Physicists get teeth into jaws

Kam Patel reports on speakers at the Institute of Physics congress in Brighton this week

A PHYSICS-based technique is being used by Loughborough University researchers to provide insights into the complex structure and behaviour of the jaw.

Called electronic speckle pattern interferometry (EPSI), the technique combines laser technology, a television camera and a computer to record how a three-dimensional surface changes when a force is applied to it.

This can show, for instance, exactly what happens when you get a sock on the jaw; the stresses and strains in rocket motors at launch; and even how a bra moves when worn.

Researchers led by John Tyre at the university's mechanical engineering department say the technique is much more accurate than mathematical models like finite element analysis, enabling examination of what is happening to a structure in situ and in real time.

Their recent work has focussed on the behaviour of a test jaw bone when force was applied to the end of the chin. Using EPSI, the researchers have concluded that the jaw is a very well designed structure. When punched, the solid bone outside wall spreads the impact around the jaw and protects the inside holding the teeth.

Dr Tyre says this kind of information is valuable for surgeons and dentists who need to decide where to pin fractured jaw bones in accident victims.

Putting metal screws in a particular part of the chin, for instance, may accidentally set up stresses elsewhere than can slow healing or cause damage. EPSI can help remove the guesswork from these situations.