The Effect of Zirconia Material and the Height of the Ceramic Coping on the Strength of Hybrid Ti-Ceramic Abutments.

The existing scientific literature lacks comprehensive information regarding the influence of zirconia crown height on debonding and fracture of the ceramic restorations on titanium base abutments. Additionally, there is a lack of comparative studies evaluating different types of zirconia as restorative options for screw-retained restorations. : The purpose of this study was to assess the fracture strength and the failure modes of the zirconia crown/titanium abutment complex by investigating the impact of increasing the height of zirconia crown and comparing different types of zirconia (3 mol% yttria-stabilized zirconia and translucent 5 mol% yttria-stabilized zirconia). : Six groups of 10 specimens in each group were fabricated. Three groups of specimens (groups # 1, 2, and 3) were fabricated from 3Y zirconia in corresponding heights of 8, 10, and 12 mm. Three more groups (groups # 4, 5, and 6) were fabricated from 5Y zirconia in the same heights (8, 10 and 12 mm). All copings were bonded to 4 mm high titanium base abutments using dual-polymerization resin cement. The specimens underwent load cycling of 100,000 cycles with a force of 100 N. Subsequently, the specimens were loaded to compression until fracture and the failure mode was visually evaluated. : Statistically significant differences in fracture strength were noted among all tested groups. : 3Y zirconia showed increased strength compared to 5Y in all heights. Ceramic copings with lower height showed increased strength compared to higher copings in both tested zirconia materials.