Flexural strength of four-unit implant-supported ceramic veneered zircon and full zircon fixed dental prosthesis

Abstract

Purpose To investigate the flexural strength and the fracture loads of bilayered and monolithic zirconia fixed dental prostheses (FDPs). Materials and methods For flexural strength test, two groups of bar-shaped (25 × 5 × 2 mm3) monolithic zirconia (n = 5) and bilayered zirconia–porcelain (n = 5) specimens were prepared using computer-aided design and manufacture system for zirconia and hand layering for porcelain. Flexural strength test was performed using universal testing machine at cross-head speed of 1 mm/min. For fracture resistance test, 20 master models composed of two implant analogues and their corresponding titanium implant abutments embedded vertically in autopolymerizing acrylic resin blocks to mimic clinical conditions for a four-unit FDPs. Twenty FDPs were fabricated and divided into two groups (n = 10): group A, bilayered zirconia four-unit implant-supported FDPs; group B, monolithic zirconia four-unit implant-supported FDPs. Samples in each group were cemented to their corresponding model and then underwent artificial ageing by thermocycling of 5000/cycle. The fracture resistance test was done using universal testing machine at cross-head speed of 1 mm/min. Statistical analysis of the results and comparison between each two groups were performed using independent t-test (significance: P ≤ 0.05). Results Monolithic zirconia group recorded statistically significant higher flexural strength and fracture resistance compared to bilayered group. Conclusion Strength of monolithic zirconia is significantly higher than bilayered zirconia.