Fracture strength of veneered translucent zirconium dioxide crowns with different porcelain thicknesses

Abstract

Objective: To evaluate fracture strength of veneered translucent zirconium dioxide crowns designed with different porcelain layer thicknesses. Materials and Methods: Sixty crowns, divided into six groups of 10, were used in this study. Groups were divided according to different thicknesses of porcelain veneer on translucent zirconium dioxide cores of equal thickness (0.5 mm). Porcelain thicknesses were 2.5, 2.0, 1.0, 0.8, 0.5 and 0.3 mm. Crowns were artificially aged before loaded to fracture. Determination of fracture mode was performed using light microscope. Results: Group 1.0 mm showed significantly (p ≤ .05) highest fracture loads (mean 1540 N) in comparison with groups 2.5, 2.0 and 0.3 mm (mean 851, 910 and 1202 N). There was no significant difference (p>.05) in fracture loads among groups 1.0, 0.8 and 0.5 mm (mean 1540, 1313 and 1286 N). There were significantly (p ≤ .05) more complete fractures in group 0.3 mm compared to all other groups which presented mainly cohesive fractures. Conclusions: Translucent zirconium dioxide crowns can be veneered with minimal thickness layer of 0.5 mm porcelain without showing significantly reduced fracture strength compared to traditionally veneered (1.0–2.0 mm) crowns. Fracture strength of micro-veneered crowns with a layer of porcelain (0.3 mm) is lower than that of traditionally veneered crowns but still within range of what may be considered clinically sufficient. Porcelain layers of 2.0 mm or thicker should be used where expected loads are low only.

Evaluation of Stress Distribution in Tooth‐Supported Fixed Dental Prostheses Made of Translucent Zirconia with Variations in Framework Designs: A Three‐Dimensional Finite Element Analysis

“…Since the total thickness in all designs was the same, the reduction in the veneer thickness in SM0.3 model enables thicker supporting material underneath it. The results were in agreement with previous studies showing the importance of coping thickness for the load‐bearing capacity of minimally veneered zirconia crowns . In the clinical scenario, the starting points for the chipping fracture of the bilayer zirconia restorations are mainly affected by the existence of critical flaws in the veneer layer .…”

“…Based on previous studies, the structural reliability of veneered Y‐TZP restorations may be enhanced by modifying the framework design . The different design modifications proposed are focused on minimizing the tensile stresses within the material by providing supportive structures in the zirconia framework.…”

Effect of different semimonolithic designs on fracture resistance and fracture mode of translucent and high-translucent zirconia crowns

“… 35 , 36 The specific aging protocol of the present study was performed in attempt to mimic the real clinical environment that the crowns would be subjected to it and to make comparisons with previous studies with similar methodologies. 6 , 9 , 24 , 25 …”

“… 22 , 23 In this study, thermocycling and preload tests were adopted from previous studies conducted by the same research group to enable comparisons. 24 , 25 …”

Effect of Lithium Disilicate Reinforced Liner Treatment on Bond and Fracture Strengths of Bilayered Zirconia All-Ceramic Crown

“…Chemical bonding can be induced by various kinds of liner treatments and selective infiltration etching (SIE) [ 15 , 20 , 21 , 22 ]. Also, the effects of these surface treatments on bond and fracture strengths between zirconia and veneering ceramic have been identified by various mechanical tests, such as shear bond test, microtensile bond strength test, 3 or 4-point bending test, progressive or cyclic load fracture test, and indentation test [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”