The purpose was to investigate the potential difference in the load-to-fracture values of several all-ceramic crown systems. Five different coping-reinforced all-ceramic crown systems were selected. Ten crowns from each system were fabricated and luted to standardized titanium dies.

The study consisted of five groups of ten samples each, all luted using G.C. Link Max resin adhesive cement. Group A: IPS Eris®, Group B: Cerac® In-lab Alumina coping, Group C: Cerac® In- lab Zirconia coping, Group D: Procera® AllCeram Alumina coping, and Group E: Procera® Zirconia coping. Following cementation, the samples were placed under a 5 Kg static load for 10 minutes insuring proper seating and stored in 100% humidity for one week. All samples were visually inspected prior to testing and were loaded to fracture at the rate of 0.5 mm/min using a universal-testing machine.

Group A = 321.49 KgF ± 113.69 (S.D.), Group B = 288.63 ± 102.82 (S.D.), Group C = 266.58 ± 69.17 (S.D.), Group D = 295.49 ± 80.54 (S.D.), and Group E = 420.37 ± 82.45 (S.D.). The data were analyzed using an unpaired t-test; this indicated a statistical difference between group E and all of the others (P-value ≤0.039).

We concluded under these conditions, the Procera® Zirconia crown system has significant higher load-to-fracture value than several other all-ceramic crown systems.

Snyder MD, Hogg KD. Load-to-fracture Value of Different All-ceramic Crown Systems. J Contemp Dent Pract 2005 November;(6)4:054-063.