Production and properties of tooth-colored yttria stabilized zirconia ceramics for dental applications

Abstract

Dense zirconia stabilized with 3 mol% yttria ceramics were produced in disc shape by first cold isostatically pressing at 100 MPa and then sintering at 1450 degrees C at ambient laboratory conditions. Coloring was accomplished by immersion the discs in NiCl2, MoCl3, and NiCl2 + MoCl3 solutions for 5, 30, and 60 s. Different concentrations (0.1, 0.25, and 0.5 wt%) were applied to get the color of natural tooth. The density, color, microhardness, fracture toughness, compressive strength, and wear rate of the discs were measured to evaluate the suitability of the colored discs for dental applications. Color assessments were made by measuring CIE Lab L*, a*, b, and Delta E* values. Low temperature degradation of the samples was evaluated by aging sensitivity tests in autoclave for 2, 4, and 6 h. Results have shown that color produced depends on the kind and concentration of the colorant solution while time of immersion has no significant effect on coloring process. Coloring solutions containing 0.1 and 0.25 wt% MoCl3 provided clinically acceptable color with the Delta E* value ranging from 5.16 to 6.42 for dental applications.