RESUMO

The purpose of this study was to evaluate the fatigue survival of 5Y-PSZ zirconia infiltrated with an experimental glass and bonded onto dentin analogues. Disc-shaped specimens of a 5Y-PSZ (Katana UTML Kuraray Noritake) were cemented onto dentin analogs (NEMA G10) and divided into four groups (n = 15): Zctrl Group (control, without infiltration); Zglz Group (Glaze, compression surface); Zinf-comp Group (Experimental Glass, compression surface); Zinf-tens Group (Experimental Glass, tension surface). Surface treatments were varied. Cyclic fatigue loading, oblique transillumination, stereomicroscope examination, and scanning electron microscopy were performed. Fatigue data were analyzed (failure load and number of cycles) using survival analysis (Kaplan-Meier and Log-Rank Mantel-Cox). There was no statistically significant difference in fatigue survival between the Zglz, Zctrl, and Zinf-comp groups. The Zinf-tens group presented a significantly higher failure load when compared to the other groups and exhibited a different failure mode. The experimental glass effectively infiltrated the zirconia, enhancing structural reliability, altering the failure mode, and improving load-bearing capacity over more cycles, particularly in the group where the glass was infiltrated into the tensile surface of the zirconia. Glass infiltration into 5Y-PSZ zirconia significantly enhanced structural reliability and the ability to withstand loads over an increased number of cycles. This approach has the potential to increase the durability of zirconia restorations, reducing the need for replacements and save time and resources, promoting efficiency in clinical practice.

Assuntos

RESUMO

O objetivo deste estudo foi desenvolver um vidro que fosse termicamente compatível ao ser infiltrado em uma zircônia parcialmente estabilizada por óxido de ítrio (5YPSZ), caracterizá-los e testá-los sob fadiga. Foram confeccionados discos de zircônia (5Y-PSZ) (N=140) dimensões 1,2x12mm e NEMA G-10 (N= 60) dimensões de 2,5x12mm que foram polidos com lixas de carbeto de silício numa politriz. Os discos de zircônia foram aleatoriamente distribuídos a fim de compor as duas partes do trabalho. A "Parte A" tratou da caracterização feita através dos grupos: Zpr (n=30) zircônia apenas sinterizada, Zinfoc (n=30) vidro aplicado na superfície oclusal e Zinfcim (n=30) vidro aplicado na superfície de cimentação. Foram testados através do ensaio de flexão biaxial (ISO 6872:2015) e as fraturas avaliadas via Microscopia Eletrônica de Varredura (MEV), Difratometria de Raios X (DRX) e Análise de Weibull. A parte B testou, via step-stress, modelos simplificados de restauração, grupos: Kctrl (controle -, n=15), Kglz (controle +, n=15), Kinfoc (infiltração na superfície "oclusal" n=15) e Kinfcim (infiltração na superfície de "cimentação", n=15). O tratamento de superfície da zircônia foi realizado com jateamento com partículas de óxido de alumínio com exceção do grupo Kinfcim que foi condicionado com ácido fluorídrico 40%, os discos de NEMA G10 foram condicionados com ácido fluorídrico 10%. Os grupos da parte B foram cimentados com cimento resinoso de cura dual e fotopolimerizados com diodo emissor de luz. Os espécimes foram avaliados via Transiluminação Obliqua, Estereomicroscopio e MEV. O grupo Zinfcim apresentou resistência característica de 824 MPa e m=9,9; Zinfoc 613 MPa e m=10,2; Zpr 534 MPa e m=8; todos os grupos diferiram estatisticamente em suas resistências características (σÏ´), entretanto foram semelhantes na homogeneidade estrutural (m). A DRX apresentou de 20-50 microns de infiltração, houve dissolução de parte do ítrio e redução de tamanho dos grãos cúbicos, além do grupo Zinfcim apresentar origem de falha no interior do material. O grupo Kctrl apresentou carga para falha em fadiga de 933 N, seguido do Kglz com 1080 N, Kinfoc com 1053 N e Kinfcim 1380 N, este diferiu estatisticamente dos demais grupos e apresentou origem da fratura no interior do material. O vidro desenvolvido foi capaz de ser infiltrado em uma zircônia de terceira geração, gerou maior confiabilidade estrutural e aumentou a resistência característica pela alteração do modo de falha e foi responsável pelo aumento de carga e ciclos para falha dos grupos infiltrados, sendo seu uso recomendado de forma gradada (AU)

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 (σÏ´), 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)

Assuntos