Chipping resistance and residual thermal stresses of Y-TZP/ veneer porcelain bars as a function of processing methods

Abstract

The objectives of this study are to evaluate specimens with the following combinations of materials and processing methods: a) feldspathic porcelain applied through traditional technique on zirconia infrastructure; b) feldspathic porcelain applied on zirconia infrastructure using press-on technique, c) feldspathic porcelain CAD-CAM blocks machined and cemented on zirconia infrastructure (rapid layer technique); d) lithium disilicate glass ceramic processed through CAD-CAM system and attached to a zirconia infrastructure using a union glass (CAD-on technique), in regards of: (1) edge chipping resistance of the veneering material by means of edge chipping test; and (2) thermal residual stress levels measured in veneering porcelain from cracks generated on the surface of the specimens by indentation method. Bilayers bars with 25 mm length, 4 mm width and a porcelain/infrastructure thickness combined to provide 1 mm of each material will be prepared according to manufacturer's recommendations. The edge chipping test will be performed on a universal testing machine using a Vickers indenter bonded to this machine and the data will be analyzed by plotting the force required to produce the fragments (Fc) as a function of the distance (Fa) between the indenter and the edge of interest. The residual thermal stress will be calculated from indentations made in the porcelain layer bars using a Vickers indenter. (AU)