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Composite, Amalgam, Varnishes, Lining and Bases

,with special emphasis on material used in

clinic(part 1)

The cavitated lesion and non cavitated lesion;

the cavitated lesion is broken because of caries, not like the

non cavitated lesion.

The big question you will face in your clinic when you

remove caries is should I stop or continue removing?!

To get the answer of this question you need to follow

certain steps, you dont need to remove all fissures, just the

carious one. Some fissures are stained we leave them.

Areas to cut away:

1. Infected areas, theyre soft, orange-brown in color.

2. Decalcified lowed bearing areas (undermined enamel).

Its important to remove any undermined enamel because

itll cause fracture and failure of your restoration after all,

especially in amalgam restoration.

3. Decalcified cavosurface margins, we need to remove them

A non cavitated caries is the first clinically notable sign of

the disease. Demineralization of hard dental tissues hasreached the level when it can be seen with the naked eye but

without a visible breakdown of dental enamel.

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because these are the marginal of the tooth and the

restoration. If these are decalcified they are force, they will

affect the marginal seal and theyre undermined so I need to

remove them.

choky enamel is decalcified, we need to remove it.

The Dr gave an example of an upper 6, there were two

cavities one on the mesial and the other on distal side

without interfere with the important and vital part of the

tooth structure(preserving), which is the oblique ridge in this

example.

So we follow the caries and then after removing them I

have to stop and make sure that the cavity is dry. We do

isolation using the suction, dry cotton rolls and we also use

the gauze to wipe the mirror and retract the tissues when

giving anesthesia.

Then I use the excavator to assess what I have

and the suspicious areas that I have within the cavity.

I check the color and the texture, the texture if its softand flaky then I have to remove it, if its hard Illleave it. The

color if its dark, hard and close to the pulp(deep) I leave it

because this is affected dentine not infected dentine its

hard, the dentinal tubules are already plugged. Otherwise if I

remove it Im opening more dentinal tubules increasing the

risk of post operative sensitivity and most important I might

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cause pulp exposure.

After that I think do I need a lining material or not?if I want to use it I have to think what lining material and

where do I need to apply it.

The lining material that we are using in our clinic:

1. Vetra bond(RMGI)

2.Calcium hydroxide(we use it in direct pulp capping).

*please refer to dental materials and read about them*

And before you bring the lining material make sure you have

the light cure in your clinic by your side.

The next step is to think of the restorative material

(Amalgam vs. composite), if its amalgam I need to modify

the cavity, amalgam bonds mechanically to tooth structure,

so I need to create the resistance and retention forms.

For the isolation of the upper centrals we put 2 cotton

rolls in the labial sulcus on both sides because of the frenum.

For the lower arch we also use two cotton rolls one in the

labial and one in the lingual.

Isolation is important during the access of the cavity,application of the lining and during cavity restoration,

whether its amalgam, composite or GIC.

Amalgam is less sensitive than composite because it takes

less time but this doesnt mean not to isolate the tooth.

~The cavity preparation now is done.

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Lining (Pulp protection)Include:

1.the varnishis placed over the floor and walls of the cavity,

the organic solvent evaporates and the resin stays there

sealing the dentinal tubules, so its temporarily seals the

dentinal tubules, decreasing the chance of post operative

sensitivity and sealing the dentinal tubules protecting themfrom the corrosion byproduct not to discolor them.(the

varnish in microns).

2.Lining material:thicker than varnish, we apply it only on

certain walls apposing to the pulp( pulp protection), it also

provides a therapeutic effect like calcium hydroxide and

provides some thermal insulation.

3. Base:its the thickest one, we use it to block some certain

areas and also to compensate for the loss of a ___ amount of

the tooth structure.

The varnish dries very fast within 10 sec and because its

thin and we apply it in tow layers after making sure that the

first layer is dry we apply the other layer, we dont use it

under the composite because it will leak the composite, we

use it with amalgam.

Calcium hydroxideis self cured, not like RMGI also

applied in thickness of 0.5mm, it composed of suspension of

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calcium hydroxide as a main indicates in organic liquid.

what we have in the clinic comes in tow pastes( base and

catalyst) .

We use ZOEas a temporary filling material, The powder

is zinc oxide and the liquid contains Eugenol among other

things. Its the least irritating material usein dentistry (ph=7).

It has a sedative effect but we dont put it directly over

exposed pulpal tissues. The only materials we use directly

over exposed pulpal tissues are calcium hydroxideand

MTA(mineral trioxide aggregate). We dont use ZOE under

composite because itll interfere with the free radicals in the

composite resin.

Glass Ionomer(GI):came as powder and liquid(what we use

in clinic), the powder contains calcium fluoroaluminosilicate

and the liquid is polyacrylic acid, we mix them together to get

the glass ionomer in an acid-base reaction. Or it may come

capsulated and we dont use itin our clinic.

# Advantages of GI:

(1) It bonds to the tooth structure.

(2) coefficient of thermal expansion, it compatible with

tooth, if its not compatible it means itll contract more than

the tooth structure or itll expand more than the tooth

structure. If it contracts more itll affect the marginal seal

between the restoration and the tooth.

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(3) It has anti bacterial properties.

(4) Fluoride release.

Resin Modified Glass Ionomer (RMGI):we use it in the clinic,

basically its glass ionomer with few composite resin(mix of

chemical reaction and light cure), So you cure it and itll

continue the setting reaction.

# Advantages of RMGI:

1.It bonds to the tooth structure.2.Has anti bacterial properties and F release.3.Strong material.

Where to apply lining material?

If we have class II cavity, we apply the lining material on

the axial wall and pulpal floor if needed but not on the

gingival floor. We apply it with the applicator not the

condenser or a spatula, not anything else. Make sure not to

apply it on the walls just the pulpal floor(axial floor in class II).

~the cavity lining is done.

The Matrix

Benefits of the matrix:

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1.Provide walls to condense against(compensate for the

missing walls).

2.Create a proper contact area.

3.Provide isolation.

Types of matrix:

1. The universal(tofflemire); we use it in the clinic, it comes in

different shapes. The occlusal part is upward and the gingival

part downward, when you apply it make sure it covers the

tooth structure not the gingival tissues, Then put the wedge

below the contact point we use the larger embrasure but if

we have any difficult we can put it from the buccal side. We

use the wedges to prevent the overhang, We have wooden

wedges and plastic wedges come in different sizes.

The wedge has an apex and base(pyramidal in shape), we putthe base toward the gingiva and the apex toward the contact

point, you should be able to see the shape of the pyramid

from above, if you place it the other way around youll open

the contact.

2.The auto matrix, we dont need a tofflemire just the matrixand we use a certain device to help adapting the matrix to

the tooth.

3.i couldnt hear it, we use it for deep subgingival areas.

4.Sectional matrix, use with composite restoration, we put

the matrix and then the rings or vice versa, the ring is to

stabilize the matrix.

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5.The celluloid strip, use in class III and IV, we put it before

applying the acid etch and the bonding agent, dont use long

celluloid strip because itll interfere with placement of the

composite so use the short one.

The Restoration

1. Amalgam:mercury + metal alloy.

Advantages:

-Low cost.

- Longevity.

- Less sensitive to clinical techniques because it takes less

time.

- More resistant to wear than composite.

Disadvantages:

- Absence of adhesion.

- We need to remove more from tooth structure to create

resistance and retention form because it bonds mechanically

to the tooth structure.-not esthetic.

- The mercury hazard.

2. Composite:

Components: Fillers, matrix, coupling agent and the

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initiator(initiate the reaction between the previous 3

components).

Advantages:- Adhesion to tooth structure, which means less removal of

tooth tissues.

- More conservative because I dont need to create

a retention and resistant form.

-More esthetic.

Disadvantages:

- Polymineralization shrinkage.

- Stress build up because of polymineralization shrinkage.

- Micro leakage and consequences like staining, recurrentcaries and sensitivity.

- Its difficult to make proper contact because of thepolymineralization shrinkage.

- Technique sensitive, very sensitive to the moisture.- More time is needed because you have more steps to

do.- Less resistance to wear.

Microleakage:

The penetration of the oral fluids and bacteria in the

interface between the preparation wall and the

restorative material, This interface should be as smooth

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as close as possible. The influx of these bacteria and

fluids can cause problems including post operative

sensitivity, marginal discoloration or staining, secondary

caries, pulpal inflammation and irritation leading for the

need of RCT.

To prevent the micro-leakage we need proper isolation

and restoration technique as well, if you applying a

composite dont apply it as a bulk we have a layering

technique, margins should be as seal and smooth as possible.How can I improve the margins of the restoration?

As you know when you choose the restorative material you

have certain criteria to choose on:

1- The difference of the coefficient of thermal expansion.

2- Polymineralization shrinkage and how to decrease it.

3- Finishing and polishing, you dont leave rough surfaces and

in the same time you dont over finish or over polish your

works because you might create some cracks and open

margins between the restorative material and the tooth.

4-Orientation of the enamel prisms, especially when youre

doing composite restoration thats one important reason

why we do the bevel.

5-Application methods, as we said when you apply it you

have to maintain good isolation control.

6-Cavity configuration.

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Composite versus Amalgam

This will guide you to which material you are going to apply .

- In the school they focus on composite, teaching thestudents more skills about how to place a good

composite restoration.

- We still dont havea very solid evidence about banningamalgam restoration, The more concern is about the

environmental hazard not about our health.

- Patients concern about esthetic and dentists concernabout being conservative.

Biocompatibilityis defined as the materials ability to

perform a proper biological response when contact with a

body or the body tissues.

The composite is not safe, we have cytotoxicity,

allergenicity and the effect of the UV light on retina.

The amalgam is the fifth source of mercury; the inorganic

one not organic mercury, organic mercury is more hazard

to our body. The source of inorganic mercury is dental

amalgam, electrical switches lamps and batteries as well.

Amalgam is there for more than 150 years but

composite is there for more than 50 years.. this gives

advantage to amalgam.

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The common mode of fracture for composite is the

fracture of the restoration in secondary caries because of the

polymineralization shrinkage. While for amalgam its tooth

fracture and __ syndrome.

Sorry for any mistake, wish you all the best..

Eman Idkaidek