RESUMO
AIM: The aim of this study was to investigate whether there is a relation between impact strength and flexural strength of different composite and ceramic materials used in dental restorations. MATERIALS AND METHODS: The three-point-bending test was used to determine the flexural strength and flexural modulus, and the Dynstat impact test was used to determine the impact strength of different composite and ceramic dental materials. The relation between the flexural strength and impact strength was mathematically investigated and a three-dimensional finite element analysis model of the impact test set-up was created to verify these results. RESULTS: We found a relation between the impact strength, adU, the flexural strength, σ, and the flexural modulus, E, which can be represented by the formula: adU=λDK(σ2/E), where λDK is a constant dependent on the test set-up. CONCLUSION: The obtained impact strength of materials is specific to the test set-up and dependent on the geometric configuration of the test set-up and the specimen thickness. The clinical significance of this investigation is that roughness and fatigue have far more influence on the impact strength than the flexure strength.
