Fracture properties of human teeth in proximity to the dentinoenamel junction.

Under conditions of controlled failure, the fracture properties of dentin at and in proximity to the dentinoenamel junction (DEJ) were studied with a work-of-fracture (Wf) technique and by scanning electron microscopy (SEM). In 37 degrees C distilled water, fracture of normal human teeth at the DEJ was a difficult failure mode to investigate. Even with high stress concentration at the DEJ, only a few specimens showed apparent DEJ failure at localized regions. SEM fractography of these localized regions revealed surfaces similar in some respects to surfaces found in other studies of the DEJ of diseased teeth and decalcified or desiccated teeth. SEM fractographs varied depending upon the distance of the fractured surface from the DEJ. The results of this research suggest that the work of fracture of dentin increases for failure in the near vicinity of the DEJ, probably reaching a maximum at the DEJ.