fa Microstructural changes produced by abrading Y-TZP in presintered and sintered conditions بیماری های دهان Oral Medicine پژوهشي Research <p> <strong>Objective </strong></p><p> To evaluate the effect of abrading before and after sintering using alumina-based abrasives on the surface of yttria-tetragonal zirconia polycrystals. Particular attention was paid to the amount of surface stress-assisted phase transformation (tetragonal→monoclinic) and the presence of microcracks. </p><p> <strong>Methods</strong></p><p>  Pre-sintered zirconia ceramic specimens (ZirCAD Ivoclar Vivadent) were first surface-ground flat with #600–800–1000-grit SiC paper. They were then surface-treated with different grain size abrasives before and after the sintering step. Samples that underwent no surface treatment were used as controls. For each condition, eight specimens were prepared. The physical/mechanical characteristics of zirconia material were determined by measuring density, porosity, grain size, hardness, and fracture toughness. The effects of surface treatments were assessed by surface roughness measurements, quantitative X-ray diffraction analysis, and scanning electron microscopy. </p><p> <strong>Results</strong></p><p>  With increased dimensions of the abrasive particles, the abraded surfaces of zirconia specimens exhibited a widespread system of microcracks and an increased monoclinic zirconia quantity. These structural changes likely affect the aging of the material during its clinical service. </p><hr><p></p><p> <strong>Source: </strong>Journal of Dentistry</p><p> <a href="http://www.jodjournal.com/article/S0300-5712(12)00177-7/abstract" target="_blank"><font color="#0000ff">Full Text</font></a></p> Zirconia, CAD CAM, Abrading, Tetragonal, Y-TZP 0 0 http://idai.ir/browse.php?a_code=A-10-32-2104&slc_lang=fa&sid=1 Carlo Monaco 10031947532846009859 10031947532846009859 Yes Department of Oral Sciences, Division of Prosthodontics and Maxillo-facial Rehabilitation, University of Bologna, Via S. Vitale 59, 40125 Bologna, Italy Antonella Tucci 10031947532846009860 10031947532846009860 No Leonardo Esposito 10031947532846009861 10031947532846009861 No Roberto Scotti 10031947532846009862 10031947532846009862 No