Effects Of The Number Of Firing On Strength Of Nano-ceramic And Traditional Ceramic In Metal-ceramic Crown Prosthsis

Objectives: To observe surface structure and porcelains fracture sections by scanning electron microscope (SEM). To compare the strength of nano-ceramic and traditional-ceramic by destruction tests on metal-ceramic crowns. The relationship between the number of firing and strength was discussed .The results were expected to provide effective experimental reference to the clinical application of nano-ceramic.Methods: 1. Models preparation: a metal die of simulating crown core was produced with precision machine. Totally 40(in 8 groups) metal-ceramic crown models with same thickness were conventionally produced. Groups A-D were traditional ceramic with different number 4, 6, 8, 10. Groups A′-D′were nano-ceramic with different number 4, 6, 8, 10. 2. The surface feature of the tested specimens was observed by SEM. 3. With Instron testing machine, destruction test on each model was performed to test fracture force values. 4. Each model's structure of fracture sections was observed with SEM.Results: 1 Metal-ceramic crown's surface microstruture: in group A and B, no obvious crack was visible. Small pores evenly scattered. In group C, the surface was uneven. Many...