Microstructure and Mechanical Properties of Nickel-Free and Nickel-Containing Stainless Steel Orthodontic Wires

Introduction: In orthodontics, contact dermatitis caused by nickel allergy should be of concern with the number of nickel-containing appliances and wires used. Stainless steel archwires are commonly used throughout orthodontic treatment. With the release of nickel from these wires, some manufacturers have turned to nickel-free stainless steel alternatives. The goal of this research was to compare nickel-free stainless steel with traditional stainless steel archwires with regard to mechanical properties and microstructure. Materials and Methods: Nickel-free stainless steel and regular stainless steel archwires from four companies were included. Five random samples of each wire, vertically mounted in fast-set acrylic, were indented three times to determine their Vickers microhardness. Force deflection properties were investigated with the three point bending test in which fifteen random samples of each wire were tested. Wire samples were horizontally mounted in fast-set acrylic, acid-etched for variable amounts of time, and then analyzed with a metallurgical microscope to assess microstructure. All quantitative data were compared using one-way analysis of variance (ANOVA) at a 0.05 significance level with a Tukey\u27s HSD (honest significant difference) test post hoc analysis, when necessary. Results: Vickers microhardness number, activation stiffness, elastic recovery, and activation bending force values were calculated for each sample. Activation modulus showed no significant differences between Dentaurum wires. All wires were statistically different when considering percent recovery. Scheu and Dentaurum stainless steel wires were statistically similar to the respective nickel-free alternatives when investigating activation stiffness. Scheu Chromium bending force values were always greater than Scheu Menzanium. Acme Monaco\u27s nickel-free alternative had force values greater than Acme stainless steel. Force values for Dentaurum wires through 1.0 mm of deflection showed no significant differences. Nickel-free alternatives and stainless steel wires manufactured by Scheu, Acme-Monaco, and Pozzi/Leone showed no statistical significant difference with regards to microhardness values. Microstructure analysis revealed differences between grain structure and sizes between all wires. Conclusions: Dentaurum Remanium and Noninium archwires appear to have the most similarities with regards to the mechanical and microstructure properties investigated in this study. With regards to the mechanical properties tested, nickel-free stainless steel may be a viable alternative to traditional stainless steel archwires

Antiretroviral therapy alone versus antiretroviral therapy with a kick and kill approach, on measures of the HIV reservoir in participants with recent HIV infection (the RIVER trial): a phase 2, randomised trial

Background: Antiretroviral therapy (ART) cannot cure HIV infection because of a persistent reservoir of latently infected cells. Approaches that force HIV transcription from these cells, making them susceptible to killing—termed kick and kill regimens—have been explored as a strategy towards an HIV cure. RIVER is the first randomised trial to determine the effect of ART-only versus ART plus kick and kill on markers of the HIV reservoir. Methods: This phase 2, open-label, multicentre, randomised, controlled trial was undertaken at six clinical sites in the UK. Patients aged 18–60 years who were confirmed as HIV-positive within a maximum of the past 6 months and started ART within 1 month from confirmed diagnosis were randomly assigned by a computer generated randomisation list to receive ART-only (control) or ART plus the histone deacetylase inhibitor vorinostat (the kick) and replication-deficient viral vector T-cell inducing vaccines encoding conserved HIV sequences ChAdV63. HIVconsv-prime and MVA.HIVconsv-boost (the kill; ART + V + V; intervention). The primary endpoint was total HIV DNA isolated from peripheral blood CD4+ T-cells at weeks 16 and 18 after randomisation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, NCT02336074. Findings: Between June 14, 2015 and Jul 11, 2017, 60 men with HIV were randomly assigned to receive either an ART-only (n=30) or an ART + V + V (n=30) regimen; all 60 participants completed the study, with no loss-to-follow-up. Mean total HIV DNA at weeks 16 and 18 after randomisation was 3·02 log10 copies HIV DNA per 106 CD4+ T-cells in the ART-only group versus 3·06 log10 copies HIV DNA per 106 CD4+ T-cells in ART + V + V group, with no statistically significant difference between the two groups (mean difference of 0·04 log10 copies HIV DNA per 106 CD4+ T-cells [95% CI −0·03 to 0·11; p=0·26]). There were no intervention-related serious adverse events. Interpretation: This kick and kill approach conferred no significant benefit compared with ART alone on measures of the HIV reservoir. Although this does not disprove the efficacy kick and kill strategy, for future trials enhancement of both kick and kill agents will be required. Funding: Medical Research Council (MR/L00528X/1)