operative instruments

PRESENTED BY,SHIJI MARGARETFINAL BDS

DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS

OPERATIVE INSTRUMENTS

CONTENTS

Introduction Classifications of

instruments Instrument parts Instrument

nomenclature Instrument formula Exploring

instruments Instrument design

Restorative instruments

Classification Types Dental burs Classification of burs Bur design conclusion Reference

CLASSIFICATIONGV BLACKS classification 1.Cutting instruments a. Handcutting instruments -hatchets -chisels -hoes -excavators b. Rotary instruments - burs -stone

-discs

2. Condensing instruments a. pluggers -hand -mechanical 3. Plastic instruments -plastic filling instruments -cement cariers - carvers - burnishers - spatulas

HAND

Orangewood sticks Polishing points Finishing strips

ROTARY

Finishing burs Mounted brushes Mounted stones Rubber cups

4. Finishing and polishing instruments

5. Isolation instruments

Rubber dam Saliva ejector Cotton roll holder Evacuating tips and equipment

6. Miscellaneous instruments

mouth mirrors explorers probes scissors pliers others

MARZOUCK CLASSIFICATION

Exploring instruments

- tweezers - Retractors - Probes - Separators

Instruments for tooth structure removal

a. hand cutting -excavators - chisels -special form of

chisel b. handpiece -burs - ultrasonic

INSTRUMENT PARTS.

a. blade.b. shank.c. handle

.SHAFT

Used as a handle , is straight without variations in size.

It may be serrated to increase friction for hand gripping.

SHANKIt connects the handle to the blade.It is here where any angulation in the

instrument can be given.

BLADE

It is the functional end of the instrument.It is connected to the handle by the shank.

The blade ends in cutting edge.

CUTTING EDGE . It is the working part of

the instrument . It is usually in the form of a bevel with different shapes

BLADE ANGLE. It is defined as the angle

between the long axis of the blade and long axis of the shaft

CUTTING EDGE ANGLE. It is defined as angle

between the margin of the cutting edge and the long axis of the shaft.

INSTRUMENT NOMENCLATURE

G. V Black described dental instruments as follows.

The order denotes the purpose of the instrument ,eg excavator , scaler .

The suborder denotes the position or manner of use of the instrument ,e.g. push or pull.

The class describes the form of the blade ,e.g. hatchet, chisel.

The subclass denotes the angle or shape of the shank.e.g straight- no angle

INSTRUMENT FORMULA The width of the blade in

tenths of millimeters. The primary cutting edge angle

formed between cutting edge and central axis of shaft.

The length of the blade in millimeters.

The blade angle in centigrade.

EXPLORING INSTRUMENTS

MOUTH MIRRORS

TYPES OF MIRROR SURFACES

1 a. front surface reflecting mirror b. rear surface reflecting mirror

2. a. plane or flat surface b. concave surface

3. a. one sided b. two sided

USES Direct vision Indirect illuminaton Transillumination Retraction

EXPLORER

Diagnostic aid in evaluating condition of teeth especially in pits and fissures

PARTS Straight explorer Shephered’s crrok or curved explorer Interproximal explorer

TWEEZERS They have angled tip and available in different

sizes. They are used to place and remove cotton rolls and other small materials.

PERIODONTAL PROBES They are used for measuring pocket depth.

INSTRUMENT DESIGN.1. Direct cutting and

lateral cutting instruments.

2. Contrangling.3. Right and left

instruments.4. Single bevelled

instruments.5. Bibevelled instrument.6. Triple bevelled

instruments.7. Circumferentially

bevelled instruments.8. Single ended and

double ended instruments.

A direct cutting instrument :The force applied in the same plane as that of

the blade and handle ; it is called single planed instrument.

Have 2 or more curves or angles in their shanks ,and in the same plane as the handle.

Used in direct or lateral cutting.

1.DIRECT CUTTING AND LATERAL CUTTING INSTRUMENTS.

Lateral cutting instruments:

The force applied at a right angle to the plane of blade and handle.

Are called double planed instrumentsHave an angle or curve in a plane at a right

angle to that of handle.Used in lateral cutting.

Have one or more angles in shank placing the working point within 3mm from the axis of handle.

This principle of design is called contrangling.

A short blade and small blade angle requires only bi angle- contrangling .

While longer blade and greater blade angles requires triple angle contrangling .

2.CONTRANGLING.

Direct instruments are made either right or left by placing a bevel on one side of the blade.

If the the cutting edge down and pointing away from the operator and the bevel is on the right side ,it will be’ right’ instrument.

If the bevel is on the left ,it will be a left instrument.

These are all single planed instruments.

.3 .RIGHT AND LEFT INSTRUMENTS.

SINGLE ENDED AND DOUBLE ENDED INSTRUMENTS.

Double ended instruments incorporating the right and left or the mesial and distal form of the instrument in the same handle.

Single ended instrument have only one specific function.

EXCAVATORS

THESE ARE DESIGNED FOR EXCAVATION REMOVAL OF CARIOUS DENTIN AND FOR THE SHAPING OF THE INTERNAL PARTS OF CAVITIES.

HOE EXCAVATOR. SPOON EXCAVATOR. DISCOID EXCAVATOR. CLEIOD EXCAVATOR. HATCHET EXCAVATOR.

SPOON EXACAVATORS.

A

B

C

A.bin-angle spoon

B.Triple angle spoon

C.spoon

Used for cutting mesial and distal walls of premolars and molars.

HOE EXCAVATOR.

DISCOID EXCAVATOR These are disc like . Have a blade which is circular in shape. Cutting edge extending around the periphery except where it is

joined to the shank. It is used for the same purpose and in the same manner as a spoon

excavator. It is double –planed instrument right or left cutting movements.

It resembles a claw ,hence the name “cleoid”.

It is essentially a spoon excavator except the blade comes to a point.

It is double –planed instrument with lateral cutting movements.

Used in carving amalgam and excavating decay.

CLEOID EXCAVATOR.

CHISEL

THESE ARE INTENDED FOR CUTTING ENAMEL. IT USUALLY BEVELLED ON ONE SIDE .

STRAIGHT CHISEL.MONO ANGLE CHISELS.BI ANGLE CHISELS.TRIPLE ANGLE CHISELS.

STRAIGHT CHISELS.

Have a straight blade in line with the handle and shank.

The cutting edge is on one side only, with the bevel of the hand running at a right angle to the shaft.

They are single planed instruments

with 5 possible cutting movements.

ENAMEL HATCHET.

The shank has one or more angles or curves.

The blade is in same plane ,parallel with the shaft.

Cutting edge is in the form of a bevel parallel to the shaft; either paired or may be bibevelled.

These are single planed instruments with vertical, push, pull, and either right or left lateral cutting.

Smaller size for anterior teeth, and larger size for posterior teeth

SPECIAL FORMS OF CHISELSThese designed to perform specific functions.

ENAMEL HATCHETS.GINGIVAL MARGIN TRIMMERS.ANGLE FORMERS.WEDELSTEADT CHISELS.OFFSET HATCHETS.TRIANGULAR CHISELS.HOE CHISELS.HATCHETS OR OFFSET HATCHETS.

GINGIVAL MARGINAL TRIMMERS. Similar to spoon excavators and

the cutting edge similar to single bevelled hatchets.

2 types are;1. Distal gingival margin

trimmers.2. Mesial gingival margin

trimmers. They are used for creating the

proper bevel of the gingival floors and also for forming sharp angles in internal parts of cavity preparations.

They are also used in pull and push motions.

RESTORATIVE INSTRUMENTS

CEMENT SPATULAS

Several types of spatulas are available in the market differing in shape and size.

On the basis of size, cement spatula can be classified into:

- large - small

PLASTIC FILLING INSTRUMENT

These instruments have a small metal ball at the working end. They are used to mix, carry and place cements.

CONDENSER

It is used to deliver the restoration to the tooth preparation and for proper condensation

AMALGAM CARRIERS

To pack amalgam material in to the tooth preparation, amalgam carriers are used.

They carry the freshly prepared restorative material in to the tooth.

CARVERS

They are used to contour the restoration. Sharp cutting edges present in carvers are used to

sharpen and form tooth anatomy from a restoration.

BURNISHERS For final condensation of amalgam Initial shaping of occlusal anatomy of

amalgam

COMPOSITE RESIN INSTRUMENT

A wide range of double ended instruments are used to transport and place resins

They are made up of plastic or titanium coating

ROTARY CUTTING INSTRUMENTS Those instruments which rotate on an axis to do the

work of abrading and cutting on tooth structure.

TYPES : - Handpiece - Bur HANDPIECES

The first rotary instruments were drill or bur heads that were twisted with the fingers for crude cutting of the tooth tissue

TYPES OF HAND PIECE Contra-angle hand piece

Head of handpiece is first angled away from and then back towards the long axis of the handle

a.Airoter contraangle handpiece-it gets power from the compressed air supplied by the compressor. It has high speed and low torque.

Micromotor handpiece

In straight handpiece long axis of the bur lies in same plane as long axis of handpiece.

DENTAL BURS It is a rotary cutting instrument which has

bladed cutting edge. They are used to remove tooth structure

either by chipping or grinding.

CLASSIFICATION OF BURSAccording to mode

of attachment latch type friction gripAccording to their

composition stainless steel tungston carbide combination

According to their motion

right bur left burAccording to the

length of their head

long short regular

According to their use

cutting burs finishing burs polishing burs

According to their shape

round bur inverted cone bur pear-shaped wheel shaped tapering

fissure straight fissure end cutting

bur

BUR DESIGN

BUR BLADE It is the projection on the bur head which

forms a cutting edge.it has two surfaces rake face-surface of bur lade on the leading

edge clearance face-surface of bur blade on the

trailing edge

RAKE ANGLE -angle between rake face and radial line

Positive rake angle-when rake face trails the radial line.

Negative rake angle-when rake face is ahead of radial line.

Zero rake angle-when rake face and radial line coincide each other.

RADIAL LINE It is the line connecting center of the bur and

the blade.

LAND It is the plane surface immediately following

the cutting edge.

CLEARANCE ANGLE This is the angle between the clearance face

and the work.

BLADE ANGLE it is the angle between the rake face and the

clearance face.

CONCENTRICITY it is a direct measurement of symmetry of the bur

head.

RUN-OUT it measures the accuracy with which all the tip of

blades pass through a single point when bur is moving.

REFERENCE

1. Sturdevants art and science of operative dentistry.

2. Marzouk. 3. Nisha Garg