Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Prosthodontics

Objective. The purpose of this study was to investigate the effect of two surface finish protocols on the fracture resistance and the surface roughness of monolithic CAD-CAM ceramic materials. Material and Methods. Thirty-six natural teeth were prepared and divided into three main groups (n=12) according to the type of crown material (katana zirconia, e-max CAD and Vita enamic). Each group was further subdivided into two main equal subgroups (n=6) according to surface finish (Polished, Polished-ground-repolished). Chewing simulating and thermo-cycling were performed in a masticatory simulator. Fracture resistance were tested by a universal testing machine. Surface roughness was measured via a Digital microscope. Results. Zirconia reploished crowns had a higher fracture resistance (4965.01 N) than the polished one (3432.09 N). The e-max re-polished group recorded higher mean non-significant value (2473.46 N) than the polished one (2329.53 N). The vita enamic re-polished group recorded statistically insignificant higher mean value (1838.33 N) than polished group (1730.44 N). Conclusion. Repolishing of all the ceramic crowns had overcome the effect of occlusal adjustment on the fracture resistance. Chair side repolishing is a reliable technique to be used after occlusal adjustment of all ceramic restorations

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