Apparent Interfacial Fracture Toughness of Resin/Ceramic Systems

Abstract

We suggest that the apparent interfacial fracture toughness (K A ) may be estimated by fracture mechanics and fractography. This study tested the hypothesis that the K A of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure. Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/ or silane (S), followed by an adhesive resin. Microtensile test specimens (n = 30; area of 1 ± 0.01 mm 2 ) were indented (9.8 N) at the interface and loaded to failure in tension. We used tensile strength

Insights on Ceramics as Dental Materials. Part II: Chemical Surface Treatments

“…A bond strength of 49.7±11.9 MPa was obtained compared to 27.2±4.8 MPa [23] but the standard deviation was quite high for the study. However, the difference between the two studies was in [40] the ceramic surface was air abraded with 30 μm Al 2 O 3 in addition to 9% hydrofluoric acid etching and the specimens were, interestingly, not subjected to water storage [23,40]. Some other studies have found that etching with 8% hydrofluoric acid and silanization was not as effective as air abrading the ceramic surface with 50 μm Al 2 O 3 followed by 8% hydrofluoric acid etching and silanizing.…”

“…It has been concluded that both etching and silanizing are crucial to achieving high bond strengths [44]. It has been reported that both hydrofluoric acid etching and silanization on lithium disilicate ceramics bonded to resin composites had significantly higher bond strengths than either treatments alone in vitro as shown in Table 1 [23].…”

“…It was observed that 9.5% hydrofluoric acid produced the roughest surface on leucitereinforced ceramics by using a surfanalyzer, which measures surface roughness by calculating the average height of irregularities from mean line within sampling mean length [22]. Reported microtensile bond strength values for lithium disilicate ceramics etched with 9.6% hydrofluoric acid for 2 min had a higher bond strength, 41.7±6.7 MPa, than those etched with 4.0% acidulated phosphate fluoride for 2 min, 19.1±2.6 MPa [23].…”

The effect of disk type and cutting speed on the micro-tensile bond strength of ceramic specimens to resin cement

“…These results could be due to the fragility of this material. The specimens submitted to tensile testing are very sensitive to edge or surface machining damage, and crack propagation is determined by varying levels of stress intensity 18,28) . Upon assessing the photomicrographs of the bars taken with the scanning electron microscope, it was observed that the fissures and cracks produced at a speed of 200 rpm were smaller and distributed mostly along the entire ceramic/cement bond area.…”

“…Conducting a fractrographic analysis should be considered in conjunction with micro-tensile testing, insofar as it allows fractures to be classified and also serves the purpose of critically evaluating the effectiveness of the method employed and the conclusions drawn 4,18,28) .…”