DLA 1201, exam 4

1. Composites and
Compomers Intro
CHAPTER 6

2. What is a Composite?
 https://youtu.be/fmzbmf03HDs

3. Direct-Placement Esthetic Restorative Materials
Direct-placement materials are those that can be
placed directly into the cavity preparation or onto the
tooth surface by the clinician without first being
constructed outside of the mouth.
Common materials
Composite resin
Glass ionomer cement
Resin-modified glass ionomer cement
Hybrid ionomer
Compomer
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4. Composite Resin
 A composite is a mixture of two or more materials with properties
superior to any single component.
They can be used in both anterior and posterior teeth.
Tooth-colored restorative materials
 Composition
 Mainly organic resin matrix
 Inorganic filler particles
 Silane coupling agent
 Initiators and accelerators
 Pigments

5. Composite Resin
 The organic resin matrix and inorganic fillers are joined
together by a silane coupling agent that sticks (adheres) the
particles to the matrix.
 The amount of filler and size and shape of the filler affect the
viscosity of the composite.
 The fillers are composed of glass, quartz, silica, and ceramic.
 The initiators and accelerators cause the material to set.
 Pigments give the material color.

6. Resin Components
Resin matrix
The most commonly used resin for the matrix of
composites is bis-GMA (bisphenol-A-glycidyl
dimethacrylate).
Another resin that is used for the composite matrix is
urethane dimethacrylate (UDMA).
These resins are thick liquids made up of two or more types of
organic molecules called oligomers.
To reduce viscosity and allow the loading of filler particles, a
low molecular weight monomer is added.
TEGDMA (triethylene glycol dimethacrylate)
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7. Resin Components
 Filler particles
Added to the organic resins to make them stronger.
Also added to control handling characteristics.
Help to reduce shrinkage.
Made up of inorganic particles, such as quartz, silica, and glass.
The higher the filler content, the stronger the material will be.
One important factor to keep in mind when choosing a composite
resin material is the size of the filler particles.
The smaller the particles, the smoother the surface of the composite
will be after finishing and polishing and the longer it will be able to
retain its luster.

8. Fillers
 Fillers may be modified with ions to improve their characteristics.
 To make the composite resin restoration show up (appear
radiopaque) on radiographs, heavy metal ions of barium, boron, zinc,
zirconium, or ytterbium may be added to the filler particles.
 Nanosized filler particles are synthesized from zirconia (a ceramic
material) and silica.
 Glass fillers are the least inert of the fillers
 They are leached slowly from the composite by dietary acids and by
application of acidulated phosphate fluoride in the dental office.

9. Particle Size
 Composites are defined by the size of the filler particles they contain
 The amount of filler in the resin and the amount of resin between the
particles are related to how the material wears.
 Large particles
 Large filler particles tend to get plucked from the resin matrix at the surface when the
restoration is under function.
 Larger particles cause the finished restoration to appear dull or rough.
 Small particles
 Smaller particles are not as easily pulled from the resin and therefore cause fewer voids that
contribute to wear.
 Smaller particles are packed more closely together, thereby exposing less of the resin
matrix to wear.
 The smaller the particles, the smoother is the surface.
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10. Resin Components
 Coupling agent
Provides a stronger bond between the organic fillers and the
resin matrix.
This coupling agent is silane, which reacts with the surface of
the inorganic filler and with the organic matrix to allow the two
to adhere to each other.
Good adhesion of the two is necessary to minimize loss of filler
particles and to reduce wear

11. Resin Components
 Pigments
 Inorganic pigments are added in varying amounts to develop a variety of
colors that approximate the basic colors of teeth.
 Pigmented resins can be used to cover discolorations, dark dentin, or
hide the greying effect of a metal post in a root canal–treated tooth.
 Colored resins come in a variety of colors including blue, white,
orange/yellow, pink, light and dark brown, ochre, and clear.
 To get an accurate color match, a shade guide is used.

12. Polymerization
 Polymerization is the chemical reaction that occurs when low
molecular weight resin molecules called monomers join
together to form long-chain, high molecular weight
molecules called polymers.
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13. Polymerization
Chemicals that cause the polymerization reaction
to begin are initiators and activators.
Chemical-cured: Chemically activated
Light-cured: Light activated
Dual-cured: Combination of chemically and light
activated

14. Modes of Cure
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Chemical cure
Chemically cured composite resins, or self-cured composites, are two-paste
systems supplied in screw-type syringes or cartridges.
One paste is called the base; the other is called the catalyst.
Equal parts of these two pastes are mixed together.
With this type of system, the operator has a limited amount of working time
before the material starts to set.
When the materials are mixed together, it is important that they be
spatulated to a homogenous mixture to allow a thorough cure.
If air is introduced during the mixing process, this may cause voids in the
restoration.

15. Modes of Cure
Light cure
Light-cured composite materials are the most common
type of composite used in dentistry.
The operator has ample working time to manipulate the
material to its desired form.
The material is set with the use of a curing light in the
blue wavelength.
Care must be taken with the operatory light so that it
does not begin to set the material prematurely.

16. Modes of Cure
Dual cure
Dual-cured composite resins utilize both visible
light and chemical reactions to cure the material.
These resins are available in a two-paste system or
may be dispensed from a syringe.
The initial set is made by the curing light, and the
chemical reaction finishes the process.

17. Light Cure Tips
 https://youtu.be/ghbhO09nWuo

18. Classification of Composites
by Filler Size
 Composite resins have steadily improved in quality over
the years.
 Filler particle size has decreased, the number of filler
particles has increased, and polymerization shrinkage
has decreased.
 Macrofilled composites
 Microfilled composites
 Hybrid composites
 Microhybrids
 Nanohybrids
 Universal composites
 Nanocomposites
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19. Macrofilled composites
The first generation of composite resin material.
They are conventional composites containing the
largest of the filler particles.
Macrofilled composites provide greater strength but
have a duller, rougher surface, and they absorb
stains more easily.

20. Microfilled Composites
Microfilled composites were developed to overcome
the problems that arose with the larger particle size.
They contain much smaller particles, which makes
them weaker; however, they polish to a glossy finish
and do not absorb stain as easily.

21. Hybrid Composites
 Hybrid composites contain both large fillers and microfine fillers.
 They can be easily polished, have greater strength than the
microfilled composites, and have a high wear resistance.
 Microhybrids use even smaller particles and contain a combination of
small particles and microfine particles.
 Nanohybrids are microhybrids with nanosized particles added.
 The ability to add increased numbers of filler particles reduces the amount
of resin, and they shrink less when polymerized.
 The hybrid composites are called universal composites because they are
esthetic, wear resistant, and strong.
 They can be used in both the anterior and posterior parts of the mouth.

22. Nanocomposites
 Nanocomposites have filler particles
that are about a thousand times
smaller than conventional fillers.
 They have excellent polishability, wear
resistance, and maintain their luster
long-term.