No-drill dentistry.

Even the sound of having a tooth filled can be painful: That high-pitched whine yon hear when drill meets tooth is the sound of healthy enamel being pulverized. Filling even the smallest cavity can be destructive; the dentist has to drill away a large amount of the tooth to create a surface that will bond with the filling. Now, Japanese researchers say they have found a way to produce an artificial tooth enamel that may allow dentists to fill some cavities without using a drill. Dr. Kazue Yamagishi of Tokyo's FAP Dental Institute and his colleagues have created a pastelike substance that can be painted onto a tooth. When the material crystallizes, it forms a seamless bond; the paste also offers some protection against tooth decay. Although it is possible for the material itself to decay, it is highly durable and somewhat more resistant to acid than natural tooth enamel. So far, the new treatment has been used only for cavities that are not large enough to penetrate the one-to-two millimeters of enamel that cover a normal tooth. But before the paste can be used commercially, says Yamagishi, "We need to study it more to confirm the safety of the therapy."