Hand instruments in operative dentistry

2.  Introduction
 History
 Materials used
 Classification
 Parts of a hand cutting instrument
 Instrument nomenclature
 Instrument formula
 Instrument design
 Instrument applications
 Techniques
 Rests and guards
 Sharpening hand instruments
 Sterilization and disinfection
 References

3. • The term ‘instrument’ refers to a tool, device or
implement used for a specific purpose or type of work
and is preferred in professional or scientific fields as
precision items to perform specific procedures.
• In order to perform the intricate or detailed procedures
associated with operative dentistry, the dentist must
have a complete knowledge of the purpose and
application of the many instruments required.
The instruments available
The purpose of the instrument
The position or manner of use
The application of the instrument.

4.  Most hand instruments used earlier were
with large, heavy handles and inferior metal
alloys in the blade, were cumbersome,
awkward to use and ineffective.
 These instruments had bone or ivory
handles.
 No uniformity of manufacturer and
nomenclature.
 Many dentists made their own hand
instruments.
 Early hand instruments were grasped in the
palm of the hand.

6.  Dr.G.V.Black- credited with the first acceptable
nomenclature for and classification of hand
instruments
 Dr.Arthur.D.Black- developed many of the
instruments and techniques
 Dr.Charles E.Woodbury- first to modify blacks
instrumentation.Designed 39 sets of hand
instruments for class III cavity preparations and
condensing points for gold foil restorations
 Dr.Wedelstaedt- developed Wedelstaedt chisel
now referred to as curved chisel
 Dr.Waldon I Ferrier- developed a new set of
instruments called ferrier set which were more
refined and had uniform thickness on the
cutting edge
 Dr.George Hollenback- invented pneumatic
condenser.

7.  Hand instruments are manufactured
from two main materials:
1. Stainless Steel
2. Carbon Steel
 Some instruments are made with carbide
inserts to provide more durable cutting
edge.

8.  Stainless steel
1. Chromium- 18%
2. Carbon-1%
3. Iron-81.4%
 Advantages-
1. Chromium in the alloy Reduces corrosion tendency
by depositing an oxide layer on the surface of the
metal.
2. Remains bright under most conditions.
 Disadvantages-
1. Maintaining the sharpness of the blade is a problem
2. Loses a keen edge during much use
 Mainly used for working points and cement
instruments.

9.  Carbon steel-
1. Carbon-1%
2. Manganeese-0.2%
3. Silicon-0.2%
4. Iron- 98.4-98.6%
 Advantages-
 Harder than stainless steel
 Disadvantages-
 When unprotected, it will corrode.

10.  Stellite
1. Cobalt - 65- 90%
2. Chromium - 35%
3. Trace amounts: tungsten, molybdenum ,
iron
 Advantages:
1. High resistance to acid
2. Hardness
 Use-
 Manufacture of mixing and inserting
instruments

11.  G.V.BLACK- first acceptable nomenclature for and
classification of hand instruments
1 ) CUTTING
A. Excavators
 ordinary hatchet
 hoes
 angle formers
 spoons
B. Chisels
 straight
 curved
 bin angle
 enamel hatchet
 GMT
C. Other cutting insruments:
 Knives,
 carvers
 files,
 Scalers
2 ) NON-CUTTING:
Amalgam condensors
Mirrors
Explorers
Probes

12.  HAND HELD
A ) Examining mouth &
teeth:
 Mouth mirrors
 Probes
B ) Scaling- scalers
C) Cutting teeth &
removing caries -
 excavators chisels,
 hatchets, hoes
D ) Placing &
condensing restorative
materials:
 plastic instruments
 condensors/
 pluggers
E ) Carving & finishing
o ROTARY o AUXILLARY
a. Fibre optic lights
for illumination
b. Lights used for
polymerization
c. Ultrasonic
scalers

13. 1. Cutting instruments
 Hand
 Hatchets
 Chisel
 Hoe
 Excavator
 Others
 ROTARY
 Burs
 Stones
 Disk
 Others
2. Condensing instruments
Pluggers
 Hand
 Mechanical
3. Plastic instruments
 Spatulas
 Burnishers
 Carvers
 Packing instruments.

14. 4. Finishing &
polishing
instruments:
 Hand
 Orange wood
sticks
 Polishing Points
 Finishing strips
 Rotary
 Finishing burs
 Mounted brushes
 Mounted stones
 Rubber cups
 Impregnated disk
& wheels.
5. Isolation instruments
 Rubber dam frame
Clamps
Forceps
Punch
 Saliva ejectors
 Cotton roll holders
 Evacuating tips &
equipment
6. Miscellaneous:
 Mouth mirrors
 Probes
 Scissors
 Pliers
 Others.

15. 1. Exploring or diagnostic
instruments:
 Mouth mirror
 Explorer or Probe
 Straight proble
 Right angled probe
 Arch shaped ( shepherd’s
hook )
 Interproximal ( back action)
 Tweezers
 Seperators
 Cheek retractors
 Air syringe
2. Isolating instruments:
 Cotton roll holder
 Rubber dam
 Saliva ejector
 Suction apparatus.
3. Hand cutting instruments
 Excavators
 Spoon
 Cleoid
 Discoid
 Hatchet
 Hoe
 Chisels
 Straight
 Mono angle
 Bin angle
 Triple angle
 Modified chisel
 Wedelsteadt
 Enamel hatchet
 Gingival marginal trimmer
 Angle former.

16. 4 ) Restoring instrument:
 Mixing instruments:
 Cement spatula
 Agate spatula
 Plastic carrying/ filling
instrument
 Packing instruments:
 Amalgam carrier.
 Condensing instrument:
 Round condenser
 Parallelogram
 Burnishing instrument:
 Ball shaped
 Egg shaped
 Conical shaped
 Carving instruments:
 Hollenbeck carver
 Diamond carver
 Ward’s carver
5 ) Miscellaneous
instruments:
 Matrices
 Retainers
 Scissors

17.  Handle/Shaft
 Shank
 Blade with cutting edge or nib with face.

18.  Straight and is usually without variations in size. It maybe
serrated to increase friction for hand gripping.
 Length-5.5 inches
 Diameter-5.5 mm
 Available in various sizes and shapes- small, medium,
large diameter
 Hexagonal or octagonal
 Smooth, serrated or knurled
 Knurled to facilitate control and to increase the friction
for hand gripping
 Instrument formula incorporated on it
 Manufacturing kit number incorporated on it
 Handle is either continuous with shank or separable.

19.  Connects the shaft with the blade or
working point or nib.
 It usually extends from its connection with
the shaft to where the blade begins.
 It is here where any angulation of the
instrument can be placed.
 Smooth, round, tapered and contrangled
 Have one or more bends to avoid the
instrument from having tendency to twist in
use where force is applied
 G.V.Black classified instruments depending
on the number of angles in the shank as-
1. Mon angle
2. Bin angle
3. Triple angle
4. Quaternary angle

20.  Balance is accomplished by
designing the angles of the
shank so that the cutting edge
of the blade lies within the
projected diameter of the
handle and nearly coincides
with the projected axis of the
handle .
 For optimal antirotational
design, the blade edge must
not be off axis by more than 1
to 2 mm.
 All dental instruments and
equipment need to satisfy this
principle of balance.

21.  Functional end of the instrument bearing the
cutting edge.
 It begins at the angle if one angle is present at the
shank, or at the last angle, if more than one angle
is present in the shank or at the point which
terminates in the shank.
 The blade ends in the cutting edge.
 For non cutting instruments the part corresponding
to the blade is termed as “nib”
 Working surface or the end of the nib is known as
the “face”

22.  It is the working part of the instrument. It is
usually in the form of a bevel in different
shapes.
 Beveled-
1. single beveled
2. Bibeveled
3. Triple beveled
4. Circumferentially beveled
 Regular bevel - distal to shaft
 Reverse bevel- mesial to shaft
eg:- binangle chisel

23.  Blade angle- defined as the angle between
the long axis of the blade and the long axis
of the shaft.
 Cutting edge angle- defined as an angle
between the margins of the cutting edge
and the long axis of the shaft.
 Some instruments have a blade on both
ends of the handle and are known as
double-ended instruments.

24.  Enamel and dentin are difficult substances
to cut and require the generation of
substantial forces at the tip of the
instrument.
 Hand instruments must be balanced and
sharp.
 Balance allows for the concentration of
force onto the blade without causing
rotation of the instrument in the grasp.
 Sharpness concentrates the force onto a
small area of the edge, producing a high
stress

25. 1. Order- denotes the purpose of the instrument.
Eg:- excavator, scaler
2. Sub order- denotes the position or manner of
use of the instrument
Eg:- push, pull
3. Class- form of the blade.
Eg:- hatchet, chisel
4. Angle/ Subclass- denotes the number of
angles in the shank/ shape of the shank
Eg:- 1- mon angle, 2- bin angle
 NAMING GOES FROM 4-1
Eg:- ‘bin angle’ ‘hatchet’ ‘push’ ‘excavator’

26.  To describe the parts of
an instrument accurately.
 3 unit instrument formula:
 First unit : Width of the
blade in 1/10 of a mm.
 Second unit : length of
the blade in mm
 Third unit : Angle the
blade forms with the axis
of handle in centigrade.

27.  4 Unit instrument formula:cutting
edge of the instrument is at an
angle other than right angle to
the blade.
 First unit : Width of the blade in
1/10 of a mm.
 Second unit : Angle the cutting
edge forms with the axis of the
handle in centigrade.
 Third unit : length of the blade in
mm
 Fourth unit : Angle the blade
forms with the axis of handle in
centigrade.
 Eg- GMT and Angle former.

28. • Most hand instruments- single bevel, end of
blade forms primary cutting edge
• Two additional edges- secondary cutting
edges , extend from primary edge for length
of blade
• Bi beveled instruments- e g:- ordinary
hatchets- 2 bevels that form cutting edge.

29. • Spoon excavators and gingival margin
trimmers : scraping or lateral cutting motion.
• Enamel hatchets- planing or direct cutting
motion, as well as a lateral cutting motion.
• For such single-beveled designs, the
instruments must be made in pairs, having the
bevels on opposite sides of the blade.

30.  Such instruments are designated as right or
left beveled and are indicated by
appending the letter R or L to the instrument
formula.
 To determine whether the instrument has a
right or left bevel, the primary cutting edge
is held down and pointing away, and if the
bevel appears on the right side of the
blade, it is the right instrument of the pair.
 This instrument, when used in a scraping
motion, ismoved from right to left. The
opposite holds true for the left instrument of
the pair.

31.  Most instruments are available with blades
and shanks on both ends of the handle-
double-ended.
 In many cases the right instrument of the
pair is on one end of the handle, and the
left instrument is on the other end.
 Sometimes similar blades of different widths
are placed on double-ended instruments.
 Single-ended instruments may be safer to
use, but double-ended instruments are
more efficient because they reduce
instrument exchange.

32.  Instruments having the cutting edge
perpendicular to the axis of the handle such
as bin-angle chisels, those with a slight blade
curvature (Wedelstaedt chisels), and hoes
are single-beveled and not designated as
rights or lefts, but as having a mesial bevel or
a distal bevel.
 If when one observes the inside of the blade
curvature (or the inside of the angle at the
junction of the blade and shank) the primary
bevel is not visible, the instrument has a distal
bevel . Conversely, if the primary bevel can
be seen (from the same viewpoint) the
instrument has a mesial or reverse bevel.

33. • Hand instruments- made of either stainless steel,
carbon steel or blades of tungsten carbide soldered
to a steel handle.
• Carbon steel (better cutting edge)> stainless steel,
however, carbide blades are most efficient in cutting,
even though they are brittle.
 Main principle- of cutting with hand instruments- to
concentrate force on a very thin cross section of the
instrument at the cutting edge.
• Thinner the cross section, more the pressure that is
Concentrated, more efficient the instrument will be.

34.  A direct cutting instrument is one in which
the force is applied in the same plane as
that of the blade & handle -> single planed
instrument ( used in direct and lateral
cutting )
 Lateral cutting instruments are those in
which the force is applied at a right angle
to the plane of the blade and handle,
usually have curved blade -> double
planed instrument (used only in lateral
cutting).

35. • In order to gain access, many instruments have shank,
bent at one or more points to angle the blade relative to
the handle.
• Depends on
- length of blade
- degree of angulation in shank
• The working point is moved out of line with the angle of
handle.
• If this occurs more than 3 mm, from the handle axis, the
instrument will be out of balance in lateral cutting motion
and force will be required to keep the instrument from
rotating in one hand.
• To solve this problem, modern instruments are designed to
have one or more angles in the shank placing the working
point within 3mm from the axis of the handle this known as
CONTRANGLING

36. • Short blade and small blade angle requires only
bin angle contrangling,while longer blades and
greater blade angles require triple contrangling.
• Length of the blade required is determined by
depth of the cavity and the blade angle is
determined by the accessibility requirements.
• Hence, greater angles are required for more
posterior teeth and incisal portions of proximal
cavities in anterior teeth.
• So, in addition to balance, contrangling will
provide better access and a clearer view for the
field of operation.

37.  Chisels:-
- Cutting edge of the instrument
is at a right angle to the axis of
the instrument.
- Used for planing or cleaving
enamel.
1) Straight chisel:-
- No bend in shank
- Single beveled/ Triple
beveled.
- Minimal accessibility.
- Used with push stroke or lateral
scraping action.

38. 2) Mono angle chisel:-
- Blade is shorter as compared to
straight chisel.
- Single angle in the shank to
enhance the convenience form.
- Used with push stroke or lateral
scraping action.
Hoe:-
Difference between mono angle
chisel and hoe:-
- If the angle of the blade is less
than 12.5 centigrade, it is mono
angle chisel and if it is more than
12.5 centigrade, it is hoe.
- Used with pull stroke.
Use:- To define line and point
angles.
- Class III and V preparations for
direct filling gold restorations.

39. 3) Binangle chisel:-
- Two angles in the shank.
- Used to cleave or split
undermined enamel.
- Reverse bevel instrument.
4) Triple angle chisel:-
- Used to flatten the pulpal
floor.

40. Hatchet:-
- Cutting edge of the instrument is
parallel to the axis of the instrument.
- Cutting edge of the instrument is at
right angle to the axis of blade.
- Mono angled
- Length of blade is very small
- Bibevelled
- Single ended
- Used with push stroke
Use:-
- Preparing retentive areas on anterior teeth.
- Sharpening internal line angles in DFG restorations.

41.  Enamel hatchet:-
- Cutting edge of the instrument is parallel to
the axis of the instrument.
- Cutting edge of the instrument is at right
angle to the axis of blade.
- Binangle hatchet
- Monobeveled
- Single plane instrument
- Paired instrument
- Bevel on right side – Right side
instrument
- Bevel on left side – Left side
instrument

42.  Used with push stroke (planing or direct
cutting motion as well as lateral cutting
motion).
 Used for smoothening buccal and lingual
walls of proximal box.
 Used for breaking enamel of proximal box.
 Used for smoothening gingival seat (lateral
scraping motion).

43.  Gingival marginal trimmer:-
- Cutting edge of the instrument is parallel to
the axis of the instrument.
- Cutting edge of the instrument is at an
angle other than a right angle to the blade.
- Modified hatchet
- Binangle instrument
- Monobeveled
- Double plane instrument (better lateral
scraping efficiency/ scooping effect).

44.  2 pairs:
1. MESIAL PAIR (RIGHT AND LEFT)
2. DISTAL PAIR (RIGHT AND LEFT)
- 4 unit instrument formula
- Mesial pair – 10- 80- 6- 8 ( < 80 )
- Distal pair – 10- 95- 6- 8 ( > 95)
- Used to give gingival cavo surface bevel.
- Used for rounding or bevelling axio- pulpal line
angle.

45.  Angle former:-
- The instruments are made by grinding the bevel
at an angle of 80 degree with the shaft, thus
forming an acute angle with the long axis of the
blade. This creates a pointed and a linear cutting
edge.
- 4 unit instrument formula
- Paired instrument- right and left
- Ring on the shank – right side
- 3 cutting edges (blade is bevelled on the sides as
well as the end).
Use:-To exaggerate line and point angles in DFG
restorations to establish the retention form.

46.  Wedelstaedt chisel:-
- Shank and blade are curved.
- Bevelled on one side of blade
only.
- If bevel is on the side towards
the
curvature of the shank:-
Mesially bevelled.
- Away from the curvature of
the shank:- Distally bevelled
- Used for cleaving undermined
enamel and for shaping walls.
- Single instrument with 3
cutting motion:-
vertical, right and left.

47. Off- angle hatchet:-
- Instruments in which blade is
rotated by 45 degrees from the
plane of the long axis of the
instrument.
- Used to create and shape specific
angulations for cavity walls,
especially in areas of difficult access.
Triangular chisel:-
- Blade is triangular in shape with the base
away from the shaft.
- Has a terminal cutting edge like straight
chisel.

48.  Spoon excavator:-
- Modified hatchet.
- Double ended instrument.
- Bin angle/ Triple-angle
instrument.
- Paired (right and left).
- Double plane instrument.
- Circumferentially beveled.
- Cutting edge either circular
(discoid) or claw like (cleoid).
Use:- Spooning or scooping of
softened carious material.
- Carving amalgam or direct
wax patterns.

49. Other instruments:-
 Knives:- Finishing knives, Amalgam knives, or
Gold knives. Used for trimming excess
restorative material on the gingival, facial or
lingual margins of a proximal restoration or
trimming and contouring the surface of class
V restorations.
 Files:-
Used for smoothening of overhanging
restorations (amalgam and gold).

50.  Diagnostic instruments:-
1 ) Mouth mirror:-
- Is an instrument having a mirror head top and a
detachable handle.
- Also called as odontoscope.
Types:-
A) Front surface:-
- Is one where the reflecting surface is on the top of the
glass piece.
- Gives better visibility.
- Absence of intervening glass.
- No double image.
- Mercury coating on top is liker to be lost due to
scratching.
B) Rear surface (regular)
- Reflecting surface is on the back surface of the mirror lens.
- Surface is less easily scratched.
- Produces a double or ghost image.

51. C) Magnifying mirror (concave):-
- Reflecting surface is on the front surface of the
mirror lens.
- Produces magnified but slightly distorted image.
- Concave surface mirror magnifies the image,
requiring the clinician to learn to accommodate
movement.
- Concave mirror rarely used except for seeing
enlarged internal details of the cavity.
- The instrument movements are smaller than the
clinician visual perception.
- For endodontic surgeries.
D) Disposable mirror:-
- Made of plastic.

52.  Uses:-
Indirect illumination.
- Mouth mirror could be held at an angle to reflect
the light onto the working area.
- Retraction : Mirror head used to retract the
patient’s lip or cheek or tongue so that the
clinician is able to view tooth surfaces.
- Protects from injury.
- Indirect vision.
- Guard.
- Trans illumination.
Different sizes of mouth mirror:-
No. 2 (5/8 inch)
No. 4 (7/8 inch)
No. 5 (15/16 inch)

54. 2 ) Probe:-
- Sharp pointed hand instrument used to
explore teeth and restoration surfaces in order
to detect caries, overhanging edges and
other defects.
- May be single-ended or double-ended.
Uses:-
- For detecting and assessing carious lesion in
the tooth
- Detecting demineralized dentin.
- Releasing debris from the tooth.
- Removing slight excess fill up around
cavo-surface margins
- Identifying hypersensitive areas in the tooth
- Assessing marginal fit of the restoration

55.  Types:-
- Straight.
- Interproximal probe
- No.2 cow horn
(arch explorer)
- No.17 back action
- No. 23 shepherd’s hook
- Orban –type explorer

56. 3) Periodontal probe:-
- Detect and measure
the depth of
periodontal pockets.
- In operative dentistry:-
Used to determine the
dimensions of
instruments and of
various features of
preparations or
restorations.

57. 4) Forceps:-
- Tweezers/ Cotton forceps
- Hemostats
- Articulating paper forceps
Tweezers:-
- Hand instrument with two narrow and
pointed, straight or curved beaks used to
grasp small objects.
- Consist of:-
2 long arms.
Locking device.
2 long arms joined at one end.
Other end remains apart.

58.  Uses:
- Useful in carrying things to and from mouth.
- Carrying cotton rolls, cotton pledges,
sponge pellets to and around the cavity.
- Carrying saliva soaked cotton rolls from the
oral cavity to the waste disposal unit.
Locking tweezer
- Has a locking device to maintain the
beaks in a closed position until released.
- This avoids the unnecessary anxiety of the
operator at the possibility of slippage of
whatever is carried by the tweezer.

60.  Mixing instruments:- Cement spatula
Agate spatula
Spatulas:-
- Flat and wide nibs with blunt edges.
- Straight Shank
- Different sizes and different degrees of stiffness in their
nibs to suit their various uses.
- Made of
Stainless steel.
Plastic.
- Doubles ended instrument.
Blunt end – for manipulating impression materials.
Sharp end - for mixing cements.
- Used for manual mixing of cements supplied as powder
and liquid.

61. 2) Plastic carrying/ filling instruments:-
- It is an instrument used for carrying the mixed
base cements which are in soft (plastic) stage
or the restorative cement from a cement
spatula to the cavity.
- Usually one end is flat and other end is
cylindrical.
- Flat end is used for carrying the cement.
- Cylindrical end is used for manipulating and
positioning the cement.
- Made of: Stainless steel
Plastic
- Also can be plated with teflon to minimize
material adhesion.

63. 3) Packing instrument:-
Amalgam carrier:-
- Amalgam carrier is a stainless steel instrument
used for carrying mixed amalgam to the
cavity.
- Use:-
1) Hollow tip of an amalgam carrier is inserted
into the mixed amalgam to pack the carrier
with amalgam.
2) It is then carried into the cavity and plunger
is pressed injecting cylindrical pellets of
amalgam.

64. 4) Condensing instruments:
- To pack material into prepared
cavity.
- Types:
A) Amalgam condenser
- Hand
- Mechanical – Vibratory
and Impact
B) Gold condenser
- Hand
- Mechanical.
Hand condenser:-
- Are double-ended instruments
with the nibs
(condensing tips) coming in
different size and
shapes.
- Force varies inversely with the
area of the face.

65. Nibs may be:-
I) Of different shapes:-
- Round
- Elliptical
- Diamond
- Triangular
- Parallelogram
- Rectangular
II) Sizes vary considerably;
- Large round condenser
- Small round condenser
III) Depending on working end;
(condenser face).
- Serrated – For spherical
amalgam
- Non-serrated (smooth) – For
admixed amalgam

66. 5) Burnishing instruments:-
- Hand instrument with rounded edges used to
polish or burnish the surface of metallic
restorations by rubbing.
- Burnishing is the process of rubbing, usually
performed to make a surface shiny or lustrous.
- Double-ended.
- Nibs are : Spherical.
Ball shaped.
Egg shaped.
Apple shaped.
Beaver tail shaped.
Conical.
Hour glass
Fish tail.
Bullet shaped etc.
› Nibs are smooth-faced.
› Different angulations and curvature in their
shank.

67.  Amalgam burnishers
- Small ball burnisher.
- Beaver tail or egg burnisher.
- Anatomic burnisher.
Other uses:-
- Shape metal matrix bands so that they
impart more desirable contours to
restorations.
- To “bend” cast gold near the margins to
narrow the gap between the gold and the
tooth (beaver tail).

69. 6) Carving instruments:-
- Hand instrument with a blade or nib used to
contour the surface of filling material in their
plastic state, waxes, models and patterns.
e.g.- Hollenback carver (Knife- edged-
elongated bibeveled)
- Diamond (Frahm’s) carver –
Bibeveled cutting edge
- Wards ‘C’ carver
- Discoid- cleoid
- Interproximal carver
› Hollenback, Diamond and Wards - One blade is
parallel to the long axis of the instrument and the
other is perpendicular to the long axis of the
instrument.

71.  Instrument grasps:-
Definition:- These are the manners of holding the
instruments which if not held properly it will result
in loss of efficiency and accumulation of
unnecessary strain on the operator.
Adv:- Instrument can be held in different areas for
maximum comforts of the operator.
- Better operator efficiency.
› Different grasps:
1) Pen grasp
2) Modified pen
3) Inverted pen
4) Palm and thumb
5) Modified palm and thumb

72.  Pen grasp:-
- Instrument is held between thumb and first
finger with middle finger below acting as a
support.
- Either the third or third and fourth fingers are
placed on adjoining tooth as rest.
- Position of middle finger is important –
1) For obtaining thrust
2) Preventing the instrument from slippage during
manipulation.
- It involves wrist movement.
Adv:-
- More flexibility of movement.
- Less power.
- Greatest versatility of movement.
- More comfortable.
- Limits application of pressure.
Disadv:-
Bracing is difficult because only the ring
and little fingers are used.

73.  Modified pen grasp:-
- Permits greatest delicacy of touch.
- Pads of thumb, index and middle finger contact the
instrument, while the tip of the ring finger (or tips of
the ring and little fingers) is placed on a nearby tooth
surface of the same arch as a rest.
- The pad of the middle finger is placed near the
“topside” of the instrument for good control and cutting
pressure.
- The fingers and the thumb engage the instrument as a
grappling hook.
- The base of the index finger and the tip of the middle
finger reciprocate, with the thumb placed midway
between them.
- The palm of the hand generally faces away from the
operator.
- Involves forearm which turns inward (pronates) or
outward (supinates).
 Adv:-
- More effective
- Controlled power to the instrument.

75. Inverted pen grasp:-
- The palm is rotated upwards with the pad of
the thumb and index fingers close to each
other but the middle finger is farther down the
shank.
- Used mostly for the tooth preparation utilizing
the lingual approach on maxillary anterior
teeth.

76.  Palm and thumb grasp:-
- The handle of the instrument is held between
the palm and four fingers firmly with the tip
of the thumb acting like a rest.
- Power grasp.
Adv:-
- More control and precision.
- Limited movement.
- Enhance bracing (a forward thrust with the
arm of wrist can be controlled by the opposing
action from the thumb, which is braced
against the teeth).
- Gives the possibility of applying pressure
precisely.
Example: holding a hand piece for cutting
incisal retention for Class III preparation on
maxillary incisor.

78.  Modified palm and thumb grasp:-
- The handle of the instrument is held by all four
fingers whose pads press the handles against the
distal area of the palm, as well as the pad and
first joint of the thumb.
- The rest is tip of thumb on tooth being prepared
or adjacent teeth.
Adv:-
- Most valuable aid in operating inside and outside
the mouth.
- Allows greater ease of instrument movement.
- More control against slippage during thrust
stroke compared to palm and thumb grasp.
- Grasping the handle under the first joint of the
ring and little finger acts as a stabilizer.
- More delicate manipulation.

80.  Rest:-
- Is to stabilize the hand and instrument by
providing a firm fulcrum as movement are
made to activate the instrument.
- Is required for steady hand during
operative procedures.
Adv:-
- A good finger rest prevents injury and
laceration of the gingiva and surrounding
tissues.
The ring finger is preferred as finger rest.

82. - When modified pen and inverted pen grasps
are used, rests are established by placing the
ring or ring and little fingers on a tooth (or
teeth) of the same arch and as close to the
operating site as possible (more reliable).
- In palm and thumb grasp, rests are created
by placing the tip of the thumb on tooth
being operated on, or on an adjacent tooth,
or on a convenient area of the same arch.
- When it is impossible to establish a rest on
tooth structure, soft tissue must be used (not
reliable).

83. Finger rests classified
- Intra oral finger rest
- Extra oral fulcrum
Intra oral finger rest:-
1. Conventional :
Finger rest is established on the tooth surfaces
immediately adjacent to the working area.

84. 2. Cross- arch :
Finger rest is established on the tooth
surfaces on the other side of the same
arch.

85. 3. Opposite-arch :
Finger rest is established on tooth surfaces
on the opposite arch (e. g:- mandibular
arch finger rest for instrumentation on the
maxillary arch).

86. 4. Finger – on – finger :
Finger rest is established on the index finger
or thumb of the non operating hand.

87.  Extra oral fulcrums :
Two most commonly used-
(1) Palm-up
Palm-up fulcrum is established by resting the
backs of the middle and ring fingers on the
skin overlying the lateral aspect of the
mandible on the right side of the face.

88. (2) Palm-down
Palm- down fulcrum is established by
resting the front surfaces of the middle and
ring fingers on the skin overlying lateral
aspect of the mandible on the left side of
the face.

89.  Guards
- Hand instruments or other items such as
interproximal wedges used to protect soft
tissue from contact with sharp cutting or
abrasive instruments.
- May be mouth mirror, check retractor,
lip retractor or even the operator’s own
finger of the other hand.
- This should be placed in the direction of
movement of instrument.
- Advantages:
› Avoid accident slippage of instrument.
› Prevent injuries.

91.  Sharpening is done by reducing the
thickness of the metal at the cutting edge,
while maintaining the angle and shape of
the bevel.
DETECTION OF A DULL CUTTING INSTRUMENT
1) Visibility of a reflection off the cutting
edge.
Sharp edge – not reflect light
Dull edge – reflect light/ presence of a
“glint”.
2) Obvious irregularities in the cutting edge
3) Won’t shave thumb nail.
4) Won’t cut tooth structure.

92.  Instruments with dull cutting edge causes:-
- More pain
- Prolong operative time
- Less controllable
- Reduce quality and precision in tooth
preparation
 Goal of sharpening instrument
- Maintain and restore a knife like cutting
edge
- Preserve the shape and proportional
dimensions of the instrument
- Increase work efficiency of the instrument

93.  VARIOUS TYPES OF SHARPENING EQUIPMENTS
1) STATIONARY STONES/ OIL STONES :
- Arkansas stone
- Silicon carbide
- Aluminium oxide
- Diamond
2) MECHANICAL SHARPENERS
- Rotary (Hand piece)
- Honing machine

94.  Stationary stones/ oil stones :
- Available in variety of grits, shapes and
materials.
Grit
Coarse (Initial reshaping of badly damaged instrument)
Medium
Fine (Final sharpening)
Shapes
Flat – sharpening instruments with straight
cutting edges.
Grooved – curved edges.
Cylindrical – concave edges.
Tapered – using portion of the stone
with a curvature matching that of the
instrument.

95.  Arkansas stone:-
- Naturally occurring mineral
containing micro crystalline
quartz.
- Used in fine sharpening
stones.
- Semi transparent, white or
grey in colour.
- Hard enough to sharpen
steel but not carbide
instruments.
- Should be lubricated with
machine oil which helps in
fineness of sharpening and
prevents clogging avoids
creation of heat.

96.  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.
 Aluminium oxide:-
- Used to manufacture
sharpening stones.
- Available in coarse, medium
and fine grits.

97.  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.

98. Mechanical sharpeners:-
1) 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.
2) Hand piece sharpening stones:-
- Mounted silicon carbide and aluminium
oxide stones for use with straight and angle
hand piece are available in various sizes and
shapes.
- Used to sharpen instruments with curved
blades.

99.  PRINCIPLES OF SHARPENING
- Sharpen the instrument only after they are
cleaned and sterilized.
- Establish the proper bevel angle (450) and
desired angle of the cutting edge to the blade
before placing the instrument. Maintain these
angles while sharpening.
- Use light strokes or pressure against the stone
to minimize frictional heat.
- Use a rest or guard.
- Remove as little metal from the blade as
possible.
- Lightly hone the unbevelled side of the blade
after sharpening, to remove the fine bur that
may be created.
- After sharpening, resterilize.
- keep the sharpening stones clean and free of
metal cuttings.

101.  Sharpness test:-
- Tested by lightly resting the cutting edge
on a hard plastic surface, such as the
handle of a plastic mouth mirror or an
evacuator tip.
- A dull blade will slide across the plastic; a
sharp blade will cut into the surface,
stopping movement.
- A specially made, sterilizable, sharpness-
testing stick is also available (Dalron Test
stick, Thompson Dental).

102. Advantages of sharp instrument:
- Few strokes
- Less effort.
- Increase tactile sensitivity
and operator control.
- Prevent gouging of the
root surfaces.

103.  STERILIZATION AND DISINFECTION
Sterilization: Destruction of both the vegetative
form and bacterial spores.
Disinfection: Destruction of only vegetative
form.
Procedures involved in instrument processing:
1) Presoaking
2) Cleaning
3) Corrosion control and lubrication
4) Packaging
5) Sterilization
6) Sterilization monitoring
7) Drying or cooling
8) Storage
9) Distribution
10) Sharpening

104.  SUMMARY AND CONCLUSION
The removal and shaping of tooth
structure are essential aspects of
restorative dentistry. Modern high
speed equipments has eliminated
the need for many hand instruments
for tooth preparation, but hand
cutting instruments are still important
for finishing many tooth preparations
and thus hand cutting instruments
remain an essential part of the
armamentarium for quality
restorative dentistry.

105.  REFERENCES:
- Sturdevant’s art and science of operative
dentistry (4th Edition)
- Principles and Practice of operative
Dentistry – By Gerald T. Charbenau (2nd
edition)
- Operator dentistry of modern theory and
practice – M.K. Marzouk (1st edition)
- Pickard’s manual of operative dentistry
(5th Edition)