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Composite
 Amalgam and gold were the primary restorative materials for
posterior teeth.
 Some forms of metals were used in anterior teeth.
 Later a variety of direct-placement tooth-colored restorative
materials were introduced.
 In the 1960s composite resins were introduced & have been
continually improved on ever since by making them more durable
& color stable.
Direct-Placement Esthetic Restorative Materials
They can be placed directly into the cavity preparation or onto the tooth
surface by the clinician w/o first being constructed outside of the mouth.
 Esthetic Materials are those that are tooth colored.
 The most commonly are:
• Composite resin.
• Glass ionomer cement.
• Resin-modified GIC.
• Compomer.
Composite Resin
• A composite is a mixture of two or more materials with properties
superior to any one component.
• Are used in both the anterior & posterior parts of the mouth.
Composition
They are composed mainly of an organic resin (polymer) matrix &
inorganic filler particles joined together by a silane coupling agent
that sticks the particles to the matrix.
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1. Organic resin (polymer) matrix
Thick liquids made up of 2 or more organic molecules that
form a matrix around filler particles.
2. Inorganic filler particles
Fine particles of quartz, silica, or glass that give strength &
wear resistance to the material.
3. Silane coupling agent
A chemical that helps bind the particles to
the matrix.
4. Initiators & accelerators that cause the material to set.
5. Pigments that give color matching the tooth.
Polymerization
It is a chemical reaction that occurs when low-molecular-weight
resin molecules (monomers) join together to form long-chain,
high-molecular-weight molecules (polymers).
Classification of composite based on polymerization:
1. Chemical Cure
 Also called Self-cured composite resins, are two-paste systems
(base & catalyst), supplied in jars or syringes.
Disadvantages:
 Limited working time.
 Voids & porosity due to manual mixing.
2. Light Cure
 They are the most common type used.
 An intense visible light in the blue wave range activates these
materials.
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 The depth of the cure depends on the location and the color of
the restoration. The darker shade needs more curing time.
3. Dual Cure
 They are two-paste systems that contain the initiators & activators
of both the light-activated &, to a smaller amount, the chemically
activated materials.
 The curing light initiates the setting reaction. The chemical setting
reaction continues in areas not reached by the light.
Physical Properties of Composite
 Biocompatibility
 Strength
 Wear
 Polymerization Shrinkage
 Thermal Conductivity
 Coefficient of thermal Expansion
 Elastic Modulus
 Water sorption
 Radiopacity
Classification of Composite
Macrofilled Composites
 Relatively large particles as fillers, ranging in size 10-100 µm.
 Difficult to polish, rough surface.
 Stronger than composite w/ smaller particles.
 No longer widely used.
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Microfilled Composites
 Much smaller particles as fillers, average about 0.04 µm.
 Have a larger total surface area than one large particle of
similar weight.
Therefore the volume of filler in microfilled composites is only 35% to
50%.
 This results in poorer physical properties.
Hybrid Composite
 Contain both macrofillers & microfillers in order to
produce a strong composite that polishes well.
 Their filler content is 75% to 80% by weight.
 Microhybrid composites contain a mixture of small particles (0.53.0 µm) & microfine particles (0.04 µm).
 Hybrids are versatile because of their strength & polishability.
 Can be used as both anterior & posterior restorations.
Flowable Composites
 Are low-viscosity, light-cured resins that may be lightly filled 40%
or more heavily filled 70%.
 The particles average in size 0.07-1.0 µm.
 These composites flow readily & can be delivered directly into
cavity preparations by small needles from the syringes in which
they are packaged.
 They adapt well to cavity walls & flow into microscopic
irregularities created by diamonds & burs, because of their low
viscosity.
 They are well suited for use in conservative dentistry (PRR).
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 Many dentists use them in place of conventional pit & fissure
sealants (higher filler content– more wear resistant).
 They are useful as liners in large cavity preparations. Their low
elastic modulus (more flexible) allows them to cushion stresses
created by polymerization shrinkage or heavy occlusal loads when
they are used as an intermediate layer under hybrid & packable
composites.
 They are useful for restoration of class V non-carious lesions as
toothbrush abrasion, acid erosion, or occlusal stresses leading to
abfraction.
 They shrink when polymerized more than the hybrids, wear more
& are weaker.
Pit and Fissure Sealants
 They are low-viscosity resins that vary in their filler content from
no filler to more heavily filled resins (same as flowable
composites).
 Used for prevention.
Packable Composites
 Also called condensable composites.
 They are highly viscous resins that contain a high volume of filler
particles, which gives them a stiff consistency.
 They shrink less when polymerized than less heavily filled
composites, because there is less resin & more filler.
 They are used for restoration of posterior teeth in areas of high
function (stronger & more wear resistant).
 They are marketed as substitutes for amalgams.
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Core Buildup Composites
 They are heavily filled composites used in badly broken-down
teeth needing crowns.
 They replace missing tooth structure lost from dental caries or
tooth fracture so that there is adequate structure to retain a
crown.
 These composites can be light-cured, self-cured, or dual-cured.
 They contain pigments that colorize them so that they can be
easily differentiated from natural tooth structure.
Provisional Restorative Composites
 They are used in place of acrylic resins for the construction of
provisional onlays, crowns, & bridges.
 They are more expensive but they wear less & shrink less, &
release less heat as they cure.
 They can be repaired easily with flowable composites.
 They are more brittle than acrylic & tend to break more easily w/
longer-span bridges.
Clinical Handling of Composites
Uses of composite resins
 They are used in all classes of restorations, from (I through VI).
 Also used for provisional restorations, core-buildups. Fiberreinforced posts, & laboratory –fabricated onlays & bridges.
Selection of Materials
This depends on:
 The position weather anterior or posterior.
 Is it in an area subjected to occlusal stresses or not?
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Shade Guides
 Many manufacturers include a shade guide w/ color tabs.
 The color tab should be moist, held adjacent to the tooth to be
restored, & viewed under different lighting conditions.
 Apply & cure a small quantity of composite selected onto the
clean, moist tooth before isolation if needed.
 It may be necessary to mix a couple of different colors together to
achieve the desired color match or to add special color modifiers.
Shelf Life
 In general, avoiding heat & light can extend the shelf life.
(Refrigerating)
 The average shelf life is 2 to 3 years if stored properly.
Dispensing and Cross-contamination
 Light –cured composites are supplied in compules or syringes.
 All of these containers are opaque so that the material is not
affected by light.
 Single-use (unidose) as compules which are small containers of
composite resin that fit into a delivery gun.
 The delivery tip on syringes of flowable composites should be
disposed of in a sharps container after use, & the syringes should
be recapped & sprayed w/ disinfectant.
 Composite in screw-type syringes should be dispensed after the
shade is selected & covered in a light-protected container until
used.
 Chemical-cured composites come in jars or screw-type tubes.
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Matrix Strips/ Bands
 For class III & IV anterior restorations, a clear plastic (Mylar)
matrix strip is used to contain & shape the composite.
 For class II restorations. Metal matrix bands or precontoured
plastic matrix strips that help shape the contact area are used.
 Metal matrix bands are either circumferential bands or sectional
bands.
 A clear matrix forms for class V cavities are also available.
 Appropriately sized & trimmed clear crown forms are used for
rebuilding large portions of the tooth.
 A wedge may be placed to seal the gingival margin or separate
teeth to make up for the thickness of the matrix band.
 Wedges can be wooden or transparent plastic.
Incremental Placement
 For most moderately sized or large
cavity preparations, the composite
resin should be placed in small
increments about 2mm thick.
 Benefits:
1. It minimizes polymerization shrinkage.
2. It permits light from the curing unit to adequately penetrate &
cure each increment.
Resin-to-Resin Bonding
 Etched enamel & dentin is infiltrated with resin bonding agents to
form the resin-rich hybrid layer.
 The initial increment of composite resin will chemically bond to
the resin bonding agent on the E & D.
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 Each additional increment will bond to the previously placed
increment.
Contaminants
 Newly etched D is kept moist for wet Dentin bonding.
 After Dentin bonding any form of moisture (water, saliva, gingival
fluids or blood) should be kept away from the tooth until the
restoration is completed. (if it is contaminated we have to re-etch
for 10-15 sec)
 Don’t use alcohol to wet the plastic instrument. Instead, use
bonding agent to prevent sticking.
 Liners, bases, or temporary fillings containing eugenol should not
be used because it inhibits the set of resins.
Light-curing
 The light probe should be held as close as possible to the
composite w/o touching it.
 Typical curing times for thin layers are 20 to 40 seconds.
 The light probe & handle are covered w/ a disposable barrier such
as a clear plastic cover.
Finishing and Polishing
 Excess composite can be removed w/ multifluted carbide finishing
burs, fine & ultrafine diamonds, and sandpaper disks.
 Small excesses at the gingival margin or interproximal can be
removed w/ scalpel blade (no. 12), needle-shaped burs or
diamonds, or abrasive strips.
 Polishing can be achieved by using successively finer sandpaper
disks and interproximal polishing strips; by rubber polishing
points, cups, disks impregnated w/ abrasives; & by polishing
pastes.
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Clinical steps:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Shade selection.
Local anesthesia.
Isolation using the rubber dam.
Tooth preparation.
Cleaning the tooth and cavity with pumice.
Dry the cavity lightly.
Apply the suitable matrix band and wedge.
Apply the acid etchant (phosphoric acid 37%) for 15-20 seconds.
Wash thoroughly then dry gently for 2-5 seconds. Don't over dry
the dentin.
10.Apply the primer with the microbrush and dry it with air then
apply 2 layers of the bonding agent, air thin it then light cure it for
10-20 seconds as recommended. Note: some composite kit have
the primer and the bonding agent in one bottle so after etching
we add the bonding agent.
11.Apply the composite with a plastic instrument in increments of
2mm in thickness and light cure each increment separately. The
condenser and burnisher can be used in adapting and forming the
composite.
12.Remove the matrix and start finishing and polishing using the
instruments explained earlier.
13.Check the occlusion with an articulating paper.
References:
 Refer to the practical manual for further explanation and
pictures and different brands of composite.
 Book: Dental Materials by Hatric and others.
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