Search

The fact that neutrinos carry a non-vanishing rest mass is evidence ofphysics beyond the Standard Model of elementary particles. Their absolute massbears important relevance from particle physics to cosmology. In this work, wereport on the search for the effective electron antineutrino mass with theKATRIN experiment. KATRIN performs precision spectroscopy of the tritium$\beta$-decay close to the kinematic endpoint. Based on the first fiveneutrino-mass measurement campaigns, we derive a best-fit value of $m_u^{2} ={-0.14^{+0.13}_{-0.15}}~\mathrm{eV^2}$, resulting in an upper limit of $m_u <{0.45}~\mathrm{eV}$ at 90 % confidence level. With six times the statistics ofprevious data sets, amounting to 36 million electrons collected in 259measurement days, a substantial reduction of the background level and improvedsystematic uncertainties, this result tightens KATRIN's previous bound by afactor of almost two.

Backgrounds: Dental avulsion due to trauma, especially in young patients, is a worldwide problem, requiring tooth replacement. Delayed replantation could cause tooth loss when the cementum is severely damaged. A small number of studies has reported that photobiomodulation (PBM) therapy using Er: YAG laser irradiation activates cellular signaling responses in different cell types, resulting in a variety of favorable biological effects. The aim of this in vitro study was to evaluate the potential biostimulatory effect of low-level Er: YAG laser irradiation on the biological responses of cultured mouse cementoblasts (OCCM-30), including the mitogen-activated protein kinases (MAPKs)., Methods: OCCM-30 cells were exposed to 2940 nm Er: YAG laser irradiation for 15 s at 0.34 W (pulse duration of 100 or 1000 μs, 17 mJ/pulse) at energy densities of 1 or 2 J/cm 2 . Irradiated and non-irradiated OCCM-30 cells were tested for migration (Scratch assay), proliferation (MTS assay) and functional differentiation (Alizarin Red S assay). Lumican ( Lum ) and Fibromodulin ( Fmod ) gene expression, and activation of MAPKs, were assessed by RT-PCR and Western blotting, respectively., Results: Low-level Er: YAG laser irradiation at 2 J/cm 2 and pulse duration of 1000 μs resulted in the highest migration rate and proliferation. Moreover, the pulse duration irradiation of 100 μs increased Lum expression. Fmod expression was increased after 1000 μs pulse duration laser stimulation. Low-level Er: YAG laser irradiation increased the mineralization of OCCM-30 cells after 7 days and activated ERK1/2, P38 and JNK signaling., Conclusions: Low-level Er: YAG laser irradiation induces OCCM-30 cell migration, proliferation and differentiation, and activates the MAPK signaling pathway., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by IMR Press.)

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 × 10 8 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., (Copyright © 2021 J Lasers Med Sci.)

Introduction: The tooth root surfaces are modified by different agents for better removal of the smear layer, the formation of fibrin clots, and the attachment of blood cells. This in vitro study compared the removal of the smear layer, the formation of fibrin clots and the attachment of blood cells after exposing periodontally compromised root surfaces to ER:YAG and CO 2 laser beams. Methods: Eighteen dentin block samples were prepared from freshly extracted periodontally compromised teeth that were deemed hopeless, and they were divided into 3 groups: exposed to Er:YAG laser beams, exposed to CO 2 laser beams, and the control group. The samples were evaluated using scanning electron microscopy and micrographs were taken. Smear layer removal and blood cell attachment were scored. Data were analyzed using Kruskal-Wallis and MannWhitney tests. Results: In the Er:YAG laser group, the smear layer was removed completely. In the specimens exposed to blood, better fibrin clot formation and blood cell attachment were observed in the Er:YAG laser group. In the CO 2 laser group, the smear layer was also removed; however, there were no significant differences between the CO 2 laser and control groups in fibrin clot formation and blood cell attachment. Conclusion: The application of the Er:YAG laser to the root dentin appears to result in the formation of a suitable surface for fibrin clot formation and blood cell attachment. Further clinical studies are necessary to support these results., (Copyright © 2020 J Lasers Med Sci.)

Background: In dentistry, cavities prepared with Erbium lasers present more advantages, compared to traditional methods, but there is still a lack of investigation about the adhesion in dentin surfaces prepared with Erbium lasers, especially with Erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser., Aim: The purpose of this systematic review was to find out which might be "The most adequate adhesive and laser parameters for adhesion in dentin prepared with Er,Cr:YSGG laser.", Methods: An electronic search was performed in the PubMed database. The search was limited to studies between 2009 and 2016., Results: Ten articles were selected to the systematic review according to TRANSPARENT REPORTING of Systematic Reviews and Meta-ANALYSES checklist., Conclusions: The adhesive that showed the best bond strength results in dentin prepared with Er,Cr:YSGG laser was the self-adhesive Clearfil™ SE (Kuraray), with preconditioning with 40% phosphoric acid. The settings 2 W, 75% water, 60% air, 140 μs pulse duration, and 20 Hz showed the best adhesion outcome., Competing Interests: There are no conflicts of interest., (Copyright: © 2019 Contemporary Clinical Dentistry.)

Introduction: Sodium hypochlorite (NaOCl) irrigation is critical for the success of endodontic treatment and several agitation techniques have been developed to improve the efficacy of this irrigation. Using a combination of contrast medium and radiographic examination, this study evaluated NaOCl extrusion during agitation of irrigant. Development of pressure, which may result in apical extrusion of the irrigant, has been described during laser-activated irrigation (LAI) and passive ultrasonic irrigation (PUI)., Methods and Materials: We examined 40 single root canals categorized as having open apices with apical lesions in 40 patients. For the final irrigation, the teeth were irrigated with a mixture of radiopaque contrast medium and 2.5% NaOCl in solution. The solution was activated for 60 sec in both groups [the Er, Cr: YSGG laser group ( n =20) and the ultrasonic group ( n =20)]. The teeth were imaged subsequently using radiography for the evaluation of contrast extrusion., Results: Radiopaque contrast medium was absent from the periapical tissues in all cases., Conclusion: Use of LAI or PUI appears to be safe as used currently in endodontic treatment., Competing Interests: ‘None declared’.

Introduction: Side effects related to antibiotic therapy for peri-implantitis are rare in laser therapy (LT); therefore, the aim of this study was to evaluate the effectiveness of LT and photodynamic therapy (PDT) on patients with primary peri-implantitis. Methods: In this randomized clinical trial, 40 implants presenting primary peri-implantitis in 20 patients with a mean age of 52.6 years old were included using the simple sampling technique. Periodontal treatment comprising scaling and root planing (SRP) was accomplished for the whole mouth while mechanical debridement with titanium curettes and air polishing with sodium bicarbonate powder was accomplished around the implants. The implants were randomly divided into two groups and treated with LT (control) and PDT (test). The clinical indices were measured at baseline, 6 weeks and 3 months after treatment. Real-time polymerase chain reaction (PCR) was used for analysis of microbial samples at baseline and 3-month follow-up. Data were analyzed with SPSS 20, using repeated-measures analysis of variance (ANOVA) and Friedman's and Mann-Whitney tests (α = 0.05). Results: Both groups showed statistically significant improvements in terms of bleeding on probing ( P < 0.001), probing pocket depth (PPD) ( P = 0.006) and modified plaque index ( P < 0.001), with no significant differences between the 2 groups ( P > 0.05). The number of Aggregatibacter actinomycetemcomitans ( P = 0.022), Tannerella forsythia ( P = 0.038) and Porphyromonas gingivalis (P = 0.05) in the test group and Porphyromonas gingivalis ( P = 0.015) in the control group significantly decreased. Conclusion: The results suggested that LT and PDT have significant short-term benefits in the treatment of primary peri-implantitis.

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment.

Dental tooth restorative procedures may weaken the structural integrity of the tooth, with the possibility of leading to fracture. In this study we present findings of coronal dentin strength after different techniques of surface modification. The fracture strength of dentin beams after superficial material removal with a fine diamond bur high speed drill hand piece, Er:YAG (2.94 μm, 8 J/cm(2)), and Er,Cr:YSGG (2.78 μm, 7.8 J/cm(2)) laser irradiation slightly above the ablation threshold was measured by a four-point bending apparatus. Untreated dentin beams served as a control. A total of 58 dentin beams were manufactured from sterilized human extracted molars using the coronal part of the available dentin. Mean values of fracture strength were calculated as 82.0 ± 27.3 MPa for the control group (n = 10), 104.5 ± 26.3 MPa for high speed drill treatment (n = 10), 96.1 ± 28.1 MPa for Er,Cr:YSGG laser irradiation (n = 20), and 89.1 ± 36.3 MPa for Er:YAG laser irradiation (n = 18). Independent Student's t-tests showed no significant difference between each two groups (p > 0.05). Within the parameter settings and the limits of the experimental setup used in this study, both lasers systems as well as the high speed drill do not significantly weaken coronal dentin after surface treatment.

Objective: The aim of this study was to evaluate the effectiveness of a radial firing tip of an Er,Cr:YSGG laser as an adjunct to a nonsurgical periodontal treatment., Methods: Twelve patients with chronic or aggressive periodontitis were treated by conventional periodontal treatment using ultrasonic devices and hand instruments and, additionally, in two quadrants with an Er,Cr:YSGG laser. A new radial firing tip (RFPT 14-5, Biolase) was used with 1.5 W, 30 Hz, 11% air, 20% water, and pulse duration 140 μs. Microbiological smears were taken before treatment, one day after lasing, and three and six months after lasing. Pocket depths of all periodontal sites were measured before and six months after treatment., Results: The total bacterial load of Prevotella intermedia, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans inside the pocket was reduced significantly throughout the whole examination time. Greater pocket depth reductions were observed in all groups. There was a slight higher reduction of pocket depth in the lased group after six months., Conclusions: These results support the thesis that Er,Cr:YSGG laser supported periodontal treatment leads to a significant reduction of periopathogenes and thereby helps the maintenance of periodontal health.

This work reports that the ablation volume and rate of porcine skin changed significantly with the change of skin water content. Under the same laser irradiation conditions (532 nm Nd:YAG laser, pulse width = 11.5 ns, pulse energy = 1.54 J, beam radius = 0.54 mm), the ablation volume dropped by a factor of 4 as the skin water content decreased from 40 wt. % (native) to 19 wt. % with a change in the ablation rate below and above around 25 wt. %. Based on the ablation characteristics observed by in situ shadowgraph images and the calculated tissue temperatures, it is considered that an explosive rupture by rapid volumetric vaporization of water is responsible for the ablation of the high water content of skin, whereas thermal disintegration of directly irradiated surface layer is responsible for the low water content of skin.

The purpose of this study was to analyze thermal effects during laser-assisted periodontal treatment. An in vitro model for temperature measurements was developed to investigate different laser settings regarding pulp safety. Additionally, the influence of transmission on pulp temperature elevation was evaluated. Longitudinal root sections were irradiated with a 940-nm diode laser with 1.0 and 1.5 W in continuous wave mode. According to wall thicknesses, irradiation times were adjusted to 20 s for upper and 10 s for lower incisors, respectively. Transmission was relatively low in both upper (4.8% to 8.3% of incident power) and lower incisors (10.2% to 15.0%). Samples were embedded in a polyurethane model and six thermocouples were affixed. Regardless of dentine thickness, the middle third of the root was identified to be the area with the most heat load, where a temperature rise of 7.5°C (1.0 W) and 10.5°C (1.5 W) was registered in upper incisors. A difference of 1.5°C to 3°C was detected in lower incisors compared with uppers. All settings were safe except for 1.5 W, 20 s. Transmission affected heat generation remarkably. The proposed model provides advantages regarding heat transfer and enables for spatially resolved temperature measurements.

Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124  J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

An innovative pump concept for diode-pumped, solid-state lasers is introduced as an example for an Er:YSGG laser, permitting its miniaturization. Embedded in a multireflective pump cavity, the laser crystal is simultaneously side and end pumped. Specially calculated and shaped deflecting optics distribute the coaxially input pumping light homogeneously over the lateral surface of the crystal, therefore reducing the size of the laser head, including the optical resonator, to a length of 27.5 mm and an outside diameter of 12.5 mm. The differential efficiency achieved is between 8.7% and 24%. The laser emits energy of 15.7 mJ at an absolute efficiency of 9.1% and a repetition rate of 4 Hz.