Gracey curets were invented in 1940 when Dr. Clayton Gracey, a dentist and educator at the University of Michigan, had an idea. He envisioned a series of instruments that would remove deposits from the deepest and least accessible periodontal pockets with minimal tissue trauma. Together with Hugo Friedman, the founder of the instrument company Hu-Friedy Mfg Co Inc, they developed the Gracey curet series of 14 single-ended, area-specific instruments that are still in use today.
The initial series consists of the Gracey 1/2, 3/4, 5/6, 7/8, 9/10, 11/2, and 13/14. These instruments are designed for specific teeth and tooth surfaces. The unique feature of the Gracey series is the offset face of the blade that results in one cutting edge lower than the other. The lower cutting edge removes calculus while the higher cutting edge permits easy insertion with minimal tissue trauma.
The original Gracey series of instruments has been redesigned many times due to innovations in materials and advances in technique. Two significant additions to the series include the Gracey 15/16 and 17/18 curets (figures 1 and 2). These instruments were introduced to increase access to molars where proper angulation of the Gracey 11/12 and 13/14 were difficult to accomplish.1-4
The Gracey 15/16 is a modified 11/12, while the Gracey 17/18 is a modification of the 13/14 (Figure 3). The Gracey 15/16 is designed to reach mesial surfaces of posterior teeth. The shank is accentuated more like the 13/14 to allow instrument access, especially in the mandibular region where access is limited because the handle is obstructed by the maxillary arch. This design permits an intraoral fulcrum close to the working area while instrumenting the molar teeth.1 The design of the shank helps the clinician maintain a neutral position of the hand, wrist, and forearm by decreasing wrist flexion.3 Table 1 lists the design comparisons between the Gracey 11/12 and Gracey 15/16.
The Gracey 17/18 is designed to reach the distal surfaces of posterior teeth while the shank is accentuated to allow instrument access in difficult-to-reach areas, especially the mandibular second and third molars. The Gracey 17/18 differs from the 13/14 in three ways:
- Accentuated angles improve access to distal surfaces and improve crown clearance and handle positioning.
- The terminal shank is 3 mm longer than the standard Gracey shank, thereby easily permitting blade placement into deep periodontal pockets.1
- The blade is 1 mm shorter than the standard Gracey to enhance adaptation of the entire blade to the tooth with minimal tissue distention, greatly improving the ability to access furcation areas and root concavities.4
Access to the distal surfaces of the mandibular second and third molars can be compromised with the handle of the Gracey 13/14. By using the Gracey 17/18, the handle is in a more horizontal position to the mandibular occlusal surfaces, minimizing contact with the opposing arch. Table 2 provides a comparison of the Gracey 13/14 and 17/18.
Carpal tunnel syndrome is a significant health risk for dental hygienists and it necessitates both medical treatment and occupational therapy.3 Instrument companies continue to research ways to make in strumentation more ergonomically friendly for the clinician. The design modifications are intended to assist the clinician in maintaining a neutral wrist position, which results in a reduction of muscular strain and nerve compression. The maintenance of a neutral wrist position is critical in the prevention of carpal tunnel syndrome.
The most mechanically efficient position is one in which the wrist is extended approximately 30° from the forearm and the fingers are slightly flexed. The use of full-arm strokes, as opposed to wrist strokes, assists in maintaining a consistent neutral wrist position that provides more power. The stroking motion is generated by the unified action of the shoulder, arm, wrist, and hand.4
An additional ergonomic consideration is handle diameter. Mechanical stress is reduced with larger diameter handles because they are easier to control and they reduce the risk of finger cramping.3
Calculus is removed by systematic scaling from tooth to tooth and section by section. Three basic stroke directions may be used with the curet in periodontal instrumentation: vertical, horizontal, and oblique. There are basically two types of working strokes used for tooth surface debridement. One type is used for calculus removal, which requires firm lateral pressure to fracture deposits from the tooth surface with a blade to tooth angle of 70° to 80°.5 The other is a root planing working stroke, which is applied over the entire root surface using very light lateral pressure with a blade-totooth angle of 60° to 80°.5 Either type of working stoke requires the clinician to use smooth, decisive strokes that aid in maintaining adequate control and precision.4
When scaling with either Gracey, debridement is initiated at the distal line angle from the facial and lingual aspect. The correct cutting edge of the Gracey 17/18 is identified when the terminal shank is parallel to the tooth surface being scaled (Figure 4).5,6 Adapt the leading third of the cutting edge in front of the distal line angle and insert subgingivally (Figure 5). Maintain parallelism with the terminal shank and the tooth surface being scaled as the instrument is moved into the distal proximal surface.4
The correct cutting edge of the Gracey 15/16 is identified when the toe third is placed against the tooth with the toe pointing in a mesial direction, and the terminal shank is parallel to the tooth surface being scaled (Figure 6).5 Insert the toe third slightly behind the distal line angle to overlap root surface instrumentation with the 17/18. Maintain a parallel terminal shank while moving the curet across the buccal or lingual surface and around the mesial line angle into the proximal surface.2
Both the 15/16 and 17/18 Graceys are a valuable addition to the traditional series of Graceys that are crucial to the hand scaling armamentarium. They allow for easier access to difficult-to-reach areas while improving clinician ergonomics. The 15/16 and 17/18 Gracey curets are available in the After-Five and Mini-Five designs with standard or rigid shank options.2,3 A clinician’s complete set of instruments should include a series of anterior and posterior instruments along with the modified Graceys to effectively access difficult areas.
- Pattison AM. Using Gracey 15/16 and Gracey 17/18 curets. Dimensions of Dental Hygiene. 2010;8(8):66.
- Daniel SJ, Harfst SA, Wilder RS. Mosby’s Dental Hygiene Concepts, Cases and Competencies.2nd ed. St Louis: Mosby Elsevier Inc; 2008.
- Schmidt CR, Mann GB, Mauriello SM. Task analysis of the gracey 15/16 curette. Journal of Practical Hygiene. 1998;7(1):21-26.
- Kunselman B, Mann GB, Mauriello SM. Task analysis of the Gracey 17/18 curet. Journal of Practical Hygiene. 1999;8(6):11-16.
- Nield JS. Fundamentals of Periodontal Instrumentation and Advanced Root Instrumentation. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2008.
- Matsuda S. Anatomy of a stroke. Dimensions of Dental Hygiene. 2008;6(11):22-26.
From Dimensions of Dental Hygiene. November 2010; 8(11): 42-44.