Engineers develop blue luminescent composite
Swiss scientists have developed a new dental filling material that contains a luminescent additive, which cures through near-infrared (NIR) light. They think that this invention could soon replace conventional hand-held polymerisers that use UV light to cure resins, since the new material may improve sealing of complex and deep carious lesions significantly.
According to researchers at the Swiss Federal Institute of Technology Zurich, the material consists of a fluoride that contains two rare metals, ytterbium and thulium. Like other composites, it contains a photoinitiator that reacts to blue light. In contrast to other materials, however, the special luminescent additive enables another indirect activation process. As NIR light penetrates the material, it starts to glow blue, which eventually activates a photoinitiator that induces polymerisation—a process called up-conversion.
The new material offers a number of advantages over conventional composites, the scientists said. For example, a cavity can be filled in one step because the NIR light penetrates the tooth and the filling material, while conventional materials have to be applied layer by layer because the blue light of conventional polymerisers is absorbed and scattered. “Composite samples of 5 mm in thickness were cured twice as fast as pure polymer cured by blue light (30 and 60 seconds, respectively),” according to the researchers in their paper.
With regard to the shrinkage that might occur during polymerisation, the scientists found that the new material shrinks far less than many conventional composites because the luminescent material enables smoother polymerisation.
The researchers think that the new composite could facilitate the work of practitioners and shorten time spent in the dentist’s chair. They are currently planning further tests in order to introduce the material into general practice. In this regard, they are already in contact with industry partners interested in marketing the material.
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