Fracture strength of Colored Zirconia Copings with Reduced Wall Thickness

Objectives: The objective was to show that copings out of colored Lava^TM Y-TZP-ZrO₂ (3M ESPE) with a reduced wall thickness of 0,3 mm have sufficient fracture strength for the anterior region in order to allow the clinician a less invasive preparation. By fractographic analysis the fracture mode of the copings was ensured to be similar to clinically occurring fracture modes.

Methods: A total of 48 coping were produced out of colored Y-TZP-ZrO₂. 24 copings were prepared from a tangential and 24 from a champher preparation and each of these were further splitted in subgroups of 12 for the fabrication of wall thicknesses of 0,3 mm and 0,5 mm. The copings were cemented with glass ionomer cement (Ketac Cem^TM) on brass dies and fracture strength has been subsequently determined in a universal testing machine (Zwick). The load was applied by an indented punch via a tin foil to ensure a load distribution similar to veneered copings. Fractography was done with scanning electron microscopy.

Fracture strength (N)