1. Resin - Matrix Composites

2. filler - glass,
quartz, or
resin particles
matrix - a diacrylate
copolymer
coupling agent - coating on glass or quartz particles

3. glass, quartz or polymer needed for glass or quartz fillers
Resin Composites
matrix
filler
coupling agent
mostly polymer
glass, quartz or polymer
needed for glass or quartz fillers

4. Small monomer: Shrinkage Large monomer: Shrinkage
When oligomer molecules are relatively small, a greater number of molecules, and consequently, a greater number of new covalent bonds are needed to form a given length of polymer. As each new bond forms, the ensemble of molecules shrinks a tiny bit. Reducing the number of molecules needed to make a given length of molecule, thereby reduces the net shrinkage.

5. BIS-GMA oligomer Resin-matrix composites - matrix oligomers
Polymer chains can grow from each of the diacrylate groups. When this occurs the chains are cross linked by the chain in the middle of the molecule. C H 3 O
methacrylate
group
BIS-GMA oligomer

6. Resin-matrix composites - matrix oligomersH H C H H H C H C 3 3 C O N C C C O C N O O C C H C H H C O H O 3 H C 3 O O 3
methacrylate
urethane
urethane
methacrylate
group
group
urethane dimethacrylate oligomer

7. Oligomer / Monomer
MMA
TEGMA
BIS-GMA
UDMA
Shrinkage (Vol. %)
20.6
13.8
4.4

8. Resin Composite
Aelitefil (Bisco)
Herculite (Kerr)
Pertac II (Espe)
TPH Spectrum (Caulk)
Z100 (3M)
Shrinkage (Vol. %)
3.7
3.5
2.7

9. Coupling Agent

10. - methacryloxypropyltrimethoxy silane
methacrylate
group H C H 3 C C C O C H 3 O H H O H C C C S i O C H 3 H H H O
silane C H 3
- methacryloxypropyltrimethoxy silane

11. C H 3 O S i
H2O

12. C H 3 O S i
CH3 OH
silanol group

13. O H O S i H O H S i O O S i O H O S i C H O S i Glass or Quartz Filler3 O S i O H O S i H O H S i O
Glass or
Quartz
Filler
Particle
water is
byproduct O S i O H O S i

14. O H O S i H O H S i O O S i O S i C H O S i Can copolymerize
with resin composite
siloxane
primary
bond O H C H 3 O S i O S i H O H S i O
Glass or
Quartz
Filler
Particle O S i O S i

15. Resin composites – curing:
chemically cured
light cured

16. Two-paste Resin Composites
base paste
catalyst paste
base
catalyst
oligomer
diluent
filler
activator
initiator

17. Typical Two-paste Resin Composite
Base Paste
(wt. %)
Catalyst Paste
Bis-GMA 16
Diluent (e.g., TEGDMA) 6 5
Filler – glass, quartz 76
Activator – tertiary amine 1 -
Initiator – BPO
0.5
Pigments & hydroquinone
Trace
UV absorber
Estimates based on Ruyter & Sjovik: Acta Odontol Scand 1981:39;

18. Single paste resin composites:
oligomer
diluent
filler
initiator system

19. Resin composite direct restorative materials:
Single-dose capsule
in syringe
Squeezing resin composite
from capsule

20. Resin composite direct restorative materials:
Curing light
Cure

21. H C C H C H O O Addition polymerization - initiator camphoroquinone 3

22. Light-cured composites chemistry:
Visible light excites the ketone (CQ) - this alone could initiate polymerization
Excited CQ can extract electrons from adjacent reducing agents (tertiary amine)
Result is three free radicals: one from the CQ and two from the amine

23. Advantages of light-cured composites:
Better surface cure
Fewer voids (no mixing)
Better color stability
Potential for reduced net setting contraction
Better esthetics is possible

24. Completely cross-linked BIS-GMAH 3 O O C O R O C C H 3 O O C O R O C C H 3 O O H C C O R O C C H 3 3 O O H C C O R O C C H 3 3 O O H C C O R O C C H 3 3 O O H C C O R O C C H 3 3 O O H C C O R O C 3

25. As the polymer becomes more viscous, it becomes less and less likely that both ends of dimethacrylate molecules will be incor-porated in polymer chains. The percentage of cross links formed is call the degree of conversion.
polymerization
dimethacrylate
oligomer
100% conversion, as shown in the previous slide, is not achieved. Actual degrees of con-version range between 35 & 55 %.

26. Filler Particles

27. Benefits of filler particles:
increase strength
increase hardness
increase translucency
decrease water absorption
decrease total contraction

28. Types of resin composite:
large particle
small particle
microfilled
hybrid

29. Types of resin composite:
large particle
small particle
microfilled
hybrid

30. Types of resin composite:
large particle
small particle
microfilled
hybrid

31. Types of composite – small particle:
0.25 – 2.5 m quartz or glass particles
matrix is diacrylate polymer – also filled with 0.05 m colloidal silica particles

32. small particle resin composites
glass or quartz
1 m
resin matrix +
0.05 m SiO2

33. Glass & Quartz filler particles:
crystalline - silicon dioxide
non-radiopaque composite
very hard
glasses
contain heavy metals – Sr, Ba, Al, Zn
radiopaque composite
fairly hard

34. Types of resin composite:
large particle
small particle
microfilled
hybrid

35. Types of composite – microfilled:
3 – 10 m prepolymerized chunks – the chucks are densely filled with 0.05 m colloidal silica particles
matrix is diacrylate polymer – also filled, but less densely, with colloidal silica particles

36. microfilled resin composites:
resin matrix +
0.05 m SiO2
prepolymerized
chunk m
SiO2

37. making prepolymerized chunks - 1
mix colloidal silica, diacrylate resin, & chloroform  chloroform helps disperse the silica
evaporate the chloroform  produces dense silica & resin paste
heat cure the the resin  gives solid bock of resin with silica filler densely dispersed within it

38. making prepolymerized chunks - 2
heat cure the the resin  gives solid bock of resin with silica filler densely dispersed within it
break up resin block  screen the powder until you have 10 to 100 m particles

39. percent of colloidal silica that can be added is limited:
small particle size - ~ 0.05 m
high surface area per volume of particle
groups of particles tend to clump together
quickly increases viscosity of resin - vol. % that can be added is limited
to keep the resin composite plastic while adding colloidal silica, the percent diluent is increased

40. percent diluent in the resin matrix:
wt. % wt. %
oligomer diluent
microfilled
resin composites
all other

41. ( TEGMA ) Resin Composites - diluents O C H N3 N
N = 1, ethylene glycol dimethacrylate
N = 2, triethylene glycol dimethacrylate
( TEGMA )

42. inorganic filler particle content:
wt. % vol. %
microfilled
resin composites
all other

43. Types of resin composite:
large particle
small particle
microfilled
hybrid

44. Types of composite – hybrid:
3 – 10 m prepolymerized chunks – the chucks are densely filled with 0.05 m colloidal silica particles
0.25 – 2.5 m quartz or glass particles
matrix is diacrylate polymer – also filled, but less densely, with colloidal silica particles

45. hybrid resin composites:
glass or quartz
resin matrix +
0.05 m SiO2
prepolymerized
chunk m
SiO2

47. Much more
flexible

49. open margins

50. Low T: composite
contracts – fluid
sucked in.
fluid in
fluid in

51. Higher T: composite
expands – fluid
forced out.
fluid
out
fluid
out

52. Low T: composite
contracts – fluid
sucked in.
fluid in
fluid in

53. Higher T: composite
expands – fluid
forced out.
fluid
out
fluid
out

54. wear of resin composites:
generalized wear
contact area wear
generalized wear
An “Adaptic” posterior resin composite 2 years.
contact area wear

55. Occlusal wear of posterior resin composites:
generalized
wear
initial surface
worn surface

56. marginal
fracture
occlusal contact
area wear

57. the resin matrix
is soft; it wears
preferentially
glass or quartz
particles are very
hard

58. As the average size of the
holes left behind by plucked-
out particles decreases, the
wear rate decreases.
Particles that are very close together may protect the matrix resin between them from wear.

59. Estilux Posterior at 14 months Estilux Posterior at 37 months

60. A hybrid composite, Estilux
Posterior, at 36 months.

61. A hybrid composite, Estilux Posterior, at 36 months showing pre-polymerized chucks that have worn less than the surrounding matrix.

62. Wear in a microfilled resin composite (Silux) at 24 months
Wear in a microfilled resin composite (Silux) at 24 months. Center of restoration.
Marginal fracture in a Silux at 24 months.

63. amalgam
small particle
< 3.6 um
microfills
hybrids

64. Light Curing Resin Composites

65. Addition polymerization – initiation:C H 3 O +
free
radical A

66. H C C H C H O O Addition polymerization - initiator camphoroquinone 3

67. Resin Composites - light curing:
Types of light source:
quartz-tungsten-halogen (QTH)
plasma arc (PAC lights)
argon laser
light-emitting diodes (LEDs)
14 – 18 s *
3 s *
5 s *
14 – 18 s
* mean curing time for 2 mm thickness; 55 colors of 5 RCs; CRA Newsletter; 1998;22(12):2-3.

68. Resin Composites - light curing:
Types of light source:
quartz-tungsten-halogen (QTH)
plasma arc (PAC lights)
argon laser
light emitting diodes (LEDs)
$ 800 – 1,600 *
$ 4,000 *
$10,000
$ 800 – 1600
Prices from Reality updated Mar. 2012;

69. Curing with QHT Lights

70. Composites – curing with QHT lights
Most important factors in determining the degree of cure that can be achieved:
exposure time
light intensity

71. composites – deterioration of QTH sources:
Tungsten evaporates from hot filament
Coats quartz – darkens it
Halogen gas promotes redeposition of W on the filament
Do not unplug or turn off unit between cures – fan running increases filament life

72. polymerization
dimethacrylate
oligomer

73. adapted from Rueggeberg et al. Oper Dent 1994;19:26-32

74. adapted from Rueggeberg et al. Oper Dent 1994;19:26-32

75. adapted from Rueggeberg et al. Oper Dent 1994;19:26-32

76. adapted from Rueggeberg et al. Oper Dent 1994;19:26-32

77. Composites – curing with QHT, Factors:
composite color darker shades decrease cure; not significant if curing in 2 mm increments
type of composite microfilled RCs absorb light more than other types; not significant if curing in 2 mm increments

78. adapted from Rueggeberg et al. Amer J Dent 1993;6:91-95

79. adapted from Rueggeberg et al. Amer J Dent 1993;6:91-95

80. adapted from Rueggeberg et al. Int J Prosthod 1993;6:364-370.

81. adapted from Rueggeberg et al. Int J Prosthod 1993;6:364-370.

82. LED Curing Lights

83. light curing – LED advantages (v. QTH)
LEDs energy over narrower range of wavelengths
Longer bulb life (10,000 hrs v 100 hr)
Many are cordless
Small, light weight
Little degradation in intensity over life
Less heat generated at light tip ???

84. light curing – LED disadvantages (v. QTH)
Some may not cure all resin composites
Some may overheat and shut themselves off if you need to cure several restora-tions consecutively
Does not have the track record of QTH

85. light curing – Evolution of LEDs
1st generation – multiple low powered LEDs – too little power
2nd generation – one high-powered LED – too narrow a spectra for some resin composites
3rd generation – use several LEDs to broaden the range of wavelengths that are cured.

86. There is little evidence that slow start, ramped intensity etc
There is little evidence that slow start, ramped intensity etc. will reduce contraction during curing.

87. Questions ?