Effect of Ceramic Conditioners on Surface Morphology, Roughness, Contact Angle, Adhesion, Microstructure, and Composition of CAD/CAM Ceramics

Abstract

SUMMARY The objective of this study was to investigate the effect of surface treatments in maximum profile valley depth (Rv), surface roughness (Sa), contact angle (Ca), shear bond strength (SBS) of a light-cured resin cement, microstructure, and composition of two CAD/CAM ceramics: Cerec Blocs/Dentsply Sirona (feldspathic - FEL) and Empress CAD/Ivoclar Vivadent (leucite-reinforced - LEU). The ceramic specimens were submitted to six surface treatments: (1) 5% hydrofluoric acid (HF) – 20 seconds; (2) 5% HF – 60 seconds; (3) 10% HF – 20 seconds; (4) 10% HF – 60 seconds; (5) self-etching ceramic primer (MEP) – 20 seconds; and (6) MEP – 60 seconds. Specimens treated with HF received silane application for 1 minute. Rv and Sa were evaluated in a confocal laser microscope (n=10) and the Ca in a goniometer (n=6). For the SBS test, two resin cement cylinders were bonded to each specimen, one tested after 24 hours in distilled water storage (37°C) and the other after one year (n=10). The microstructures and compositions were analyzed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) (n=4). Rv, Sa, and Ca data were analyzed by two-way ANOVA, and the SBS data by three-way ANOVA, all followed by post-hoc Tukey’s test (α=0.05). Results: Surface treatments with HF always produced higher Rv and Sa, and lower Ca than MEP 60s for both ceramics. After 1-year water storage, FEL ceramic treated with MEP for 60 seconds produced higher SBS values than HF treatments, whereas for LEU ceramic there were no differences among treatments. Application of MEP for 20 or 60 seconds produced no difference in Rv, Sa, Ca, and SBS for both ceramics. Surface treatments produced considerable differences in ceramic topography, but subtle ones in composition, for both ceramics. Conclusions: The results indicated that for FEL ceramic, MEP application for 60 seconds yielded higher SBS compared with HF etching, while for LEU ceramic the surface treatments did not influence the SBS results.

Adhesive Performance of Resin Cement to Glass-Ceramic and Polymer-Based Ceramic CAD/CAM Materials after Applying Self-Etching Ceramic Primer or Different Surface Treatments

“…According to the results of this study, MEP leads to higher bond strength than AL and lower bond strength than HF in glass ceramics, but no significant difference was found between MEP and HF. Previous studies have obtained similar results, but some reported that HF gave higher results, although not significantly, while others reported that MEP increased the bond strength more [ 6 , 10 , 13 , 15 , 16 , 19 , 35 ]. The variations arise from factors such as whether aging was performed, the method and duration of aging if applied, the use of ultrasonic bath for post-surface treatment cleaning, alcohol utilization in the bath, differences in silanes and resin cement, variations in HF concentration and application duration, the utilization of different bonding strength tests, or the testing of diverse load applications [ 3 ].…”

Hydrofluoric acid concentration and etching time affect differently the microstructure and surface properties of pressed lithium disilicate glass ceramics

“…[23][24][25][26] The increase in surface roughness is also reported to be proportional to exposure time and acid concentration. 26,27 Although the surface roughness alteration is necessary to enhance adhesion strength, the use of a higher acid concentration and more exposure time may not result in greater bond strength 28,29 and this procedure should be performed with caution in order to not jeopardize the material's strength.…”

“…However, this clinical procedure should follow an ideal protocol for each material, since over‐etching can promote a weakening effect, by a substantial surface disruption and greater flaws formation, compromising its mechanical performance 23–26 . The increase in surface roughness is also reported to be proportional to exposure time and acid concentration 26,27 . Although the surface roughness alteration is necessary to enhance adhesion strength, the use of a higher acid concentration and more exposure time may not result in greater bond strength 28,29 and this procedure should be performed with caution in order to not jeopardize the material's strength.…”