use of monolithic zirconia crowns in implant prostheses is increasing,
especially when the interdental space is insufficient. However,
fractures have been reported in clinical practice.
purpose of this study was to determine the minimal thickness of a
complete zirconia crown used for an implant prosthesis in the posterior
Material and methods
complete zirconia crowns were produced using a computer-aided
design/computer-aided manufacturing technique. In each group, 5 crowns
of varying thicknesses (0.4, 0.5, 0.6, 0.7, and 0.8 mm) were subjected
to cycles of vertical and 10-degree oblique compressive loading at 5 Hz
and 300 N in a servohydraulic testing machine. Five finite element
models comprising 5 different occlusal thicknesses (0.4, 0.5, 0.6, 0.7,
and 0.8 mm) were simulated at 2 loading angles (0 and 10 degrees) and 3
loading forces (300, 500, and 800 N). Data were statistically analyzed,
and fracture patterns were observed with a scanning electron microscope.
loading tests revealed that the fracture resistance of the specimens
was positively associated with prosthesis thickness (P<.01).
Low von Mises stress values were obtained for prostheses with a minimal
thickness of 0.7 mm under varying loading directions and forces.
prostheses with a minimal thickness of 0.7 mm had a high fracture
resistance and the lowest stress values. Therefore, dentists and
laboratory technicians should carefully choose the optimum thickness of