Sharpening Hand Instrument

Aquino, Karl Yveth A.

DDM2B

“Stone”

• The most frequently used sharpening equipment consist of block or stick of abrasive material.

• Supported on a firm surface and the instrument is oriented and held by hand while being stroked against the stone surface.

Types of Sharpening Equipment

1. Stationary Sharpening Stone

2. Mechanical Sharpeners

3. Handpiece Stone

1.Stationary Sharpening stone• are often called oilstone.

• Available in coarse, medium, or fine grits.

• Can obtained in a variety of shapes including Flat, grooved, Cylindrical, and tapered.

Grit – Coarse initial reshaping of

Medium badly damage instrument

Fine Final Sharpening

Shapes of Stone• Flat stone

– Preferred for sharpening all instrument which have straight cutting edge .

• Cylindrical stone

– Used for sharpening instrument with concave edges

• Grooved

– curved edges.

• Tapered stone

– Permit using a portion of a stone with a curvature matching that of the instrument.

1.Stationary Sharpening stone

4 Types of material for sharpening stone :

Arkansas Stone

Silicon Carbide

Aluminum Oxide

Diamond

Arkansas stone

• Naturally occurring mineral containing micro crystallinequartz.

• Used in fine sharpening stones.

• Semi transparent, white or grey in color.

• Hard enough to sharpen steel but not carbide instruments.

• Should be lubricated with machine oil which helps infineness of sharpening and prevents clogging avoidscreation of heat.

Silicon carbide

• Widely used as an industrial abrasive.

• Used for grinding wheels, sand papers and sharpening stones.

• Hard enough to cut steel but not to sharpen carbide instruments.

• Available in medium and coarse grits.

• Black or greenish black in color and require lubrication with oil.

Aluminum Oxide

• Used to manufacture sharpening stones

• Available in coarse, medium and fine grits

Diamond

• Hardest available abrasive.

• Effective for cutting and shaping hard materials.

• Used in sharpening carbide and steel instruments.

• Diamond hones are small blocks of metal with fine diamond particles impregnated in the surface

2. Mechanical Sharpeners

• Honing machine:-- This instrument moves a hone in a reciprocating motion at a slow speed, while the instrument is held at the appropriate angulation and supported by a rest.- This type of sharpener is very versatile, and can fill almost all instrument sharpening needs.

3.Handpiece Stone

- Mounted silicon carbide and aluminum oxide stones for use with straight and angle hand piece are available in various sizes and shapes.- Used to sharpen instruments with curved blades.

Basic Principle of Sharpening

1. Sharpens instrument only after they have been cleaned and sterilized.

2. Establish the proper bevel angle (usually 45⁰)and the desired angle of the cutting edge to the blade before placing the instrument against the stone and maintain this angles while sharpening.

3. Use a light stroke or pressure against the stone to minimize frictional heat

4. Use a rest or guide whenever possible

5. Remove as little metal from the blade as possible.

6. Lightly hone the unbeveled side of the sharpening to remove a fine bur that may be created.

7. After sharpening, resterilize the instrument along with other items on the instrument tray setup.

8. Keep the sharpening stone clean and free of metal cutting.

Mechanical Techniques

• When chisels, hoes, angle formers, or gingival margin trimmers are sharpened on a reciprocating honing sharpener, the blade is placed against the steady rest, and the proper angle of cutting edge of the blade is established before starting the motor.

Stationary Stone Techniques

Should be at least:

– Wide : 2 inches

– Long : 5 inches

• It also should be of medium grit for hand cutting instrument, before the stone is used, a thin film of light oil should be placed on working surface.

FUNDAMENTAL RULES that apply to using stationary stone

1. Lay the stone on a flat surface and do not tilt the stone while sharpening.

2. Grasp the instrument firmly.

3. To ensure stability during the sharpening strokes, use the ring and little fingers at rest and guide along a flat surface or along the stone.

4. Use a light stroke

5. Use different areas of the stone’s surface while sharpening.

Burr or burr-edge

⁻ Single bevel instrument are sharpened, a thin, rough ridge distorted metal

⁻ This burr is eliminated by a light stroke of the unbeveled side of the blade over the stone

Amalgam or Gold knife

⁻ Has a very thin blade tapering to the sharpened edge.

⁻ There is a narrow edge bevel on both side of the blade

Spoon excavator and discoid

⁻ The most instrument to sharpened.

⁻ The sharpening can be achieved by using a grooved stone, mounted discs or stone for use with a straight handpiece

Sterilization and storage of hand cutting instrument

• It can be accomplish by autoclaving, dry heat procedure, ethylene oxide equipment and chemical vapor sterilize.

• Boiling and chemical solution will nit sterilize instrument and should be considered as disinfection procedure.

• Storage of any hand instrument should be in a sterile wrapped tray setup, or in an individual sterile wrapping

Powered Cutting EquipmentDevelopment of rotary equipment

Date Instrument Speed (rpm)

1728 Hand-Rotated Instrument 300

1871 Foot Engine 700

1874 Electric Engine 1000

1914 Dental Unit 5000

1942 Diamond Cutting Instrument 5000

1946 Old Unit converted to increase speed

10000

1947 Tungsten Carbide Burs 12000

1953 Ball Bearing Handpiece 25000

1955 Water Turbine angle Handpiece

50000

1955 Belt-Driven angle Handpiece 150000

1957 Air Turbine angle Handpiece 250000

1961 Air Straight Handpiece 25000

1962 Experimental Air Bearing Handpiece

(800000)

1994 Contemporary air turbine Handpiece

300000