Nondestructive 3D-evaluation of human dentin by microtomography using synchrotron radiation

Abstract

Results of Synchrotron Radiation (SR) microtomography of human dentin specimens subjected to compression tests are presented. A special attention is paid to cracks formed in the samples under compression. In all the samples, the dominant crack paths were observed to deviate and deflect around certain areas at or near to dentinal tubules. It is confirmed that secondary (satellite) cracks play an important role in dominant crack blunting. It is shown that microtomography is an effective method for investigation of the formation of satellite cracks and crack-tubule interactions over surface areas and across the whole depth of a dentin specimen. These processes can be visualized and evaluated using reconstructed 2D slices. A qualitative model for the formation of secondary cracks opening at stress concentrators that are dentinal tubules is suggested. It is shown that on the surface of the tubules, which are the closest to the tip of a mode II crack, the tensile circumferential stress can reach extremely high values that are more than enough for generation of secondary cracks.