Purpose: The purpose of this study is to compare fatigue resistance to mechanical properties of CAD-CAM restorative blocks. Method: An experimental fracture resistant composite, containing short-cut fibers (Kerr Exp) was tested along with current products, Paradigm MZ 100 (P MZ100) and porcelains E Max CAD, IPS E CAD. Fatigue data were measured according to P. Magne et al, Quint Int. 40 (2) 2009. Flexural strength (FS), flexural modulus (FM), fracture toughness (K1C) were measured (5 specimens) according to IADR Abst. 288, 2000. The parameter, Work of Fracture (W of F), was also calculated from the data. Results: The data are reported in the table. The initial force to failure in the fatigue data were plotted against the mechanical strength data. No correlation was found with FS, FM or K1C, but a good correlation was found with W of F, R2=0.96. In fracture mechanics, W of F is the energy required to create a new surface in a propagating flaw. Conclusion: A good correlation to fatigue resistance was found with the mechanical property, Work of Fracture (supported by Kerr Corp.).
Material | FS | FM | K1C | W of F, | Fatigue (185K cyc), Survival % @ Load (N) | |||||
| MPa (s.d.) | GPa, (s.d.) | MPa m1/2 (s.d.) | K1C2/E , J/m2 | 400 N | 600N | 800N | 1000N | 1200N | 1400N |
E.Max CAD | 257 (44) | 81 (3.3) | 2.59 (0.27) | 8.3 x 10-2 | 100% | 80% | 20% | 0% | 0% | 0% |
IPS E CAD | 141 (10) | 57.6 (2.6) | 1.09 (0.25) | 2.1 x 10-2 | 50% | 0% | 0% | 0% | 0% | 0% |
P MZ100 | 153.7 (23.6) | 17 (0.8) | 1.55 (0.23) | 14.1 x 10-2 | 100% | 100% | 90% | 90% | 90% | 60% |
Kerr Exp | 171.4 (15.6) | 10 (0.3) | 2.39 (0.56) | 57 x10-2 | 100% | 100% | 100% | 100% | 100% | 100% |