Effect of Ceramic Conditioners on Surface Morphology, Roughness, Contact Angle, Adhesion, Microstructure, and Composition of CAD/CAM Ceramics
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.SUMMARY
Detailed photographs of shear bond strength specimen preparation (A) at which two adhesive tapes isolated the bonding area (B). After surface treatment was performed, tweezers were used to hold an additional silicone mold in a position centered on the tape’s hole (C) and a probe was used to insert the resin cement inside the mold (D, E). After light activation (F), the mold (G) and the tape (H) were carefully removed. The same steps would be then repeated to obtain two resin cement cylinders bonded to each specimen (I, J). Blue blockers were used to protect the first resin cylinder from the light activation of the second cylinder.
Representative images and mean (SD) contact angle of feldspathic and leucite-reinforced ceramic surfaces treated with different conditioning protocols. Uppercase letters compare ceramics for the same surface treatment, and lowercase letters compare surface treatments for the same ceramic (p<0.05). Abbreviations: HF, hydrofluoric acid; MEP, Monobond Etch & Prime.
Failure modes of experimental groups tested for shear bond strength: (A) ADE: adhesive failure; (B) COC: cohesive failure within ceramic; (C) COR: cohesive failure within resin cement; (D) MAC: mixed failure involving adhesive and cohesive failure in ceramic; (E) MAR: mixed failure involving adhesive and cohesive failure in resin cement; (F) MARC: mixed failure involving adhesive, cohesive failures in resin cement and ceramic. Failure modes distribution for feldspathic (G) and leucite-reinforced (H) ceramics.
Representative confocal 3D images (100×, left column), scanning electron microscopy images (1000× and 5000×, center columns), and energy dispersive X-ray spectrometry analyses (right column) of the surface treatments for feldspathic ceramic. Abbreviations: HF, hydrofluoric acid; MEP, Monobond Etch & Prime.
Representative confocal 3D images (100×, left column), scanning electron microscopy images (1000× and 5000×, center columns), and energy dispersive X-ray spectrometry analyses (right column) of the surface treatments for leucite-reinforced ceramic. Abbreviations: HF, hydrofluoric acid; MEP, Monobond Etch & Prime.
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