The air-powder dental abrasive unit--an evaluation using a model system.

Air-powder abrasive systems are used in dentistry to remove dental plaque, calculus and stain from the surfaces of teeth. A model system consisting of a thin layer (14 micron) of vacuum-deposited aluminium was used to demonstrate the effectiveness of such a system. Photomicrographic analysis showed two distinct areas of removal: an inner area where removal of aluminium was complete, surrounded by an area where removal was incomplete. With the aid of a relocation pin attached to the nozzle of the instrument it was demonstrated that nozzle-target distance, the air pressure input, the flow of water and the time of operation were all factors which affected the clinical efficiency of the instrument.