It's been a mystery: how can our teeth withstand such an enormous amount of pressure, over many years, when tooth enamel is only about as strong as glass?

A new study by Prof. Herzl Chai of Tel Aviv University's School of Mechanical Engineering and his colleagues at the National Institute of Standards and Technology and George Washington University gives the answer.

The study, published in the May 5, 2009, issue of the Proceedings of the National Academy of Science, shows that it is the highly-sophisticated structure of our teeth that keeps them in one piece - and that structure holds promising clues for aerospace engineers as they build the aircraft and space vehicles of the future.

"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."

Creating a super-smile

Dental specialists looking for new ways to engineer that picture-perfect Hollywood smile can use Dr. Chai's basic research to help invent stronger crowns, better able to withstand oral wear-and-tear. "They can create smart materials that mimic the properties found in real teeth," he says.

In natural teeth, there may not be any way to speed up the self-healing ability of tooth enamel, which the Tel Aviv University research found is accomplished by a glue-like substance that fills in micro-cracks over time. But fluoride treatments and healthy brushing habits can help to fill in the tiny cracks and keep teeth strong.

"It's been a mystery: how can our teeth withstand such an enormous amount of pressure, over many years, when tooth enamel is only about as strong as glass? (Credit: Courtesy of Wikimedia Commons)"

Source: Tel Aviv University