Fracture resistance of all-ceramic zirconia bridges with differing phase stabilizers and quality of sintering

Objectives The mechanical properties of zirconia ceramics are affected of stabilizing oxides and quality of sintering. The purpose of this study was to investigate the fracture resistance of frameworks manufactured using prefabricated zirconia blanks with differing stabilizing oxides and quality of sintering. Methods After dynamic loading in water, the fracture resistance was determined of stylized three-unit fixed partial dentures made of prefabricated homogenous ceramic green-body yttria-stabilized zirconia (Y-TZP) blanks (Vita YZ) or of densely-sintered magnesia partially stabilized zirconia (Mg–PSZ) blanks (Denzir-M); (i) as supplied from the manufacturer, (ii) after subjection to heat treatment in a way similar to veneering, and (Hi) after veneering with a feldspar-based ceramic. Results After veneering, the load at fracture of the Vita YZ specimens was significantly higher (p < 0.05) than that of Denzir-M. The load necessary to fracture Denzir-M as supplied after machining was significantly (p < 0.05) higher than that of heat-treated Denzir-M, Vita YZ as supplied and heat-treated Vita YZ specimens. There was no significant difference (p > 0.05) between the heat-treated and veneered Denzir-M specimens. For Vita YZ the load at fracture of the veneered specimens was significantly (p < 0.05) higher than of those as supplied or heat-treated, whereas no significant difference (p > 0.05) was seen between heat-treated Vita YZ and Vita YZ specimens as supplied. Significance The fracture strength of the Vita YZ specimens increased considerably after veneering. Denzir-M and Vita YZ seem to be interesting alternatives for use as core materials in all-ceramic restorations. Long-term studies are, however, necessary before general clinical recommendations can be issued.