8/4/2019 Lecture 4, Composite II (Script)
http://slidepdf.com/reader/full/lecture-4-composite-ii-script 1/18
8/4/2019 Lecture 4, Composite II (Script)
http://slidepdf.com/reader/full/lecture-4-composite-ii-script 2/18
بسم الرحن الرحيم
>> Dental Material (II)
>> Lec # (4)
>> Composite (part 2)
PLZ chick your seat number on E-learning or the group on FB so that
next lecture you set in your own seat …
dentalsomething from theclarifyAt first the Dr. just wanted to
lecture which is that … when we talk about spherical andamalgamadmixed in surface area … in the reference it says that spherical
amalgam surface area will be a greater or available to react with
mercury … and in the slides it says that low surface area of spherical
amalgam requires less mercury … they are two different things … if
we for example add the surface area of the irregular particles it
would be more than the spherical … but when we talk about the area
that is available to react in the environment the spherical particles
all of its surface area is going to be out there to the environment …
the irregular particles some of it because of its shape won't be
exposed to the outer environment and so not all of the parts are
there for reacting with mercury … while spherical amalgam all of its
surface would be exposed to mercury … so they are two different
things … one is that how much area is exposed to the outerenvironment (spherical > irregular) and the other is how much of sum
surface area is there (irregular > spherical) both are correct
because they are two different things …
learning and-… the slides are on Ecomposite >> Now we talk about
the slides of next lecture as well (glass ionomer cement)
8/4/2019 Lecture 4, Composite II (Script)
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Clinical handling of composite:
Composite is used for many types of cavity preparations, before
they used to use it only for anterior teeth; because it is not very
strong, newer composite (hardened) could be used both anteriorly
and posteriorly, so they can be used in class I preparation, class II,
III, IV, V … so any surface that is involved can be restored with
composite, but in some places we prefer amalgam, in the posterior
part of the mouth especially if the cavity is large, if it is not too big
composite can be placed there … with no fears that the filling will
fracture there and have to replace it.
So when you want to select whether you want composite or not you
need to look at two things mainly:
-Esthetics: if you want to make a strong restoration posteriorly
amalgam is your first option … but if you're looking the esthetics or
esthetics is important for you pt. go for composite … anteriorly the
option is always very easy it is composite always … the force is notvery high … and you need something that is similar to the natural
tooth shade (color) …
Anteriorly you might choose microfills or microhybrids they give a
nicer surface when you finish and polish them compared to normal
hybrid composite or macrofill composite
-Strength demands
Posteriorly hybrid will do well they companied esthetics and
strength
Many types are available and you can choose according to these
criteria … what you want your restorative material to provide
Whether I want esthetics … strength … or both
8/4/2019 Lecture 4, Composite II (Script)
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Shade guide:
We talked about shade guides last semester … we talked about heo
… croma … value
Shade guides are now available and it has got several shades that
you can select from to have the appropriate composite filling
There are many ways to do shade selection; there is certain light you
need to make selection under, some dentists place a small composite
material on the tooth and cure it to see whether the shade is
matching … there is certain guide lines we need to follow … forexample you shouldn't use the dental unit light (orange), you should
not use fluorescence light the best light is the natural day light, not
in the early morning not during sunset during the day this is the best
light to select your shade under
Another thing … if your pt. is wearing colorful clothing this will
affect how you see the color so you need to cover the upper part of
the pt. with an apron which is usually colored light blue or light gray
which will not affect how you see the colors wave length (so it will
not let you see color differently) it is a neutral color, so you need a
neutral back ground so you can select the shade properly, even if the
pt. is wearing a bright lipstick she should remove it … all of these
things can affect how you see colors because it is just a wave length
that is sent to your eyes then it will be interpreted into your brain
So we have a neutral back ground and use normal day light it will help
you select best accurate shade that is suitable for your pt.
And it is better to select the shade before you do cavity
preparation; when you do cavity preparation you drill teeth and you
may dehydrate them because of the drilling which will change their
color
8/4/2019 Lecture 4, Composite II (Script)
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Another thing … when you want to select the shade and use the
shade guide you need to place some water on it (on the taps) because
natural teeth have saliva all over … so when you want to compare
between the pt. teeth and the shade guide you need to wet it withwater because natural teeth are wet by saliva, dry tooth look
differently they have a different shade
All of these are guide lines you need to be aware of, shwai shwai you
are going to memorize them
Shelf life:
When you want to store your composite or your bonding agent and so
you need to follow the manufacturer instructions … keep them away
from heat or light because they can activate setting of the material
Some of the composite are available in small containers so each one
of which is designed for one pt. (disposable) by this it helps to
disinfect and to avoid cross-contamination between pt.s
And always when you want to take part of the composite from the
syringe (from the container) you need to use a clean instrument and
not use it with other pt.s to prevent cross-infections … and when you
take a piece of composite you need to cover it
Keep it away from light … so we need to cover composite keep away
from light to prevent setting or initiation of setting because later onif it starts to set before you start working with it … it will be very
hard or start becoming hard it will not follow properly in your cavity
and you will not be able to manipulate it easily
Isolation:
Composite is a technique sensitive material … it is very sensitive to
moisture contamination (no saliva no Bld at all) … it needs to be very
8/4/2019 Lecture 4, Composite II (Script)
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well isolated from the oral cavity … you need good isolation to
maintain good bond (strength) between composite and tooth
structure … if contamination occurs it will compromise your bonding
and your material as well (setting of the material) … the material willnot bond properly to enamel and dentine if there is saliva or Bld all
around which will lead to microleakage later on which will lead to
sensitivity and recurrent caries … so you would need to repeat the
filling again pay more money which is not good for your pt. he will not
be happy
Always maintain good isolation when you want to work with composite… as soon as you finish your cavity and you want to start your filling
restoration >> isolation
We can use cotton rolls like in slide #34 we can use what is called
rubber dam which is placed around the tooth (or teeth) and you will
learn how to place it later on
We have a light cure unit blue light comes out of it
Sometimes if your cavity is subgingival … we can place something
that can push the gingival a little pit away from the margins of your
cavity which we call a retraction cord … it is like a small rope that is
inserted between the tooth and the gingival margin … it will push the
gingival away which will help control the bleeding and it will expose
your cavity margins, they will be clear to you so that will know whereto place your composite
So the retraction cord is placed between the gingival and the tooth
so all the cavity margins are exposed … you can place your
restoration … you know where your cavity ends … you're not going to
place extra and have trouble removing it later on
8/4/2019 Lecture 4, Composite II (Script)
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Isolation can be done with cotton rolls … can be done with cord dam
placement … in cases of subgingival cavity a retraction cord can be
placed between the gingival and the tooth so that it will push the
gingival away and make the margins of the cavity clear to you
In slide 35 we can see a light activated composite which is provided
by a syringe … there can be disposable tips to use one for one pt.
only and then you throw it away
on the right you can see what we call plastic instrument it is similar
to the plastic instrument in your kit it is used to place composite
they are made specially so the composite will not stick to yourinstrument … it makes placing the composite easier
in the pic down left you can see two paste composite no longer used
now mostly we use light cure composite one component one paste
that is cured or sets by light activation
Slide #36:
In cases of class III cavity preparation which involves the mesial or
distal surfaces of anterior teeth you want something to help you
adapt your filling inside the cavity and reproduce the margins
(contact) between teeth … to do that we need to place a band around
the teeth the one that is used for composite is called a Matrix
strip/band which is made of cellulose and it is transparent (whyshould it be transparent?) so that light can go in through and cure
composite … so it helps to make a smooth surface and to reproduce
the mesial or distal surface of the tooth … if this strip was made of
metal light won't pass through and no curing of the composite!
A small wooden wedge is also used to prevent excess from going
subgingivally … you will learn about these in the lab
8/4/2019 Lecture 4, Composite II (Script)
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You will see them and learn how to use them to prevent excess
filling, to maintain good contact between teeth to prevent excess
composite from going subgingivaly
When you place composite you need to make sure that when subject
it to light the light will go through all of the layer that we placed …
you have to make sure that the light has passed through the whole
thickness of the layer to cure it … to insure setting
That is why increment should be maximum two mm thick … when you
have a large cavity that is 4 mm deep you need to place at least two
layers of composite reach one is two mm thick … a layer of two mm
thickness is okey in regards to the light penetration … it will be able
to penetrate it from top to bottom and insure good setting … a
composite that did not set will it will be weak it will shrink more it
will break off
We need a layer that is not more 2 mm in thickness when we place it
in the cavity … so you should not fill the whole cavity once and for all… 2mm layer so when we cure it with light it will pass all through and
set the whole material
If the bottom did not set it will be weak it might break off it may
shrink and microleakage may occur
The material that has not set very well its components might be
harmful and make some damage … if we look at those materials and
their components individually it might be harmful but when the whole
material sets it will be okey
So a complete setting should be done so that we guarantee that
there are no damaging components out of the material
8/4/2019 Lecture 4, Composite II (Script)
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So incremental filling of the cavity should not be more than 2 mm or
less … more than 2mm is not acceptable
Q: what is there in the two pastes composite?
A: base and catalyst
You can see in slide #37 incremental placement of composite … we
have two examples of class II cavity with several ways of placing
composite … you can place it horizontally or you can place one
diagonally and then horizontally … it doesn't matter as long as youfollow the guide lines … maximum 2 mm thickness if you have a
composite that has a dark shade it will not allow light to pass easily
compared to a composite with a light shade because the dark one will
absorb some of the light that is passing through … so when you use a
composite with a dark shade the increment should be less than 2 mm
… 1 mm for example
So the shade of your composite will affect the increment of the
filling or the layer … darker shades should be placed in thinner
increments … to make sure that the light will go all the way through
because they are dark in color they will absorb the light before
allowing it to go through to the bottom
Etching and Bonding:
Unlike amalgam composite needs some tooth preparation before you
actually put the restorative material
In amalgam we prepare the cavity wash it (clean it) place amalgam
and that’s it
In composite it is a different story … you need to prepare enamel
and dentine in a certain way so that composite will bond to enamel
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and dentine this bond is called micromechanical (how is that done?)
by two steps Etching and Bonding
Etching basically means that you are placing a certain concentration
of an acid on enamel and dentine … this acid will create roughness on
enamel and dentine it will remove some of the minerals it will open up
dentinal tubules … so there will be micro holes or pores on the
surface of enamel and dentine … the surface will be rough … a rough
surface provides better adhesion or better bond compared to a
smooth surface
So to create such as rough surface an acid is added in the form of a
gel which is phosphoric acid (con. 35-37%)
It is placed on enamel and dentine after cavity preparation for few
seconds and then it is washed away and the tooth dries … when they
looked at it in the microscope they saw that it created roughness
holes and pores on the surface of enamel and dentine … dentinal
tubules are open … and this rough surface will bond composite better… because when you place it it will flow into these pores or holes and
lock … it will not be detached easily
After doing this etching (placement of the acid on the tooth
surface) there is another step just before placing composite placing
a bonding agent which is a liquid … it is made of resin … it will help
to make a connection between composite and the tooth surface … soit will act as an intermediate layer … without this bonding agent
composite will not be attached to the tooth surface … one of the
reasons is that tooth surface is hydrophilic … composite is a
hydrophobic material … so you need something in between that will
be able to attach itself to the tooth surface and to composite … it
will have two arms … so it will form what we call a hybrid layer … so
this bonding agent is placed and it is light cured … so you have to
8/4/2019 Lecture 4, Composite II (Script)
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subject it to light for 20 sec usually … once it is placed you can start
adding composite
You add the 1st layer of composite and cure it … the next layers will
bond chemically to each other … because they are the same material
So you don't etch and bond between each layer only on tooth
surface
Q: why bonding agent is not used in amalgam?
A: because amalgam will not be able to flow in these micro pores and
holes … and interlock itself with them … particles are too big … and
in amalgam it sets as one block it will change the shape of your
cavity rather than making the surface rough … so the whole cavity
should be shaped in a certain way … particles are too big …
You can see in slide #39 the etching gel the color is usually blue
green … it is placed on both enamel and dentine … it is called total
etch technique (involves enamel and dentine) … after it is removedthe color of enamel will be chalky white … because the enamel has
been deminerelized a little pit and dehydrated … bonding agent is a
liquid it is added using a brush or a small sponge on the tooth
surface and light cured … and then composite is added
In slide #40 you can see acid etched enamel … do you notice the
rough surface? These are enamel prisms if you remember them (>.>)
So when you place your composite there will be tooth surface into
which the bonding agent will flow and composite a hybrid layer and
your composite material
This hybrid layer is composed on one end of bonding agent and
composite on the other end bonding agent and enamel and dentine
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When you finish and place the final layer of composite the surface
of this layer will be a little pit sticky because it is exposed to
oxygen it will not be cured properly only a very thin surface layer …
it is a sticky layer … so we wipe this layer with some cotton or whenwe do the finishing and polishing to smoothen the filling this layer
will be removed so it will not cause any problem … but this layer is
oxygen inhibited layer because it is in contact with oxygen it will not
be cured properly … it is a very small surface layer (thin) and usually
removed when you do finishing and polishing of the filling
And as we said we need to maintain good isolation … so if during yourrestoration contamination happens you need to do etching and
bonding again (even for a few sec of contamination with saliva or Bld
means your whole surface is contaminated because they have
bacteria have debris which will block your micro holes or pores so
you will not have a rough surface) and contamination will prevent the
flow of your bonding agent to cover all areas … the larger the
surface area for bonding is the better the bond … so the surface
needs to be clean and rough
Q: does the bonding agent go into the dentinal tubules?
A: it goes into the dentinal tubules
Q2: why is that?
A2: it will cause retention
I will show you a picture next lecturesSs and I will show you how
bonding agent goes into dentinal tubules and cause retention
Q: not heard :S
A: no bonding agent could be used to prevent sensitivity (in ppl that
have sensitive teeth)
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(ya jamaa3ah shoo fe? Ya3ne bes2al sha3'lat mohemeh!! )
Some people have sensitive teeth so bonding agent is used and goes
into the dentinal tubules and prevent things from going inside and
stimulating the nerve endings … so it can be used as a desensitizing
agent
(Dentinal tubules have inside fluid and at the end of which we have
nerve endings)
For amalgam we use another bonding agent which is called a burnish
(it is made of resin) … in terms of research they say that amalgamdoesn't cause sensitivity as much as composite … it is related to the
composition of the material … it is related to the size of the
particles that can go into dentinal tubules … in composite the chance
is bigger compared to amalgam … but they try using it to improve the
bond between amalgam and tooth structure and it is not really that
effective … but if you want to minimize sensitivity another material
which is called abarnish (not sure of the spelling) is used and we willtalk about it in another lecture (cement lecture)
Sometimes when you do a cavity and you don't have time to place
your composite you need to place some sort of a temporarily filling …
send your pt. home when he comes back again you place your
composite (7ashweh mo2aqateh ya3ne) as the Dr. do in the markets
… in case of anterior teeth you cannot place zinc oxide eugenol as atemporary material (they should not be placed under composite
because eugenol prevents the setting of composite … so when the pt.
come you need to remove your temporary filling you might not
remove it completely there might be some remnants of zinc oxide
eugenol inside the cavity which will prevent complete setting of
composite later on when you place it and it may cause staining of
composite.
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So it you want to temporize your anterior tooth you can place
another thing like glass ionomer cement which we will talk about next
lecture
In cases of light curing it is good to always follow manufacturer
instructions … more it will not have any effect … less it will prevent
good setting … so stick to the recommended curing time stated by
the manufacturer
In general composite that we work with here bonding agent needs 20
sec … composite 40 sec … so each layer 40 sec subjected to the light
it will set
Thicker layers … and a dark shade … few researches say it will have
no effect … the best way to do it is to minimize the thickness of the
layer … so in terms of darker shade or deeper locations always use
thinner layer of composite
Finishing and polishing: to produce a nice shiny tooth surface
(fe 7ad jala6 el Dr. w eza bedhum yekamlo 7aki yetla3o barah … w fe
shab msh daroore yetala3 3aleehom w yetsahwan maho 2abel shwai
7aka ma3hum :P )
Certain material is used to produce a smooth surface … these
materials are abrasive … they have a rough surface … usually we
start with a rough material that is placed in a hand piece then we gosmoother and smoother to produce a fine smooth surface … so first
we need to remove excess with a rough disc for example and then we
go to smoother discs to produce the shiny smooth surface … you will
be familiar with all of these in one of the lectures at the end of the
coors
Some dentists when they finish the filling and do finishing andpolishing they place another layer of bonding agent on the top … just
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to make sure if there are any small holes or voids on the surface of
the composite they will be filled with this bonding agent … they will
get a better surface a smoother surface … preventing any bacteria
from going in
Light curing units:
There are many instruments that can be used for light curing … one
of them is based on halogen bulbs (here we mean the type of gas is
different) … so halogen light bulbs can be used in light curing … you
should always protect your light source from any dirt for example
from any damage … from falling over … from any remnants from
sticking on its surface … because it will prevent light from coming
out … we could put a plastic wrap to prevent any damage or any dirt
or composite pieces sticking to it because they will prevent light
from properly coming out
Some of them might be – cordless (wireless) and some of them -
needs to have a cord that will be attached to electric outlet
Some of the light sources may have High intensity light unit which
lowers your curing time
If the light has high intensity it means that you will have less curing
time … examples: - Plasma arc units (PAC) and – Argon laser units
Again the type of gas might be slightly different
Precautions:
All the time these instruments you need to set them because light
become weaker with time
You need to subject the composite to light and protect your and the
pt.s eyes because they may cause damage to your eyes and they
cause cataracts (el mai el zarqah aw el soodah)
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If you look directly into this light it might cause damage to your
eyes you need to protect yourself and your pt.
And also it can produce heat so you should not hold it very close to
your cavity … especially in deep deep cavities it will be close to the
pulp unless you place a liner … something to isolate your pulpal floor
So in deep cavities it is better to isolate the pulp by placing a liner
or a base
In slide #46 you can see the light curing unit and a shield all of
these can be placed between you and the light and to protect thept.s eyes from this light …
Compomers:
A modification on composite … a Compomer it is a material that has
been modified a little pit … because they wanted something that is
able to release florid so they added what we call poly acrylic acid
These materials once activated and placed in cavities they say that
they are able to release florid … they changed the components they
added some acrylic acid and florid so once they set and exposed to
the oral cavity they might be able to release florid … prevent caries
… the problem is that after curing … after the material sets the
resin components might prevent florid from being released properly
… so a very small amount is released of florid … so this is just amodification to composites … they are called Compomers we call
them polyacid modified resins
They are light cured (how do they set?)
Part of the setting rxn is also chemical … we call it acid base rxn
between the resin and the acid that has been added … so it has two
types of rxns light activation and Acid-Base rxn (chemical set
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reaction) … they need to be placed in layers … and they need bonding
agents … so similar to composite
Indirect esthetic materials:
In addition to directly placed in cavities there is composite or resin
can be made in the lab … you make your cavity … or prepare the
tooth … take an impression … to the lab … they use composite …
either normal composite or modified composite which is reinforced …
they add certain powders to it to make it stronger and make the
restoration … and then when the lab tech. finishes the restoration
for you he send it back to you and you attach it to the tooth
So they use it to make veneers which are placed on the labial
surface … it can be used to make crowns … inlays (similar to a class
II cavity) involves the mesial and occlusal surfaces or distal and
occlusal surfaces … for example in slide #49 this pt. has diastema (a
space between his two incisors) … these teeth were prepared … part
of the labial surface was removed … about half a mm thickness … anda veneer was cemented on top … the tooth was made larger by
this veneer and it caused the space to be closed so >> esthetics … if
you have staining on teeth this can also be done a veneer which is
called in Arabic (qishreh) it looks like the labial surface of the tooth
… its thickness about .5 mm they bring it and stick it to the tooth …
This is indirect because you are preparing the tooth … taking animpression … sending it to the lab … lab makes the restoration … and
they give it back to you …
Laboratory processed composites:
The type of composite used is usually reinforced composite … or to
save time … you take an impression and send it to the lab … in the
next visit these restorations will be very small blocks and ready to
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be attached inside the cavity by using cements (paste) a special type
of paste that is used to stick the restoration inside the cavity
One benefit of indirect restoration is that the curing happens
outside the cavity … they will not shrink in your cavity because they
are made in the lab …
Restorative materials used:
These composites are either:
-Conventional composite
-Fiber reinforced composite
-Particle reinforced composite
They have fibers to make them stronger … or particles … or normal
composite … all of these can be used to make indirect restorations
In some cases you can do this in your clinic … you can prepare the
tooth … take an alginate impression … pour your impression in silicon
(rubber) on this model or cast you can do your restoration … and
then place it in the pt.s mouth … if you don't remember this PVS
material go back to the lecture in the summer we've talked about it
…
We talked about Shade taking … in slide #55 you can see the shade
guide … and we talked about the guidelines for taking the shade.
Good luck to all … Forgive me for any mistake …
Becoming older is not my fav. thing on earth so PLZ don't
congratulate on nothing :P :p .