Effect of thermal and mechanical cycles on shear bond strength of zirconia core to porcelain veneer under different surface treatments

Abstract

Background. Due to the fragile nature of all-ceramic restorations, it is necessary to provide an appropriate (core) infrastructure to support the veneering porcelain. The veneer detachment and chipping are disadvantages of these restorations. Several techniques have been proposed to minimize these problems. This study evaluated the effect of thermal and mechanical cycles on the shear bond strength of zirconia core to porcelain veneer under different surface treatments. Methods. Sixty disk-like zirconium samples were randomly divided into three groups. The first group was polished and veneered with porcelain, without additional surface treatments. The two other groups were subjected to different surface treatments (modified aluminum oxide by silica and activator‒aluminum oxide and primer) and veneering with porcelain. Half of the samples in each group were subjected to 6000 thermal cycles and 20,000 masticatory cycles of 50 N to imitate the intraoral conditions; the other half were placed in distilled water at 37°C until the shear strength test. Each sample was then buried using PMMA in a mounting jig so that the gap between the core and the veneer could be placed upward. Then, they were exposed to shear stress using a universal testing machine at a rate of 1 mm/min until fracture. The maximum force leading to the fracture was recorded. Results. Comparison of the groups showed that the highest shear bond strength was related to the samples treated with aluminum oxide and primer, without applying thermal and masticatory cycles, which indicated no significant difference from the group treated with aluminum oxide and primer, with thermal and masticatory cycles. The lowest shear bond strengths were related to the polished samples without surface treatment by applying thermal and masticatory cycles (P=0.001), which indicated no significant difference from the untreated group without thermal and masticatory cycles. Conclusion. Based on the results, treatment with aluminum oxide and primer increased the shear bond strength of zirconia core to porcelain veneer. Thermocycling and masticatory cycles failed to reduce the shear bond strength in all the three groups significantly

Effects of dimensions of laser-milled grid-like microslits on shear bond strength between porcelain or indirect composite resin and zirconia

“…Therefore, the change in SBS before and after thermocycling was assessed for indirect composite resins. On the other hand, previous studies reported that thermocycling had no influence on the bond strength between porcelain and zirconia [35,36]. This may be because the CTE of porcelain is close to that of zirconia and is less susceptible to moisture.…”

Shear Bond Strength of Colored and Sandblasted Zirconia to Ceramic Veneers Fabricated by the Pressing and Layering Techniques: An In Vitro Study

“…However, Kim et al [ 11 ] reported that sandblasting significantly increased the SBS of zirconia to the veneering porcelain applied by the layering technique; this difference may be due to variations in the sandblasting protocol since they used 110 μ m alumina particles with 0.4 MPa pressure for 10 s for sandblasting. Also, Ghaffari et al [ 14 ] showed higher SBS in the group sandblasted with 110 μ m alumina particles with 3.5 bar pressure for 5 s. Thus, it appears that sandblasting with larger alumina particles and higher pressure may increase the SBS. In a study by Okada et al [ 24 ] the highest SBS value was observed in the sandblasted group with 0.25 MPa pressure.…”

“…Kim et al [ 11 ] showed that sandblasting significantly increased the shear bond strength (SBS) of zirconia to porcelain; however, another study indicated that the sandblasted group had lower biaxial strength than the control group [ 12 ]. Tarib et al [ 13 ] and Ghaffari et al [ 14 ] reported that sandblasting had no significant effect on SBS of zirconia to porcelain. With respect to the effect of coloring of zirconia on its SBS, some studies showed that coloring of zirconia had no significant effect on its SBS [ 15 , 16 ]; whereas, Ebadian et al [ 17 ] indicated that coloring had a significant adverse effect on biaxial strength.…”

Comparison of Debonding of Different Composite Resin Bonds and Acrylic Tooth with Acrylic Denture Base after Thermocycling Regimes.

“…The percentage of cohesive fractures in this group(90.5%) was significantly more than that in other groups (P<0.001)22 if we convert this result to MPa we see the result of (287.38 ± 51.82 N ≃ 14.6 MPa) however the tested material and management are same but the applied force are differed so that un-matching result seen in responses to that un-similarities.On the other hand researchers cover the space in studying the light-curing composite with the denture base and they give a different impression, (Ghaffari T et al , 2019 B) during comparison of bond strength of light-cured teeth concluded that the shear load that makes the untreated composite tooth displaced in its place is 238.33 ± 24 MPa where for Nano compo-site one this amount increased to 311.56 ± 32 MPa24 , there are differences among this result and current study outcome which it's may come from different applied load and thermocycling management in the current study.CONCLUSION:Within the limitation of this study it has been concluded that, Tokoyama required the highest force for debonding (7.05 MPa) whereas the lowest one Cerama brand (5.122 MPa) among the composite one at the same time the Cold cure Acrylic one have inferior debonding property(2.07 MPa). Replacement of missing artificial teeth on the denture base with a different brand of the composite can be done as an alternative to acrylic teeth.…”