A new application in dentistry is emerging for blue Multi-watt LED Light Engines operating at around 460 nm. Multi-watt LED Light Engines are used in place of conventional halogen lamps for curing polymers, which are part of the composite material used to fill teeth.

The use of Multi-watt LED Light Engines based light sources in dental light-curing devices, should 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 wavelength region.

This light is directed down a waveguide such as a fused glass bundle. The end of the 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 photo-initiator, a tertiary amine, and silica particles to provide the required hardness. When excited by the absorption of blue light, the photo-initiator 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 colour filters, while the low voltage DC operation allows small handheld and cordless designs which would allow lower safety constraints a wider adoption. Halogen lamps require intensive fan cooling, and have a short lifetime compared to Multi-watt LED Light Engines 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.

In addition to adhesive curing, tooth whitening is another rapidly expanding dental application where Multi-watt LED Light Engines are effective. Teeth enamel discoloration can be caused by staining, aging, or chemical damage to teeth. Whitening of the teeth is achieved via the combination of a photoactive bleaching agent and a blue light source.

This combination of light and bleaching agent speeds up the process of bleaching allowing for shorter treatment times and thus better patient acceptability and larger throughput for the dentist.

Multi-watt LED Light Engines would again provide a safe, low cost flexible system for such treatments. In addition, research is underway to investigate a combined chemical and light activated system similar to the patch arrangement intended for the PDT treatment markets.