Abstract: The present invention relates to a instrument for use in an air abrasion dental instrument that allows direct contact between a nozzle which delivers a stream of abrasive particles directly through a primary opening to a tooth surface. As the primary opening if the nozzles of this invention are in continuous close contact with a tooth surface, exhaust amounts of abrasive-laden fluid escape secondary openings at a direction lateral to the tooth surface. The invention also embodies removable nozzle covers having both primary and secondary openings that enable prior art nozzles to be easily converted to contact nozzles. Both the nozzles and removable nozzle covers of this invention define areas for dental restoration that remove a minimal amount of healthy tooth structure. The invention allows the comfort of air abrasion dentistry to the patient as well as both visual and tactile feedback to the dentist, the latter filling a long felt need of the practicing dental community.

Abstract: The invention enables accurate control of particle flow with regard to feeding abrasive material to a surface. The unit does not employ a vibrator and may be used to remove undesired material from a surface. A particular application is in a dental air abrasion unit for both cleaning and cutting tooth surfaces. When used in an air abrasion dental instrument, the abrasive material is stored in a container which is separated from a mixing chamber by an orifice member. The flow of particles is electronically controlled by the differential in pressure in the container section above the particle level and the pressure below an orifice member in a mixing chamber. The resulting particle flow to the surface is substantially linear and less erratic than that of prior air abrasion instruments.

Abstract: A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.