Mechanical and structural characterization of ultra-translucent glassinfiltrated zirconia and survival after adhesive cementation

Author(s)

Jonas Vinicius Meireles Rodrigues

• Document type: Master's Dissertation
• Press: São José dos Campos. 2023-02-01.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Ciência e Tecnologia. São José dos Campos
• Defense date: 2022-05-16
• Advisor: Renata Marques de Melo Marinho; Tiago Moreira Bastos Campos

Abstract

The aim of this study was to develop a glass that was thermally compatible when infiltrated into a zirconia partially stabilized by yttrium oxide (5Y-PSZ), to characterize it and to test it under fatigue. Zirconia discs (5Y-PSZ) (N=140) dimensions 1.2x12mm and NEMA G-10 (N=60) dimensions of 2.5x12mm were made, which were polished with silicon carbide sandpaper in a polisher. The zirconia discs were randomly distributed in order to compose the two parts of the work. “Part A” dealt with the characterization made through the groups: Zpr (n=30) zirconia only sintered, Zinfoc (n=30) glass applied to the occlusal surface and Zinfcim (n=30) glass applied to the cementation surface. They were tested using the biaxial bending test (ISO 6872:2015) and the fractures evaluated using Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD) and Weibull Analysis. Part B tested, via step-stress, simplified restoration models, groups: Kctrl (control -, n=15), Kglz (control +, n=15), Kinfoc (infiltration in the “occlusal” surface n=15) and Kinfcim (infiltration on the “cementing” surface, n=15). The surface treatment of the zirconia was carried out by sandblasting with aluminum oxide particles, with the exception of the Kinfcim group which was conditioned with 40% hydrofluoric acid, the NEMA G10 discs were conditioned with 10% hydrofluoric acid. The groups in part B were cemented with dual-curing resin cement and light-cured with light-emitting diode. Specimens were evaluated via Oblique Transillumination, Stereomicroscope and SEM. The Zinfcim group showed a characteristic strength of 824 MPa and m=9.9; Zinfoc 613 MPa and m=10.2; Zpr 534 MPa and m=8; all groups differed statistically in their characteristic strengths (σϴ), however they were similar in structural homogeneity (m). The XRD showed 20-50 microns of infiltration, there was dissolution of part of the yttrium and reduction in the size of the cubic grains, in addition to the Zinfcim group presenting an origin of failure within the material. The Kctrl group presented a fatigue failure load of 933 N, followed by Kglz with 1080 N, Kinfoc with 1053 N and Kinfcim 1380 N, this one differed statistically from the other groups and presented the origin of the fracture inside the material. The developed glass was able to be infiltrated in a third generation zirconia, generated greater structural reliability and increased the characteristic resistance by changing the failure mode and was responsible for the increase in load and cycles to failure of the infiltrated groups, being its recommended use of graduated form. (AU)

• FAPESP's process: 20/04435-5 - Strength, microstructure of fully stabilized zirconia infiltrated with glass and its survival rate after adhesive cementation
• Grantee: Jonas Vinicius Meireles Rodrigues
• Support Opportunities: Scholarships in Brazil - Master