Abstract
Specimens with heat treatment and without heat treatment of four commercially available composite resin inlay products and two composite resins for posterior use were prepared and fracture toughness test, tensile test and compressive test were performed.Fracture toughness test was performed using the single edge notched three-point bending specimen with three different shapes of notches.As the angle of the notch became smaller, fracture toughness became smaller.The tests were not affected by the method of the preparation of fatigue crack.Tensile strength and compressive strenth of composite resin inlay products were similar or better than those of composite resins for posterior use, but fracture toughness of some composite resin inlay products was inferior to those of composite resins for posterior use.Fracture toughness of composite resins increased after heat treatment when they showed some permanent deformation before fracture without heat treatment, but not much after heat treatment when they became brittle before fracture.
