The Effect of Variation in Sintering Parameters on the Optical Properties and Microstructure of Multi-Shaded Cubic Zirconia " (In vitro Study) "

Abstract

In the last years, manufacturers have made admirable efforts to produce dental ceramics replicating both the mechanical and esthetic properties of natural teeth. This resulted in launching numerous types of dental ceramics. Ultimately, a dental ceramic material should meet two principal requirements: outstanding mechanical property and ideal esthetics. A ceramic with these two essential properties functions properly in the oral environment while mimicking a tooth-like appearance. The present study was designed to assess the effect of variation in sintering parameters on the optical properties and microstructure of ultra-translucent multi-shaded cubic zirconia in order to detect changes in color, translucency, opalescence and chromaticity in addition to variations in microstructure and phase composition that might affect the daily clinical applications. Ultra-Translucent Multi-Layered (UTML) cubic zirconia blanks were wet sectioned with dimensions 20% larger than the desired final dimension to compensate for the sintering shrinkage using a low speed cutting saw. Each blank was vertically sectioned into serial slabs. Each slab was vertically divided into blocks. So that, the sectioned zirconia blank has perpendicular cuts in order to obtain blocks with dimensions (13 X 13 mm). Each sectioned zirconia block is composed of 4 layers (Enamel, Transition 1, Transition 2, Dentin). Within each block, the plates were sectioned from the middle of each layer with thickness of 1.3 mm that will reach 1 mm after the sintering procedure. After that, the plates were placed inside the sintering furnace to be sintered according to the proposed sintering parameters.