Lecture 2, Instrumentation

8/3/2019 Lecture 2, Instrumentation

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Instrumentation

**** Note : The reference for this lecture in " The Art and Science " book

has too many pages ,and more information than what the doctor needs us to

know ,so she announced that we don't have to study all the information there

.However ; we should read all the details about the instruments that will be

mentioned later in this lecture ,and she said that the exam will have questions

not only from the lecture but what is mentioned in the book ,too !

ᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥᴥ

Dental Instruments are divided into two types:

1- Hand instruments: instruments that are used by hands.

2- Rotary Instruments: e.g. Hand-piece with burs.

Slide No.2:

Hand Instruments are made from Carbon steel or Stainless steel .

Carbon steel is brittle (easy to break) and susceptible to corrosion which is

considered to be disadvantages of it. The instruments have to be sterilized after

every use which will expose it to air and water, thus it's very important for it to

be resistant to corrosion.

In the other hand, Stainless steel does not tarnish or corrode, but it won't

maintain a sharp cutting edge. Instruments have to be sharp for a long period of

time, but after few uses of a stainless steel instrument it won't be sharp anymore

which is considered a disadvantage as it should maintain sharpness for a long

period of time.

To overcome these problems they have made the whole instrument from

stainless steel (handle and shank), but the nib which is the cutting /working



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edge is made from Carbon steel that will be painted ( يطلى ) with a material that

resists corrosion .

Some Instruments are one ended instruments and

others are double ended. Double ended instruments

have two working sides e.g. the Condenser; where

usually one side is larger than the other so that we

can use it in larger areas than the other.

***MOST OF THE INSTRUMENTS ARE DOUBLE ENDED.

Instruments can be classified into:

1- Cutting Instruments; this is used in cutting

the tooth structure.

2- Non-cutting Instruments; which have other uses such as condensing or

manipulation of the material.

In this picture above, the instrument in the left is a hand cutting

instrument that is called "Hatchet ", and on the right is a non-cutting

instrument which is "the condenser".

Slide No.3: Parts of the hands instruments:

Any hand instrument has three parts:

1- Blade or Nib (working end); when the working end of the hand

instruments is used for cutting it's called "Blade". But when it is a non-

cutting instrument it's called "Nib ".



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In the picture above, this is a double ended amalgam carver that is used

to cut amalgam, so the working end is called a blade. But for example the

working end in the condenser doesn’t used for cutting so it's called a nib.

The working end (blade or Nib) forms 45° angle with the shank,

which is the best degree for easy manipulation of the instrument.

2- Shank; connects the handle to the blade /nib .It used to transform

forces that is applied on the instrument to the blade/nib.

3- Handle; is used to hold, stabilize and control the instruments.

***Most of the instruments are striated for better stabilization and

control, but if they are smooth they will easily slip from our hand.

The name of the working

end depends if it's

Hand cutting Blade

Or

Non-cuttin end Nib

In the picture above there are 1 handle, 2 shanks, and 2

blades/nibs.



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Slide No.4: Now, we will start talking about some of the instruments that you

will use either in the lab or in your practice after graduation:

Hatchet (Enamel Hatchet):

It's a popular instrument that you may use in private clinics after

graduation, but unfortunately it's unavailable neither in the lab nor the

university clinic!!

It is double ended; has cutting ends in

both sides.

Right and left cutting ends to use in both

sides of the preparation, one is used in the

mesial side and the other is used in the

distal side.

It's often used in class 2 cavity preparation

in buccal and lingual walls.

It's used to remove unsupported enamel.

You've noticed that in class 1 cavitypreparation we only used the rotary instruments

(hand piece, burs) , but sometimes specially in

class 2 cavity preparation we will use hand

cutting instruments because we will be very

close to the adjacent tooth, and because you can't

control the rotary instruments well, you may hit the adjacent tooth.



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Slide No.5: Gingival Marginal Trimmer; is another instrument that is used

to cut unsuported enamel on the gingival margin .

*** Note: this instrument is unavailable in our labs but you may use it in the

clinic after graduation.

It is double ended.

Mesial & distal gingival marginal trimmers.

Right and left cutting ends.

It usually comes in a set (two instruments together) ;one for the

mesial side of the tooth and the other for the distal side ,and each one

has double ended one for the buccal surface and the other for the

lingual surface in order to trim the unsupported enamel in the gingival

margins in class 2 .

The best instrument to use in removing

unsupported enamel without hitting the

adjacent tooth is the Hatchet ; which is a

hand cutting instrument.

Mainly used in Class 2 Cavity Preparation



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Slide No.6:

Spoon Excavator :

It's named Spoon because in cross sections it looks like a spoon,

Excavator because it's used for excavation (removal) of soft dentine.

Right and left cutting spoons.

They are used for removal of carious tooth structure and soft

dentin.

***We will use this instrument in the last

lab in this semester, when we remove

caries from a natural tooth.

It's mainly used for removal of soft

dentine ,and Dr Ghada personally uses

it for amalgam carving in class 2. "She

will teach us how to carve the marginal

ridges in class 2 with it".

It has different shapes, long-shaped, round and oval shapes but

all of them in cross sections look like a spoon.

Slide No.7:

Amalgam Condenser:

It is used to compress amalgam in all

areas of the preparation. We don’t use it

in cutting the tooth structure so it is

Hand Non-Cutting instrument.



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It may also be used to adapt Resin composite material.

It has different shapes, but what make it special is that it has a flatend (Nib) for condensation of the amalgam in the cavity or to

adapt composite. (You can't say to condense composite because it

can't be condensed) ….. We will talk about Composite adaptation later

through the semester.

Double ended , the small end is used in small parts of the cavity

and the larger end is used for larger parts .The small end is used at

the beginning to condense the amalgam inside the cavity ,then thelarge end is used when we reach the top.

Slide No.8:

Carvers:

Are Cutting hand instruments which areused in cutting amalgam, because when

we apply amalgam in the tooth we have

to re-gain the normal shape of the tooth

by carving the amalgam.

Why it is important to retain the shape of

the tooth ?

1- For the Function.2- Occlusion ;if the amalgam is highly set it

will cause problems in the occlusion ( high occlusion) .In the

other hand if the restoration was less than what we want, it will

cause something that is called post eruption ,because if the

tooth doesn’t face the opposing tooth to stop it, it will continue

to erupt.



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Most popular carver for carving the occlusion surfaces has a

double ended oval shaped and round shaped so that the round

head is used to carve the occlusal surface and the oval head for

the marginal ridges. What we have is used to carve the occlusalsurface not the marginal ridges, for this reason we will use a

spoon excavator for the marginal ridges.

Slide No.9:

Burnishers:

Hand Non-Cutting instruments.

It is used :

1. To burnish (smooth) amalgam

restorations. 2. To shape the metal matrix band when

doing class 2.3. To condense amalgam at the margins. 4. To adapt composite in posterior resin

composite restorations.

It has different shapes, oval head, or it

looks like American football or rounded head.

It is double ended; usually one end is smaller than the other.



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Slide No.10:

Amalgam Carrier (Amalgam Gun):

*** The one in the picture differs a little bit

from what we have as this one is double

ended but ours are one ended.

It's usually double ended so that you can

carry amalgam in both ends in order to be

faster. Usually one end is larger than the

other so you can put small amount in one

area and larger amount in other areas.

It is used to carry amalgam from the

dappen dish outside to inside the cavity.

Slide No.11:

Plastic Instruments:

They are NOT made of plastic, they are stainless steel

instruments. They are called "plastic" because they are used in

esthetic materials (Composite and Glass Inomer Cement) which are

plastic materials.

Are used to adapt composite in class 3,4 ,5 composite restoration .



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Slide No.12:

Cement Spatulas:

Used in mixing the materials

(luting cements and liners).

Slide No.13:

Other Instruments:

*** They are usually called the Exam Kit, which is used for patient

examination.

This kit has three main instruments:

Mouth Mirror, the head of the mirror

usually is separated from the handle, as

sometimes the mirror get scratched so we

just replace it and keep the handle .



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The Dental probe:

Is double ended as some areas are

difficult to be reached by one end but

easier with the other.

It is used to detect the cavity

preparation; sharpness of the cavity

walls and the depth of the cavity

It is used to detect caries (mainly),

but there are some controversially about this use!!

Why Is That?

The caries starts by demineralization

and white spot lesion formation; where the

surface area is mineralized but the sub-

surface area is demineralized, so there is a

chance for a reverse action. Thus

sometimes if you use the probe in detecting

the early lesion you may break the surface area and cause a cavity;

and by that you remove the chance for incipient caries or white

spot lesion to be remineralized .

However; as a dentist the first thing you do to detect caries is

handling the mirror in the left hand and the probe in the right hand.

Forceps or tweezers :

Is used to handle things to or out from the oralcavity such as cotton roles and so on.



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Periodontal probe (perio probe):

-- Is graded and can be used to look for pockets

or to know the depth of the cavity.

-- It is not a main instrument; it's just a

measurement instrument that helps you to know

how much 0.5mm is.

Slide No.14:

Rotary Instrument:

Air driven hand pieces, they are not connected directly to

electricity; i.e .the electricity is connected to a compressor which

will produce air that will drive the hand piece.

Rotary Instruments are divided into:

Low speed hand piece. High speed hand piece.

Low speed hand piece has a speed equals to 10,000-15,000 rpm. It's used for removal of caries and bad dentine (not for enamel

removal, but we use it in the lab to remove enamel because we are

working on plastic teeth).

Enamel is the hardest tissue in the human

body that can NOT be removed with a lowspeed instrument.

Plus low speed hand-piece can be used for

smoothening the tooth and finishing

restoration.



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It has different attachments: latch (you have to move the latch to

the side then put the bur, and finally return the letch to its first

position), or friction grip (you put the bur and click it inside,so

that it will fix there by friction ) High speed hand-piece is friction grip

Slide No.15:

*** The instrument in the picture is an old one.

High speed hand-piece has a speed equalsto 100,000 rpm .(The difference is big

between high and low speed )

It is used for cavity preparation (cutting

Enamel).

The hand-piece that we use is friction grip

hand piece.

On real teeth we have to use high speed

hand-piece, so please try to get high-

quality plastic teeth to use high speed on

them.



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Slide No.16:

Burs (The cutting part):

Burs are milling devices and function by chip removal of tooth

structure (Its action is chipping the tooth structure to prepare

the cavities).

The Burs are about 4 mm in length.

It is made by Tungsten carbide (that what we use) or it can be

made from another material which is Diamond material (wewill use it for cavity preparation in crowns and bridges).

Their heads are composed of a number of metal cutting blades

and must rotate counterclockwise.

In Low speed Hand-piece we can control the rotation either

clockwise or counterclockwise .But It must be

counterclockwise to be cutting, because in clockwise direction

it will not cut.

In High speed Hand-piece we don’t have the choice to changethe direction, it's always counterclockwise.

The End

Done By: Enas Salameh

Lecture 2, Instrumentation

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