Good description about recent advances in composites..Enjoy studying..!!

1. DR.VIVEK TADURI
JSS DENTAL COLLEGE AND
HOSPITAL
1

2. 2
•Introduction
•History
•Classification of Composites
•Composition
•Properties of Resin-based Composites
Recent commercial composite formulations
•Recent Monomer systems
•Antibacterial Composites
•Flowable composites
•Packable composites
•Compomers
•Giomers
•Ormocers
• Photoinitiators
•Smart composites
•Self- healing composites
•Fiber Reinforced composites

3. 3
•Bulkfill Composites
•Indirect composites
•Bioactive Formulation
•Miscellaneous
•Conclusion

4.  Esthetic and restorative dentistry aims to replace lost or damaged structures
with artificial materials that possess biological, physical, and functional
properties similar to natural teeth.
 Among these materials, composite resins occupy a paramount position
because they offer excellent esthetic potential and acceptable longevity
without the need for extensive sound structure preparation, allowing
minimally invasive preparation or sometimes no preparation at all.
 Numerous composite systems have been developed in recent years with a
multitude of shades, translucencies, opacities, and effects that, together with
innovative placement techniques, make the fabrication of restorations that
faithfully emulate the polychromatic variations and optical characteristics
present in natural teeth possible.
 This conceptual evolution in materials and techniques gives clinicians the
option to treat a large range of problems faced in everyday practice in a
reliable, predictable, and conservative way.
4

5.  1955: M. Buonocore-acid etch technique.
 1956: Dr. Bowen formulated BIS-GMA resin.
 1962: Silane coupling agents introduced. Macro filled
composites developed.
 1964 : Bis-GMA composites marketed.
 1968 Development of polymeric coatings on fillers (Dental
Fillings Ltd)
 1970: First photo-cured composites using UV light.
 1972:Visible light curing unit introduced.
 1976: Microfilled composites developed
 Early 1980’s –posterior composites introduced
5

6. 6
 Mid 1980’s-Hybrid composites developed
I generation indirect composites
 Early 1990’s-II generation indirect composites
 1996- Flowable composites developed and ceromer
developed
 1997-Packable composites developed
 1998- Ormocers developed
 1999- Single crystal modified composites developed
 2000- Nanofills and Nanohybrids
 2010- self adhering flowables/restoratives

7. I. Based on the mean particle size of the major filler.
Traditional (conventional/macrofilled)composites : 8-12µm.
Small particle composites :1-5µm.
Micro filled composites : 0.04 - 0.4µm.
Hybrid composites : 0.6-1µm.
7

8. 8
Based on Filler Particle size and Distribution
1. Megafilled composites: Very large fillers.
2. Macrofilled composites: 10-100µm.
3. Midifilled composites: 1-10µm.
4. Minifilled composites: 0.1-1µm.
5. Microfilled composites: 0.01-0.1µm.
6. Nanofilled composites: 0.005-0.01µm.

9. 9

10. 10
Based on Method of Polymerization
• Self cured, auto cured or chemically cured composites.
• Light cured composites-
1.Ultraviolet light cured composite.
2.Visible light cured composite.
• Dual cured composites: both self curing & light curing
mechanism.
• Staged curing composites: initial soft-start
polymerization followed by complete polymerization.
• Direct And Indirect

11. Based on Mode of presentation
1. Two paste system.
2. Single paste system.
3. Powder liquid system.
Based on Use
a. Anterior composites.
b. Posterior composites.
c. Core build up composites.
d. Luting composites.
11

12. 12
Resin matrix
Fillers
Coupling agent
Activator-initiator system
Inhibitors
Optical modifiers/coloring agents.

13. 13
Continuous phase to which other ingredients are incorporated.
Composed of monomers which are aromatic or aliphatic diacrylates.
Most resin matrices are made of….
1.BisGMA – Bisphenol A-glycidyl methacrylate.
2.UDMA- urethane dimethacrylate
3.Combination of BisGMA & UDMA.
BIS-GMA and UDMA have reactive carbon double bonds at each end that can
undergo addition polymerization.
A diluent such as TEGDMA – Triethylene glycol dimethacrylate is added to lower
the viscosity & produce a working consistency

14. 14
Improves physical, mechanical & optical properties of resin matrix.
The fillers used include:
1.Amorphous silica (microfiller)
2.Quartz
3.Radiopaque glasses, barium, strontium, others
4.Sol-gel zirconia-silica
5.Fluoride containing fluorosilicates, ytterbium and yttrium trifluoride
1.Lower polymerization shrinkage.
2.Increase compressive, tensile strengths and modulus of elasticity.
3.Increase abrasion resistance.
4.Lower water sorption.
5.Lower coefficient of thermal expansion.
6.Improve translucency.

15. 15

16. 16

17. 17
•Binds the filler particles to the resin matrix and allows the more flexible
resin matrix to transfer stresses to the stiffer filler particles.
•Organic silanes like gamma-methacryloxy propyl trimethoxy silane is
commonly used as coupling agent in composite resins.
•Improves the physical & mechanical properties of the composite resin and
also provides hydrolytic stability along the resin/filler interface.
•Since coupling agents work best with silica particles, therefore all modern
composite resins are based on silica containing fillers.

18. 18
Composite resins polymerize by an addition polymerization
mechanism that is brought about by the release of free radicals.
Free radicals are released by:
1.Chemical activation
2.Light activation: -ultraviolet light
-visible light

19. 19

20. •Added to prevent spontaneous polymerization of the
monomers by inhibiting the free radical.
•Butylated hydroxy toluene 0.01% is added as inhibitor in
light cure composites.
•Hydroxyquinone - self cure
20

21. 21
•Metal oxides added in minute amounts-produces different
shades of composites.
•Opacity- Aluminium oxide & titanium oxide(0.001-0.007%)
•Darker shades & greater opacities have a lesser depth of curing
than lighter shades.

22. 22
•Also called Macrofilled composites.
•Fillers- 8-12µm in size. Ground quartz in a concentration
of 70-80% by weight or 60-65% by volume.
•Only used in stress bearing areas.

23. 23
Advantages :
• All properties are superior to
those of unfilled acrylic resins
Disadvantages :
 Rough surface due to “plucking”
of fillers from the matrix.
 Increased wear.
 Non-polishability.
 Prone to staining & discoloration
due to the rough surface

24. 24
•Improved surface smoothness.
•Average filler size- 1-5µm.
•Heavy metal glasses like lithium, barium, zirconium glasses but
some have quartz fillers.
•Filler content 80% by weight or 65% by volume.
•Colloidal silica added in small amounts to adjust the viscosity
of the paste.

25. ADVANTAGES : DISADVANTAGES :
Physical & mechanical
properties than traditional
& micro-filled composites.
Wear resistance.
compressive strength.
modulus of elasticity
Polymerization
shrinkage,coefficient of
thermal expansion.
 Heavy metal glass fillers are
softer & prone to hydrolysis
so long term durability of
these resins is lowered.
25

26. 26
•Developed to overcome the surface roughness and low translucency of
traditional and small particle composite resins.
•Fillers used are colloidal silica of size 0.04-0.4µm.
•Small particle size, hence agglomerate and form long chains.
•Filler content is 50% by wt. or 30-40% by volume.

27. 27
Advantages :
 Provide the smoothest surface
finish.
Disadvantages:
 Inferior properties due to increased
matrix content.
 Elastic modulus, tensile strength.
 Wear due to poor bond between the
pre-cured composite particles & the
clinically cured matrix.
Examples
•Durafill® VS
•Renamel® Microfill
•Matrixx™ Restoratives Anterior Microfill

28. 28
•Contain two kinds of filler particles - colloidal silica and ground particles of
glasses containing heavy metals
•Content -75 to 80 wt%.
•Average particle size - 0.6 to 1.0 µm
•Colloidal silica represents 10 – 20 wt% of total filler content.
•Surface smoothness and reasonably good strength
•Currently are the predominant direct esthetic restorative material used.
•Have almost universal clinical applicability

29. 29
Examples:
•Filtek™ Z250
•Synergy® D6
•Tetric® Ceram
•Venus®
Advantages
 Superior surface smoothness
close to that of micro-filled
composites.
 Improved radio opacity due
to heavy metal glass fillers.
 Reasonably good strength.
Disadvantages
 Mechanical properties are
inferior to those of small
particle composites.

30. 30
•Nanofilled composites were recently introduced and they consist of nanomers
(5 nm to 75 nm particles) and “nanocluster” agglomerates as the fillers.
•Nanoclusters are agglomerates (0.6 µm to 1.4 µm) of primary zirconia/silica
nanoparticles (5 nm to 20 nm in size) fused together at points of contact, and
the resulting porous structure is infiltrated with silane.
•The nanofilled composites present similar mechanical and physical properties
to those of microhybrid composites, but when it comes to polish and gloss
retention they perform significantly better.

31. 31
The main example of nanofilled composites is Filtek™ Supreme Plus.
However, several manufacturers are now incorporating nano-sized
particles into their formulations, resulting in the creation of yet
another category, the “nanohybrid” composites. Some examples are:
Premise (Kerr Dental), Aelite Aesthetic Enamel (Bisco, Inc), Clearfil
Majesty™ Esthetic (Kuraray America, Inc), and Artiste

32. 32

33. 33

34. 34
•The DC is a measure of the percentage of carbon-carbon double bonds that have been
converted to single bonds to form a polymeric resin.
•It depends on : Resin Composition,Trnasmission of light,
Concentrations of initiator,sensitizer and inhibitor

35. 35
•The strength of composite depends on the ability of the coupling agent to
transfer stresses.
•As the crack propogates to a bonded filler, the crack must pass around the
particle since it is stonger than the matrix and the interfacial bond

36. 36
•Water is absorbed preferentially into the resin component and the water
content is therefore increased when resin content is increased.
•If the stress is greater than the bond strength, the resulting debond is referred
to as HYDROLYTIC BREAKDOWN.
•Beneficial- Due to closing of the marginal gap caused by shrinkage
•But, this swelling is usually not enough to overcome the shrinkage.
•ONLY CLOSE ADAPTATION, WITHOUT ADHESION

37. 37
It arises as the monomer is converted to polymer and the free space it occupies reduces.
In turn it produces unrelieved stress in the resin. 2.9-7.1 Vol %...Contaction stresses 7Mpa
It is affected by:

38. 38

39. 39
•Many of the current light-curing composite restorative techniques are
rationalized in compliance with the theory that composite shrinks toward
the light
•In a study, a finite element technique is used to analyze the direction of
composite shrinkage as it cures.
•The analysis showed that the shrinkage direction was not significantly
affected by the orientation of the incoming curing light, but instead was
mostly determined by the bonding of the restoration to the tooth and by the
free surfaces.
•It was concluded that composite does not shrink toward the light, but that
the direction is predominantly determined by cavity shape and bond
quality.

40. 40

41. 41
•The final Stiffness or rigidity of a resin Composite may play a
compensating role in coping with polymerization stress.
•Viscous Adhesive---Thick resin layer
Stretching of this layer provide sufficient elasticity
to relieve stress of resin composite.
• Bonding layer thickness of 125um

42. 42

43. 43

44. 44

45. 45
•Microfracture theory
•Hydrolysis theory
•Chemical degradation theory
•Protection theory

46. 46

47. 47
- The monomer spiroorthocarbonate for use with dimethacrylate resins
• Expanding monomer
• Mixed them with epoxy (oxirane) resins capable of cationic polymerization.
• Suggested that the overall cure of the mixture with an SOC is less than that
of dimethacrylate systems and that this may explain some of reduction in
shrinkage and contraction stress.

48. 48

49. 49

50. 50
Due to high frequency of recurrent caries after restorative treatment much
attention has been paid to the therapeutic effects revealed by composite resins.
Attempts to provide composites with antibacterial activity have been
conducted in two ways.
Alterations to the resin components
Alterations to the filler components

51. 51
Fluoride releasing
Resin matrix-
Methacryl flouride and
Acryl amine (Lewis salt)
Fillers-
fluoroaluminosilicate
and Yttrium triflouride
Quaternary
ammonium salts
(QAS)
MDPB
DMAE-CB
DMAEMA
DDMAI
most recent: DMADDM
Nanoparticles of
silver
Furanonone
derivatives
Polymeric
Phosphonium salt
Ag-ZnO
whiskers
ZnO
nanoparticles
Silver based
agents
Added to Resin matrix Added to fillers

52. 52

53. 53
Polymeric rigid inorganic matrix material this system also consists of a resin and
a ceramic component.
Rather than ground filler, however, the inorganic phase consists of a
continuous network or scaffold of ceramic fibers.
Composed of alumina and silicon dioxide, the individual fibers are
superficially fused together at selected sites, which generate a continuous
network of small chambers or cavities

54. 54
•After silinating, the manufacturer infiltrates the spaces within the fibrous
network with an optimized BIS-GMA or UDMA resin.
• If the ceramic fiber component is maximized, most of the resin will be
located inside the scaffolding matrix. Only the interfacial regions between
the individual domains and the walls of the preparation contain BIS-GMA
resin component.
• Because of this, the curing shrinkage of the polymeric rigid inorganic
matrix material (PRIMM) can be reduced substantially.

55. 55
The term "flowable" was applied in 1996 to a reduced viscosity hybrid
composite that could be delivered with disposable syringe tips. (Behle C 1998)
 Created by retaining the same small particle sizes of micro fill, hybrid and
micro hybrid universal composites and by reducing the filler content the
viscosity of the mixture was reduced.
This material flows readily, spreads uniformly and intimately adapts.
Indicated:
Base or Liner in Class II(difficult access)
Used like a Fissure sealant

56. 56
Paste consistency of composites dictates a careful wedging of matrix band
in posterior teeth in order to obtain acceptable contour.
Packables incorporate elongated,fibrous fillers 100µm long & textured
surfaces that interlock & resist flow.
Advantages:
•Material is resistant to slumping but is mouldable
•Decreased Shrinkage
•Improved wear resistance

57. 57
•Introduced in 1994.
•An acronym of the words compo site and glass ionomer.
•Formerly classified as polyacid-modified resins.
•Some authors classify compomers light-cured, low fluoride
releasing composite resins.
• Primarily composite resin-like materials that contain one or
more basic GIC components.
•Composed of an ion-leachable glass embedded in a polymeric
matrix.

58. 58
 Containing monomers with acidic functional groups that
can participate in an acid/base glass ionomer reaction
following polymerization of the resin molecule.
 Lower wear resistance
 Less strength, and
 Poorer esthetics than composites.

59. 59
 A single component system
 Doesn’t contain any water thus a premature GI reaction is
prevented.
 Contain partially silanized glass particles which provide a
direct bond to the resin matrix
 The matrix is formed by a light activated, radical
polymerisation reaction.

60. 60
•Hybrids of glass ionomers and composites
• Contain pre-reacted glass-ionomer (PRG) particles-
fluoroaluminosilicate glass reacted with polyalkenoic acid
•Incorporated into silica filled urethane resin.
•Light activated ,require a bonding agent.
•Advantages:
•Fluoride release
•Fluoride recharge
•Excellent esthetics
•Easy polishability
•Biocompatibility
•Clinical Stability.

61. 61

62. 62
Acronym –Organically Mo dified Ce ramic technology.
Organically modified nonmetallic inorganic composite material.
Introduced by Fraunhofer Institute for Silicate Research.
Inorganic-organic co-polymers with inorganic silanated fillers.
Described as 3-dimensionally cross-linked copolymers with
multi-polymerization with no residual unreacted monomer & is
more biocompatible

63. 63

64. Manufactured by a Sol-Gel Process from Multifunctional Urethane
and thioether(meth)acrylate alkoxy silanes.
High molecular weight,flexible,low viscosity, cross linkable
molecules(Oligomers) result.
ADVANTAGES
Cattani-Lorente et al –shrinkage of ormocer equals that of
Hybrid composite despite lower filler content.
Has thermal coefficient of expansion similar to tooth.
Low shrinkage(1.88%),High abrasion resisitance,
Biocompatibility, Excellent Esthetics.
64

65. •The term ceromer stands for Ceramic Optimized Polymer and was
introduced by Ivoclar to describe their composite Tetric Ceram.
•Contains barium glass (< 1 µm), spheroidal mixed oxide, ytterbium
trifluoride, and silicon dioxide (57 vol%) in dimethacrylate monomers (Bis-
GMA and urethane dimethacrylate.
• Setting is by a polymerization of C=C of the methacrylate.
.
•The properties of the ceromers are identical to those of composites and they
exhibit fluoride release lower than conventional glass-ionomers or
compomers.
65

66. 66
.
Most investigations concerning dental resins have utilized
camphorquinone (CQ) as a photo sensitizer in combination with variety of
reducing agents.
However, CQ is inherently yellow, which causes problem in color
matching.

67. 67

68. 68

69. 69
Dental composites essentially consist of an organic resin matrix
loaded with finely dispersed glass or silica filler that is bonded to the
matrix polymer through a silane coupling agent.
Effective coupling between resin matrix and filler has been reported
a) to slow degradation process
b) to protect the filler surface against fracture
c) to improve stress distribution and transmission from flexible resin
matrix to stiffer and stronger inorganic filler particles
- presilanization decontamination of silica filler improves silanization
efficacy

70. • Ariston pHC in 1998.
•Ariston is an ion releasing composite material, which releases fluoride,
hydroxyl and calcium ions as the pH drops in the areas immediately
adjacent to the restorative material. This is said to neutralize the acid and
counteract the decalcification of enamel / dentin.
•The paste consists of Barium, Aluminium and Fluoride silicate glass filler
(1 m) with Ytterbium trifluoride, silicon dioxide and alkaline calcium
silicate glass in dimethacrylate monomers.
•Fluoride release from this material is claimed by the manufacturer to be
lower than glass ionomers but more than that of compomers.
70

71. 71
•Impact damage to composite structures can result in drastic
reduction in mechanical properties.
•Bio-inspired approach is adopted to effect self healing which
can be described as mechanical, thermal or chemically induced
damage that is autonomically repaired by materials already
contained within the structure.
• Resin matrix- GRUBB’s catalyst
• Dicyclopentadiene (DCPD) in
microcapsules

72. 72
•Major components: resin matrix and fibers
•Fibers- Ceramic
Glass
Carbon
Alumina
Silicon nitride
- Polymer
KEVLAR (unidirectional)
HDLPE
•Due to translucent appearance of these materials no masking materials
are needed, which allows a thin layer(0.5mm) of composite to be
placed , which is esthetic .

73. Triaxial Woven Spectra Fibers
Ultra-high Molecular Weight Polyethylene
(Spectra)
RIBBOND
EVER STIK
73

74. 74

75. 75
 The incremental layering technique is accepted as a golden standard for the
placement of resin-based composite (RBC) restorations. When restoring cavities,
conventional light-curing resin composites should be placed in increments of a
thickness generally not exceeding 2 mm. Consequently, when restoring deep
cavities, such a procedure is rather time-consuming.(1)
 However, the latest developments in composite technology are materials
intended for posterior bulk-filling placement, the so-called bulk-fill RBC. The
materials can be applied in increments up to 4 mm thickness.

76. 76
The bulk-fill resin composites are curable up to 4 mm thickness, thus
skipping the time-consuming layering process.
Improved self-leveling ability, decreased polymerization shrinkage stress,
reduced cusp deflection in standardized class II cavities, and good bond
strengths regardless of the filling technique and the cavity configuration are
reported

77. 77

78. 78
Filtek Bulk Fill Posterior Restorative contains two novel methacrylate monomers
that, in combination, act to lower polymerization stress.

79. 79

80. 80

81. 81
•Considerable tooth structure has been lost
•Direct composite is not possible, indirect composite may be
an excellent choice.
• Resin-bonded inlays, Onlays, Veneers and Crowns.
Some examples are:
•SR Isosit
•Belleglass HP
•Art glass
•Targis

82. 82
Based on conventional resin composite monomers: Urethane and aliphatic
dimethacrylates.
It has 78wt % content of barium glass with a mean particle of 0.6 m .
Belleglass HP is cured under pressure (approximately 5 bar) at an elevated
temperature (140°C) in the presence of nitrogen.

83. 83
•Elevated temperature is used to obtain an increased degree of conversion.
•Nitrogen is applied to exclude oxygen inhibition of the polymerization
process and results in a higher degree of conversion of resin matrix.
•Furthermore, less entrapped air is thought to improve the translucency of
the restorative material.

84. 84
• Also called ceromer (ceramic optimized polymer)
• Contains approximately 77wt% of filler and 23wt% of organic resin.
• Filler part is trimodal consisting of barium glass with mean particle size
of 1 m, spheroid silica filler (0.25 m) and colloidal silica (0.015 –0.050
m).
• Superior properties of Targis are claimed to result from an “Optimized
chemical composition” and an “Optimized curing process”.
• The curing takes place in a Targis power light curing unit at
approximately 97°C for 25 minutes.

85. 85
oCalcium phosphate has been used as a filler to make composites that serve as
bioactive liners and bases to enhance remineralization.
oSome authors have described bioactive polymeric composites based on
amorphous calcium phosphate (ACP) that strengthened by hybridization of the
fillers with glass forming elements.
oBIS-GMA, TEGDMA, HEMA resins containing zirconyl methacrylate as a
dispersing agent for the ACP to which glass forming elements, such as zirconyl
chloride and tetraethoxysilane, were added during synthesis to improve filler
strength.
oThough these materials show improved properties and maintain remineralizing
potential, they are not strong enough to be used as restorative materials without
further modification

86. 86

87. 87
•Novel filler technology, using 3 different
fillers--prepolymerized filler, patented
Point 4 filler, and 0.02 micron filler.
• Excellent polishability, durability, and
strength,

88. 88

89. 89
Fantasista's 4-part filler system combines the best properties of
•TMPT reactive organic filler that polishes magnificently and maintains the finish long
after other composite resins have begun to dull
•The best balanced combination of a nanofiller and a microfiller for strength, wear-
resistance and easy handling
•A proprietary strontium filler for shade and translucency control
This distinctive technology creates a unique restorative material with extraordinary
handling properties, cosmetics and long-term performance

90. 90
Based on Polyhedral Oligomeric Silsesquioxane(POSS)
These are 12-sided silicate cages produced from silane and
functionalized to copolymerize with other monomers
•Highly Polishable
•Excellent Polish retention
•Wear Resistance

91. 91
•Fusio™ Liquid Dentin is a 4-META (4-methacryloxyethyltrimellitic acid)
based flowable composite featuring nano-sized amorphous silica and glass
fillers.
• Fusio Liquid Dentin’s unique formula is both acidic (low pH value) and
hydrophilic. Upon contact with the tooth surface, the negatively charged
carboxylic acid groups of the methacrylate monomers bond to the mineral
ions in the tooth structure.
•As the carboxylic acid groups are neutralized and the monomers
polymerized they become incorporated into the dentin surface enhancing
both dentin bonding and sealing ability.

92. 92
ESTELITE® SIGMA is a light-cured submicron filled resin composite
containing 82 wt% , 71 vol% of filler.
Every inorganic filler contained in Estelite® Sigma is a spherical submicron
filler
Size range: 0.1 um-0.3um that enables excellent polishability, gloss
retention, wear resistance and a wide range of the "chameleon effect".
Together with its outstanding mechanical strength, it offers superior
esthetics as well as the strength required for
posterior restorations. Estelite® Sigma provides
an ideal sculpting feature with a non-sticky
consistency.
There are 18 different shades available.

93. 93

94. 94

95. 95
Like the tooth, G-aenial contains different interfaces with different optical
properties, resulting in varied reflection of light.
The excellent scattering ability of G-anial is related to the extremely
diverse structural composition, which results in it mimicking the reflectivity of a
natural tooth
The ability of a composite to scatter light and diffusely reflect it similarly to the
natural tooth make it possible to achieve a perfect match with the surrounding
tooth structure. A composite material becomes invisible only when it has this
scattering property

96. 96
ESTELITE® SIGMA QUICK utilizes Tokuyama's patented innovative
initiator system "Radical Amplified Photopolymerization Technology"
(RAP), to offer reduced curing time and excellent stability to ambient
light while maintaining the superior esthetic and physical properties

97. 97

98. 98

99. 99

100. 10
0

101. 10
1

102. 10
2

103. 10
3

104. COUPLING AGENT FILLERS RESIN MATRIXINITIATORS
CQ+TPO
CQ+BAPO
CQ+TPO+BAPO
CQ/4E
MISCELLANEOUS
TECHNIQUES
Polycarbonate DMA
DX-511
DDCDMA
TCDDMA
Quartz
Ceramic fillers
Ytterbium fluoride
Lucirin
BAPO
Ivocerin
Nanofillers
Zirconates
10
4

105. 10
5
Vastly improved bonding system and enhanced formulations of resin
composites has resulted in their increased durability and reliability in a wide
spectrum of restorative procedures.
Subtle modifications in comonomer formulation of commercial materials have
produced composites with enhanced handling properties and colour stability.
Major emphasis for research on new reins for composites has been in the area
of reduced polymerization shrinkage and shrinkage stress..
The future use of polymers in dentistry will undoubtedly expand, by the
investigations of dental manufacturers and researchers

106. 10
6