Keynote Address: Do Physical Parameters Predict the Fractures and Wear of Composite Restorations?

Abstract Body: The mechanical stability of direct restorative materials is one of the prerequisites for the long-term clinical success of composite resin restorations. However, material fractures are – apart from marginal caries – the predominant reason for the failure and replacement of restorations. Furthermore, excessive material wear compromises the esthetic appearance of restorations. There are plenty of laboratory tests to characterize and predict the mechanical stability of composite materials. They include flexural strength tests of different kinds (three point/four point bending tests, biaxial flexural strength tests), fracture toughness tests, tensile strength tests, compressive strength tests, as well as various surface hardness tests, elastic modulus tests, etc. In order to assess which test is the most appropriate to predict the clinical performance of a composite resin, it is worth correlating physical parameters with variables from prospective clinical studies such as the frequency of fractures/chipping and loss of anatomical contour (wear) in relation to the composite material. The results of such a correlation study will be presented.This lecture will try to answer the following questions: (1) Do specific composite materials show more fractures and wear in clinical studies than others? (2) Which physical parameters predict the fractures of composite restorations? (3) Which physical parameters predict the wear of composite restorations? (4) Does artificial ageing such as thermocycling or the pre-test storage of specimens in water/saliva or ethanol enhance the prediction probability of physical parameters? (5) Are there cut-off values for the acceptance of a specific test?