Bond and topography evaluation of a Y-TZP ceramic with a superficial low-fusing porcelain glass layer after different hydrofluoric acid etching protocols

Arthur Chaves Simões,Rodrigo Othávio De Assunção E Souza,Jean Soares Miranda,Fabíola Pessôa Pereira Leite,Estevão Tomomitsu Kimpara

doi:10.1590/1807-2577.10118

Abstract

Abstract Introduction Despite being one of the most studied ceramics today, zirconia still does not have a well-defined adhesion protocol. Objective Evaluate the influence of different etching times and hydrofluoric acid (HF) concentrations on the zirconia surface and bond strength between a vitrified Y-TZP ceramic and a resin cement. Materials and method The zirconia surface treatments were: sandblasting with silica-coated alumina (Co); glaze application + 5% HF etching for 5s (G5-5s), 10s (G5-10s) or 20s (G5-20s); glaze application + 10% HF etching for 5s (G10-5s), 10 (G10-10s) or 20s (G10-20s) . Then, cement cylinders (3.3 × 3.3 mm) were built up for shear bond test on all specimens. The specimens were subjected to 6000 thermal cycling before the test. Fractures were analyzed by stereomicroscope. Data were statistically analyzed by Kruskal-Wallis and Dunn statistical tests (5%). Extra samples of each group were made to obtain profilometry and scanning electron microscopy (SEM). Result Zirconia-cement bond strength was affected by the ceramic surface treatments (p = 0.001). G10-5s (2.71 MPa) recorded the highest bond strength values, followed by the Co (2.05 MPa) while G5 groups had the lowest bond value. Adhesive failure of the samples predominated. The image analysis revealed G5 groups seem to have a lower roughness when compared to groups treated by 10% HF. The creation of pores in the low-fusing porcelain glass layer surface occurred only when 10% HF was used. Conclusion The low-fusing porcelain glass layer application was able to overcome the sandblasting and obtain a greater adhesive bond to the resinous cement, however, only when 10% HF was used for an interval of 5 seconds.

Highlights

Despite being one of the most studied ceramics today, zirconia still does not have a well-defined adhesion protocol
These surface treatment options were sandblasting with aluminum oxide particles[13], laser irradiation[14], sandblasting with aluminum oxide coated by silica particles[3,15], the use of metal primers[10,13,14], plasma selective infiltration[15] and a low-fusing porcelain glass layer application[16,17,18,19] was tried
The sintered blocks were randomly assigned to seven groups (n = 10) according to surface treatment, as follows: Co: The sandblasting with silica-coated alumina was performed by Rocatec Soft

Summary

Introduction

Despite being one of the most studied ceramics today, zirconia still does not have a well-defined adhesion protocol. It was necessary to develop some different surface treatments options to zirconia, trying to promote micro retentions and/or make the surface chemically reactive to an adhesive system[12] These surface treatment options were sandblasting with aluminum oxide particles[13], laser irradiation[14], sandblasting with aluminum oxide coated by silica particles[3,15], the use of metal primers[10,13,14], plasma selective infiltration[15] and a low-fusing porcelain glass layer application[16,17,18,19] was tried. This last surface treatment referred as vitrification aims to enrich the surface with silicon oxides and allow hydrofluoric acid (HF) etch to selectively attack this glass layer and change its topography, providing areas for mechanical retention This etching would increase the ceramic surface energy and its adhesive potential, a necessary condition to obtain a stable and durable bonding of the resin cement to the substrate[5,7,13,20]. The silane is applied to ensure a chemical bond, similar to what happens in the glass- ceramic adhesion process[12,20]

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Conclusion