Análise comparativa do desgaste das interfaces titânio/titânio e titânio/zircónia dos conjuntos pilar/implante após envelhecimento

Objectives: Due to its hardness, zirconia abutments may damage the titanium of the implant's connection during its clinical use. This study aimed to assess the wear of the seating platforms of externally hexed titanium implants when connected to zirconia abutments comparing to titanium abutments, after thermocycling and mechanical loading (TCML).Methods: Six BNT (R) S4 external connection implants (Phibo (R) Dental Solutions, Barcelona, Spain) were selected and divided into two groups (n=3): TiCE, screwed to titanium abutments and ZrCE, screwed to zirconia abutments. The samples underwent thermocycling (5000 cycles; 5-55 degrees C) and mechanical loading (1.2 x 106 cycles; 88.8 N; 4 Hz). Before and after TCML, the seating platforms of the implants were analyzed by 3D profilometry in two areas to measure their topography based on the superficial analysis parameters (Sa and Sz) parameters, and were studied by scanning electron microscopy (SEM). Data were statistically analyzed by Mann-Whitney test (p 0.05 and p = 0.059). The abutment's material (titanium/zirconia) did not statistically significantly influence the Sa and Sz values after TCML (p = 0.886> 0.05 and p = 0.200, respectively). However, the SEM analysis reveals a mild wear in some vertices of the hex when connected to zirconia abutments.Conclusions: After simulating five years of clinical use, the externally hexed implants, analyzed by 3D profilometry, showed similar wear patterns in the corresponding seating platforms when connected to zirconia or titanium abutments. The SEM images showed zirconia particles being transferred to the implant, which requires further study. (C) 2016 Sociedade Portuguesa de Estomatologia e Medicina Dentaria.Objetivos Devido á sua dureza, os pilares de zircónia podem provocar danos sobre o titânio da conexão do implante durante a utilização clínica. O presente trabalho pretendeu avaliar o desgaste das plataformas protéticas de implantes de titânio com conexão hexágono externo quando conectados com pilares de zircónia em comparação com pilares de titânio, após carga cíclica e termociclagem (TCML). Métodos Foram selecionados 6 implantes de conexão externa BNT® S4 Phibo® Dental Solutions (Barcelona, Espanha), que foram divididos em 2 grupos (n = 3): TiCe aparafusados a pilares de titânio e ZrCe aparafusados a pilares de zircónio. As amostras foram submetidas a TCML (5.000 ciclos; 5–55 °C) e carga cíclica (1,2 × 106 ciclos; 88,8 N; 4 Hz). Antes e após TCML, as plataformas de assentamento de conexão dos implantes foram sujeitas a análise por perfilometria 3 D em 2 localizações para a medição da sua topografia com utilização dos parâmetros de análise superficial (Sa e Sz) e examinadas por microscopia eletrónica de varrimento(MEV). Análise estatística: Mann-Whitney test (p < 0,05). Resultados Não se observaram diferenças estatisticamente significativas nos valores de Sa e de Sz entre os implantes no estado inicial e após TCML (p = 0,573 > 0,05 e p = 0,059). O material do pilar (titânio/zircónia) não exerceu influência estatisticamente significativa nos valores de Sa e Sz após TCML (teste U p = 0,886 > 0,05 e p = 0,200, respetivamente). No entanto, a análise por MEV revelou ligeiro desgaste em alguns vértices do hexágono quando conectados com pilares de zircónia. Conclusões Após uma simulação de 5 anos de utilização clínica, os implantes com hexágono externo, analisados por perfilometria 3 D, apresentaram padrões de desgaste das plataformas de assentamento equivalentes quando conectados a pilares de zircónia ou de titânio. As imagens de MEV mostram a passagem de partículas de zircónia para o implante, aspeto que merece investigação suplementar.Authors gratefully acknowledge the funding of Project NORTE-01-0145-FEDER-000022 - SciTech - Science and Technology for Competitive and Sustainable Industries, cofinanced by Programa Operacional Regional do Norte (NORTE2020), through Fundo Europeu de Desenvolvimento Regional (FEDER)

Assessment of an in vitro whole cigarette smoke exposure system: The Borgwaldt RM20S 8-syringe smoking machine

<p>Abstract</p> <p>Background</p> <p>There have been many recent developments of <it>in vitro </it>cigarette smoke systems closely replicating <it>in vivo </it>exposures. The Borgwaldt RM20S smoking machine (RM20S) enables the serial dilution and delivery of cigarette smoke to exposure chambers for <it>in vitro </it>analyses. In this study we have demonstrated reliability and robustness testing of the RM20S in delivering smoke to <it>in vitro </it>cultures using an in-house designed whole smoke exposure chamber.</p> <p>Results</p> <p>The syringe precision and accuracy of smoke dose generated by the RM20S was assessed using a methane gas standard and resulted in a repeatability error of ≤9%. Differential electrical mobility particle spectrometry (DMS) measured smoke particles generated from reference 3R4F cigarettes at points along the RM20S. 53% ± 5.9% of particles by mass reached the chamber, the remainder deposited in the syringe or connecting tubing and ~16% deposited in the chamber. Spectrofluorometric quantification of particle deposition within chambers indicated a positive correlation between smoke concentration and particle deposition. <it>In vitro </it>air-liquid interface (ALI) cultures (H292 lung epithelial cells), exposed to whole smoke (1:60 dilution (smoke:air, equivalent to ~5 μg/cm²)) demonstrated uniform smoke delivery within the chamber.</p> <p>Conclusions</p> <p>These results suggest this smoke exposure system is a reliable and repeatable method of generating and exposing ALI <it>in vitro </it>cultures to cigarette smoke. This system will enable the evaluation of future tobacco products and individual components of cigarette smoke and may be used as an alternative <it>in vitro </it>tool for evaluating other aerosols and gaseous mixtures such as air pollutants, inhaled pharmaceuticals and cosmetics.</p

Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

Premature failure of wind turbine gearbox bearings is an ongoing concern for industry, with sudden overload events potentially contributing towards raceway damage, significantly hindering performance. Subsurface stresses generated along a line contact cause material yielding, and a probable crack initiation site. Currently, the ability to study subsurface plastic zone evolution using non-destructive techniques is limited. Neutron Bragg edge imaging is a novel technique, allowing for two-dimensional mapping of the Bragg edge broadening parameter, indicative of bulk plastic deformation. An experiment on the ENGIN-X strain scanning instrument, at the ISIS neutron source, UK, was setup for Bragg edge transmission imaging, to measure the effect of in situ loading on the raceway of a bearing, scaled-down from a traditional wind turbine gearbox bearing. Results demonstrate a strong correlation between load and the Bragg edge width, and allow for future experimental development in studying, not only the effect of overloads on fatigue life, but also the use of neutron imaging for evaluating plastic deformation in engineering components

Managing the Pre- and Post-analytical Phases of the Total Testing Process

For many years, the clinical laboratory's focus on analytical quality has resulted in an error rate of 4-5 sigma, which surpasses most other areas in healthcare. However, greater appreciation of the prevalence of errors in the pre- and post-analytical phases and their potential for patient harm has led to increasing requirements for laboratories to take greater responsibility for activities outside their immediate control. Accreditation bodies such as the Joint Commission International (JCI) and the College of American Pathologists (CAP) now require clear and effective procedures for patient/sample identification and communication of critical results. There are a variety of free on-line resources available to aid in managing the extra-analytical phase and the recent publication of quality indicators and proposed performance levels by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) working group on laboratory errors and patient safety provides particularly useful benchmarking data. Managing the extra-laboratory phase of the total testing cycle is the next challenge for laboratory medicine. By building on its existing quality management expertise, quantitative scientific background and familiarity with information technology, the clinical laboratory is well suited to play a greater role in reducing errors and improving patient safety outside the confines of the laboratory