Comparing and Evaluating the Effect of Different Thickness of Two Metal-Free Restoration on Fracture Resistance in Molar Implant Prosthesis

Abstract

Aim: The objectives of this article was to determine the minimum thickness of two monolithic materials for a posterior implant prosthesis. Materials and methods sixty monolithic IPS E.MAX CAD and zirconia crowns with different occlusa l thicknesses were made with the use of a computer-aided design/computer-aided manufacturing technique was divided into 3 experimental groups: group (1) 0.5 mm group (2) 0.7mm group (3)1mm. A universal testing machine was used to determine the fracture load value. The restoration was loaded until fracture; the fracture resistance was registered. Two-way ANOVA has been used to examine the data., followed by the least significant difference LSD test. One-way ANOVA variance analysis was used to examine the differences in fracture load of monolithic zirconia or IPS E.MAX CAD at various thicknesses (p=0.05). Results vertical load test revealed that the fracture resistance of monolithic zirconia higher than the lithium disilicate crown (E.MAX CAD). The results showed that the highest mean value of fracture load test was obtained in the ice zirconia translucent with 1mm thickness group (1880N), while the lowest mean value was in the E.MAX CAD with thickness 0.5mm Group (223N). Conclusions: The fracture resistance of CAD-CAM monolithic crowns is influenced by the occlusal thickness. zirconia prosthesis with occlusal thickness 0.7mm,1mm had a high fracture resistance when compared with E.MAX CAD.