Mechanical and microstructural characterization and influence of thickness on optical properties of monolithic zirconia and lithium disilicate

• Grant number: 17/08411-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2018
• End date: February 28, 2019
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Gelson Luis Adabo
• Grantee: Lucas Torres de Oliveira
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The use of zirconia (Y-TZP) as core in all-ceramic restorations is growing in dentistry due to its high mechanical strength when compared to other ceramic systems and due to the better biological properties in relation to metal-ceramic. However, cohesive fracture or chipping of veneer porcelain is a recurrent problem. In order to eliminate the necessity of porcelain veneering, high translucency Y-TZP has been introduced, which as well as lithium disilicate, were developed for monolithic indication. To achieve better optical properties, microstructural changes have been performed on zirconia, which can influence on mechanical properties. Thus, this study aims to perform the mechanical and microstructural characterization of two types of zirconia for monolithic indication (Prettau and Prettau Anterior) and a lithium disilicate (IPS e.max CAD), as well as to evaluate the optical properties in different thicknesses. Furthermore, compare them with conventional zirconia (Vita In-Ceram YZ) and CAD/CAM porcelain (Vita). To mechanical characterization of the materials, flat specimens (discs) will be made (12mm of diameter and 1.2 mm of thickness) (n=30) to biaxial flexural strength (piston on three-balls) in universal testing machine (EMIC DL 2000). Weibull modulus will be calculated through the flexural strength values and the reliability and probability of failure of materials will be measured. The determination and quantification of ceramic crystalline phases will be performed by x-ray diffraction. Scanning electron microscopy (n=3) will be performed to quantify the vitreous and crystalline phase in lithium disilicate and to measure the average grain size in the zirconia. To optical properties, the transmittance and reflectance at wavelengths of 360-740 nm, of the specimens with different thickness (0.5 mm, 1 mm and 1.5 mm) will be evaluated. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

LONGHINI, D.; ROCHA, C. O. M.; DE OLIVEIRA, L. T.; OLENSCKI, N. G.; BONFANTE, E. A.; ADABO, G. L.. Mechanical Behavior of Ceramic Monolithic Systems With Different Thicknesses. Operative Dentistry, v. 44, n. 5, p. E244-E253, SEP-OCT 2019. (16/09640-0, 17/16927-7, 17/08411-0)