Rebuilding Faces with Stereolithography

UK scientists from the University of Nottingham have teamed up with Russian researchers to create the honeycomb-like polymer which readily bonds with bone without causing adverse reactions.

The implants have been developed by teams led by Professor Steve Howdle and Dr Vladimir Popov from the Institute of Laser and Information Technology in Troitsk. The made-to-measure implants are light, tough, flexible and cheap, providing an excellent alternative to traditional titanium.

"Precision is vital in this type of operation since every injury will be unique in some way and the patient is obviously hoping for the best possible visual affect after surgery,” Howdle explains.

Scientists use X-rays and tomography images to create a three-dimensional plastic cast of the damaged area. These solid biomodels, built by laser stereolithography allow surgeons to plan operations with great precision before they even lift a scalpel. The outline of the implant is initially "drawn” by a laser beam which leaves a very fine coating of polymer. This process is repeated hundreds of times until the model is complete.

The polymer is hydroxyapatite, which makes the polymer tough and ‘bone-friendly'. The collaborating scientists have also found a way to increase porosity and clean out toxins from polymers using high-pressure carbon-dioxide. Without this process the implants could cause damaging reactions in the patients.

Although the PolyHap implants have produced good results there is a possibility they might have to be replaced as the child grows and bones develop. So Professor Howdle and Dr Popov's teams have started work on a bio-degradeable version which will slowly dissolve as the repairing bone begins to re-grow.

In order to make these ‘vanishing' implants they are developing a new Surface Selective Laser Sintering technique. This involves using a laser beam to melt just the polymer surface, leaving the bioactive inner section intact - a crucial factor in creating a bio-degradeable implant.

COMPAMED.de; Source: University of Nottingham