Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic

Abstract

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

Effect of Surface Pretreatments on the Microtensile Bond Strength of Lithium-Disilicate Ceramic Repaired with Composite Resin

“…This glass matrix is selectively removed and the crystalline structure is exposed. As a result, the surface of the ceramic becomes rough, which is expected for micromechanical retentions (6). This roughly etched surface also helps to provide more surface energy prior to combining with the silane solution (14).…”

“…Effective etching of the ceramic surface is considered an essential step for the clinical success of indirect ceramic-bonded restorations and direct ceramic repair procedures (4). Acid etching increases the surface area and the wettability of ceramics, changing their surface energy and the bonding potential of ceramic to resin (5,6).…”

“…The incorporated silica of acid-sensitive ceramics such as lithium disilicate ceramics is well-exposed by HF acid gel to give increased surface roughness, which is available for mechanical interlocking (4,6,7).…”

“…As médias (D.P.) dos valores de resistência de união em MPa foram: G1: 32,14 (7,98), G2: 35,00 (7,77) e G3: 18,36 (6,17). G1 e G2 apresentaram maiores valores de resistência de união que G3 (p<0,05).…”

Enhancement of the Bonding Durability of Resin-based Cement to Lithium Disilicate Glass Ceramics Using Surface Modification Methods

“…4 , HFT featured a unique surface topography relative to the other specimens. Hydro uoric acid reacts with the Si-based surface, resulting in an increased surface area and enhanced adhesive strength with micro retention effects 29 . Moreover, the shear bond strength of HFT was signi cantly higher than those of SCA and ASB, and was maintained even after thermal cycling.…”