Abstract: A toothbrush for cleaning teeth, especially the interproximal region between adjacent, closely spaced or normally contacting teeth, has at least one fin extending from the body of the toothbrush through the bristled head. The fin is a thin, tapering, blade-like member with a distal edge for cleaning teeth by scraping motion. The fin is molded from plastic resin, and is constructed so as to resist buckling loads to tend to penetrate and clean the interproximal tooth surfaces, even to the point of temporarily separating lightly contacting surfaces of adjacent teeth. Various fin embodiments are presented, including one that has an outwardly-biasing loop portion. Methods of use and manufacture and preferred materials are also disclosed.