Abstract: A hand-held ultrasonic tooth-cleaning apparatus which may be inserted into the mouth to remove materials from the teeth by cavitation using a lip seal or a continuous liquid flow. Electromechanical transducer elements are used to establish propagation of ultrasonic energy in a transverse mode with respect to the longitudinal axis of a vibrating member one terminus of which constitutes the probe which is inserted into the mouth by the user.

Abstract: An ultrasonic method and apparatus for removing dental plaque from teeth in situ and for cleaning the teeth employing a liquid couple for imparting ultrasonic energy to the surface of the teeth at ultrasonic energy levels which are not harmful to the teeth or gums.

Abstract: A unique "compass" device for drawing and measuring circles, and employing a template with a center pin and many holes. Indicia are provided on the template to indicate concentric and generally annular zones centered at a certain center, each such zone having its boundary relatively adjacent the center located a first distance from the center (on the particular distance scale employed on the compass), and also having its boundary relatively remote from the center located a second and higher distance from the center on such distance scale. The holes lie along an Archimedes spiral centered at the center, and all holes located a first perdetermined fraction of each whole number (of the particular distance scale) are disposed along one radial line extending from the center; all the holes located a second and next-higher predetermined fraction of each whole number of the particular distance scale are disposed along a second radial line, etc.