Micro-shear bond strength and surface micromorphology of a feldspathic ceramic treated with different cleaning methods after hydrofluoric acid etching

Abstract

Objective The aim of this study was to evaluate the effect of feldspathic ceramic surface cleaning on micro-shear bond strength and ceramic surface morphology. Material and Methods Forty discs of feldspathic ceramic were prepared and etched with 10% hydrofluoric acid for 2 minutes. The discs were randomly distributed into five groups (n=8): C: no treatment, S: water spray + air drying for 1 minute, US: immersion in ultrasonic bath for 5 minutes, F: etching with 37% phosphoric acid for 1 minute, followed by 1-minute rinse, F+US: etching with 37% phosphoric acid for 1 minute, 1-minute rinse and ultrasonic bath for 5 minutes. Composite cylinders were bonded to the discs following application of silane and hydrophobic adhesive for micro-shear bond strength testing in a universal testing machine at 0.5 mm/min crosshead speed until failure. Stereomicroscopy was used to classify failure type. Surface micromorphology of each treatment type was evaluated by scanning electron microscopy at 500 and 2,500 times magnification. Results One-way ANOVA test showed no significant difference between treatments (p=0.3197) and the most common failure types were cohesive resin cohesion followed by adhesive failure. Micro-shear bond strength of the feldspathic ceramic substrate to the adhesive system was not influenced by the different surface cleaning techniques. Absence of or less residue was observed after etching with hydrofluoric acid for the groups US and F+US. Conclusions Combining ceramic cleaning techniques with hydrofluoric acid etching did not affect ceramic bond strength, whereas, when cleaning was associated with ultrasound, less residue was observed.

Adhesive/silane application effects on bond strength durability to a lithium disilicate ceramic

“…The high bond strength values observed in the group in which silane agent was applied without adhesive, in the specimens tested after 12 months, may be due to the ability of hydrofluoric acid to create micro‐retentions on the internal surface, ideal situation for the flow of the resin cement to the ceramic surface . As well as the effectiveness of the silane agent in the formation of three‐dimensional chains through siloxane bonds formed between the hydroxyl groups (‐OH) present in the silica‐based ceramic, and the methacrylate group present in both the adhesive and resin cement …”

“…Different methods for treating ceramic surfaces have been proposed: mechanical, with the use of aluminum oxide particles; chemical, with application of hydrofluoric acid in concentrations between 5% and 10%; or the association of both treatments . Hydrofluoric acid etching promotes microretentions in the ceramic surface, which is ideal for micromechanical interlocking of the resin cement . Following etching and rinsing off residues, the application of a coupling agent is recommended.…”

“…etching promotes microretentions in the ceramic surface, which is ideal for micromechanical interlocking of the resin cement. [8][9][10] Following etching and rinsing off residues, the application of a coupling agent is recommended. The silane is an agent of bifunctional bond constituted of organic and inorganic elements.…”

“…6 Inner surface etching of glass ceramics and silanization has been the most recommended procedure to improve adhesion, resistance and durability of the complex ceramic-cement-tooth structure. 8,10 However, if one of the steps is not correctly performed, the long-term success of the restoration can be compromised. 12 The reduction of steps without compromising the quality of restorations is highly desired among practitioners.…”

Acid Etching and Surface Coating of Glass-Fiber Posts: Bond Strength and Interface Analysis

“…The micro-shear bond test is a common testing method, but it often produces cohesive fracture within the substrate rather than the interface. This occurs due to the generation of complex stress distribution during the test and may lead to erroneous results interpretation (21). The (22) in an attempt to eliminate the non-uniform stress distribution within the adhesive zone.…”