| 초록 |
Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has been widely used as a dental material because of its excellent mechanical properties. However, since aesthetic issues have been emphasized recently, opacity of zirconia has been pointed out as a disadvantage and researches are underway to improve it. Basically, Y-TZP has excellent mechanical properties due to tetragonal-monoclinic transformation, but it has low transmittance due to intrinsic birefringence. On the other hand, yttria-stabilized cubic zirconia polycrystal (Y-CZP) has the advantage of excellent transparency although it lacks mechanical properties.Researches can be done in two direction: one is to improve the transmittance of Y-TZP while maintaining its mechanical properties and the other is to improve the mechanical properties of the Y-CZP while maintaining its transmittance. The transmittance is influenced by the pores(size and volume), composition and grain size. Since scattering at the pore is one of the most dominant factors that hinders transmittance, it is the most important to make a pore-free sintered body. Particularly in Y-TZP, the smaller the grain, the higher the transmittance. The smaller the grain, the better the mechanical properties, also. In this study, the grain growth of Y-TZP was suppressed by doping with La2O3 and by applying the two-step sintering method. |
