The fracture toughness characteristics of three dental composite resins

A fracture mechanics approach has been adopted in the present study to investigate the fracture toughness behavior of three commercial composite resins for dental use named Clearfil photo posterior, P-50 and Occlusin. The resins have been cast in to ring-shaped specimens for the determination of individual fracture toughness values. The experimentally determined values have been compared with fracture toughness values obtained from the indentation micro-fracture method, which is the currently more popular test method for determining fracture toughness characteristics of composite resins. Occlusin was found to exhibit higher fracture toughness values than any other resin, employing the ring specimen test procedure. However, this was not the case when using the indentation method which gave comparable fracture toughness values for all three resins. It was concluded that the ring specimen provides a simple, accurate and reproducible method for providing a measure of the materials fracture toughness.