Lecture 2, Instrumentation
Transcript of 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