Instrument Sharpening at Its Best! By Judy Valdez, RDH, BSDH

Objectives: Know the main points to instrument sharpening Benefits to sharpened Instruments Consequences of using dull manual instruments Describe the steps involved for instrument sharpening Identify the instrument: Sickle or curette How many blades (cutting edges) Identify the correct blade angulation Understand correct sharpening position Describe the sharpening step by step process How to test your sharpened instrument Understand the different sharpening techniques What research says about sharpening

Main Points to Sharpening Instruments Manual sharpening procedures are the methods of choice so that the blade is not reduced unnecessarily by a rapid-cutting mounted stone. Technique objectives: preserve the original contour of the blade. Sharpen frequently to prevent need for excessive recontouring of the blade.

Benefits of sharpened instruments Greater precision of treatment, improved quality of results, and less working time involved Increased tactile sensitivity during instrumentation A sharp instrument does not have to be gripped as firmly as a dull one Greater control of the instrument because of the lighter grasp needed Less pressure on the tooth being scaled or planed and decreased pressure on the finger rest are required Fewer strokes required. Less possibility of burnishing rather than removing the calculus Prevention of unnecessary trauma to gingival tissues and, therefore, less discomfort experienced by the patient Decreased possibility of nicking, grooving, or scratching the tooth surfaces Less fatigue for the clinician.

Consequences of using dull manual instruments: stress and frustration of using ineffective instruments Wasted time, effort, and energy Loss of control and increased likelihood of slipping with instrument and lacerating the gingival tissue Loss of patient confidence in clinician’s ability Increased likelihood of developing work-related musculoskeletal disorders (WMDs) from excessive muscle strain and increased number of stroke repetitions

Steps for Instrument sharpening Examine cutting edge Review angulation Stabilize and position the instrument Apply the stone

Scaler (Sickle) or Curette

Identifying the cutting edge

Sickle Versus Curette

Stationary instrument—moving stone technique Grasp the instrument with the nondominant hand. Stabilize the hand on the edge of a stationary table or bench and provide good light on the instrument. The stone is angled with the face of the instrument at 110 degrees to maintain the internal angle of the blade at 70 to 80 degrees. Stone reversed to sharpen the opposite cutting edge of a universal curet.

Stationary stone technique Stationary stone technique for a straight scaler. With a modified pen grasp and a finger rest established on the side of the stone, the scaler is positioned for sharpening. The portion of the cutting edge nearest the lower shank is applied first with an angle of 110 degrees between the face and the stone. The instrument is turned continuously to follow the arc-like shape of the blade. The cutting edges are sharpened to the pointed tip.

Stationary stone technique, cont. Stationary stone—moving instrument technique for a curet. Stone placed flat with blade in position at the beginning of the sharpening stroke. With the finger rest stabilized on the edge of the stone, the cutting edge is maintained at the proper angulation (110 degrees) as the instrument is drawn along the stone with an even, moderate pressure. The movement of the blade is shown by the arrows, which indicate each portion of the cutting edge as the blade is turned on the stone from the beginning (a) to the completion (b) of the stroke at the center of the round toe of the curet. For a universal curet, the instrument is turned over and the opposite cutting edge is sharpened.

Why is 'Stationary Instrument, Moving Stone' the most commonly used technique? The "Stationary Instrument, Moving Stone" technique provides the best view of the lateral face of the instrument against the stone. You can see the angle of the stone against the lateral side of the blade as you hold the instrument with your nondominant hand braced on a counter, and look at the angle of the stone as you move it around the curve of the blade with up and down strokes. That is the advantage to the technique; it allows you to see the blade against the stone. It does not, however, afford the best control of the stone for adapting to the blade since the stone is being held in midair without a fulcrum. And holding the instrument perfectly stationary is not possible by most clinicians. If you watch someone perform this technique, you will see that the instrument moves slightly (at best) with every movement of the stone.

Why is 'Stationary Stone, Moving Instrument' not a commonly used technique? This technique requires the clinician to put his or her hand down on the stone and adjust the face-to-stone angle without having a bird's eye view of the face-to-stone relationship. Those with an acute tactile sense can actually feel the face of the blade against the stone. They can be quite accurate at adapting and moving the instrument from heel to toe using either a back and forth or sweeping motion. This is the technique Group 1 used in the study. Because the instrument is sharpened along the length of the blade, there are no wire edges such as those produced when moving the stone up and down against the cutting edge as Group 3 did with "Stationary Instrument, Moving Stone."

Compare the differences! (Stationary Stone, moving instrument) (Stationary instrument, moving stone)

Tests for Instrument Sharpness Visual or glare test : Examine the cutting edge under adequate light using magnification. Because the sharp cutting edge is a fine line, it does not reflect light. The dull cutting edge presents a rounded, shiny surface, which reflects light. The dull cutting edges are tiny surfaces that reflect light. Plastic testing stick : Press lightly but firmly Confirming sharpness with test stick: The sharp cutting edge engages or grips the plastic as the length of the blade is tested. Each portion of the cutting edge will engage the plastic uniformly as the blade advances. The dull cutting edge does not catch without undue pressure and slides easily over the surface of the stick

Dull Instrument Cross section of a dull curet. A sharp curet has a fine line at the cutting edge that will not reflect light. A dull cutting edge is like a small surface and reflects light as shown.

Ideal Technique!

Sharp instruments are the greatest asset for periodontal therapy!

Test Your Knowledge Restoring a sharp cutting edge is one of the two main objectives to instrument sharpening. What is the other objective? A) Maintain the internal angle of the cutting blade at about 90 degrees B) Remove metal equally from the face and lateral surface C) Preserve the original shape of the instrument D) Maintain the angle between the instrument face and stone at 90 degrees

Answer C) Preserve the original shape of the instrument is the correct answer. Restoring an edge while maintaining the shape of the instrument is most important in sharpening. The internal angle of the cutting blade should be 70 degrees. More metal is typically removed from the lateral surface. The stone-to-instrument face is at 110 degrees while sharpening.

Before you sharpen your instruments and start scaling be sure to care for yourself

References 1. Andrade Acevedo RA, Cézar Sampaio JE, Shibli JA. Scanning electron microscope assessment of several resharpening techniques on the cutting edges of Gracey curettes. J Contemp Dent Pract. Nov. 2007; 8(7):70 2.Nield-Gehrig JS. Fundamentals of Periodontal Instrumentation and Advanced Root Instrumentation. 5th ed, Philadelphia: Lippincott Williams & Wilkins. 3. Leiseca CB. New Breakthrough in Instrument Sharpening. Dental Health Educators' Newsletter. July 2010; 1(3). www.dhmethed.com. 4. Miller CH, Palenik CJ. Instrument Processing. In: Miller CH, Palenik DJ, eds. Infection Control and Management of Hazardous Materials for the Dental Team, 4th ed St. Louis: Mosby: 2009:160. 5. Andrade Acevedo RA, Cardozo AKV, Sampaio JE. Scanning electron microscopic and profilometric study of different sharpening stones. Braz. Dent J 2006; 17(3):237-242. 6. Moses O, Tal H, Artzi Z, Sperling A, Zohar R, Nemcovsky CE. Scanning electron microscope evaluation of two methods of resharpening periodontal curets: a comparative study. J Periodontol. 2003; 74:1032-1037. 7. Huang CC, Tseng CC. Effect of different sharpening stones on periodontal curettes evaluated by scanning electron microscopy. J Formos Med Assoc. 1991; 90:782-787. Wilkins. E. (2013). Clinical Practice of the Dental Hygienist. 11ed