March 23, 2005
Nature has brilliantly engineered our teeth to transfer mechanical stresses, such as chewing, to a thin, supportive region below the surface of the tooth, where our bony dentin and rigid enamel meet. This biologically complex region, known formally as the dentin-enamel junction, or DEJ, has captured the interest of dental researchers in hopes of better characterizing its stress-resistant capacity and unique ability to halt developing cracks in the outer enamel from spreading throughout the tooth and causing fractures. Despite the long-term research interest, largely missing from the scientific literature has been a comprehensive and technologically sophisticated analysis of structural variations and stress resistance across the DEJ, information of great benefit to the dental community. As published in the March issue of the journal Nature Materials, NIDCR grantees and colleagues provide this broad structural analysis and, based on their data, provide a new estimate on the toughness of the DEJ, characterizing the region as up to 10 times tougher than enamel but 75 percent less tough than dentin. They also conclude that a tooth's ability to stop the spread of cracks resides in the mantle dentin itself, not the DEJ.
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about this paper by Imbeni, Ritchie, et. al.