4. • In composite resin, the addition of filler
• Reduces the coefficient of thermal expansion
Reduces polymerizaton shrinkage
Increases abrasion resistance
Decreases water sorption
Increases tensile and compressive strengths
Increases fracture toughness
Increases flexure modulus
Provides radiopacity
Improves handling properties
Increases translucency
4
5. Coupling Agents
• Interfacial bonding between the matrix phase
and the filler phase is provided by coating the
filler particles with silane coupling agents
• a coupling agent is used to bond the filler to
the organic resin
5
6. • Functions of coupling agents
Bonding of filler and resin matrix
Transfer forces from flexible resin matrix to stiffer filler particles
Prevent penetration of water along filler resin interface, thus
provide hydrolytic stability
Examples: Organic silane.
r–methacryloxypropyltrimethoxysilane
10–methacryloxydecyltrimethoxysilane.
6
7. Coloring Agents
• Coloring agents are used in very small
percentage to produce different shades of
composites.
• Mostly metal oxides such as titanium oxide
and aluminum oxides are added to improve
the opacity of composite resins.
7
8. Ultraviolet Absorbers
• They are added to prevent discoloration, in
other words they act like a “sunscreen” to
composites.
• Commonly used UV absorber is
benzophenone.
8
9. Initiator Agents
• These agents activate the polymerization of
composites.
• Most common photoinitiator used is
camphoroquinone.
• Currently most recent composites are polymerized by
exposure to visible light in the range of 410 to 500 nm.
• Initiator varies with type of composites whether it is
light cured or chemically cured.
9
10. Inhibitors
• These agents inhibit the free radical generated
by spontaneous polymerization of the
monomers.
• For example, Butylated hydroxyl toluene
(0.01%).
10
11. CLASSIFICATION OF COMPOSITES
• According to Skinner:
– Traditional or conventional composite—8-12 µm
– Small particle filled composites—1-5 µm
– Microfilled composites—0.4-0.9 µm
– Hybrid composites—0.6-1 µm
11
12. • Philips and Lutz classification according to filler
particle size:
– Macrofiller composites (particles from 0.1-100 µ)
– Microfiller composites (0.04 µ particles)
– Hybrid composites (fillers of different sizes).
12
13. • Classification according to Bayne and
Heyman
Category Particle size
– Megafill 1-2 mm
– Macrofill 10-100 µm
– Midifill 1-10 µm
– Minifill 0.1-1 µm
– Microfill 0.01-0.1 µm
– Nanofill 0.005-0.01 µm
13
16. TYPES OF COMPOSITE RESINS
• Composite resin can be divided into three
types based on the size, amount and
composition of the inorganic filler
1. Macrofilled composite resins
2. Microfilled resins
3. Hybrid composite resins.
16
17. Macrofilled Composite Resins
• Average particle size of macrofill composite resins is from 5 to
25 micron.
• Filler content is approximately 75 to 80 percent by weight.
17
18. Microfilled Composites Resins
• Average particle size of microfilled resins ranges from 0.04 to
0.1 micrometer.
• Filler content of microfilled resins is 35 to 50 percent by
weight
18
19. Hybrid Composite Resins
• Hybrid composites are composed of glasses of
different compositions and sizes, with particle size
diameter of less than 2 µm and containing 0.04 µm
sized fumed silica.
• Filler content in these composites is 75 to 80 percent
by volume
19
21. Nanofill and nanohybrid composites
• Nanofill and nanohybrid composites have average particle size
less than that of microfilled composites.
• The introduction of these extremely small fillers and their
proper arrangement within the matrix results in physical
properties equivalent to the original hybrid composite resins.
21
23. Microhybrid composites
• Microhybrid composites have evolved from traditional hybrid composites.
• Filler content in microhybrids are 56 to 66 percent by volume.
• The average particle size in these composites range from 0.4 to 0.8 µm.
• Incorporation of smaller particles make them better to polish and handle
than their hybrid counterparts. Because of presence of large filler content,
microhybrid composites have improved physical properties and wear
resistance than microfilled composites.
23
26. Flowable Composite Resin
• Filler content in flowable resins is 60 percent by weight
• particle size ranging from 0.02 to 0.05 µm
• incorporation of lower filler content results in poor
mechanical properties of these composites than conventional
composites.
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28. Indications
• Preventive resin restorations
• Small pit and fissure sealants
• Small, angular Class V lesions
• For repairing ditched amalgam margins
• Repair of small porcelain fractures
• Inner layer for Class II posterior composite resin placement for sealing the
gingival margin
• Resurfacing of worn composite or glass ionomer
cement restorations
• For repair of enamel defects
• For repair of crown margins
• Repair of composite resin margins
• For luting porcelain and composite resin veneers
• Class I restorations
• Small Class III restorations
• As base or liner
• Tunnel restorations.
28
29. Condensable (Packable) Composites
• to improve the compressive, tensile and edge strength
and handling of the composite.
• Filler content in packable composites ranges from 48 to
65 percent by volume.
• Average particle size ranges from 0.7 to 20 µm.
• Packable composites posses improved mechanical
properties because of presence of ceramic fibers
(alumina and silicon dioxide)
29
30. Indications
• Indicated for stress-bearing areas
• In class II restorations as they allow easier
establishment of physiological contact points.
30
32. Giomers
• Giomer is hybrid of words “glass ionomers” and “composite”.
These are relatively new type of restorative materials. they
are also known as PRG composites
(Prereacted glass ionomer composites).
• Giomers have properties of both glass ionomers (Fluoride
release, fluoride recharge) and resin composite (excellent
esthetics, easy polishability, biocompatibility)
32
37. PROPERTIES OF COMPOSITE
RESTORATIVE MATERIALS
• Coefficient of Thermal Expansion
• Coefficient of thermal expansion of composites is
approximately three times higher than normal tooth
structure
• result in loosening of the restoration
• This can be reduced by adding more filler content
37
38. Water Absorption
• Composites have tendency to absorb water which
can lead to the swelling of resin matrix, filler
debonding and thus restoration failure.
• Composites with higher filler content exhibit lower
water absorption and therefore better properties,
than composites with lower filler content.
38
39. Wear Resistance
• Composites are prone to wear under masticatory
forces or use of tooth-brushing and abrasive food.
• Wear resistance is a property of filler particles
depending on their size and quantity.
• The site of restorations in dental arch and occlusal
contact relationship, size, shape and content of
filler particles affect the wear resistance of the
composites.
39
40. Polymerization Shrinkage
• Composite materials shrink while curing which
can result in formation of a gap between resin
based composite and the preparation wall.
• It accounts for 1.67 to 5.68 percent of the
total volume.
40
43. Working and Setting Times
Light Cure Composites
• In case of light cure composites, application of
light source to the composite material starts
the polymerization.Usually, 70 percent of
polymerization takes place during the first 10
minutes, though the polymerization reaction
continues for period of 24 hours.
43
44. Mixing for Self-cure Composites
• Self-cure composites comes in two syringes.
• One syringe contains the peroxide initiator or catalyst
• other syringe contains the amine accelerator.
• they are dispensed in equal amounts and then thoroughly mixedfor
20 to 30 seconds.
• For mixing, plastic or wooden spatulas are preferred.
• Use of metal spatula is avoided because inorganic filler particles are
abrasive, they can abrade small amount of metal and thus discolor
the composite.
• the working time for self-cure composite resins is 1 to 1½
minutes.
• Once the mix starts hardening, it should not be disturbed for 4 to 5
minutes (setting time).
44
45. Curing Time
• Curing time depends on different factors like
shade of the composite,
intensity of the light used,
temperature,
Depth of the preparation,
thickness of the resin,
curing through tooth structure, composite filling.
45
46. Shade of Composite
• darker composite shades polymerize
slower when compared to lighter shades.
46
47. Distance and Angle between Light
Source and Resin
• the recommended distance between light source and
resin is 1 mm.
• Intensity of light decreases as the distance is increased.
• If the cavity is deep, then use high power density
lamp (about 600 mW/cm2) so that deeper layer is also
cured
• The angle of source should be at 90° to the resin. If angle
diverges from 90°, intensity of light decreases
47
48. Temperature
• Composite curing would be less if it is taken
out immediately from refrigerator.
• Composite should be atleast kept at room
temperature 1 hour before use
48
49. Resin Thickness
• Resin thickness is also one of the main factors
for its curing.
• It should be ideally 0.5 to 1.0 mm for optimum
polymerization of resin.
49
50. Intensity of Curing Light
• Intensity of curing light usually decreases as
the lamp ages.
• Decrease in intensity of light affect the
properties of composites significantly
50
