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

## TL;DR

This study examines how the height of zirconia crowns and their material type affect the strength and failure of hybrid titanium-ceramic dental abutments.

## Contribution

The study provides new comparative data on 3Y and 5Y zirconia crown strength and failure modes in varying heights on titanium abutments.

## Key findings

- 3Y zirconia showed higher strength than 5Y zirconia across all tested heights.
- Shorter zirconia crowns exhibited greater strength than taller ones in both materials.
- Load cycling and compression testing revealed significant differences in fracture strength among groups.

## Abstract

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. Purpose: 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). Materials and Methods: 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. Results: Statistically significant differences in fracture strength were noted among all tested groups. Conclusions: 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.