Journal of lasers in medical sciences最新文献

Introduction: Photodynamic therapy(PDT)is a minimally invasive technique increasingly used in dentistry for its antimicrobial properties. This research aimed to evaluate the influence of photodynamic therapy (PDT) on the viability of dental pulp stem cells (DPSCs). Methods: In this laboratory-based, experimental study, DPSCs were cultured in Dulbecco's modified Eagle's medium and maintained at 37 °C. The cells were separated into five groups: Toluidine blue (TBO) at concentration of 0.1 mg/mL and 0.5 mg/mL, as well as methylene blue (MB) at concentrations of 0.01 mg/mL and 0.05 mg/mL were added to the wells in groups 1 to 4. The fifth group served as the control group. After 5 minutes of incubation, the experimental groups were irradiated with Fotosan® light-emitting diode (LED) for one minute. Cell viability was assessed after 8, 24, 48, and 72 hours using the methyl thiazolyl tetrazolium (MTT) assay. Results: Time (P<0.000), photosensitizer type/concentration (P<0.0001), and their interaction effect (P<0.000) on cell viability were all significant. Viability in both MB groups was considerably higher than that in the control group at 8 hours (P<0.001). At 24 hours, no significant difference was observed between the experimental groups and the control (P>0.05). At 48 and 72 hours, cell viability in the TBO groups was markedly lower compared to the control group (P<0.01). Conclusion: PDT with MB at the tested concentrations had no adverse effect on DPSCs even in the long- term (48 and 72 hours).

Introduction: White spots are a common complication of orthodontic treatment. Several prevention methods such as fluoride therapy and laser irradiation have been proposed, but there is still no conclusive evidence. Therefore, this study aimed to evaluate the combined application of diode laser and fluoride varnish in preventing white spots. Methods: Thirty-nine sound human premolars were extracted for orthodontic purposes and randomly divided into three groups of thirteen teeth each (C: Control, FV: fluoride varnish (5% sodium fluoride), and FV+L: fluoride varnish+980 nm diode laser (2 W)). The freshly extracted teeth were disinfected in a 0.5% chloramine T solution and stored in saline at room temperature. Each tooth was coated with nail polish, leaving a 2×3 mm² window on the midbuccal. Surface treatments were applied, and primary Vickers microhardness was evaluated in the gingival sections. Then, the samples were immersed in alternating demineralizing (6 hours/day) and remineralizing (18 hours/day) solutions and incubated at 37 °C for 9 days to produce artificial caries. Afterward, the samples were immersed in a remineralizing solution for one day. Finally, secondary microhardness was measured. The data were analyzed using one-way ANOVA. Results: The primary microhardness was higher in groups C and FV than in group FV+L. The lowest secondary microhardness was recorded in group C, and there was no significant difference between the other two groups. The change in microhardness was greater in group C, while no difference was observed between the FV and FV+L groups. Conclusion: Within the limitations of this study, the combined application of laser irradiation and fluoride varnish may not improve white spot lesion (WSL) prevention compared to the use of fluoride varnish alone.

Introduction: The relapse of rotated teeth is a significant concern in orthodontics, and circumferential supracrestal fiberotomy (CSF) presents a potential solution. Traditionally, CSF is performed using a surgical blade; however, employing a laser may reduce complications. This study aimed to systematically review the literature comparing laser-assisted CSF with conventional methods in orthodontic patients. Methods: A comprehensive search was conducted across the PubMed, Scopus, Web of Science, and Cochrane Library databases using a specific search strategy up to June 16, 2024. Data extraction was done in accordance with the defined inclusion and exclusion criteria. Results: Initially, a total of 293 articles were identified through the search process, and ultimately, four were selected for analysis based on specific inclusion and exclusion criteria. The studies involved various types of lasers including diode (810 to 940 nm), Er:YAG, and Er,Cr:YSGG lasers, and examined the effects of low-level laser therapy (LLLT) in conjunction with surgical interventions. Regarding relapse rates, two studies reported that both laser and surgical blade techniques demonstrated comparable efficacy, while adjunctive LLLT was effective in reducing relapse. In the other two studies, the use of laser therapy was found to be effective in decreasing relapse rates compared to the control group. Pain assessment results were inconclusive; one study reported reduced pain in the laser group, while another found no significant difference in pain levels between the laser and blade techniques. Furthermore, no significant differences were observed in periodontal pocket depth or gingival recession between the two methods. Conclusion: Within the limitations of the current systematic review, our findings indicate that there is no significant difference in relapse rates between laser and blade CSF procedures. Furthermore, our results suggest that the incorporation of photobiomodulation at higher doses is correlated with a reduction in relapse rates following fiberotomy procedures.

Introduction: Photodynamic therapy (PDT) is a photochemical treatment that involves the use of light and photosensitizer. This method is applied as a therapeutic approach against several types of cancer. The main aim of this study is to compare the efficacy of PDT with that of cisplatin (a well-known chemotherapy agent) through protein-protein interaction (PPI) network analysis. Methods: Gene expression profiles of human melanoma A375 cells from the Gene Expression Omnibus (GEO) were selected for analysis via directed PPI network analysis. The significant differentially expressed genes (DEGs) were identified and assessed based on co-expression interactions. The critical DEGs were introduced by considering out-degree and in-degree values. Results: Two directed PPI networks for upregulated and downregulated DEGs were constructed. TP53 was identified as a critical upregulated gene in response to cisplatin in comparison with PDT. EGFR, PPARG, MMP9, PTGS2, FOXO1, and RUNX2 were highlighted as the crucial downregulated genes due to the effect of cisplatin on the gene expression of the treated cells. Conclusion: Cisplatin directly targets key cellular functions such as cell growth, differentiation, migration, and invasion. It seems that the combination of cisplatin and PDT is a suitable method for treating cancers because cisplatin targets the key genes responsible for cancer development, while PDT intensifies the effect of cisplatin and reduces its side effects.

Introduction: This study aimed to compare the effects of high-intensity laser therapy (HILT) and low-level laser therapy (LLLT) on the disability and architecture of the quadriceps in patients with knee osteoarthritis (OA). Methods: Ninety-eight patients with knee OA (KOA) were selected by convenience sampling and then divided into three groups: control, LLLT and HILT. Disability was determined using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Quadriceps structures including thickness, fascicle length and pennate angle of the vastus lateralis (VL) and thickness, volume and fiber angle of vastus medialis obliquus (VMO) muscles were assessed using ultrasonography. All evaluations were performed before interventions, immediately after interventions, and one month later. Between-group data were analyzed with two-way ANOVA and paired-samples t-test. Results: The within-group comparisons of WOMAC scores before, after and at a one-month follow-up showed significant differences between the groups (P<0.001). The VMO thickness revealed significant increases after the treatment in both HILT (P<0.001) and LLLT (P=00.03) groups. The between-group comparison revealed a significantly lower score of WOMAC in the HILT group compared to the other groups after a one-month follow-up (P=00.03). VMO thickness showed a significant increase in the HILT group after the treatment (P=0.002). The VL structures and VMO fiber angle and volume did not exhibit significant changes in within-group and between-group comparisons (P>00.05). Conclusion: Both HILT and LLLT may improve functional ability and VMO thickness in patients with knee osteoarthritis. After a one-month follow-up, functional ability was greater in the HILT group.

Introduction: Photoacoustic imaging (PAI) uses nonionizing radiation for tumor features and thus can be used as an alternative method for medical features without inducing biological effects. The study aimed to characterize a PAI system utilizing a 650-nm diode laser to detect pathological conditions (benign and malignant tumors) in human uterine tissue, including healthy tissue. The benign tumor tissue used is a leiomyoma, which is a benign tumor that occurs in the middle layer of the uterine (myometrium). Meanwhile, the malignant tumor tissue used is a type of endometrial carcinoma, which is a malignant tumor that occurs in the inner layer of the uterine (endometrium). Methods: The human uterine tissue was obtained from the hysterectomy procedure conducted to determine the histopathological diagnosis. The PAI system uses a condenser microphone as the acoustic signal detector and a diode laser as the radiation source. Results: The characterization results of the PAI based on a diode laser with a wavelength of 650 nm and power of 250 mW showed an optimal performance for human uterine tissue in a laser modulation frequency of 16500 Hz and a duty cycle of 50%. Obtained photoacoustic images could differentiate between healthy uterine, leiomyoma, and endometrial carcinoma tissues, as indicated by the intensity level values in each tissue type. Healthy uterine, leiomyoma, and endometrial carcinoma tissues had intensity values of 11.87, 26.84, and 37.26 a.u, respectively. A One-way ANOVA test with Bonferroni post hoc analysis revealed a significant difference in the acoustic intensity level between the groups (P<0.05). Conclusion: The resulting intensity levels indicate a direct correlation with the nature of uterine tumors. The poorer the differentiation, the higher the resulting intensity.

Introduction: With an alarmingly growing number of patients diagnosed with colorectal cancer, adopting innovative anti-cancer approaches has recently garnered great attention. One interesting concept is the co-administration of cytotoxic agents and safer modalities such as photodynamic therapy (PDT), which can subsequently improve therapeutic efficacy and potentially reduce the risks of severe adverse effects and drug resistance. In the course of PDT, a locally injected photosensitizer (PS) is irradiated with a light source, which subsequently generates reactive oxygen species (ROS) and induces programmed cell death in tumor cells. Methods: In this study, to evaluate the potential anti-cancer effects of chemotherapy combined with PDT, in comparison to each alone, we employed PDT, comprising methylene blue (MB) and diode lasers at 630 and 810 nm wavelengths, in conjunction with the chemotherapeutic agent doxorubicin (DOX). Results: The MTT assay showed that the viability of colorectal cancer HT-29 cells decreased significantly following DOX+PDT treatment. Similarly, lactate dehydrogenase (LDH) release and lipid peroxidation rates were substantially higher in DOX+PDT treatment groups. Lastly, the catalase (CAT) assay indicated that the combination reduced the ability of CAT in the detoxification of H₂ O₂. Conclusion: Our study suggests that MB-mediated PDT combined with chemotherapy might provide a promising avenue to improve therapeutic efficacy and potentially reduce the risk of adverse effects and drug resistance. Without a doubt, further investigations need to delve into the pharmacological advantages and disadvantages of PTD-based combination therapy and optimize its administered doses along with other modalities.

Introduction: The heat distribution and the resulting thermal damage pattern following the light absorption in tissue can be used for treatment optimization. Besides rejuvenating effects, CO2 fractional-induced microtunnels have recently become a tool for drug delivery. To minimize the unwanted thermal damage in this latter use and to optimize the laser program, we simulated the heat distribution and thermal damage models of CO2 fractional lasers of different sizes, pulse durations, and powers. Methods: COMSOL software is used for simulation. The skin is modeled as three homogeneous layers of epidermis/dermis/hypodermis. The photothermal coefficient of the tissue model and the irradiation laser system (CO2, 10600 nm) are defined as 0.07 mm spot size, 10, 12 and 15 W power range, and 0.5, 10 and 15 ms pulse durations, respectively. Results: Our results show that the power of 10 W with different time pulses creates a better micro-tunnel in the tissue while preventing unwanted injuries. At a power higher than 15 W and 5 pulses, the tissue will be damaged inconsiderably. The fractional laser creates heat only at the desired point of the treatment, and this heat is absorbed through the tissue, and micro-tunnels in it form the tissue. Also, 10 W power with a shorter pulse duration did not have a good effect on the tissue. Instead, by increasing the pulse duration, less damage to the surroundings resulted. Conclusion: Due to the absorbed laser light in tissue and the creation of heat, skin damage as micro-tunnels are caused. The greater distance between the created micro-tunnels indicates better tissue preservation. Also, COMSOL seems to be promising software for preclinical investigations and optimizing laser treatment plans.

Introduction: The treatment of chronic testicular pain is a complex condition that will be encountered by most practicing clinicians. In this study, the influence of low-level laser irradiation of the red and infrared spectral range for treating chronic testicular pain was evaluated and compared. Methods: In this double-blind, placebo-controlled randomized clinical trial study, 60 patients were randomly divided into three groups of 20: (1) low-level laser group with red (650 nm, 50 mW), (2) low-level laser group with infrared (820 nm, 100 mW) and (3) laser placebo group. The treatment protocol consisted of 15 minutes, three times a week, for only 12 sessions. Then the patients were evaluated for pain and sexual satisfaction during the follow-up. Results: There was a significant reduction in the pain score in the two groups of the low-level laser group with red (650 nm, 50 mW) and the low-level laser group with Infrared (820 nm, 100 mW) spectra compared with the control, at 6 and 12 weeks after the treatment (P<0.05). Also, the level of sexual satisfaction in the two groups of low-power laser with red and infrared spectra showed a significant improvement (P<0.05). Conclusion: Low-level laser therapy is a safe, noninvasive, and useful method for treating patients with chronic testicular pain. Therefore, red (650 nm, 50 mW) and Infrared (820 nm, 100 mW) spectra low-level laser therapies improve testicular pain and sexual satisfaction.

Introduction: Gingival depigmentation with the help of lasers is known as an effective technique. The aim of this study was to compare the efficiency of 980nm diode and CO2 lasers in the treatment of gingival hyperpigmentation. Methods: In this clinical trial study, 14 individuals (8 females and 6 males) with the age range of 19 to 47 years were selected. One quadrant was randomly treated with CO2 laser (10600 nm, non-contact, super pulse mode) and the opposite quadrant was treated with a diode laser (980 nm, continuous wave [CW], 1.5 W). The area of the pigmented region, Dummett oral pigmentation index (DOPI), the amount of changes in the RGB parameter (red, green, blue) and ΔE* in clinical photographs before, one and three months after the treatment were calculated by ImageJ and Photoshop software. Pain and discomfort were assessed one hour, one day and one week later by the visual analogue scale (VAS). In addition, after 3 months, the cosmetic results achieved for the different therapeutic approaches were evaluated by patients and professional evaluator. Data were analyzed by the paired samples t test, repeated measures ANOVA and Wilcoxon test. Results: The results of this study showed that the duration of CO2 laser treatment was statistically and significantly shorter than the time of 980-diode laser treatment (P<0.05). There were no statistically significant differences in the pigmented lesion area (P>0.05), RGB parameter (P>0.05), DOPI index (P>0.05) and ΔE parameter (P>0.05) in one month and three months after treatment follow-ups between the two types of lasers. There was no statistically significant difference in patient satisfaction (P>0.05) and professional evaluation (P>0.05) between the two groups of lasers. Post-treatment pain scores were not statistically significant between the two groups. Conclusion: Both 980-nm diode laser and 10600-nm CO2 are effective in the treatment of gingival depigmentation while CO2 laser radiation with super pulse mode is faster in terms of operating time. While working with the diode laser is more controllable. Trial Registration Number: IRCT20200309046728N1; https://irct.behdasht.gov.ir/.