Quick Peek into NIOM Labs and the Three-Point Bending Test

Get a quick peek into our laboratories and a demonstration of a three-point bending test.
NIOM aims to ensure the safe and effective use of biomaterials. We work with all kinds of dental materials, including ceramics, alloys, and polymers. As a polymer chemist, Head of Laboratory, Hilde Molvig Kopperud, has a special interest in resin-based materials.
When investigating biomaterials, we try to mimic the clinical situation. However, as individuals, we are all different, and this can be quite difficult. Therefore, standardised methods are often used to achieve comparable and reliable results.
The three-point bending test is a standardised method present in many dental material standards to investigate the mechanical properties of a material by measuring the flexural strength. The test can be seen as simulating what might happen when external forces are applied to a material, for instance, during chewing.
As polymers, ceramics, and alloys have very different properties, the specifics of the test method are different for each type of material. However, the principles of the test are the same, using supports and a load to create flexure of the specimen, usually until fracture. This flexure will produce compressive forces around the point of impact and tensional forces on the opposite side of the specimen, causing the material to fracture.
Polymer materials are elastic or viscoelastic, and in the three-point bending test, we can see a deflection in the specimen that for some materials may be quite substantial. In some cases, the material will not fracture but just bend.
However, ceramics are brittle materials and will fracture after only a small deflection, but with a larger load exerted on them. The intended use of the material is reflected in the requirements given in the different standards. For instance, single-unit restorations will have a lower requirement for flexural strength compared to bridges with several units.
Please watch our webinar below to learn more about this topic.