Letter abstract
Nature Materials 4, 229 - 232 (2005)
doi:10.1038/nmat1323
Subject Categories: Biological materials | Mechanical properties
The dentin–enamel junction and the fracture of human teeth
V. Imbeni1,3, J. J. Kruzic1, G. W. Marshall2, S. J. Marshall2 and R. O. Ritchie1
The dentin–enamel junction (DEJ), which is the interfacial region between the dentin and outer enamel coating in teeth, is known for its unique biomechanical properties that provide a crack-arrest barrier for flaws formed in the brittle enamel1. In this work, we re-examine how cracks propagate in the proximity of the DEJ, and specifically quantify, using interfacial fracture mechanics, the fracture toughness of the DEJ region. Careful observation of crack penetration through the interface and the new estimate of the DEJ toughness (
5 to 10 times higher than enamel but 75% lower than dentin) shed new light on the mechanism of crack arrest. We conclude that the critical role of this region, in preventing cracks formed in enamel from traversing the interface and causing catastrophic tooth fractures, is not associated with the crack-arrest capabilities of the interface itself; rather, cracks tend to penetrate the (optical) DEJ and arrest when they enter the tougher mantle dentin adjacent to the interface due to the development of crack-tip shielding from uncracked-ligament bridging.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, California 94143, USA
- Present address: SRI International, Menlo Park, California 94025, USA
Correspondence to: R. O. Ritchie1 e-mail: RORitchie@lbl.gov
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