To clarify the influence of translucent tetragonal zirconia polycrystals (TZP) on wear properties of esthetic dental materials, twobody wear test was performed using translucent TZP as abrader specimen, and bovine tooth enamel (BTE), two resin composites including hybrid filler (CRH) and nano filler (CRN), two glass ceramics including leucite reinforced feldspar porcelain (POR) and lithium disilicate (LDC), or translucent TZP as substrate specimen. After the wear test, wear volume were determined from substrate specimen and surface roughness were measured from abrader specimen. In addition, Vickers hardness was measured and surface morphologies were observed after wear test using a scanning electron microscope. The wear volume of the esthetic dental material against translucent TZP was greater in glass ceramics (POR, LDC), smaller in resin composite (CRH, CRN) and BTE, and no wear in translucent TZP. Microstructures of the esthetic dental material may play a crucial role for wear behavior against translucent TZP.

The objective of this study was to clarify the fatigue behavior of hollow yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) specimens assuming its use for two-piece implants. The fatigue properties of a solid specimen (which simulated a one-piece implant) and 3 types of hollow specimens (which simulated two-piece implants) were evaluated. Specimens were either solid with a diameter of 4.0 mm (S) or hollow with an inner diameter of 3.0 mm and outer diameters of 4.0 mm (H0.5), 4.5 mm (H0.75), or 5.0 mm (H1.0). For each group, 25 specimens were prepared followed by blast and acid etch treatment. Static fracture and cyclic fatigue tests were conducted by modifying the methods provided in ISO6872. Fracture modes were determined by observing the surfaces under a scanning electron microscope. As a result, the cyclic fatigue load of S and H1.0 were similar, and hollow specimens with outer diameters greater than 0.75 mm displayed the ability to withstand molar occlusal forces.