Effect of etching with distinct hydrofluoric acid concentrations on the flexural strength of a lithium disilicate‐based glass ceramic

Abstract

This study examined the effects of distinct hydrofluoric acid concentrations on the mechanical behavior of a lithium disilicate-based glass ceramic. Bar-shaped specimens were produced from ceramic blocks (e.max CAD, Ivoclar Vivadent). The specimens were polished, chamfered, and sonically cleaned in distilled water. The specimens were randomly divided into five groups (n = 23). The HF1, HF3, HF5, and HF10 specimens were etched for 20 s with acid concentrations of 1%, 3%, 5%, and 10%, respectively, while the SC (control) sample was untreated. The etched surfaces were evaluated using a scanning electron microscope and an atomic force microscope. Finally, the roughness was measured, and 3-point bending flexural tests were performed. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). The Weibull modulus and characteristic strength were also determined. No statistical difference in the roughness and flexural strength was determined among the groups. The structural reliabilities (Weilbull moduli) were similar for the tested groups; however, the characteristic strength of the HF1 specimen was greater than that of the HF10 specimen. Compared with the untreated ceramic, the surface roughness and flexural strength of the ceramic were unaffected upon etching, regardless of the acid concentration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 885-891, 2017.

Impact of Hydrofluoric Acid Etching Duration on Translucency, Flexural Strength and Surface Topography of Lithium Silicate Based Glass Ceramic

“…In addition, as the etching periods increased, the size and number of the voids also increased as was seen in samples etched for 60 seconds (group IV), versus those etched for 10 seconds (group II), which demonstrated fewer microstructure alterations. These observations are in agreement with some previous studies (6,28,29) , which found that non etched ceramic surface is normally smooth and flat, However HF etching can transform it into porous and irregular due to the dissolution of the glass phase. Hence, the longer the etching period, the larger the voids and channels appeared until it reached to an extreme case where disilicate crystals can be easily seen from the glassy matrix.…”

“…Yet, lower roughness values were obtained in that study. This difference could be attributed to the using of different polishing protocols, contact profilometry, and different roughness parameters to report the surface roughness (6,28,29) .…”

The Effect of Surface Treatments on the Mechanical and Optical Behaviors of CAD/CAM Restorative Materials

“…However, in this study, all of the recommended surface treatment methods decreased the flexural strength of the tested materials. Prochnow et al suggested that besides removing the glassy matrix and exposing the crystalline content, HFA etching might remove the fine grains of lithium disilicate. It has also been indicated that airborne‐particle abrasion can damage the surfaces and a volume loss can happen in the material .…”

Fracture Resistance and Retention of Metal-Free Inlay Retained Fixed Partial Dentures

“…Prochnow et al (46) reported that ceramic etching is a dynamic process, and its impact is dependent on the substrate constitution, substrate surface topography, in addition to acid concentration, and etching period. Hence, pre-pressed industrially manufactured blocks of e.max CAD and BioHPP resisted surface conditioning by HF acid and sandblasting respectively, more than pressed materials.…”