Journal of Lasers in Medical Sciences

Introduction: Diverse microbiotas which have some contributions to gene expression reside in human skin. To identify the protective role of the skin microbiome against UV exposure, protein-protein interaction (PPI) network analysis is used to assess gene expression alteration.

Methods: A microarray dataset, GEO accession number GSE117359, was considered in this respect. Differentially expressed genes (DEGs) in the germ-free (GF) and specific pathogen-free (SPF) groups are analyzed by GEO2R. The top significant DEGs were assigned for network analysis via Cytoscape 3.7.2 and its applications.

Results: A total of 28 genes were identified as significant DEGs and the centrality analysis of the network indicated that only one of the seven hub-bottlenecks was from queried genes. The gene ontology analysis of Il6, Cxcl2, Cxcl1, TNF, Il10, Cxcl10, and Mmp9 showed that the crucial genes were highly enriched in the immune system.

Conclusion: The skin microbiome plays a significant role in the protection of the skin against UV irradiation and the role of TNF and IL6 is prominent in this regard.

Introduction: Enterococcus faecalis is a resistant bacterium which is the most abundant species in infected root canals. Photodynamic therapy (PDT) is a method for killing the bacteria with active Oxygen radicals generated in a photosensitizer when exposed to centralized light. Furthermore, as a new method of canal disinfection, a variety of irrigation activation systems have been introduced, one of which is GentleFile (GF) with rotary movements and spiral effects for antibacterial action. This study aimed to compare the effectiveness of the two mentioned methods when used with and without Sodium Hypochlorite in eliminating E. faecalis from infected root canals.

Methods: Fifty-eight uniradicular teeth were randomly divided into 4 experimental groups of 14. Two specimens were selected for later scanning electron microscopy in order to screen the procedure steps. In each experimental group, 10 samples were selected to be treated with GF or PDT; 3 of them were selected as positive controls and the other one sample was chosen as a negative control. Experimental groups were as follows: (1) Irrigation activation system, (2) Irrigation activation system + sodium hypochlorite, (3) PDT, and (4) PDT+ sodium hypochlorite. The specimens were then cultured for a bacterial colony count.

Results: The decrease in the bacterial count after the treatment with the irrigation activation system was 99.8% (P = 0.011) and when the system was used with sodium hypochlorite, it was 100% (P = 0.001). The antibacterial effect of PDT was 90.08% (P = 0.011) and it was 99.7% when PDT was combined with sodium hypochlorite (P = 0.011).

Conclusion: All four methods can be administered as complementary methods in root canal disinfection. According to the results of disinfection in the experimental groups of current study it is concluded that integration of new technologies such as activation irrigation system or PDT in Combination with NaOCl ameliorates disinfection of root canal and can provide several advantages in the endodontic outcome.

Introduction: This double-blind, placebo-controlled, clinical trial aimed to investigate the analgesic efficacy of low-level laser therapy (LLLT) with two different locations, and their comparison, in postoperative endodontic pain (PEP) levels in molars diagnosed with symptomatic irreversible pulpitis.

Methods: Seventy-five patients with a molar tooth, diagnosed with symptomatic irreversible pulpitis, were divided into three groups of placebo, buccal only irradiation (BI), and buccal and lingual irradiation (BLI), with 25 cases being in each group. The participants received similar singlevisit nonsurgical endodontic treatments. Then, a sham laser was used in the control group instead of LLLT. Individuals in BI and BLI groups received 80-second irradiation on the buccal surface and 80-second irradiation on each of the buccal and lingual surfaces respectively. A laser with an 808 nm wavelength, power of 100 mW, a fiber diameter of 600 μm, and a dose of 70 J/cm2 was used. PEP was assessed using a 0-100 mm VAS 4, 8, 24, and 48 hours after the treatment.

Results: BLI showed a significantly higher reduction of PEP compared to placebo in all time intervals of this study. BLI was significantly more effective than BI 8 hours after the treatment. However, intragroup differences between BLI and BI groups at other time intervals and between BI and placebo groups in all time intervals were not significant. The number of taken analgesics in the BLI group was significantly lower than the placebo group and was on a statistical borderline compared to the BI group.

Conclusion: LLLT with BLI was an effective measure as a supplement to oral analgesics in the reduction of PEP compared to the placebo.

Introduction: The axillary hair removal laser is one of the most often used procedures to treat unwanted hairs in that region. Employing this technology can be helpful in decreasing the bromhidrosis.

Methods: In the present research, a clinical trial study over the effect of the hair removal laser on normal microbial flora at the axillary region is presented. The intervention group consisted of 30 women referred to the dermatologic clinic for the purpose of removing axillary hair by the alexandrite 755 nm laser and the control group consisted of 30 women referred to the same clinic for any other reasons. Both groups were evaluated for the type of bacterial strains on the first visit and after three and six months.

Results: The results showed that the sense of sweat smell improved by about 63% after the last laser session. The frequency of all bacterial strains decreased in the intervention group except Staphylococcus epidermidis which was significant. In the control group, there was no significant decrement in any bacterial strains and even the prevalence of more strains including Staphylococcus aureus and S. epidermidis increased. Counting the mean bacterial colon showed a slight decrement of the bacterial count following the laser.

Conclusion: The use of laser radiation, even with the aim of hair removal, can alter the microbial flora, and it can be accompanied by the improvement of the smell of sweat. The effect of the laser on different bacterial strains is quite different, which can depend on the amount of energy, the wavelength, the characteristics of the area under the laser, and also the structural properties of the membrane of the microorganism itself.

Introduction: This experimental study investigated the mRNA expression of aquaporins (AQPs) 1 and 5 in the parotid glands of rats irradiated with volumetric modulated arc therapy (VMAT) and subjected to low-level laser therapy (LLLT) at different time points.

Methods: The sample consisted of 30 Wistar rats (Rattus norvegicus) divided into the following groups: control, LLLT alone (LG), radiotherapy alone (RG), and experimental groups that received LLLT at 24 hours (early experimental group [EEG], n=12) and 120 hours (late experimental group [LEG], n=12) after radiotherapy. VMAT was delivered at a single dose (12 Gy) and LLLT was performed with an aluminium-gallium-arsenide diode laser (660 nm, 100 mW), spot area of 0.0028 cm2, energy of 2 J/cm2 applied to 3 spots in the region corresponding to the right parotid gland, for 10 consecutive days. The right parotid gland was resected and prepared for RNA extraction. The gene expression of AQPs was evaluated by quantitative polymerase chain reaction (qPCR) using specific TaqMan probes, with the HPRT gene as an internal control.

Results: The lowest AQP1 gene expression was 0.83 (0.27) with the use of LLLT 24 hours after radiotherapy (EEG), and the highest was 1.56 (0.80) with the use of LLLT alone (LG). Likewise, the lowest AQP5 gene expression was found in the EEG (mean = 0.88; SD = 0.49) and the highest in the LG (mean = 1.29; SD = 0.33).

Conclusion: The use of LLLT after radiotherapy may contribute to the maintenance and an increase of these proteins, even when used at a later time point after radiotherapy.

Introduction: Tooth hypersensitivity is among the most common patient complaints caused by the response of exposed dentin to external stimuli. No definite treatment has been suggested so far for dentin hypersensitivity (DH). This study aimed to compare the efficacy of the diode laser alone and in combination with Gluma and chromophore in occluding opened dentine tubules and the treatment of DH.

Methods: This in vitro study was conducted on 30 extracted human third molars kept in 0.1% thymol solution. The teeth were mounted in transparent acrylic resin and the buccal enamel was cut to expose the outer third of dentin. The samples were then divided into 6 groups of negative control (no smear layer removal), positive control (smear layer removal with 6% citric acid application), 810 nm diode laser irradiation (energy density 55.55 J/cm2, 1 W for 20 seconds in a continuous mode), chromophore (1 mg/mL indocyanine green, ICG) plus diode laser irradiation (1 W, 20 seconds), Gluma plus diode laser irradiation, and Gluma + chromophore + diode laser. Dentinal tubules were evaluated under a scanning electron microscope at x2000 magnification. The mean percentage of the obstruction of dentinal tubules was reported as mean and standard deviation. Considering the normal distribution of the data, two-way ANOVA was applied to compare the efficacy of treatments, and an independent-samples t test was used for pairwise comparisons at P<0.05 level of significance.

Results: The highest mean percentage of the obstruction of dentinal tubules was noted in the diode laser/chromophore/Gluma group (65.68±12.31%) while the lowest value was noted in the diode laser/Gluma group (24.33±5.90%). Pairwise comparisons revealed significant differences between all groups (P < 0.05) except for the difference between the laser/Gluma/chromophore and laser/chromophore groups (P = 0.20).

Conclusion: It seems that chromophore increases the efficacy of the diode laser for the obstruction of dentinal tubules.

Introduction: This study aimed to determine the effect of low-level laser therapy (LLLT) on reducing complications following tooth extraction.

Methods: This randomized clinical trial consisted of 40 subjects who underwent lower molar extraction. The patients were randomly assigned to 4 groups. Group 1 was irradiated with a 660 nm laser (200 mW, 30 seconds radiation to lingual, buccal and occlusal surfaces of the socket, 6 J/area). In group 2, an 810 nm laser was applied similar to group 1. In group 3, a combination of 660 and 810 nm lasers was used. The patients in group 4 served as a placebo group. LLLT was performed after 0.5-1 hour of extraction and 2 days later. The participants were asked to record pain degree using a visual analogue scale (VAS) over 7 days. The amount of wound healing was evaluated on the third and seventh days.

Results: There was no significant difference in pain scores among the groups at any of the assessment intervals (P > 0.05). The between-group differences in wound healing scores were small and insignificant (P > 0.05).

Conclusion: LLLT with 660 nm or 810 nm lasers or their combination had no greater effect than the placebo laser for reducing the complications of tooth extraction.

Introduction: Photobiomodulation (PBM) is known as low-level laser (or light) therapy and is applied in different fields of medicine. However, it is required that its molecular and cellular mechanism be investigated. This study aims to assess the neuroprotective properties of PBM in the rat retina.

Methods: GSE22818 was downloaded from Gene Expression Omnibus (GEO) and the regulation of the significant differentially expressed genes (DEGs) which are produced by light damage in the rat retina by the pretreatment of PBM application was assessed via network analysis and gene ontology enrichment.

Results: The 78 produced DEGs by light-damage in the rat retina were protected via PBM pretreatment action. Among these determined DEGs, 53 individuals were included in the main connected component of the constructed protein-protein interaction (PPI) network. Ccl2, Icam1, Cxcl10, Timp1, and Fos were determined as hub nodes. Eight clusters including 26 regulated biochemical pathways by PBM pretreatment were identified. The critical DEGs based on the action maps were introduced.

Conclusion: The finding indicates that PBM treatment protects rat retina against light damage via the prevention of Fos, Ccl2, Icam1, Cxcl10, and Myc dysregulation.

Introduction: In recent decades zirconium oxide has been introduced in the field of dentistry as a high-strength ceramic. Unlike its mechanical advantages, however, due to its inert chemical properties, it bonds poorly to other substrates, so improving bonding strength to an adhesive material is necessary.

Methods: In this experimental study, 70 ceramic zirconia blocks were prepared and distributed randomly among 7 groups. Then the shear bond strengths were determined and the samples were examined by a scanning electron microscope (SEM). Statistical analysis was performed by one-way ANOVA and multiple Tukey comparisons.

Results: One-way analysis of variance (ANOVA) showed that laser irradiation distance has a significant effect on orthodontics brackets bond strength to zirconia-ceramics. Based on the Tukey post hoc test, each group was compared with other groups and the contact mode and 2 mm distance groups showed significantly higher bond strength than other groups (P-value <0.05).

Conclusion: Orthodontic bracket bond strength to zirconia-ceramics will be reduced by increasing Er: YAG laser irradiation distance from samples. The highest bond strength will be achieved when the laser irradiation distance is 2 mm or when the laser beam is in contact with samples.

Introduction:

Sexual dysfunction is a complex problem in postmenopausal women with a prevalence rate of 68 - 86 %. This study aimed to evaluate the effect of a fractional CO2 laser or vaginal cream on the improvement of sexual function in menopausal women.

 Methods:

This is a two-group clinical trial study.   Postmenopausal women with the inclusion criterion were enrolled and randomly divided into two groups of intervention (n=25) and control group (n=25). In the intervention group, the CO2 laser therapy was performed every month for three months, and in the control group, Premarin vaginal cream was applied (0.625 mg  )، 1 gr, three nights a week for 3 months. Vaginal Health Index scoring( VHI)  and Female Sexual Function Index( FSFI) questionnaires were completed before and after three months of treatment.

Results:

The effects of the laser treatment was greater than the Premarin group with respect to improvement in sexual desire, orgasms, sexual satisfaction, less pain during sexual relations, and overall sexual function. ( P<0.05)

Conclusion:

It seems that the fractional CO2 laser may be more effective than hormonal therapy in improving sexual function in postmenopausal women.

Introduction: Parkinson’s disease (PD) is one of the most common neurodegenerative disorders. The neuroinflammation in the brain of PD patients is one of the critical processes in the immune pathogenesis of PD leading to the neural loss in the substantia nigra. Due to the anti-inflammatory effects of curcumin (CU) and low-level laser therapy (LLLT), we examined the protective effect of CU and LLLT on PC12 cells treated with 6-hydroxydopamine (6-OHDA) as a Parkinson model.

Methods: PC12 cells were pretreated using various concentrations of 6-OHDA for 24 hours to induce oxidative and cellular damages. PC12-6-OHDA cells were co-treated with CU and LLLT. The effects of CU and LLLT on Bax/Bcl2 and LC3/ATG10 expression were analyzed by real-time PCR and cell viability was assessed by MTT assay. Cell A Software was used to calculate the length of the Neurite and cell body areas.

Results: The results of this study show that the combination of CU dose-dependently and LLLT has a significant neuroprotective effect on cells and cellular death significantly decreases by increasing CU concentration. CU+LLLT decreases Bax/Bcl2 ratio which is an indicator of apoptosis and it also rescued a decrease in LC3 and ATG10 expression in comparison with 6-OHDA group.

Conclusion: This study shows that the combination of 5 μM CU and LLLT has the best neuroprotective effect on PC12 cells against 6-OHDA by decreasing the BAX/BCL2 ratio.

Introduction: Urinary stone disease is the third most common affliction of the urinary tract that has been associated with an increasing incidence. Over decades, great advances have been made in the minimally invasive treatment of urinary stones. Recently, transurethral lithotripsy (TUL) by holmium laser was introduced as a possible therapeutic option. This study evaluated the effect of propofol on the success rate of TUL by holmium laser.

Methods: A double-blind randomized controlled trial was conducted on 180 patients to investigate the effect of propofol on the success and complication rate of TUL by holmium laser. The enrolled patients were divided into two groups: the first group received sodium thiopental (n = 89) while the second group received propofol (n = 91). The two groups were compared in terms of the fluctuations of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), operation time, future stone-free rate (SFR), stone migration, post-operative fever, and ureteral complications such as perforation and mucosal damage. Other developed complications were also recorded. After data gathering, statistical analysis was performed with SPSS version 21.

Results: the patients’ data such as age, sex, stone diameter, stone laterality, duration of stone impaction, primary SBP, DBP and HR were not significantly different between the two groups (P > 0.05). TUL and anesthesia duration, first-minute and fifth-minute SBP and DBP, and also changes of HR were significantly lower in the propofol group compared with the sodium thiopental group (P < 0.001). Moreover, SFR of TUL was more evident in the propofol group. Ureteral mucosal damage was significantly less in the propofol group.

Conclusion: Propofol was associated with a higher reduction in SBP and DBP, decreased duration of TUL, fewer fluctuations in HR, and an increased success rate of stone removal by TUL with holmium laser.

Introduction: The most common causes of the abrupt onset of unilateral facial weakness are stroke and Bell’s palsy. The drug regimen plus electrical stimulation was more effective in treating Bell’s palsy than conventional drug treatment alone. We aimed to evaluate more effective and safe for the treatment of Bell’s palsy.

Methods: This clinical interventional study was conducted on 30 diabetic patients with Bell’s palsy who presented to pain clinic over one year and were treated by low-level laser. The system of House- Brackmann was used for the severity of damage and patients were evaluated by electromyography and nerve conduction velocity before and after treatment of low-level laser. These patients did consume any other medication for facial nerve palsy.

Results: In the present study, 30 cases with poor control diabetes mellitus (18females, 12 males) were studied. After 12 sessions of low-level laser therapy, we could observe complete recovery in 18 patients and partial recovery in 6 patients after 3months.

Conclusion: Recovery rate showed us that LLLT is a safe, reliable, and proper alternative approach to the treatment of facial nerve palsy especially in the presence of underlying conditions such as diabetes mellitus.

In the field of endodontics, lasers have been used for a long time for the optimization of Endodontic irrigation in particular. The laser-activated irrigation (LAI) technique is based on the photomechanical effects of the lasers at low settings. They create specific cavitation phenomena and acoustic streaming in intracanal fluids. More recently, a new technique with a Er:YAG laser has been used with sub-ablative energy (20 mJ, 15 Hz) and ultra-short pulses (50 μs). This leads to intracanal cavitation and shockwaves as a result of photoacoustic and photomechanical effects. This phenomenon is called photon-induced photoacoustic streaming (PIPS). PIPS and Laser activated irrigation are described in the literature as a revolutionary and powerful method to activate the irrigant; however, systematic literature on this topic is missing. This review compares the literature on Er:YAG LAI and PIPS on endodontic irrigation with other irrigation methods. An article search was performed on the PubMed database using a series of keywords related to endodontic irrigation, including Er:YAG LAI and PIPS; 59 articles were selected for the review according to the inclusion and exclusion criteria. No in vivo study was found. The Er:YAG LAI and PIPS outperformed other methods in 33 of the 59 articles. There was a great variety in the study designs including bacterial incubation time, laser parameters, irrigation protocols, and irrigating solution used. The evidence suggests that the Er:YAG LAI and PIPS are promising in canal disinfection as well as debris and smear layer removal. However, the large variety in the study methods makes the results less significant. Further studies are needed to better evaluate the efficiency of these techniques, especially in vivo studies.

Introduction: The aim of the study was to perform a literature review to analyze the effect of photobiomodulation in experimental studies on peripheral nerve regeneration after sciatic nerve crush injury in rodents.

Methods: A bibliographic search was performed in the electronic databases, including MEDLINE (PubMed), SCOPUS, and SciELO, from 2008 to 2018.

Results: A total of 1912 articles were identified in the search, and only 19 fulfilled all the inclusion criteria. Along with the parameters most found in the manuscripts, the most used wavelengths were 660 nm and 830 nm, power of 30 and 40 mW, and energy density of 4 and 10 J/cm2. For total energy throughout the intervention period, the lowest energy found with positive effects was 0.70 J, and the highest 1.141 J. Seventeen studies reported positive effects on nerve regeneration. The variables selected to analyze the effect were: Sciatic Functional Index (SFI), Static Sciatic Index (SSI), morphometric, morphological, histological, zymographic, electrophysiological, resistance mechanics and range of motion (ROM). The variety of parameters used in the studies demonstrated that there is yet no pre-determined protocol for treating peripheral nerve regeneration. Only two studies by different authors used the same power, energy density, beam area, and power density.

Conclusion: It was concluded that the therapeutic window of the photobiomodulation presents a high variability of parameters with the wavelength (632.8 to 940 nm), power (5 to 170 mW) and energy density (3 to 280 J /cm2), promoting nerve regeneration through the expression of cytokines and growth factors that aid in modulating the inflammatory process, improving morphological aspects, restoring the functionality to the animals in a brief period.
Keywords: Phototherapy; Nerve regeneration; Sciatic nerve; Experimental studies; Injury; Lasers and light sources.

Introduction: Panretinal photocoagulation (PRP) remains the gold standard treatment for severe non-proliferative and proliferative diabetic retinopathy (PDR), as it reduces the risk of severe visual loss by more than 50%. In the conventional single-spot laser, the procedure involves the application of moderate-intensity burns of 200-500 microns, placed one spot-size apart to achieve a total of 1200-2000 applications in 2 or 3 sessions. The more advanced retina lasers like the Pattern Scan Laser (PASCAL) and the VITRA multi-spot laser are 532 nm frequency-doubled (Nd: YAG) solid-state lasers. These modern lasers enable the application of multiple laser burns in a rapid pre-determined sequence with reduced pulse duration (10-20 ms) to facilitate the PRP to be completed in a single sitting with lesser collateral tissue damage.

Case Report: Though multi-spot lasers have significantly reduced the adverse events when compared with the conventional single-spot lasers, we report a case of rare adverse events (serous choroidal detachment) following PRP with the VITRA multi-spot double frequency Nd-YAG (532 nm) laser.

Conclusion: Most of the serious choroidal detachments following PRP are self-limiting. We recommend complete retinal evaluation post-laser procedure even with the modern multisport laser to look for such adverse events.

Introduction: Necrotizing sialometaplasia (NS) is a rare locally destructive inflammatory benign disease that commonly affects the minor salivary glands. It is frequently associated with the glands located in the posterior portion of the hard and soft palates. Low-level laser therapy (LLLT), also called photobiomodulation therapy (PBMT), has been deemed a substantial method for the regenerative wound process.

Case Presentation: A 32-year-old male patient was referred with a chief complaint of two asymptomatic crater-like ulcers measuring approximately 1.5 cm wide on the right side of the hard and soft palates, and another measuring 0.3 cm wide on the left side of the hard palate. The lesion had two weeks of evolution followed by a previous infectious “sore throat” event that kept the patient hospitalized for 4 days. A clinical diagnosis of NS was made. LLLT was applied during 2 sessions per week, favoring the total wound healing within 2 weeks. At 3 months of clinical follow-up, the patient did not present any complication or relapse and was thus released.

Conclusion: This is, to our knowledge, the first clinical report of LLLT applied for the management of NS. Large palatal ulcers caused by NS usually have long healing periods. The shortened healing period observed in this case encourages the inclusion of LLLT in any treatment protocol for similar lesions.

Background: In spite of some advances in periodontal generative methods, it is impossible to stop progressive Loss of supporting alveolar bone in some end-stage periodontitis. The aim of this study is to report a kind of treatment modality which was seemed to be successes full in maintaining teeth. In this case-report, a hopeless tooth was saved by combined non-surgical periodontal-endodontal treatment and antimicrobial photodynamic therapy (aPDT).

Case Report: A 58-year-old male presented with a chief complaint of pain and mobility of tooth number 38. Clinical examinations revealed a periodontic-endodontic lesion with clinical attachment loss exceeding 10 mm and grade III mobility. To preserve the tooth, we operated non-surgical periodontal treatment including scaling and root planning (SRP) plus root canal therapy (RCT) combined with intra-root canal non-aPDT laser decontamination. Then we applied laser pocket therapy with and without aPDT. Following 6 months of the aPDT treatment, the mobility and pocket depth of the tooth improved from grade III to I and from 10 to 3 millimeters respectively.

Conclusion: aPDT is a novel adjunctive therapy that can be used for various conditions with microbial etiology. This case report demonstrated that aPDT might be effective in the treatment of periodontic-endodontic lesions in a hopeless tooth.