Effect of the crystallisation time and metal oxide pigments on translucency and the mechanical and physical properties of mica glass-ceramics

Mica glass-ceramics tend to be opaque making them less desirable, from an aesthetic point of view, for dental materials. This research focuses on the development of a mica glass-ceramic for use as a restorative dental material with improved translucency. A ceria-based pigment and a zircon-based pigment consisting of Pr-ZrSiO₄ and Fe-ZrSiO₄ were added to glass-ceramic and the effect on translucency, phase development and morphology, strength, thermal expansion and chemical solubility were studied. The addition had no effect on the level of crystallinity obtained, the morphology of the crystals formed or the strength. The use of the pigments allowed for the control of the translucency and values of the translucency parameter similar to natural teeth were produced. The characteristic strength values and chemical solubility obtained to make these materials acceptable as dental ceramics type II class 2, for single-unit anterior or posterior prostheses adhesively cemented, according to ISO 6872.