Teeth inspire aerospace design

The sophisticated structure of human teeth could inspire future designs of aircraft and space vehicles.

So believe engineers at Tel Aviv University's School of Mechanical Engineering, the National Institute of Standards and Technology and George Washington University in the US.

The team has sought to discover why teeth can withstand enormous pressure, over many years, when tooth enamel is only about as strong as glass. The results, they hope, could be applied to aerospace design.

The researchers applied varying degrees of mechanical pressure to hundreds of extracted teeth and studied what occurred on the surface and deep inside them.

‘Teeth are made from an extremely sophisticated composite material that reacts in an extraordinary way under pressure,’ said lead researcher Herzl Chai, a mechanical engineer from Tel Aviv University. ‘Teeth exhibit graded mechanical properties and a cathedral-like geometry and, over time, they develop a network of micro-cracks that 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, such as nuts.’

The automotive and aviation industries already use sophisticated materials to prevent break-up on impact. For example, some aeroplane bodies are made from composite materials - layers of glass or carbon fibres - held together by a brittle matrix.

In teeth, fibres are not arranged in a grid but are ‘wavy’ in structure. There are hierarchies of fibres and matrices arranged in several layers, unlike the single-thickness layers used in aircraft.

Under mechanical pressure, tooth architecture presents no clear path for the release of stress. Therefore tufts - built-in micro cracks - absorb pressure in unison to prevent splits and major fractures.

Chai explained that tooth fractures ‘have a hard time deciding which way to go’, making the tooth more resistant to cracking apart. He claimed that a new generation of much stronger composites for aeroplanes could be developed by harnessing this property.

He suggested that if engineers can incorporate tooth enamel’s wavy hierarchy, micro-cracking mechanism and capacity to heal, lighter and stronger aircraft and space vehicles can be developed.

Chai also claimed that the results of the research could be used by dentists to help invent stronger crowns that are better able to withstand oral wear and tear.