Physorg -- A blue curing light used to harden dental fillings also may stunt tumor growth, Medical College of Georgia researchers say. “The light sends wavelengths of blue-violet light to the composite, which triggers hardening,” says Alpesh Patel, a rising MCG School of Dentistry junior. “The light waves produce free radicals that activate the catalyst and speed up polymerization of the composite resin. In oral cancer cells, though, those radicals cause damage that decreases cell growth and increases cell death.”