Sharpening Instruments

Inspect instruments before using:

• Clean

• Sterile

• Good condition

• Scalers need to be sharp to be effective

• Stored correctly

Instrument Wear Over Time

• Cutting edge can become narrow

• Shape may become altered

• Working end reduces in size

• Instrument becomes weak

• Discard instruments that are worn due to risk of fracturing whilst working in the oral cavity

Sharp Instruments

• Enhance tactile sensitivity

• Allow clinicians to work more precisely and effectively

• Are safer - less risk of trauma to the tooth and soft tissues

• Improves comfort for the patient

Sharp instruments improve technique

• Easier to remove calculus - difficult to remove deposits with blunt instruments, takes longer, strokes less effective

• Improved stroke control

• Reduced number of strokes

Therefore:

• Reduced clinician fatigue and an increase in work-related musculoskeletal disorders

• Risk of fracture of instrument tip with blunt or over-sharpened instruments

Cutting Edge

• Need to understand cross-sectional design of scalers

• The cutting edge is formed by the junction of the face and the lateral surface

• Overtime the metal cutting edge is worn and becomes rounded

• Instrument with tungsten carbide tips can only be sharpened by the manufacturer

Checking the Cutting Edge:

• Vision (has length but no width)

• A sharp cutting edge is a line

• A dull cutting edge will reflect the light

Cutting Edges

• Sickle = triangle

• Curette = Semi-circle

Tactile:

• Feel by testing the instrument on a sharpening test stick

Sharpening Systems - Natural Stone

• Arkansas - hard, quarried from mineral deposits and is used because of its fine abrasive particle size

• Man-made synthetic- swallow Gleason and Dentsply

Hand held stones:

• Flat

• Cylindrical shaped

• Electronic

Different systems are used in conjunction with oil, water or kept dry

Dynamics of Sharpening

• Some suppliers provide a more abrasive stone to reshape instruments

• Sharpening is accomplished by grinding the surfaces that form the cutting edge (lateral surface, face)

• Know the shape of the instrument you are sharpening

• Identify the cutting edges

Technique

• Stationary stone, moving instrument

• One hand hold a the stone, the other holds the instrument and it is this hand that moves

• Pen or palm grip

• Hold stone with one hand and the instrument with the other

• Maintain correct angle of the instrument with the stone

• No more than 3 strokes at a time

• Check for sharpness and repeat if necessary

After Sharpening

• Reshaping/recontouring

  • May need to reshape the back of a curette to maintain a smooth rounded back

• Removal of metal bits/wire edge

  • Wire edge (metal particles) attach to the edge after sharpening and may gouge cementum if left

  • Remove with a light stroke using the cylindrical sharpening stone

  • Burs can be prevented by finishing with a down stroke if the sharpening stone towards the cutting edge

Common Sharpening Errors

• Altering working edge design

• Removing unnecessary metal

• Sharpening only the tip and mid third of the working edge

• Flattening a rounded cutting edge

Health and Safety

• Instruments should be sterile prior to sharpening to prevent disease transmission

• Stones and testing sticks should be decontaminated according to manufacturer’s guidelines

• Once sharpened, instruments should be rasterised and package according to decontamination

Chair side Guide:

• Stone always 110° position

• Face of blade parallel to the floor

• Toe pouting towards you

• Graceys = 110°

• Sickle/curette = 90°

Ash Sharpening Kit:

• 2x test sticks should - angle handle 45° to the stone to test the sharpness

• Sharpening oil - lubricate the stone and carry debris

• Sharpening rod - gives final edge to curved blades

• Flat sharpening stone

• Magnifying glass or x10 loupe

Getting started

• Understand instrument shale and cutting edges

• View/assess cutting edge in good light

Pen Grip or Palm Grip

Instructions

To begin sharpening, place the stone about 15cm in front of you and hold it with one hand to steady it. Sharpen with a flat stone on a level surface, to reduce the risk of cutting your hand should the instrument or stone slip, and make no more than 3 strokes at any one time; check and repeat if more sharpening is necessary

Dentsply recommend replacement when the blade js reduced by 50%

Sickle Scaler (H6)

1. Pen grip and place the blade flat to the stone

2. Angle the handle 45° to the stone

3. Push the instrument forward and back over the stone but apply pressure when pushing the instrument away

4. Test the tip for sharpness and remove any wire edge

Universal Columbia Curette (13)

• Blades are 90° to shank

1. Pen grip and then the blade so that the hook faces the left. If viewed from the side, the curved portion toward the toe will face down

2. Angle the blade 30° to the stone

3. Move forwards and back over the stone, putting pressure on the pull direction and moving around the curve of the blade

4. Turn the blade over and change to the palm grip

5. Move stone to edge of the table and lower the handle angle to 10°

6. Move forwards and back, applying pressure to the pull

7. Test the tip for sharpness and remove any wire edge

8. Ensure toe has not become pointed (rework if necessary)

Gracey Dedicated Curette (9)

• Blades 70° to shank

1. Pen grip, turn blade so hook faces the left. If viewed from the side, the curved portion towards the toe will face down

2. Angle the blade to 30° to the stone

3. Move forward and back, putting pressure on the pull and moving around the curve of the blade

4. Test tip for sharpness and remove any wire edge

5. Ensure toe has not become pointed (rework if necessary)