The fracture toughness of dental composites

A fracture mechanics approach has been adopted to quantify the failure of dental composites under stress. The parameter K_IC has been determined by the use of SEN specimens subject to the variables of composite product type, storage environment, test environment and temperature, and polymerization time. The results show that K_Ic varies from product to product, increasing significantly if there is sufficient time for the absorption of storage water. The effect of test environment and temperature (over the range expected in vivo) is minor.