Lecture 4, Composite II (Script)

8/4/2019 Lecture 4, Composite II (Script)

http://slidepdf.com/reader/full/lecture-4-composite-ii-script 1/18



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)



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



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



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



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



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



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



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



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



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



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)



(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.



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



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)



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



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



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 .

Lecture 4, Composite II (Script)

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