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

• We present a new approach to push-out tests: a material testing stage (MTS) inside the μCT.
• μCT images facilitated proper alignment of specimens during push-out test.
• μCT image and mechanical test provided qualitative and quantitative bond strength data.
• MTS technology resulted in consistent root-filling bond strength evaluation.

IntroductionCurrent 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 (μCT).MethodsRoots 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 μCT scanner. The apparatus was scanned before and after the test to evaluate areas of filling material ruptures. The images provided by μCT 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).ResultsProper 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.ConclusionsThe micromechanical model with the μCT images resulted in a consistent root-filling bond strength evaluation.