Measuring the Static and Dynamic Elastic Modulus in Y-TZP Ceramic Applied to Dentistry

Abstract

Yttria tetragonal zirconia polycrystal in the form of presintered commercial blocks is used to manufacture dental prostheses through computer-aided design/computer-aided manufacturing technology. Although it presents appropriate mechanical properties, it may fail because of defects resulting from the forming, presintering, machining, or sintering processes. The aim of the current study is to evaluate the influence of the presintering process on the microhardness of presintered blocks and on the elastic modulus of sintered materials. Blocks were formed by means of uniaxial and isostatic pressing. Next, they were presintered at different temperatures and soaking times, besides being subjected to the Vickers microhardness and mechanical tests to evaluate their elastic modulus. Statistical analyses showed that the presintering time at 900°C had no effect on microhardness, although it was significant at 950°C. The postsintering elastic modulus ranged from 205.7 to 231.9 GPa, which is similar to the range recorded in the literature. The presintering process had no influence on the postsintering mechanical resistance results.

Physical Properties and Color Stainability by Coffee and Red Wine of Opaque and High Translucency Zirconia Dental Ceramics after Hydrothermal Degradation

“…Among the several changes, it is worth mentioning the use of metal-free ceramic materials. Dental ceramics have a more natural, translucent look than metal-ceramic restorations [ 3 , 4 ], but the mechanical properties and the color are susceptible to degradation in the oral environment. In the oral environment, materials are in contact with acidic and basic solutions and are subject to temperature variations and compressive, torsion, and shear loads.…”

“…Tetragonal zirconia partially stabilized with 3% mol yttria (3Y-TZP) has a flexural strength of 1000 to 1300 MPa [ 4 – 6 ], which is larger than that of traditional ceramics. One of its drawbacks is the possibility of long-term mechanical degradation in the oral environment, known as low-temperature hydrothermal degradation (LTHD), which occurs through spontaneous and progressive transformation of the metastable tetragonal phase to a monoclinic phase [ 7 – 10 ].…”