Instruments and equipment for tooth preparation

Dr. Mazen D Doumani

Hand instruments

General classification of instruments

Cutting hand instruments excavators, chisels

Non-cutting hand instruments amalgam condensers, mirrors, explorers, probes

A) Diagnostic instruments B) Restoring instruments

Instruments that are used by the hands.

Parts of the hand instruments Composed of 3 parts:Handle , shank , and blade(nib). Noncutting instruments:the part corresponding to blade

is termed Nib Blade on both ends of the handle are known double-

ended instruments

I. Hand instruments

Blade

Handle (shaft)

Shank

The handle is used to hold the instrument. Different sizes and shapes . It may be smooth or serrated. The number , series , manfacturer’s name are written

on the handle.

Handle(shaft)

It connects handle with the working point\nib , blade\ of the instrument.

It tapers from the shaft down to the blade and is normally smooth , round or taperd

It may be straight or bent for better control of the working point when force is applied.

The working point should be within 3mm to the center of the long axis of the handle.

shank

According to the numbers of angles , the instruments are classified as:

- Straight :no angle

- Mon-angle: one angle

- Bin-angle: two angles

- Triple-angle: three angles

If the shank has more than one angle ,it is termed (contra-angled).

it is connected to the handle by the shank.

For cutting instrument, the working point is called blade.

For non cutting instrument, the working point is called nib.

If the blade is only in one end it is called single ended instrument.

If the blade is only in two ends it is called double ended instrument.

Working point :Blade(nib)

Most blades have three bevels :

- one on the end of the blade forming the primary cutting edge.

- two along the side of the blade forming the secondary cutting edge .

- the instrument is called bi-beveled instrument .

Working point :Blade(nib)

1- function (scaler , excavator).

2- manner of use (hand condenser).

3- design of the working end (spoon excavator , sickle scaler).

4- shape of the shank (mon-angle,bin-angle).

5- these names were combined to form the complete description of the instrument:bin-angle spoon excavator

Black’s classification system by instrument name categorized instruments by

Dr. G. V. Black classified instruments according to order names, suborder names, class names, and subclass names. Order names :denote the purpose for which the instrument is to be used, such as mallet or clamps. Suborder names :define the manner or position of use of the instrument, such as hand mallet or molar clamps. Class names: describe the working point of the instrument, such as spoon excavator or inverted cone bur. Subclass names: indicate the angle of the shank, such as bin-angle.

Black’s instrument formula

Black’s formula describes :

the dimensions of an instrument.

the angulation of the instrument.

Hand - cutting instruments (cut hard or soft tissues)

A- Excavators Hatchet,hoes,spoons,

angle former

B- Chisels Straight ,curved, bin –angle,

enamel hatchet

C- Others Knives,files,carvers,gingival

marginal trimmer

Ordinary hatchet excavator:

The cutting edge of the blade directed in the same plane of the long axis of the handle and is bi-beveled.

we use it primarily on anterior teeth to prepare retantative areas and sharpening internal line angles

A- Excavators

Hoe excavators:

has the primary cutting edge of the blade perpendicular to the axis of the handle.

we use it for: planning tooth preparation walls and forming line angles.

used in class III and V for direct golden restorations.and intended for use on enamel of posterior teeth.

A- Excavators

angle former:

• it is used for sharpening line angles and creating retentive feauters in dentin in preparation for gold restorations .

• It also may be used in placing a bevel on enamel margins.

• It is mon-angled and has the primary cutting edge at an angle (other than 90 degrees) to the blade.

• It may be described as a combination of a chisel and gingival margin trimmer.

• It is available in pairs (right and left).

A- Excavators

Spoon excavators:

they are used for removing caries and carving amalgam or direct wax patterns.

The blades are slightly curved and the cutting edges are either circular or clawlike.

The circular edge is known as a discoid, whereas the clawlike blade is termed a cleoid.

The shanks may be bin-angled or triple-angled to facilitate accessibility.

A- Excavators

Straight Chisel: The straight chisel has a straight shank and blade, with the

bevel on only one side.

Its primary edge is perpendicular to the axis of the handle.

B- Chisels

The bin-angle and Wedelstaedt chisels:

the primary cutting edges is in a plane perpendicular to the axis of the handle.

may have either a distal bevel or a mesial (reverse) bevel.

The blade with a distal bevel is designed to plane a wall that faces the blade's inside surface.

B- Chisels

Enamel hatchet:

it is similar in design to the ordinary hatchet except that the

blade is larger, heavier, and is beveled on only one side.

It has its cutting edges in a plane that is parallel with the axis of the handle. It is used for cutting enamel and comes as right or left types for use on opposite sides of the preparation.

B- Chisels

Gingival margin trimmer:

is designed to produce a proper bevel on gingival enamel margins

of proximoocclusal preparations.

It is similar in design to the enamel hatchet, except the blade is curved.

the primary cutting edge is at an angle (other than perpendicular) to the axis of the blade.

It is made as right and left types

B- Chisels

Other hand cutting instruments, such as the knife, file, and discoid-cleoid instrument, are used for :

trimming restorative material rather than for cutting tooth structure.

C- Other cutting instruments

1- knives: known as finishing knives, amalgam knives,or gold

knives, are designed with a thin, knifelike blade that is made in various sizes and shapes.

Knives are used for trimming excess restorative

material on the gingival, facial, or lingual margins of a

proximal restoration or trimming and contouring the

surface of a Class V restoration.

C- Other cutting instruments

File: They used to:

trim excess restorative material.

They are particularly useful at gingival margins.

Blades of files are very thin, and teeth on the cutting surfaces are short.

C- Other cutting instruments