IADR Abstract Archives
Impact of CAD/CAM Milling Protocols on Polycrystalline Zirconia Properties
Objectives: The study objective is to evaluate the effect of the CAD/CAM milling protocol on the topography, flexural strength and reliability of 3 mol.% yttria partially stabilized zirconia (3Y-PSZ).
Methods: Disc-shaped specimens (1.2 mm x 12 mm) were fabricated using three different CAD/CAM dry-milling protocols (n=20): slow (S), normal (N), and fast (F). Control polished specimens were fabricated by cutting pre-sintered CAD/CAM blocks using a cutting machine and polishing with silicon carbide papers, in wet (Pwet) and dry (Pdry) conditions (n = 20). Surface topography was evaluated using an optical profilometer (n=3). Specimens were subjected to a piston-on-three balls flexural strength test in a universal testing machine. Fractographic analysis was performed. The characteristic flexural strength (σ0) and Weibull modulus (m), and their respective 90% confidence intervals (90% CI), were estimated using Weibull statistics. XRD was used to identify tetragonal, cubic, and monoclinic crystal phases.
Results: Distinct topographies were observed in polished and CAD/CAM milled specimens. Surface roughness followed a decreasing order: F > N > S > P. There was no difference for σ0 and m values among the three CAD/CAM milling protocols. Pdry had similar σ0 and m values to the CAD/CAM milled groups, while Pwet resulted in lower values.
Conclusions: Although the type of CAD/CAM milling protocol produced different surface topographies, there was no effect on the flexural strength and reliability of 3Y-PSZ. Yet, specimens produced in wet conditions showed inferior mechanical behavior.
Methods: Disc-shaped specimens (1.2 mm x 12 mm) were fabricated using three different CAD/CAM dry-milling protocols (n=20): slow (S), normal (N), and fast (F). Control polished specimens were fabricated by cutting pre-sintered CAD/CAM blocks using a cutting machine and polishing with silicon carbide papers, in wet (Pwet) and dry (Pdry) conditions (n = 20). Surface topography was evaluated using an optical profilometer (n=3). Specimens were subjected to a piston-on-three balls flexural strength test in a universal testing machine. Fractographic analysis was performed. The characteristic flexural strength (σ0) and Weibull modulus (m), and their respective 90% confidence intervals (90% CI), were estimated using Weibull statistics. XRD was used to identify tetragonal, cubic, and monoclinic crystal phases.
Results: Distinct topographies were observed in polished and CAD/CAM milled specimens. Surface roughness followed a decreasing order: F > N > S > P. There was no difference for σ0 and m values among the three CAD/CAM milling protocols. Pdry had similar σ0 and m values to the CAD/CAM milled groups, while Pwet resulted in lower values.
Conclusions: Although the type of CAD/CAM milling protocol produced different surface topographies, there was no effect on the flexural strength and reliability of 3Y-PSZ. Yet, specimens produced in wet conditions showed inferior mechanical behavior.