Med Sci b https://doi.org/10.1007/s10103-021-03453-4 In the published online paper, two supplemental tables (Supplemental Table 1 and Table 2) were missing, and the table numbers were misstated in the text. Correction to: Efficiency and safety of laser-assisted hatching on vitrified-warmed blastocyst transfer cycles: a prospective control trial The original article can be found online at https://doi.org/10.1007/s10103-021-03453-4. [Extracted from the article]

There are many laser technologies that are being tested that claim to support hair regrowth for patients with alopecia areata (AA). In this paper, we will determine whether the body of evidence supports the use of devices using monochromatic light sources to treat AA. Articles were gathered from PubMed, Embase, and the Cochrane database using these keywords: lasers, excimer laser, low-level laser therapy (LLLT), low-level light therapy, alopecia, alopecia areata, and hair loss with a category modifier of English. Ten clinical trials and seven case reports/abstracts were assessed. Eight clinical trials and two case reports demonstrated hair regrowth with the 308-nm excimer laser/light in men, women, and children. One case report demonstrated hair regrowth with the ALBA 355® laser. One clinical trial and two case reports demonstrated hair regrowth with LLLT. While two case reports demonstrated hair regrowth with fractional laser therapy, one clinical trial showed no improvement. The 308-nm excimer laser is a safe and effective treatment for men, women, and children with refractory AA of the scalp and beard. Larger, double-blinded clinical trials should be conducted to compare excimer laser therapy to standard treatments. More data is needed to determine the efficacy of LLLT and fractional laser therapy in the treatment of AA. [ABSTRACT FROM AUTHOR]

This paper reports on the application of the motion history image (MHI) method on dynamic laser speckle processing as a result of a specific drug action on Trypanosoma cruzi parasites. The MHI procedure is based on human action recognition, and unlike other methods which use a sequence consisting of several frames for recognition, this method uses only an MHI per action sequence for recognition. MHI method avoids the complexity as well as the large computation in sequence matching-based methods and detects a change in the speckle pattern. Experimental results of MHI on real-time monitoring of activity (motility) under the influence of the drug demonstrate the effectiveness of the proposed method. The MHI showed an online result without loss of resolution and definition if we compare with routine LASCA method. The obtained results highlight the advantage of the MHI analysis over traditional qualitative image intensity-based methods and demonstrate the potential of measuring the activity of parasites via dynamic laser speckle analysis. The data was further numerically analyzed in the time domain, and the results presented the ability of the technique to monitor the action of the drug, particularly Epirubicin (100 μg/ml).

This paper implemented a model study of combined electrical and near-infrared (808 nm) neural stimulation (NINS) on the bullfrog sciatic nerve. The model includes a COMSOL model to calculate the electric-field distribution of the surrounding area of the nerve, a Monte Carlo model to simulate light transport and absorption in the bullfrog sciatic nerve during NINS, and a NEURON model to simulate the neural electrophysiology changes under electrical stimulus and laser irradiation. The optical thermal effect is considered the main mechanism during NINS. Therefore, thermal change during laser irradiation was calculated by the Monte Carlo method, and the temperature distribution was then transferred to the NEURON model to stimulate the sciatic nerve. The effects on thermal response by adjusting the laser spot size, energy of the beam, and the absorption coefficient of the nerve are analyzed. The effect of the ambient temperature on the electrical stimulation or laser stimulation and the interaction between laser irradiation and electrical stimulation are also studied. The results indicate that the needed stimulus threshold for neural activation or inhibition is reduced by laser irradiation. Additionally, the needed laser energy for blocking the action potential is reduced by electrical stimulus. Both electrical and laser stimulation are affected by the ambient temperature. These results provide references for subsequent animal experiments and could be of great help to future basic and applied studies of infrared neural stimulation (INS). [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p < 0.05). The highest SBS was found after additional phosphoric acid treatment in dentin groups (p < 0.05). There were no statistically significant differences between the laser-etched and non-etched groups in enamel and dentin (p > 0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p > 0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive.

Photodynamic therapy (PDT) using photosensitized reaction to produce cytotoxicity was used for cancer therapy in recent years. To study the effectiveness of PDT mediated by a novel photosensitizer (PS), DTPP 5-(4'-(2″-dicarboxymethylamino)acetamidophenyl)-10, 15, 20-triphenylporphyrin, on lung cancer A549 cell lines in vitro, DTPP was employed in different concentrations (2, 4, 6, 8, 10, 12, 15, 20, 25, and 30 μg/ml) and combined with 650 nm laser of different power densities (0.6, 1.2, 2.4, 4.8, 7.2, and 9.6 J/cm(2)) that resulted in obvious inhibition of cell proliferation and apoptosis. Results showed that cell survival rates have a dependent relationship with time and PS concentrations and no significant cytotoxicity was induced by DTPP itself. Apoptosis and cell cycle S arrest were observed; cytoskeleton morphologic observation revealed collapse, sparkling, and shrunken shapes. Apoptosis-related protein caspase-3 overexpression was detected while caspase-9, bcl-2, and cytoskeleton protein beta-catenin were in low levels of expression than the control. Cleavage of beta-catenin by caspase-3 or other proteases from the lysosome might be the main reason for the cytoskeleton collapse as beta-tubulin and actin were at a stable level 12 h after PDT. This paper gives a better understanding of the effectiveness of DTPP-mediated PDT in lung cancer A549 cells both with regard to dosimetry and apoptosis changes.

This paper presents the results of endovenous laser ablation (EVLA) of varicose veins in vitro using radiation of a solid-state laser based on the crystal LiYF4:Tm, with a wavelength of 1.885 μm and power output of around 3 W. An experimental series with saline solution and red blood cell (RBC) suspension in the venous lumen was performed to identify the impact of a heated carbonized layer precipitated on the fiber end face versus the efficiency of EVLA. Results of these experiments confirmed that the presence of a heated carbonized layer on the fiber end face increases the efficiency of EVLA. [ABSTRACT FROM AUTHOR]

Low-intensity laser irradiation (LILI) can improve the deformability of red blood cells (RBCs). It might be due to the LILI effects on adenosine triphosphate (ATP) level. However, ATP content may not be a valid surrogate marker for RBC deformability. The LILI effects on RBC glycolysis were studied in this paper. Hypertonic RBCs were used in this study. After 5 min irradiation with low-intensity He-Ne laser irradiation (LHNL) at 632.8 nm and 4.4 mW/cm(2), the concentration of intracellular glucose and the activities of phosphofructokinase (PFK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were measured, respectively. There was no significant change in intracellular glucose concentration. The activity of PFK decreased significantly, but the activity of GAPDH increased significantly. In hypertonic RBCs, LHNL irradiation may decrease the activity of energy-consuming enzymes, but increases the activity of energy-generating enzymes in glycolysis, to improve the RBC deformability. [ABSTRACT FROM AUTHOR]

In the present paper, the influence of tubule orientation on surface texture development was studied. Specimens of dentin with a wide range of tubule orientations were extracted from caries-free human teeth, processed using KrF laser radiation, and analyzed by scanning electron microscopy. When a transverse cross section of dentin cut perpendicularly to the tooth axis is processed with KrF laser radiation, a cone-like topography develops in the inner dentin where tubules are parallel to the laser beam. When laser processing is carried out in the outer dentin, because tubules are significantly tilted with respect to the laser beam, flat surfaces are achieved. The surface texture after laser processing depends effectively on the angle between the tubules and the laser beam. The dependency of cone growth on tubule orientation was confirmed using a simple differential ablation model.

During the last decade, several methods have been devoted to the detection and imaging of tumor-like objects embedded in turbid slab media. Optical methods are broadly investigated as potential non-invasive medical diagnosis used for the detection of tumors. In this paper, we model the photon migration due to a pulsed source laser, through a multiple scattering slab to locate and characterize heterogeneities of different optical properties. The time-dependent diffusion equation is used and solved by means of a finite element model, taking into account air-tissue boundary conditions. The transmitted time-spectra associated to their Fast Fourier Transforms are used to detect embedded objects within diffusive slab media. We show that for an inclusion of identical scattering coefficient to the surrounding medium, the phase shift increases as the absorption coefficient of the inclusion is increased. For a homogeneous absorption, the phase shift is very sensitive to local variations in scattering properties. We then compare these results with those reported by other workers and conclude that the computational model allows the lateral detection of these inclusions, so it should be possible to enhance the detection of a malignant tumor surrounded by the healthy breast tissue.

When calculating applied flux densities in practice, the beam profile of a laser is often erroneously assumed to be homogeneous. In addition, there is usually no consistency in the choice of a suitable measuring method for determining the beam diameter. This failure to observe the inhomogeneous intensity distribution within the beam cross-section, combined with the imprecise knowledge of the beam diameter, leads to flux densities being stated that represent mean values at best. The present paper gives definitions for the flux densities of simple, radially symmetrical beam cross-sections, taking the top-hat and Gaussian profiles as examples. In connection with the inhomogeneous energy distribution in the Gaussian beam, a concept of integral and local energy density is discussed, which differs from the customary definition of the energy density as a constant. Also presented are the consequences of the mathematical concepts in terms of measurement, giving particular consideration to the case where the energy density as the measured variable matches the integral energy density. The significance of the integral and local energy density for hard-tissue ablation is described, based on the practical example of the ablation of dental hard substance. The central result is that the integral flux density is directly accessible as a measured variable, while the effect on the tissue is determined by the local flux density. If the form of the beam is known, the integral flux density can be converted into the local flux density.

Uniform dosimetry is a prerequisite for reproducible laser applications in research and practice. The light-tissue interaction is dependent on the absorbed energy (J) per unit of time (tau) in the case of pulsed lasers, and on the absorbed power (W) per unit of volume (e.g. mm3) in the case of continuous-wave (cw) lasers, and thus directly dependent on the energy distribution within the laser beam. Consequently, precise knowledge of the spatial beam profile, and of the pulse duration and treatment time, is indispensable. The objective of this paper was a theoretical study of the impact of different mode profiles on energy distribution in the beam. Also examined was the question of the influence of changes in the laser parameters on the mode structure. Three erbium:YAG lasers (lambda=2.94 microm) were used for this purpose. The transversal mode structure of the lasers was observed by irradiating thermal paper and verified by means of calculations. The effect induced in the mode profile by changing the pulse energy and pulse repetition rate was investigated. The results of the tests show that changes in the laser parameters result in jumps in the transversal modes and associated energy distributions in the beam. The experiments confirm that simply changing the transversal modes has a substantial effect on the threshold energy required for the ablation of dental enamel (50 mJ with TEM00, 22.6 mJ with TEM31). In practice, inhomogeneity makes it impossible to determine the irradiated area in order to calculate the energy or power density. In addition, the energy distribution in the beam changes as a result of variation of the laser output energy and the pulse repetition rate. Consequently, simply measuring the beam diameter yields a totally incorrect result for the applied flux density when using a beam profile with a relatively high mode.

Photodynamic therapy (PDT) is an anticancer combination therapy, which requires a photosensitiser, which tends to accumulate preferentially in the tumour, and light. Historically large, complex lasers have been used to carry out PDT treatment. Nowadays there is a wide range of coherent and non-coherent sources that can be used. This paper considers the important characteristics of light sources for PDT, including dye lasers pumped by argon or metal vapour lasers and frequency-doubled Nd:YAG lasers. Non-laser sources including tungsten filament, xenon arc, metal halide and fluorescent lamps are also discussed. New exciting developments such as LEDs and femtosecond lasers are also reviewed. The relative merits of laser and non-laser sources are critically examined.

The scientific investigation of fundamental problems plays a decisive role in understanding the mode of action and the consequences of the use of lasers on biological material. One of these fundamental aspects is the investigation of the ablation threshold of various laser wavelengths in dental enamel. Knowledge of the relationships and influencing factors in the laser ablation of hard tooth tissue constitutes the basis for use in patients and the introduction of new indications. The present paper examines the ablation threshold of an Er:YAG laser (lambda=2.94 micro m) and an Er:YSGG laser (lambda=2.79 micro m) in human dental enamel. To this end, 130 enamel samples were taken from wisdom teeth and treated with increasing energy densities of 2-40 J/cm(2). The sample material was mounted and irradiated on an automated linear micropositioner. Treatment was performed with a pulse duration of tau(P(FWHM)) approximately 150 micro s and a pulse repetition rate of 5 Hz for both wavelengths. The repetition rate of the laser and the feed rate of the micropositioner resulted in overlapping of the single pulses. The surface changes were assessed by means of reflected light and scanning electron microscopy. On the basis of the results, it was possible to identify an energy density range as the ablation threshold for both the Er:YAG and the Er:YSGG laser. With the Er:YAG laser, the transition was found in an energy density range of 9-11 J/cm(2). The range for the Er:YSGG laser was slightly higher at 10-14 J/cm(2).

Laserneedles represent a new non-invasive optical stimulation method which is described for the first time in this paper. We investigated 27 healthy volunteers (mean age+/-SD: 25.15+/-4.12 years; range: 21-38 years; 14 female, 13 male) in a randomised cross-over trial to study differences between laserneedle acupuncture and manual needle acupuncture in specific cerebral parameters. Mean blood flow velocity ( v(m)) showed specific and significant increases in the ophthalmic artery during laserneedle stimulation ( p=0.01) and during manual needle stimulation ( p<0.001) at vision-related acupoints. At the same time insignificant alterations in v(m) were found in the middle cerebral artery for both acupuncture methods. The eight laserneedles used in this study were arranged at the end of the optical fibres. Each fibre was connected to a semiconductor laser diode emitting at 685 nm with a primary output power of about 55 mW. Optical stimulation using properly adjusted laserneedles has the advantage that the stimulation can hardly be felt by the patient and the operator may also be unaware of whether the laserneedle system is active, and therefore true double blind studies in acupuncture research can be performed.

Traditional hair-removal techniques have included shaving, waxing, chemical depilation, and electrolysis. All of these methods result in temporary hair removal. The theory of selective photo thermolysis led to the development of a variety of different laser systems. These lasers range from the short end of spectrum, with the 694-nm ruby laser, to the middle, with the 755-nm alexandrite and 810-nm diode lasers, and to the long end with the 1,064-nm Nd:YAG laser. We made a systematic review on the clinical trials with use of various laser sources for hair removal, so all clinical trials related to hair removal lasers in 1998-2003 were considered after elimination of heterogenite sources in data store. Trial results were synthetized on the basis of kind of laser. Our study clarified that hair reduction at least 6 months after the last treatment and hair reductions were 57.5, 42.3, 54.7, and 52.8% after three sessions for diode, Nd:YAG, alexandrite and ruby, respectively. We compared the result with use of analysis of variance method (Scheffes) and double comparison with use of Student's t test. Our results clarified that diode laser is the most effective, and Nd:YAG has the least effect of hair removal.It seems that diode and alexandrite lasers are proper for hair removal, but as we need high fluence in the darker skin types and this is accompanied with higher complications, diode is advised for lighter skin, and we advised alexandrite laser for darker skin types. [ABSTRACT FROM AUTHOR]

Esthetics is an important factor for patients seeking orthodontic treatment, and not always is the orthodontist able to make adjustments on the gingival contour, and this aspect is neglected. Many orthodontists are familiar with the name laser. However, there is a lack of information regarding their application on the orthodontic practice. There are several options for the use of CO(2) lasers on surgical procedures of interest to orthodontists, especially on soft tissues. There is no evidence that the use of the CO(2) laser has any side effect or contraindication on surgical procedures. This paper reports a series of surgical procedures carried out on orthodontic patients. It is concluded that the carbon dioxide laser not only allows surgeons to enhance current surgical options for treatment but also have contributed to the evolution of a variety of new procedures that are now commonplace in oral surgery, and its use shows several benefits for the orthodontic patient. [ABSTRACT FROM AUTHOR]

Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The original article can be found online at https://doi.org/10.1007/s10103-023-03865-4. [Extracted from the article]

Laser therapies have been well-established in ameliorating skin-aging consequences. This systematic review aims to determine the efficacy, safety profile, and satisfaction rates of laser combination therapies on skin rejuvenation resurfacing. A systematic search was performed in four major databases up to September 2022. Skin rejuvenation studies were eligible comprising at least one laser combination arm, inclusive of all laser types (ablative or non-ablatives), and one monotherapy arm selected from one of the combined modalities. Studies combining one laser modality with radiofrequency (RF) or intense pulse light (IPL) were also assessed. Trials that did not encompass a monotherapy control arm were evaluated independently as single-arm studies. Eighteen clinical trials recruiting 448 cases were included after screening. A total of 532 nm KTP + 1064 nm Nd:YAG and 2940 nm Er:YAG + Nd:YAG were the two most utilized laser combinations and exerted higher improvements and milder adverse events, compared to their monotherapy in most studies. Combining CO2 with rhodamine-IPL or gallium arsenide laser increased efficacy and satisfaction and brings about faster skin recovery time. Augmenting CO2 + RF did not increase improvement vs CO2 laser alone but prolonged skin erythema. Our meta-analysis revealed the pooled prevalence of quartile improvement rates as 0%, 28%, 40%, 27% in laser combination group, and 0%, 9%, 31%, 17% in laser monotherapy group, respectively. The satisfaction within each quartile category was 39%, 25%, 15%, 7% in laser combination and 20%, 25%, 16%, 17% in laser monotherapy, respectively, suggestive of the higher efficacy and satisfaction of laser combination group. The pain scores were lower in laser combination group than monotherapy (4.8 ± 1.18 vs 7.18 ± 0.7, converted on a scale of 0 to 10). Post-laser skin erythema lasted less longer in the combination group (12.8 vs 15.24 days). Laser combination therapies were discovered to be superior to their monotherapies in terms of clinical improvement rates, diminished adverse events such as pain and erythema and patients satisfaction rates. Due to paucity of high-quality reportings, additional trials are warranted to corroborate these results. [ABSTRACT FROM AUTHOR]

Thermal effects during bone surgery pose a common challenge, whether using mechanical tools or lasers. An irrigation system is a standard solution to cool the tissue and reduce collateral thermal damage. In bone surgery using Er:YAG laser, insufficient irrigation raises the risk of thermal damage, while excessive water lowers ablation efficiency. This study investigated the potential of optical coherence tomography to provide feedback by relating the temperature rise with the photo-thermal expansion of the tissue. A phase-sensitive optical coherence tomography system (central wavelength of λ=1.288 μm, a bandwidth of 60.9 nm and a sweep rate of 104.17 kHz) was integrated with an Er:YAG laser using a custom-made dichromatic mirror. Phase calibration was performed by monitoring the temperature changes (thermal camera) and corresponding cumulative phase changes using the phase-sensitive optical coherence tomography system during laser ablation. In this experiment, we used an Er:YAG laser with 230 mJ per pulse at 10 Hz for ablation. Calibration coefficients were determined by fitting the temperature values to phase later and used to predict the temperature rise for subsequent laser ablations. Following the phase calibration step, we used the acquired values to predict the temperature rise of three different laser-induced cuts with the same parameters of the ablative laser. The average root-mean-square error for the three experiments was measured to be around 4 °C. In addition to single-point prediction, we evaluated this method's performance to predict the tissue's two-dimensional temperature rise during laser osteotomy. The findings suggest that the proposed principle could be used in the future to provide temperature feedback for minimally invasive laser osteotomy. [ABSTRACT FROM AUTHOR]

Implantable central venous (CV) ports are widely used for chemotherapy and parenteral nutrition. Generally, CV ports are used safely; however, some patients suffer from drug leakage around the port septum due to mispuncture. Therefore, we developed a CV port that is visible under the skin. We created a prototype of a CV port using a 3D printer. Three red light-emitting diodes (LEDs) were attached around the septum that made the puncture site visible by applying wireless energy transmission technology using electromagnetic resonance. The CV port was implanted under the skin of pork rose meat. The thickness of the skin of pork loin was measured. Fifteen medical doctors participated in the study to visually confirm the lighted CV port. The visibility of the center of the septum with and without lights was scored 0 as non-diagnostic; 1, slightly visible; 2, well visible; and 3, obviously visible. The visibility with or without lights was assessed. The relationship between the years of experience and the visibility score was assessed. The Wilcoxon test was used for statistical analysis. LEDs were easily transmitted through the skin of pork rose meat. The median visibility scores with or without lights were 2 (range, 1–3) and 3 (range, 1–3), respectively (p = 0.005). No significant relationship was found between experience and visibility score (p = 0.289). CV ports with LEDs can be easily recognized compared with those without LEDs. This technique may contribute to medical safety by improving its visibility to avoid mispuncture. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of chitosan on dentin treatment after selective removal of caries lesions with Er:YAG laser in reducing Streptococcus mutans, as well as its effect on the performed restorations. The sample consisted of children (aged 7 to 9 years) with active carious lesions and dentin cavitation located on the occlusal surface of deciduous molars. Eighty teeth were randomly distributed into 4 groups according to the caries removal method: Er:YAG laser (250 mJ/4 Hz) or bur and dentin surface treatment: 2.5% chitosan solution or distilled water. The bacterial load of caries-affected dentin was quantified by counting CFU/mg (n = 10). The teeth were restored and evaluated at 7 days, 6 months, and 12 months using modified USPHS criteria (n = 20). Microbiological data was analyzed by Mann–Whitney and clinical analyses were done using Kruskal–Wallis and Dunn test (α = 0.05). The results showed that the Er:YAG laser significantly reduced the amount of Streptococcus mutans (p = 0.0068). After dentin treatment with chitosan, there was a significant reduction in the amount of Streptococcus mutans for both removal methods (p = 0.0424). For the retention and secondary caries criteria, no significant differences were observed along the evaluated time (p > 0.05). The laser-treated group was rated "bravo" for discoloration (p = 0.0089) and marginal adaptation (p = 0.0003) after 6 and 12 months compared to baseline. The Er:YAG laser reduced the amount of Streptococcus mutans and the chitosan showed an additional antibacterial effect. After 1 year, the Er:YAG laser-prepared teeth, regardless of the dentin treatment, showed greater discoloration and marginal adaptation of the restorations. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the efficacy of fluoride-free remineralizing agents in initial enamel caries, with and without combined Er,Cr:YSGG laser application. The remineralization effect of various agents and their combinations on artificial initial caries was investigated using 10 experimental groups (n = 7): NC, negative control; PC, positive control; TM, calcium-phosphate compounds (CPP-ACP); TD, theobromine-containing toothpaste; RG, ROCS® remineralizing gel; L, Er,Cr:YSGG laser (2780 nm; 0.25 W; repetition rate, 20 Hz; pulse duration, 140 μs; tip diameter, 600 μm; without air/water cooling); L + fluoride toothpaste; L + TM; L + TD; and L + RG. The demineralized bovine enamel specimens were subjected to an 8-day pH cycle by daily application of the remineralizing agents and laser therapy once prior to the pH cycle and paste application. The enamel samples underwent the Vickers surface microhardness test, and one sample per group was analyzed with scanning electron microscopy. The Kruskal Wallis test was used to compare the microhardness recovery percentage (SMHR%) for each group, and multiple comparisons were made with the Dunn test. Groups L (p = 0.003), RG (p = 0.019), L + TM (p < 0.001), L + fluoride toothpaste (p = 0.001),and L + RG (p = 0.036) exhibited significant increase in SMHR%. The tested remineralizing agents exhibited no statistically significant difference in effect when used alone and in combination with Er,Cr:YSGG laser. Combined application of Er,Cr:YSGG laser and ROCS® remineralization gel effectively promoted enamel remineralization, while use of CPP-ACP and fluoride toothpaste alone was ineffective. Theobromine-containing toothpaste exhibited the least SMHR%. Long-term evaluation of these agents is recommended. [ABSTRACT FROM AUTHOR]

The photothermal effect is one of the most promising photonic procedures currently under development to successfully treat several clinical disorders, none the least some kinds of cancer. At present, this field is undergoing a renewed interest due to advances in both photothermal materials and better-suited light sources. However, scientific studies in this area are sometimes hampered by the relative unavailability of state-of-art materials or the complexity of setting up a dedicated optical facility. Here, we present a simple and affordable approach to do research in the photothermal field that relies on a commercial NIR laser pointer and a readily available everyday pigment: China ink. A proof-of-concept study is presented in which mice bearing intradermal LM3 mammary adenocarcinoma tumors were successfully treated in vivo employing China ink and the laser pointer. TUNEL and Ki-67 post-treatment tissue assessment clearly indicates the deleterious action of the photothermal treatment on the tumor. Therefore, the feasibility of this simple approach has been demonstrated, which may inspire other groups to implement simple procedures to further explore the photothermal effect. [ABSTRACT FROM AUTHOR]

This paper describes the ablative effect of argon laser light, delivered fibre optically in vitro, on 234 segments of atherosclerotic human aorta. Variables such as energy density, type of atheroma and immersion media were taken into account. All irradiated specimens were subsequently submitted to histological examination and crater volumes in mm were derived from micrometer measurements made at light microscopy. Results showed: (1) a linear relationship between energy dose and crater volume in fibrous atheroma; (2) significantly greater surrounding tissue damage in the higher energy dose groups; (3) a lower dose response in calcified tissue than in fatty streaks or fibrous atheroma; (4) immersion of tissue in blood during ablation resulted in a significantly greater dose response than immersion in plasma or saline, and the corresponding surrounding tissue damage was greatest under blood. Thus, argon laser light is both effective and predictable in response when ablating atheromatous tissue, and the efficiency of the process depends on the immersion medium. The degree of surrounding tissue damage depends on the energy dose. [ABSTRACT FROM AUTHOR]

This article reports on the results of a project evaluating effectiveness and cost-effectiveness of laser applications in health care. The literature was collected, emphasizing well-designed clinical trials and cost-effectiveness analyses. Few randomized clinical trials (RCTs) have been done outside the specialty of ophthalmology. Even fewer cost-effectiveness studies have been done, despite the frequent claims of cost-effectiveness in the medical literature. Review papers were commissioned, and a group of laser experts, economists, and policy-analysts met for 2 days to discuss the policy implications of lasers. The main conclusion from the conference is that inappropriate and unskilled use of lasers is presently the greatest problem with their application in health care. [ABSTRACT FROM AUTHOR]