Abstract
This study evaluated the shear bond strength (SBS) and biaxial flexural strength (BFS) of resin cements according to the surface treatment method using low-temperature hot etching with hydrofluoric acid (HF) on a yttrium-stabilized tetragonal zirconia (Y-TZP) surface; 96 discs and 72 cubes for BFS and SBS tests for Y-TZP were randomly divided into four groups of BFS and three groups of SBS. Specimens were subjected to the following surface treatments: (1) no treatment (C), (2) air abrasion with 50 μm Al2O3 particles (A), (3) hot etching with HF at 100 °C for 10 min (E), and (4) air abrasion + hot etching (AE). After treatments, the specimens were coated with primer, and resin cement was applied with molds. The specimens were evaluated for roughness (Ra) via scanning electron microscopy and x-ray diffraction, and the data were analyzed by an analysis of variance (ANOVA) and Kruskal–Wallis tests. Group E produced significantly higher SBS compared to group A and AE before and after thermocycling. The BFSs of all groups showed no significant differences before thermocycling; however, after thermocycling, C and E treatment groups were significantly higher compared to group A and AE. All groups showed phase transformation. Group E was observed lower monoclinic phase transformation compared to other groups.
Highlights
The use of partially stabilized zirconium dioxide ceramics in dental restorations has recently been increasing owing to their excellent physical properties, such as high hardness, high compressive strength, optimal biocompatibility in a variety of applications, and adequate optical properties [1,2].In particular, due to the development of computer-aided design and manufacturing (CAD/CAM)technology, these ceramics are increasingly being used as prosthetic restoration materials [3].Zirconia restorations are not silica-based ceramics; resin bonding is difficult
Our study aims to evaluate the effect of hot etching surface treatment using low-concentration hydrofluoric acid (HF) (9%) at a low temperature on the shear bond strength (SBS) between partially stabilized zirconia ceramic and resin cement and the biaxial flexural strength (BFS) of zirconia
There were no significant differences between the SBS values of A and abrasion + hot etching (AE)
Summary
Zirconia restorations are not silica-based ceramics; resin bonding is difficult. Numerous researchers have focused on characterizing the effects of zirconia surface treatment methods (STMs) on the adhesions between resin cement and zirconia [4,5,6,7]. STMs include the following five micro-mechanical and chemical bonding techniques: mechanical treatment, chemical treatment, lasers, silicon coatings, and coupling agents [8]. Among the mechanical treatment techniques, the most commonly used is airborne-particle abrasion. Several studies have found that the abrasion method contributes to the increase in the adhesive strength between the resin cement and zirconia. The effects of the surface treatment vary according to the specific type of abrasion method; in particular, there are uncertainties regarding
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