Summary. Multilayered zirconia products made with various yttria contents by layer have decreased flexural toughness than those developed with gradient shade technological innovation and the exact same yttria information for each layer. As a result, many things like the type of prostheses, nesting techniques of prostheses inside the zirconia disc, https://www.directivepublications.org/journal-of-dentistry-and-oral-research/