Given the increased aesthetic demands of patients, along with improvements in the formulation of resin composites, the ability of these materials to bond to tooth structures, and concerns about dental amalgam fillings, the applicability of resin composites in dentistry has become increasingly widespread. As resistance to wear represents an important factor in determining the clinical success of resin composite restoratives, the aim of this article was to define what constitutes wear; the major underlying phenomena involved in this process-adhesion, abrasion, fatigue, and corrosion-being described. Discussions were also focused on factors that contribute both to the magnitude and minimization of resin composite wear. Finally, insights were included on both in vivo and laboratory studies used to determine wear resistance.

Background Implants or implantable devices should integrate into the host tissue faster than fibrous capsule formation, in which the design of the interface is one of the biggest challenges. Generally, bioactive materials are not viable for load-bearing applications, so inert biomaterials are proposed. However, the surface must be modified through techniques such as coating with bioactive materials, roughness and sized pores. The aim of this research was to validate an approach for the evaluation of the tissue growth on implants of porous alumina coated with bioactive materials. Methods Porous alumina implants were coated with 45S5 Bioglass® (BG) and hydroxyapatite (HA) and implanted in rat tibiae for a period of 28 days. Ex vivo resections were performed to analyze osseointegration, along with histological analysis, Scanning Electron Microscopy with Energy Dispersive X-Ray spectroscopy (SEM-EDX) line scanning, radiography and biomechanical testing. Results Given that the process of implant integration needs with the bone tissue to be accelerated, it was then seen that BG acted to start the rapid integration, and HA acted to sustaining the process. Conclusions Inert materials coated with bioglass and HA present a potential for application as bone substitutes, preferably with pores of diameters between 100 μm and 400 μm and, restrict for smaller than 100 μm, because it prevents pores without organized tissue formation or vacant. Designed as functional gradient material, stand out for applications in bone tissue under load, where, being the porous surface responsible for the osseointegration and the inner material to bear and to transmit the loads.

This paper presents the development of an advanced ceramic material for manufacturing aerostatic porous bearing. The results show that there is homogeneous distribution of the pores in the alumina matrix by using different concentrations of the added component (sucrose). The average pore diameter remained around 0.14 µm and respective porosity around 28%, with small standard deviation. The mathematical model of the aerostatic porous bearing is presented, and numerical results indicate that the parameter related to porous medium (G) strongly affects the resultant bearing load capacity and stiffness. Considering the experimental and numerical results, the porous matrix obtained with 40% of sucrose concentration is more suitable for the aerostatic porous bearing application in study. Keywords: porous ceramic materials, aerostatic bearings, permeability identification, bearing modeling. Resumo Este trabalho apresenta o desenvolvimento de materiais cerâmicos porosos, obtidos a partir de cerâmicas estruturais (alumina), para a fabricação de mancais aerostáticos. Os resultados iniciais indicaram que, houve homogeneidade na distribuição dos poros na matriz de alumina, obtida com diferentes concentrações de agente poroso (sacarose). O valor médio dos poros foi de

The new wheelchair pushrim provides a proper fit for the hands due to its ergonomic design and its polyurethane composition, making wheelchair propulsion easier and more comfortable than the conventional wheelchair pushrim. Assistive technology devices should be design based on ergonomic concepts that involve less effort and offer greater comfort for the user. [Box: see text].