Experimental Evaluation of Fatigue Parameters in Modern Resin Composites

Methods: The dynamic fatigue method (constant stressing rate technique) was used to obtain the crack growth exponent n and σfo, a material constant dependent on the test environment and the initial strength of the material. For the fracture test, twenty six disk-shaped specimens were produced from Ceram-X Mono (CX), Clearfil Majesty (CM) and Saremco els (SM) resin composites (all of A2 shade). The specimens were loaded to fracture using the biaxial flexure test (ball-on-three-balls test) at various stressing rates, ranging from 0.4 to 66.9 MPa/s. Fatigue parameters (n and σfo) were statistically analysed employing linear regression analysis (a:0.05).

Results: The initial strength of CM (92±10 MPa) was the highest. SM (63±9 MPa) showed higher initial strength values than CX (20±11 MPa) (for all p<0.05). Νo statistically significant differences (p>0.05) were found among the n values of the materials tested (25.0-35.1 range).

Conclusions: Since fatigue parameters obtained from dynamic testing provide significant information for the mechanical degradation rate of the materials, it follows that significant performance differences are anticipated among the materials tested.