# Gracey curette number 17/18 is used for:
A. Mesial surfaces of anterior teeth
B. Distal surfaces of anterior teeth
C. Mesial surfaces of posterior teeth
D. Distal surfaces of posterior teeth
The correct answer is D. Distal surfaces of posterior teeth.
Double-ended Gracey curettes are paired in the following manner:
Gracey #1-2 and 3-4: Anterior teeth
Gracey #5-6: Anterior teeth and premolars
Gracey #7-8 and 9-10: Posterior teeth: facial and lingual
Gracey #11-12: Posterior teeth: mesial
Gracey #13-14: Posterior teeth: distal
Single-ended Gracey curettes can also be obtained; a set of these curettes comprises 14 instruments. Although these curettes are designed to be used in specific areas, an experienced operator can adapt each instrument for use in several different areas by altering the position of his or her hand and the position of the patient.
Recent additions to the Gracey curette set have been the Gracey #15-16 and 17-18. The Gracey #15-16 is a modification of the standard #11-12 and is designed for the mesial surfaces of posterior teeth.
The Gracey #17-18 is a modification of the #13-14. It has a terminal shank elongated by 3 mm and a more accentuated angulation of the shank to provide complete occlusal clearance and better access to all posterior distal surfaces.