Objectives

  The purpose of this study was to evaluate the influence of thermal and mechanical cycling and veneering technique on the shear bond strength of Y-TZP (yttrium oxide partially stabilized tetragonal zirconia polycrystal) core–veneer interfaces.

 Materials and methods

 Cylindrical Y-TZP specimens were veneered either by layering (n=20) or by pressing technique (n=20). A metal ceramic group (CoCr) was used as control (n=20). Ten specimens for each group were thermal and mechanical cycled and then all samples were subjected to shear bond strength in a universal testing machine with a 0.5mm/min crosshead speed. Mean shear bond strength (MPa) was analysed with a 2-way analysis of variance and Tukey's test (p<0.05). Failure mode was determined using stereomicroscopy and scanning electron microscopy (SEM).

 Results

 Thermal and mechanical cycling had no influence on the shear bond strength for all groups. The CoCr group presented the highest bond strength value (p<0.05) (34.72±7.05MPa). There was no significant difference between Y-TZP veneered by layering (22.46±2.08MPa) or pressing (23.58±2.1MPa) technique. Failure modes were predominantly adhesive for CoCr group, and cohesive within veneer for Y-TZP groups.

 Conclusions

 Thermal and mechanical cycling, as well as the veneering technique does not affect Y-TZP core–veneer bond strength.

 Clinical significance

 Different methods of veneering Y-TZP restorations would not influence the clinical performance of the core/veneer interfaces.

 Source: Journal of Dentistry

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