c. Gracey Curettes. Gracey curettes are used to remove subgingival calculus
deposits. The shape of the blade makes subgingival adaptation possible without
trauma to the adjacent tissue. Each instrument in this series (see figure 3-5) is
designed for a specific region of the mouth.
(1) Gracey 1-2--Anterior teeth, and facial, lingual, mesial, and distal
surfaces of all teeth.
(2) Gracey 7-8--Anterior teeth, plus facial, lingual, mesial, and distal
surfaces of bicuspids.
Gracey 11-12--Primarily for mesial surfaces of posterior teeth.
Gracey 13-14--Primarily for distal surfaces of posterior teeth.
Figure 3-5. Gracey curettes.
ULTRASONIC DENTAL UNIT
a. General. The ultrasonic dental unit is widely used to perform oral prophylaxis
treatments. See figure 3-6. The unit works by converting alternating current into
25,000-cycle current. The unit handpiece converts electrical power supplied by the
unit's generator into 25,000 microscopically small mechanical strokes. These strokes
are transmitted to the insert tip. A continuous flow of water is required to cool the
handpiece. The same water, warmed inside the handpiece, is delivered through the
nozzle and sprayed at the activated tip. Using a very light guided touch, the activated
tip with the bubbling action of the water rapidly dislodges calculus and stain.