MECHANICAL PERFORMANCE OF A DENTAL COMPOSITE - PROBABILISTIC FAILURE PREDICTION

In clinical situations, the mechanical performances of dental structur es-for example, composite restorations-depend on many factors. Most of them have a probabilistic character. Because composites are brittle m aterials, their strength, should also be considered as a probabilistic quantity. For successful prediction of mechanical failure of structur es consisting of these materials, a probabilistic approach is indispen sable, and a suitable definition of equivalent stress must be introduc ed. An equivalent stress facilitates the transfer of strength data of laboratory specimens to situations where the stress state is much more complicated. The tensile and compressive strengths of composites diff er considerably. Of two equivalent stress definitions that potentially describe this experimental fact (the Drucker-Prager and the Modified von Mises equivalent stress), the predictive capacity was investigated for a microfine composite. In a probabilistic approach to failure, us e of the Drucker-Prager equivalent stress appeared to be superior, bec ause the average failure load of notched beams was predicted with an e rror smaller than 8%.