Abstract
Dental caries starts locally on a tooth surface; thus, the selective protection by metal films on pits and fissures is simple and effective. The method and apparatus for forming preventive coatings by sputtering are described wherein metal atoms originate in a Penning discharge space and are then guided through a duct in order to reach a tooth and then to form a spot coating on the surface. A compact-size sputtering apparatus for the coating of a gold film on a surface of extracted teeth or glass substrates has been designed and the film-deposition characteristics examined. The typical deposition rate is 1 nm/s for a 6-mmφ film on a glass substrate. After gold films are coated on extracted teeth, the teeth are immersed in an 0.1 mol lactic acid solution (pH=4.0). The obtained results indicate that a thickness of about 200 nm is necessary and satisfactory for protecting against dental caries in vitro.