title: Fracture stability of anterior zirconia crowns with different core designs and veneered using the layering or the press-over technique.
abstract: In the current in vitro study, the fracture stability of anterior crowns with zirconia cores of different designs was investigated after applying different veneering techniques. Four groups of zirconia cores (n = 10 in each group) were produced using a computer-aided design/computer-aided manufacturing (CAD/CAM) process. Cores with a standard cervical design were veneered using the layering technique (CCL) or the press-over technique (CCP). Further cores were designed with a porcelain shoulder, where the cervical margin of the zirconia core was reduced by 1 mm. These cores were also veneered using the layering technique (PSL) or the press-over technique (PSP). All crowns were cemented onto metal teeth and loaded until fracture in a universal testing machine. Chipping or fracture of the core was found to occur for CCL at 919±265 N (mean ±SD), for CCP at 798±226 N, for PSL at 739±184 N, and for PSP at 734±209 N. anova did not show significant differences between the four groups. For CCL and CCP, fracture lines ran in a mesio-distal orientation. For PSL and PSP, fracture lines ran into the porcelain shoulder. In summary, the use of a porcelain shoulder can be recommended with zirconia crowns in combination with either the layering or the press-over veneering technique.
authors.affiliation: Department of Prosthetic Dentistry and Biomedical Materials Science, Hannover Medical School, Hannover, Germany. Eisenburger.Michael@mh-hannover.de
authors.forename: Michael
authors.initials: M
authors.lastname: Eisenburger
authors.forename: Tobias
authors.initials: T
authors.lastname: Mache
authors.forename: Lothar
authors.initials: L
authors.lastname: Borchers
authors.forename: Meike
authors.initials: M
authors.lastname: Stiesch
mesh_terms: D003442:Crowns; D003764:Dental Materials; D003776:Dental Porcelain; D017267:Dental Prosthesis Design / Q000379:methods*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D008422:Materials Testing; D013314:Stress, Mechanical; D015040:Zirconium
chemical_list: D003764:Dental Materials; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide