Push-out of root canal filling using the material testing stage (MTS) inside a Micro-CT: preliminary observations

Aims Mechanical testing has been performed to evaluate the bond strength of root canal fillings to dentin surface of root canal. In this scenario, the push-out testing is widely used, although the results from several studies are sometimes inconsistent (1-4). The variability of specimen’s geometry and thickness; and diameters of tip applying the load are some factors that can to alter the stress distribution and consequently the results (4,5). In addition, the fixation and parallelism of specimens during push-out testing is difficult to obtain (6). These drawbacks claim for a more rigorous protocol to perform the bond-strength testing (5). Micro-computed tomography (μCT) is a non-destructive tool producing three-dimensional images used for different purposes in dental researches (7,8). A recently developed technology is able to provide specimen’s images during the mechanical tests. For this purpose, a material testing stage (MTS) is fitted inside a μCT scanner (9). Since MTS records load-displacement data during the test, a digital push-out micromodel can be created by using μCT permitting to evaluate with more accuracy the bond-strength values. In addition, μCT datasets once converted into numerical models facilitates the finite element analysis (FEA) of the material and its geometrical structure (9). Thus, this study presents some preliminary observations on push-out bond strength of root canal filing using MTS technology associated to a μCT. FEA was used to provide additional information on this micromechanical experimental model.