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Closing the Gap

May 17, 2013

Do cracks in dental enamel have an innate ability to heal?

SEM image of a selected indentation crackDental enamel is the hardest and most mineralized tissue in the human body. But as a close look in the mirror readily shows, enamel is prone to hairline cracks. While numerous studies have evaluated how and why these cracks form and spread, few have ever looked at whether enamel has the innate ability to heal thyself and, if so, to what degree. As published online on March 14 in the Journal of the Mechanical Behavior of Biomedical Materials, an NIDCR grantee and colleagues provide some of the first data to indicate that enamel does have some capacity to fill in the gaps. In the study, they mechanically induced cracks in the enamel of 21 extracted third molars and measured the length of the injuries. They determined that the cracks gradually shortened over time, with over 90 percent of the closure occurring within 24 hours and the efficiency of repair decreasing the greater the depth of the break. Taking an extremely high-resolution look at the cracks with a scanning electron micrograph, they detected organic proteins within the fissure, ostensibly creating a viscoelastic stress, or mechanical pull, to help the crack narrow and repair. “The present study has provided the first quantitative evidence that enamel undergoes mechanical processes essential to repair and the eventual healing of mechanical damage,” the authors concluded. “Future study of this important topic may provide further bioinspiration for design and fabrication of high performance composite materials.”

The paper is titled, “Indentation damage and crack repair in human enamel,” and the authors are: C. Rivera, D. Arola, and A. Ossa.



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This page last updated: February 26, 2014