How to measure strength of dental filling materials

The strength behaviour of different types of dental filling materials was studied in order to find out the most informative and the most convenient testing procedure. Several common compression, tensile and bending tests were utilized. Additionally, size and shape of the specimens or the surface treatment were varied in some series. The results not only show the well known large differences in the strength values depending on the testing method but also contradictory evaluation when comparing materials. From these findings it is concluded that pure compression tests are not useful. Furthermore, taking into account the practicability of the different procedures it is proposed to perform diametral tensile tests in order to determine volume strengths, or 4-point-bending-tests if surface influences are of interest.