A Novel Dentin Push-out Bond Strength Model That Uses Micro-Computed Tomography

Introduction: Current push-out experimental methods used in endodontic research should be improved. This study introduced a novel dentin push-out bond strength model that uses micro computed tomography (mu CT). Methods: Roots filled with gutta-percha cones and different resin-based sealers (n = 10) were sectioned transversely to obtain two 2-mm-thick slices per root third. The first slice was subjected to a push-out test by using a material testing stage fitted inside a mu CT scanner. The apparatus was scanned before and after the test to evaluate areas of filling material ruptures. The images provided by mu CT were also used to generate models for a 3-dimensional finite element analysis. Confocal laser scanning microscopy was used to assess failure modes after the test and to measure interfacial gaps in slices not subjected to push-out. Bond-strength and gap data were statistically analyzed (P < .05). Results: Proper coefficients of variation (average less than 30%) were observed for all the experimental conditions. The finite element analysis helped explain the results of bond strength and root-filling ruptures. A significant, moderate, indirect correlation was observed between the bond strength and gaps. Conclusions: The micromechanical model with the mu CT images resulted in a consistent root-filling bond strength evaluation.