Dentistry opens up new LED market

17 Dec 2002

Lumileds has won orders for its 460 nm LEDs to replace halogen lamps in dental curing applications.

A new application in dentistry is emerging for blue LEDs operating at around 460 nm. The devices are used in place of conventional halogen lamps for curing polymers, which are part of the composite material used to fill teeth.

According to Lumileds, several companies are now incorporating its Luxeon V Dental LED-based light source in dental light-curing devices, which provide faster curing times, easier use, and consume less energy than current products.

Currently, most blue light sources in dentistry use tungsten filament halogen lamps that incorporate a blue filter to produce light in the 400-500 nm region. This light is directed down a waveguide such as a fused glass bundle. The end of this waveguide is placed adjacent to the soft uncured composite filling material positioned in a tooth cavity.

A typical dental composite contains a mixture of monomers, a photoinitiator, a tertiary amine, and silica particles to provide the required hardness. When excited by the absorption of blue light, the photoinitiator stimulates the production of free radicals from the tertiary amine, which causes polymerisation and hardening of the composite.

LEDs offer a number of advantages for such applications. The use of a monochromatic light source with typical 460 nm peak wavelength eliminates the need for inefficient color filters, while the low voltage DC operation allows small handheld and cordless designs. Halogen lamps require intensive fan cooling, and have a short lifetime compared to LED sources. Further benefits include instant illumination, precise beam control, minimum glare, low UV light, mercury-free operation, and a cool light beam that is safe to the touch.

The Luxeon V Dental has a radiant output of 600 mW for blue light. The Italian company Mectron has launched the Starlight Pro, incorporating the power and small size of the device into a hand piece that weighs just 105 g. The product provides faster curing times for patients, while for dentists it has less weight, a smaller design and is more energy efficient. A division of 3M Company's Health Care Business also recently launched a product based around the Luxeon V Dental.

Author
Tim Whitaker is editor of Compound Semiconductor magazine.