INSTRUMENT SHARPENING

INSTRUMENT SHARPENING

WHY SHARPEN?

  • Increase efficiency:

    • Decreased working time during procedures.

  • Decrease tissue & tooth trauma:

    • Less damage caused to tissues and teeth while performing procedures.

  • Increase tactile sensitivity:

    • Better feel through instruments improves clinical outcomes.

  • Increased control:

    • Results in less slippage and fewer strokes required during procedures.

  • Decreased clinician fatigue:

    • Reduced strain allows for more effective and prolonged use of instruments.

DYNAMICS OF SHARPENING

  • Cutting Edge:

    • Defined as a very fine line formed where the face and lateral surfaces of the instrument blade meet at an angle.

  • Dull Edge:

    • Occurs when the two planes of the blade no longer meet at a fine edge and become flattened.

  • Objective of Sharpening:

    • The goal of sharpening is to reshape the cutting edge back to a fine line while minimizing material removal.

SHARPENING STONES

  • Natural Abrasive Stones:

    • Quarried from mineral deposits.

    • Arkansas Stone (Fine Grit):

    • Produces a better cutting edge compared to synthetic stones or powered sharpening devices.

    • India Stones:

    • Used for manual sharpening; available in various grits.

  • Artificial Materials:

    • Comprises hard, nonmetallic substances impregnated with abrasive particles such as aluminum oxide, silicon carbide, or diamond.

    • Examples:

    • Ruby Stone, Carborundum Stones, Diamond Stones.

    • Diamond-coated stainless steel sharpening cards: approximately the size of a credit card; have been researched for their efficiency in removing metal compared to ceramic stones, which leads to more frequent scaler replacements.

WHICH EDGE TO SHARPEN

  • General Guidelines for Sharpness:

    • Universal Instruments:

    • Both cutting edges and rounded toe need to be sharpened.

    • Area Specific Instruments:

    • Sharpen on the longer cutting edge and rounded toe.

    • Scaler Instruments:

    • Focus on sharpening the two sides, ensuring the tip is pointed.

SHARPENING PRINCIPLES

  • Objectives of Sharpening:

    • To produce a sharp cutting edge.

    • To preserve the original shape of the instrument.

  • When to Sharpen:

    • At the first sign of dullness noticed during an appointment.

    • Recontouring an overly dull instrument might lead to more frequent replacements.

    • Restoring the original contour to a grossly dull instrument often results in an unfunctional blade.

    • Replace instruments that are severely dulled.

SHARPENING BASICS

  • Essential Setup:

    • A sterile sharpening stone and testing stick are crucial for a clinical scaling appointment.

  • Technique Maintenance:

    • Maintain the angle by:

    • Using a firm grip, secure hand rest, moderate pressure, and short strokes tailored to the specific instrument.

    • Ensure even reduction across the entire surface to prevent grooves on the stone by varying instrument placement areas.

SHARPNESS TEST

  • Visual or Glare Test:

    • Examine the cutting edge under sufficient light with magnification.

    • A sharp cutting edge appears as a fine line and does not reflect light.

    • A dull edge has a flat shiny surface that reflects light, indicated by tiny shiny areas.

  • Plastic Testing Stick Method:

    • Use a sterile plastic or acrylic rod (1/4-inch thick, 3 inches long).

    • Position the fulcrum finger at the end of the stick.

    • Apply the heel of the cutting edge to the stick first at 90° and then closer to 70°.

    • Apply gentle yet firm pressure.

    • Roll the cutting edge forward from the shank end to the toe through turning or rolling.

SHARP CURET VS. DULL CUTTING EDGE

  • Sharp Curets:

    • Has a fine line at the cutting edge that will not reflect light.

  • Dull Cutting Edges:

    • Resemble a beveled or flattened surface, reflecting light prominently.

SHARPENING CURETS & SCALERS

  • Scalers/Sickles:

    • Most scalers are universal instruments.

    • Cutting edges on both sides of the face are sharpened using a two-step sharpening procedure.

  • Curets:

    • Universal Curets:

    • Both sides of the face and the toe are sharpened using a three-step sharpening procedure.

    • Area Specific Curets:

    • Cutting edges on one side and the toe are sharpened, typically done on the longer cutting edge (farthest from the handle) with a two-step procedure.

ANGULATION FOR SHARPENING

  • Cross-Section of Curet:

    • Maintains a specific internal angle.

  • Cross-Section of Scaler:

  • Correct Angulation:

    • The instrument’s face must align at a 70° angle against the flat sharpening stone.

MOVING STONE/STAIONARY INSTRUMENT

  • Setup:

    • Position the stone perpendicular to the floor at the shank third of the cutting edge.

    • From a 90° alignment with the face of the instrument, open the stone to a 110° angle.

  • Activation Steps:

    • Keep the stone in contact with the blade and at the correct angle throughout the sharpening process.

    • Firmly grasp the instrument (using the nondominant hand) while applying smooth even pressure.

    • Move the stone with short rhythmic strokes about ½-inch height, applying more pressure on the downstroke and maintaining the exact 110° angle.

    • Finish each area with a down stroke.

MOVING STONE/STAIONARY INSTRUMENT (STEPS 1 & 2)

  • Procedure:

    • Follow the cutting edge until the curvature for the toe begins, applying three or four overlapping downward strokes for each millimeter of cutting edge.

    • Proceed to the opposite side of the blade and repeat the previously described steps.

    • For universal curets, apply sharpening strokes only to the selected side and then sharpen around the toe in a final third step.

  • For Area-Specific Curets:

    • Follow the same procedure until the cutting edge tapers to the sharp tip; continue sharpening in that same direction.

  • For Sickle Scalers:

    • Follow similar procedures adapted for curved or angled edges.

MOVING STONE/STAIONARY INSTRUMENT (STEP 3)

  • Sharpening the Toe:

    • Position the tip curet downwards to align the toe with the floor at a 90° angle.

    • Open the stone to a 110° angle and apply sharpening strokes as previously described for the blade sides.

  • Testing for Sharpness:

    • Run the testing stick along the entire cutting edges to ensure sharpness.

    • Repeat sharpening procedures as necessary to maintain clear, sharp edges.

CARE OF SHARPENING EQUIPMENT

  • Flat Sharpening Stone Maintenance:

    • Soak in an ultrasonic cleaner or scrub with soap and water to remove metal shavings post-sharpening.

    • Follow manufacturer guidance for maintenance.

  • Storage Requirements:

    • Sharpening stones should be stored in sealed, sterilized packages to maintain quality.

    • Ensure a stone and testing stick accompany each instrument setup in the treatment cassette.

    • Adhere to the manufacturer’s instructions for all artificial stones involved in the process.