composite curing methods

8/3/2019 composite Curing Methods

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Curing Methods Of Composite

Prepared By :

Mustafa Samir

Ban Noori


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What is Composite Curing ?

Composite curing means toughening or hardening

of a composite made from several different materials.this is achieved using chemical additives, or with theuse of visible lights.


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Curing Methods Of Composite

1- Self curing

2- Light curing

3- Dual curing


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1- Self curing Composite resin :

It is available as a two- paste system composed of a

Catalyst and a Base material .

One part contains an organic amine accelerator and

the other part includes a peroxide initiator.

Catalyst and Base materials are usually mixed in a ratio

of approximately 1:1 .

Their polymerization processis chemically activated .

It does not need any special

equipments .


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Disadvantages :

1- Air incorporation during mixing result in greater internal

porosity , reduce wear resistance and staining.

2- The working time is restricted by the speed of chemical

reaction .

3- Color stability is less stable because of eventual breakdown

of the polymerization initiating chemical ingredients , tertiary

amines .


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2- Light curing Composite resin :

It is supplied as single paste system.

Polymerization is either by ultraviolet or visible light .

The use of UV Light is replaced with visible light curing

system due to:

( retina and self tissue damages, low curing depth 1.5 mm )

Photo initiator (camphoroquinone) is added to initiate

polymerization

It absorbs visible light of wavelength (400-500)

(blue light) forming free radicals which initiate

polymerization.

Its placed incrementally and each layer is cured for 20

to 30 seconds by holding the light source close to it.


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Advantages :

1- Flexible working time

2- Better wear resistance

3- Reduced porosity

4- Greater curing depth (up to 2 mm)5- More color stable


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Light Cured Units

1- QuartzTungsten- Halogen ( QTH)

It generates light through the heating of tungsten

filaments to high temp.

Its broad emission spectrum allows the polymerizationof all known photo-activated materials.

Its generate high heat energy so filters are used to

reduce the emitted heat energy.

The setting timerequired for QTH is (20 40 sec).

Disadvantages :

Its inexpensive and most widely used.

1- The bulbs, filters and reflectors in the optical system degradewithtime, and so reduce light output.

2- The power densityof the light decreases dramatically withdistance.


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Its principle that, when electricityis passed through xenon gas,

ionization produces a plasma ofcharged particles that emitblue-white light.

2- Plasma Arc (PAC)

Its more expensive.

The light intensity given by plasma-arc unitsis greater than that for halogen-basedunits,which can decrease curing time to (2-6 sec).

Its generate high heat energy so filters areuse to reduce the emitted heat energy.


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3 - Argon Laser

Advantages: greater curing depth ( up to 5 mm)single short exposure time (10 sec)

Disadvantages : large and expensive.chances of pulpal damage due tomore heat

Laser can emit light at specific wavelengths

as a result of

the excitation of atoms of Argongas to specific energylevels.

There is no need for filters to be used.

The photons are coherent and do not diverge

and more concentrated into a tiny area.


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4 Blue LED Curing Lights

The diode is designed to activatecamphorquinone initiator

around 460 nm.

Advantages :

Battery powered Portable ,compact. lightweight Energy-efficient ,long battery life Low emitted heat Durable - diodes last 5.000 hours

Disadvantages :

Narrow spectral range so mostunits only work with CQ initiator.


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3 - Dual Cured Composite resin

Dual cure means chemical initiation isused and combined with photochemicalinitiation so either and both techniquespolymerize composite.

Common photochemical initiator are:CamphoroquinoneAcenaphthene quinoneBenzyl

Photochemical initiator is activated by visible,

blue light to produce slow reactions. Aminesare added to accelerate curing time.


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THANK YOU

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