Effect of Connector Designs on Flexural Strength of Gradient Versus Translucent Monolithic Zirconia Fixed Dental prosthesis, An in Vitro Study.

Abstract

Background: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has been used due to its high strength and unique transformation toughening properties. Despite the exceptional mechanical properties of using zirconia its opacity limited their use in only posterior regions. Improvements of translucency were done in monolithic zirconia “gradient zirconia” restorations. Since several clinical data reported a high failure rate of (FDP) around connector areas. Aim of the study: to evaluate the effect of connector designs on the flexural strength of gradient zirconia in comparison to translucent zirconia Fixed dental prosthesis. Materials and Methods: A total of twenty-three-unit Fixed dental prosthesis were fabricated for the current study. The FDP will be divided into two main experimental groups (n =10). With 4 subgroups as the following: Group B (BruxZir zirconia) with subgroups: SubGroup BS: BruxZir Zirconia with sharp connector design. SubGroup BR: BruxZir Zirconia with round connector design. Group G (Gradient zirconia) with subgroups: SubGroup GS: Gradient zirconia with sharp connector design. SubGroup GR: Gradient zirconia with round connector design. Results: Revealed that the lowest flexural strength mean value was related to group B BruxZir with sharp connector design with value (578.77), followed by Group B BruxZir with round connector design (709.10), while the highest flexural strength value was found in ZirCAD group with round connector designs (964.78). Conclusions: Flexural strength of gradient 3Y & 5Y zirconia is higher than translucent 4Y zirconia. Round connector designs show higher flexural strength than that of sharp designs.