Methods: Five different shapes of dental preparations are designed. We manufacture by CAM, for each shape, a series of five aluminum supports. Glass-reinforced ceramic crowns are duplicated using CAD-CAM and optical imprints. They are glued identically on the aluminum supports. These samples are submitted to a compressive loading in occlusal direction until rupture. The compressive tests are performeded by using a DARTEC mechanical press at a constant load speed. Simultaneously, a LVDT sensor monitors the compressive displacement response of the sample. In order to measure the evolutive response of the structure (stiffness, strength), a sequenced loading is applied: So partial unloadings (-100N) are conducted after each progressive loadings (+300N).
Results: The results (mean values, standard deviations) for each series and between series are discussed. The ultimate compressive force for the different series is between 1.01 and 1.90 kN. The minimum standard deviation is about 0.02 kN for a series, which proves the reproducibility of the method. These values and the analysis of force-displacement curves allow to estimate the influence of the supports geometry. Because it avoids most of “operator-dependent” tasks, CAD-CAM is an ideal way of producing samples for reproducible mechanical tests in the fixed prosthesis field.
Conclusions: This new approach shows a great promise and could be implemented for the study of reconstruction materials, interfaces and samples geometry. A complementary study by finite element modeling will lead to highlight on the local stress-strain responses of materials used.