Antibacterial Effects of a 940 nm Diode Laser With/ Without Silver Nanoparticles Against Enterococcus faecalis

Introduction: The final goal of root canal therapy is to remove of the most bacteria from the root canal. This study aimed at comparing the antibacterial effects of a diode laser with a wavelength of 940nm and silver nanoparticles and the synergic effects of both techniques on Enterococcus faecalis. Methods: Ninety single-rooted human teeth were decoronated and prepared with rotary files. The samples were irrigated with sodium hypochlorite and EDTA17%. Then they were autoclaved and contaminated with E. faecalis suspension (1.5 × 108 CFU/mL) for 21 days. The samples were fixed in a microtube and were randomly divided into 4 experimental (n=20) groups and a negative control group (n=10) as follows: Group 1: hypochlorite sodium 5%, Group 2: silver nanoparticle, Group 3: diode laser, and Group 4: diode laser and silver nanoparticle. The samples were obtained from dentin chips before and after the intervention. The data were analysed using the Kruskal-Wallis nonparametric test. Furthermore, alterations in bacterial colonies were entered using the Wilcoxon signed ranks test (α=0.05). Results: There was a significant decrease in colony counts for all groups after interventions (P value<0.05). Also, all groups showed more reductions in colony counts compared with the negative control group (P value <0.004). There was a significant reduction for group 1 in comparison with other groups (P value <0.001) and this group had an extreme decrease of colony counts (RCC=100%). There was an important differential between silver nanoparticles and diode laser groups in bacterial counts (P value<0.001) and silver nanoparticles (RCC=83.15%) had more efficiency than the diode laser (RCC=41/33%). RCC of group 4 was 68/52%. Conclusion: Followed by sodium hypochlorite 5%, silver nanoparticles were the most effective antibacterial substances. The 940 nm laser diode had less antibacterial effect compared to its use with silver nanoparticles.

Clinical Effect of Non-Thermal CO2 Laser Therapy (NTCLT) on Pain Relief of Oral Aphthous Ulcers of Behçet’s Disease

Introduction: Behçet’s disease (BD) is a debilitating and chronic vasculitis which can affect multiple organs. Recurrent oral aphthosis is the most common clinical feature of BD. The remarkable pain associated with painful oral ulcers can exert a major impact on the patients’ quality of life. Relieving pain of these oral ulcers is an essential approach in the management of mucocutaneous lesions of BD. Non-thermal CO2 laser therapy (NTCLT) as a novel photobiomodulative approach has recently been used for significant and immediate pain reduction of some types of painful oral lesions such as recurrent aphthous stomatitis, pemphigus vulgaris, and so on. In this procedure by some considerations, the conventional CO2 laser is used as a non-surgical, non- thermal, photobiomodulative laser without any visible thermal adverse effects. In this article, we report our experiences about the analgesic effects of NTCLT on painful oral aphthous ulcers of BD. Case Presentation: We report four cases of BD, whose painful oral aphthous ulcers were irradiated with NTCLT. Immediately after NTCLT, the pain of the lesions was significantly relieved with no visible complications. Conclusion: The results of this study suggest that NTCLT could be proposed as a hopeful procedure for significant and instant pain relief of oral aphthous ulcers of BD without any visible thermal adverse effects.

Effect of Ti: Sapphire and Nd: YAG Lasers on Shear Bond Strength at the Zirconia - Veneering Ceramic Juncture

Introduction: This study was conducted to assess the impact of nanosecond and femtosecond lasers on shear bond strength at the zirconia - veneering ceramic juncture. Materials and Methods: The first 60 samples of partially sintered zirconia cylindrical discs measuring 7 mm diameter and 4 mm height were milled and sintered. Then they were randomly divided into three groups namely group C (control, n=10), group N (Nd: YAG laser, n=10), and group T (Ti: sapphire laser n=40) which was further divided based on the duration of laser irradiation, into 4 subgroups (n=10 each) which were 30 seconds, 1 minute, 2 minutes and 3 minutes. Surface treatment was done on sintered zirconia discs based on the group. Following the treatment, the discs were ultrasonically cleaned followed by liner application (IPS Emax Zirliner, Ivoclar-Vivadent) and veneer ceramic layering (IPS e.max Ceram, Ivoclar-Vivadent) of 1.5 mm height. Each sample underwent shear stress in the universal test machine on the mounting jig, and bond strength was evaluated. Data were assessed using ANOVA followed by Tukey’s post hoc multiple comparison analyses. Results: According to one-way ANOVA, there was a significant difference in shear bond strength between the groups. Tukey’s post hoc pair wise comparison test showed a significant difference (P value=0.001) in shear bond strength of all pairs except group C and group N. The results of repeated measures, ANOVA (related and dependent groups) and Tukey’s multiple pair wise comparison test showed that there was a significant difference (P value=0.001) in shear bond strength at 30 seconds and all other groups. Conclusion: Ti: sapphire laser irradiation for 30 seconds can be used as potential surface treatment to increase shear bond strength at the zirconia-veneering ceramic juncture.

Evaluation of Surface Roughness of a Ni-Cr Alloy Treated With the Nd/YAG Laser and the Sandblast Technique

Introduction: This study was to assess the effect of various output parameters of laser treatment on roughening the surface of a commercial nickel-chromium (Ni-Cr) alloy as compared to the sandblasting technique. Materials and Methods: Ninety-six disk-shaped (5 mm diameter and 2 mm thickness) specimens in total were made of a nickel-chromium alloy by using the lost-wax technique. Air-abrasion surface treatment was used for sixteen specimens. Specimens were divided into six groups; one of them was sandblasted and the rest were irradiated by different Nd:YAG laser output parameters as follows: Group A: energy: 122 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 1.5 mm; Group B: energy: 122 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 3.5 mm; Group C: energy: 122 mJ, frequency: 10 Hz, irradiation duration: 20 seconds, spot size: 3.5 mm; Group D: energy: 102 mJ, frequency: 10 Hz, irradiation duration: 20 seconds, spot size: 3 mm; Group E: energy: 102 mJ, frequency: 20 Hz, irradiation duration: 20 seconds, spot size: 3 mm. The surface roughness of all surface-treated specimens was evaluated by using a profilometer, and their average roughness (Ra) was calculated. The average value of each group was analyzed by t test and one-way ANOVA (SPSS 17). Results: Significant differences (P<0.05) were observed between the study groups. The highest Ra was achieved for the sandblasted group. The Ra value in group C was the highest value among the laser-etched groups. Conclusion: Based on the results, Nd:YAG laser irradiation increases surface roughness, but it is not as efficient as the sandblasting method as a gold standard.

Effects of Laser Acupuncture Therapy for Patients With Inadequate Recovery From Bell’s Palsy: Preliminary Results From Randomized, Double-Blind, Sham-Controlled Study

Introduction: Inadequate recovery from Bell’s palsy exists in a third of patients and results in physical and social impairments. The controversial nature of existing medical treatment options means that novel, alternative approaches are needed. In basic and clinical studies, low-level laser therapy (LLLT) has proven successful in regenerating peripheral nerves. Laser acupuncture therapy (LAT) is a rapidly growing treatment modality; however, its effectiveness for treating chronic Bell’s palsy is unknown. The feasibility of this innovative approach is the focus of this pilot study. Methods: A two-armed, parallel, randomized, investigator-subject-assessor-blinded, sham-controlled pilot study was conducted, and 17 eligible subjects were randomly allocated to either LAT (n=8) or sham LAT (n=9). The LAT group received three treatments each week for six weeks (18 sessions), while the sham LAT group received the same procedure but with a sham laser device. The change from baseline to week 6 in the social subscale of the Facial Disability Index (FDI) was the primary outcome. Secondary outcomes were changes in the House-Brackmann facial paralysis scale (HB), the Sunnybrook facial grading system (SB) and a stiffness scale at weeks 3 and 6. Results: A significant difference was shown in the HB score (P=0.0438) between baseline and week 3 and borderline significance was observed in both SB and stiffness scores from baseline to week 6 (P=0.0598 and P=0.0980 respectively). There was no significant difference in the FDI score between baseline and week 6. Conclusion: To the best of our knowledge, this clinical trial is the first such investigation on this topic. Our findings suggest that using LAT may have clinical effects on long-term complications of Bell’s palsy and justify further large-scale studies.

Physicochemical Changes of Contaminated Titanium Discs Treated With Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) Laser Irradiation or Air-Flow Abrasion: An In Vitro Study

Introduction: Peri-implantitis is a common complication of dental implant treatment. A cause-and-effect relationship has been previously documented between microbial plaque and peri-implantitis and implant failure. A difference has been reported in the disinfection efficacy of erbium laser irradiation and air-flow abrasion for contaminated titanium surfaces. Also, the surface changes caused by lasers and air-flow abrasion have not been well studied. Thus, the purpose of this study was to compare the surface changes of contaminated titanium discs following decontamination by erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation and air-flow abrasion. Methods: Twenty-eight intact, sandblasted, and acid-etched (SLA) titanium discs were used. Twenty-four titanium discs were contaminated with Escherichia coli. Then, they were decontaminated by using Er:YAG laser irradiation and air-flow abrasion. Four discs remained intact. The mean and standard deviation of the contact angle and the weight percentage of aluminum, titanium, oxygen, carbon, phosphorus, and calcium were measured. Qualitative changes in surface topography of titanium discs were assessed by scanning electron microscopy (SEM). Results: The mean weight percentage of carbon in the air-flow abrasion group (4.98%) experienced a significant reduction compared with the contaminated (positive control) group (P=0.035). The contact angles were 46.54° and 38.67° in the laser and air-flow abrasion groups respectively, which were significantly lower than the value in the positive control group (75.15°) (P ≤0.001). SEM micrographs showed no significant change in the surface area in either technique. Conclusion: Air-flow abrasion was more successful in improving the surface characteristics of titanium discs with no alteration in surface topography or elements, compared with Er:YAG laser irradiation. Further studies regarding the safety of the Er:YAG laser for the decontamination of titanium surfaces are recommended.

Clinical Efficacy of the 940-nm Diode Laser in the Treatment of Recurrent Pockets in the Periodontal Maintenance Phase

Introduction: The basis of periodontal treatments is the mechanical removal of bacterial biofilm, which is often not sufficient. Therefore, laser therapy can be effective as an adjunct treatment. The aim of the present study was to evaluate the clinical efficacy of the 940-nm diode laser in the treatment of recurrent pockets of patients in the periodontal maintenance phase. Methods: The present clinical trial study was performed on 20 patients. Clinical indices, including bleeding index (BI), probing pocket depth (PPD), and clinical attachment level (CAL) of the studied teeth were recorded before the test. The different quadrants were randomly divided into two experimental (scaling and root planing (SRP)+Laser) and control groups (SRP alone). Both groups were matched in terms of plaque index (PI). Clinical indices were re-recorded using therapeutic methods 30 and 90 days after the treatment, and data analysis was carried out using the t test and LSD. Results: There were no significant differences in PI, PPD, CAL, and BI in both groups before the treatment (P>0.05). However, there were significant differences in PPD, CAL, and BI in the two groups one month after the treatment (P<0.05); it means that improvements were more significant in the experimental group than in the control group. Comparing experimental and control groups, we found that there were no significant differences in PPD and CAL indices three months after the treatment (P>0.05); however, there were significant improvements in the BI index in both groups (P<0.05), so that the improvement was better in the experimental group than the control group. Conclusion: Both SRP+Laser and SRP alone improved clinical indices in patients. In short-term follow-up, the effect of SRP+Laser treatment on BI, CAL, PPD was significantly superior to SRP treatment alone, but in long-term follow-up, SRP+laser was more effective than SRP alone in improving the BI index.

Intravenous Laser Therapy in Patients With Acute Kidney Injury: A Randomized Clinical Trial

Introduction: Although intravascular laser irradiation of blood (ILIB) is deemed an innocuous and useful technique for laser therapy, particularly when systemic effects are required, no study, to our knowledge, has been conducted on the effectiveness and innocuousness of ILIB in treating acute kidney injury (AKI). Objective: This study aimed to assess the feasibility and outcomes of ILIB in the management of patients with AKI and comparing them with the Sham-laser group. Materials and Methods: Twenty-six patients with intra-renal AKI (24-95 years old) at Tajrish Hospitals were evaluated for enrollment eligibility in this clinical trial study. This study was conducted at the nephrology department of Shahid Beheshti University of Medical Science, Tehran, Iran, between 2018 and 2019. Based on the treatment method, the patients’ assignment to two groups (ILIB or Sham-laser) was randomly done. Demographic characteristics, need for dialysis, hemoglobin and serum biochemistry changes, serum and urine neutrophil gelatinase-associated lipocalin (NGAL) changes, laser complications, and the hospitalization period were recorded. Results: In terms of the baseline characteristics and biochemistry serum level, no differences were seen between the two groups. All post-treatment parameters, except the hemoglobin value, significantly improved in both groups. Urine NGAL and serum NGAL show declines from the baseline in both groups; however, the reduction slope of these parameters occurred faster in the laser group in a statistically significant manner. Conclusion: A decline in NGAL levels in the laser group during the treatment may suggest that the ILIB can help patients with AKI recover better.

A Systematic Review of Elective Laser Therapy during Pregnancy

Introduction: Currently, lasers are used to treat many diseases and their complications. However, the use of lasers in pregnant patients is still controversial. Methods: In this review, the application of lasers in the fields of urology, surgery, obstetrics, dermatology, and musculoskeletal disorders is evaluated. The following keywords were used to search through PubMed, Google Scholar, and Scopus: pregnancy, laser, urolithiasis, endovenous laser ablation (EVLA) or treatment, leg edema, varicose vein, venous insufficiencies, hair removal, pigmentation, telangiectasia, vascular lesions, Q switch laser, diode laser, holmium, holmium-YAG laser, erbium laser and Pulsed dye laser, low-level laser therapy, high-intensity laser therapy, pain, musculoskeletal disorders, twin to twin transfusion syndrome (TTTS), amnioreduction, and safety. Results: Totally, 147 articles were found, and their abstracts were evaluated; out of 53 articles extracted, 14 articles were about dermatology, 24 articles were about urology, 12 articles were about obstetrics and gynecology, 10 articles were about musculoskeletal disorders and three articles were related to surgery. Conclusion: Laser therapy can be used as a safe treatment for urolithiasis, skin diseases, TTTS and varicose veins of the lower extremities. However, the use of laser therapy for musculoskeletal disorders during pregnancy is not recommended due to lack of evidence, and also we cannot recommend endovenous ablation.

The Photobiomodulation Effect of 940nm Laser Irradiation on Enterococcus faecalis in Human Root Dentin Slices of Varying Thicknesses

Introduction: An increase in dentine thickness could result in an inadequate depth of laser energy penetration. This study aimed to evaluate the effect of a 940 nm laser on Enterococcus faecalis through varying thicknesses of human root dentin slices. Methods: Thirty-five dentin slices of root dentin with thicknesses ranging between 500 and 3000 µm were produced. Six experimental groups (500, 1000, 1500, 2000, 2500, and 3000 µm (n=5 each) were lased and the seventh, non-lased group served as the positive control with a dentine thickness of 2000 µm. The slices were inoculated with 2 µL of E. faecalis suspension of 1.5 × 108 E. faecalis cells/mL. All the lased slices were lased from the opposing side of the inoculation. A non-initiated 200 μm bare end fibre at the power of 1 W, in a continuous wave was used. Four doses of laser irradiation of 5 seconds with a side to side movement with the tip held at a 5º angle to the dentine slice were performed. The colony-forming units of E. faecalis were determined and the bacterial photobiomodulation effect analysed using one-way ANOVA with a Bonferroni and Holm post hoc test at a significance level of P>0.05. Results: There were statistical differences between the dentin slices of 500, 1000, and 1500 μm treated with the laser compared to the positive control (P<0.01). However, there were no statistical differences between the lased 2000 and 2500 μm slices compared to the positive control. There was significantly more photobiomodulation of the E. faecalis for the dentine slices of 3000 μm than the positive control (P<0.01). Conclusion: Laser treatment through dentine slices of 2000 μm and thinner significantly reduced bacterial growth. The photobiomodulation effects started to occur in dentine slices thicker than 2500 μm compared to the positive control.