operative instruments
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Transcript of 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