Lecture 6

Operative Instruments

Operative Instruments

Wide variety of dental instruments are used in dental procedures.

CARBON STEEL

STAINLESS STEEL

CARBIDE STEEL

Types of steel used to manufacture hand instruments

Carbon Steel

Hardness and sharpness

Susceptibility to corrosion and fracture

Stainless steel (Material of choice)

Bright in appearance

Does not corrode

Tends to lose their sharpness with repeated use

Can be sterilized by steam or dry heat

Carbide Steel

Hard and wear resistant

Brittle

Handle/Shaft

Shank

Blade/NIB

Parts of Hand Instruments

Handle or Shaft

Where the instrument is held by the operator

Available in various sizes and shapes (Small,,medium or large, smooth or serrated)

Shank

Part of the instrument that connects the blade to the handle; may be STRAIGHT or ANGLED

Black classified instruments on the basis of the number of shank angle as:

STRAIGHT → Having no angle

MON - ANGLE → One angle

BIN - ANGLE → two angles

TRIPLE - ANGLE → Three angles

Blade or NIB

Working end of instrument

Connected to the handle by the shank;

Designed for a specific function

NIB

Part corresponding to the blade in a non-cutting instrument

Tip of the blade

Primary cutting edge (known as working end)

Side of the blade

Secondary cutting edges; cut tooth structures; bevels

Face

End of the nib or working surface

Cutting instruments

Non-cutting instruments

Categories of Hand Instruments

Cutting Instruments

Used to ASSIST IN THE DESIGN of the cavity preparation

REFINE AND DEFINE the cavity walls and margins

Non-cutting instruments

Include basic examination instruments used to insert and finish amalgam and composite restorative materials.

Cutting Instruments (CHISEL family)

CHAD

Chisel, Hoes, Angle formers, Discoid and Cleoid

Cutting Instruments (HATCHET family)

HEG

Hatchet, Excavators, Gingival trimmer

Chisel

Used to SHAPE AND PLANE (make surface flat or level) enamel and dentin walls of the cavity preparation

COMMON TYPES:

STRAIGHT CHISELS

BIN-ANGLE CHISEL

WEDELSTAEDT CHISELS

ANGLE-FORMED CHISELS

Hatchet

Sometimes called enamel hatchet

To cut, clean and smooth walls in cavity preparation

To REMOVE ENAMEL NOT SUPPORTED BY DENTIN

Hoes

To clean and smooth floor and walls in cavity preparation with a push-pull action.

Gingival Margin Trimmers

To ELIMINATE UNSUPPORTED ENAMEL on gingival walls of proximal preparations; bevel the margin wall of the cavity preparation

SIMILAR IN DESIGN TO THE ENAMEL HATCHET except the blade is curved and the primary cutting edge is at an angle to the axis of the blade

DOUBLE-ENDED AND PAIRED INSTRUMENT; one end curves toward the left and the other end curves toward the right

Angle Formers

Used in a DOWNWARD PUSHING MOTION to form and define point angles and to sharpen line angles

SIMILAR TO THE HOE except the cutting edge is angled liked the gingival margin trimmer

Excavators

Also known as SPOON EXCAVATOR

Used to REMOVE CARIOUS MATERIAL AND DEBRIS from the teeth

Working end that is CIRCULAR OR ELONGATED

Cleoid - Discoid

It is MODIFIED CHISEL with different shape of cutting edges

In cleoid, it is CLAW-LIKE in discoid it is DISK-LIKE and the edge is rounded

Used for REMOVING CARIES and CARVING AMALGAM OR WAX PATTERN

What are non-cutting instruments?

Basic Instruments: Mouth Mirror, Explorer, Cotton

Burnishers

Carriers

Carvers

Composite Instrument

Condensers

Files

Finishing knives

Plastic filling Instruments

Non-cutting instruments

AMALGAM CONDENSER

MIRRORS

EXPLORERS

PROBES

Other cutting instruments

KNOVES

FILES

SCALERS

CARVERS

Rotary instruments

Operated in hand-piece

Nomenclature for the instruments

ORDER

SUBORDER

CLASS

SUBCLASS

Order

FUNCTION OR PURPOSE of the instrument

example:

EXCAVATOR

CONDENSER

Suborder

POSITION, mode or manner of use

example:

PUSH

PULL

Class

Design or form of the working end

example:

HATCHET

SPOON EXCAVATOR

Subclass

Shape of the shank

example:

BINDANGLE

CONTRA – ANGLE

Instrument Formula #3 FORMULA

Used instruments in which cutting edge is at right angle to the long axis of the blade.

1st # Width of the blade or primary cutting edge in mm

2nd # Length of the blade in mm

3rd # Angle of the blade against long axis of handle

Instrument Formula #4 FORMULA

Used for the instruments in which primary cutting edge is not at right angle to the long axis of the blade.

1st # Width of the in tenths of mm

2nd # Cutting edge angle

3rd # Length of the blade in mm

4th # Angle of the blade against long axis of the handle

EXAMINATION

HAND CUTTING (manual)

RESTORATIVE

ACCESSORY

Classification of General Dental Instruments

Examination Instruments

Allow the operator to thoroughly examine the health status of the oral cavity

Hand (Manual) Cutting Instruments

Allow the operator to remove decay manually and to smooth, finish, and prepare the tooth structure for its final restoration

Restorative Instruments

Allow the operator to “RESTORE” a tooth by placing, condensing, and carving a dental material to the original anatomy of the tooth structure.

Accessory Instruments

Are miscellaneous instruments and items that are used to compete a procedure.

Used for examining the teeth but are also common to all tray set-ups.

Mouth Mirror

Explorer

Cotton Pliers

Periodontal Probe - optional

Basic Examination Instruments

INDIRECT VISION

LIGHT REFLECTION

RETRACTION

TISSUE PROTECTION

Use for the mouth mirror

Restorative Instruments

Used to place, condense, and carve the restorative dental materials back to normal anatomy of the tooth.

AMALGAM CARRIER

CONDENSER

BURNISHER

CARVERS

AMALGAM KNIFE

COMPOSITE-PLACEMENT INSTRUMENTS

Amalgam Carrier

To carry & dispense amalgam into the cavity preparation

Condenser

Also known as PLUGGER

Used to condense (pack down) freshly placed amalgam into the preparation

Burnisher

Used to smooth rough margins of the restoration and to shape metal matrix bands

Carvers

Used to remove access restorative material and to carve tooth anatomy in the restoration before the material hardens.

Amalgam Knife

For the removal of excess restorative material along the margin where the material and the tooth structure meet

Composite Placement Instruments

For the placement of composite restorative materials

Made from anodized aluminum or Teflon.

These materials prevent the composite material from being scratched

CEMENT SPATULA

SCISSORS

AMALGAM WELL

HOE PLIERS

ARTICULATING PAPER HOLDER

Accessory Instruments

AMALGAM CARRIER

CONDENSER

BURNISHERS

AMALGAM CARVERS

˃ HOLLENBACK (Contour carver)

˃ DISCOID – CLEOID

˃ INTERPROXIMAL (Class II preparations)

Hand Instruments for Amalgam Restorations

Amalgam Carriers

Transfers amalgam to cavity preparation.

Aids in dispensing and placement of amalgam into cavity preparation.

Can be used to begin condensation of amalgam

Amalgam Condensers

Used to condense amalgam into all areas of preparation

Types:

ROUND

ELLIPTICAL

Burnishers

Conforms amalgam to margins

Aids initial shaping of restorations

Types:

ACORN

ROUND

FOOTBAL

Carvers

Used to place distinguished grooves and fossae into amalgam restoration types:

DISCOID – CLEOID

HOLLENBACK (contour carvers)

INTERPROXIMAL (for Class II preparations)

MODIFIED PEN Grasps

INVERTED PEN Grasps

PALM and THUMB Grasps

MODIFIED PALM and THUMB Grasps

Instrument Grasps

Modified Pen Grasps

Provides four (4) points of support

Allows considerable force to be applied to instrument

Provides more control of measurement

Invented Pen Grasps

This grasps is used mostly for tooth preparations utilizing the lingual approach on anterior teeth.

Palm and Thumb Grasps

This grasps has limited use, such as preparing incisal retention in a class III preparation on a maxillary incisor.

CONVENTIONAL PEN GRASPS

MODIFIED PEN GRASPS

Grasping Instruments

Conventional Pen Grasps

Used for writing

Modified Pen Grasps

Used in dentistry