Teeth are resilient: sea otter

1 of 1 Sea otter cracking a mollusk / Simon Bisson / License

Teeth of sea otters resist damage due to 'stress shielding' by neighbors, prism interweaving (decussation), and self-healing.

Biomimicry Taxonomy

	Maintain physical integrity >
	Manage structural forces >
	Compression

Biomimetic Application Ideas

Lightweight laminate structures Synthetic enamel replacements for bones, teeth, soft tissues

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[Collapse all sections] Summary

"Tooth enamel is inherently weak, with fracture toughness comparable with glass, yet it is remarkably resilient, surviving millions of functional contacts over a lifetime. We propose a microstructural mechanism of damage resistance, based on observations from ex situ loading of human and sea otter molars (teeth with strikingly similar structural features). Section views of the enamel implicate tufts, hypomineralized crack-like defects at the enamel–dentin junction, as primary fracture sources. We report a stabilization in the evolution of these defects, by 'stress shielding' from neighbors, by inhibition of ensuing crack extension from prism interweaving (decussation), and by self-healing. These factors, coupled with the capacity of the tooth configuration to limit the generation of tensile stresses in largely compressive biting, explain how teeth may absorb considerable damage over time without catastrophic failure, an outcome with strong implications concerning the adaptation of animal species to diet." (Chai et al. 2009:7289)

"Teeth are made from an extremely sophisticated composite material which reacts in an extraordinary way under pressure," says Prof. Chai. "Teeth exhibit graded mechanical properties and a cathedral-like geometry, and over time they develop a network of micro-cracks which help diffuse stress. This, and the tooth's built-in ability to heal the micro-cracks over time, prevents it from fracturing into large pieces when we eat hard food, like nuts." (Dr. Herzl Chai, Tel Aviv University's School of Mechanical Engineering)

About the inspiring organism

Sea Otter
Enhydra lutris (Linnaeus, 1758)
[Sea otter]

IUCN Red List Status: Endangered
Habitat(s): Marine Neritic, Marine Oceanic

Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Synthetic enamel replacements for bones, teeth, soft tissues. Laminate structures for lighter and safer airplanes.

Industrial Sector(s) interested in this strategy: Medical, manufacturing,

Experts

Materials Sciences and Engineering Laboratory, Ceramics Division
Brian R. Lawn
National Institute of Standards and Technology

References

Chai, H; Lee, JJ-W; Constantino, PJ; Lucas, PW; Lawn, BR. 2009. Remarkable resilience of teeth. Proceedings of the National Academy of Sciences. 106(18): 7289-7293.

Teeth are resilient: sea otter

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