1. Notes
9/10/2018
Bonding to Dentin
denting bonding

2. Types of dentin surfaces:
Notes
9/10/2018
Types of dentin surfaces:
fractured
smear layer covered
sclerotic dentin (hypermineralized)
caries altered (demineralized)
denting bonding

3. Bonding to dentin: etching the dentin
Notes
Bonding to dentin: etching the dentin
9/10/2018
Buonocore (1956) tried to bond MMA to etched dentin
Hydrophobic resins would not adapt to etched tubules
In any case, the pre-vailing paradigm was that etching dentin would kill the pulp.
5 μm
Resin repels pulpal fluids. These
fluids keep the resin from adapting
to tuble walls.
denting bonding

4. Adhesion to dentin - Steps
Notes
9/10/2018
Adhesion to dentin - Steps
Conditioner
Primer
“Adhesive” Resin
denting bonding

5. Adhesion to dentin - Definitions
Notes
9/10/2018
Adhesion to dentin - Definitions
Conditioner – an acid the etches dentin
Total Etch – the technique that uses a single acid to simultaneously etch both dentin and enamel
denting bonding

6. Smear layer
Mixture of hydroxyapatite, collagen, saliva, & blood.
weakly attached to surface
thought to seal dentinal tubules

7. Dealing with the smear layer - Strategies
bond primer to surface of smear layer. (strategy 1)
dissolve smear layer and demineralize near-surface dentin with an acid; treat demineralized dentin with primer. (strategy 2)
dissolve smear layer & demineralize near- surface dentin with an acidic primer. (strategy 3)

8. Strategy 1: bonding to the smear layer
strategy used by in Scotchbond & subsequent DBSs marketed in early 1980s
Produced low bond strengths 3 – 8 MPa

9. DBSs - bond to surface of smear layer (strategy 1)
Goal is leave the smear layer intact – smear layer is viewed to be protective – little or no etching
DBS interacts superficially with the dentin (no hybrid layer)
mechanism ?? mechanical / chemical bond

10. Dealing with the smear layer - Strategies
bond primer to surface of smear layer. (strategy 1)
dissolve smear layer and demineralize near-surface dentin with an acid; treat demineralized dentin with primer. (strategy 2)
dissolve smear layer & demineralize near- surface dentin with an acidic primer. (strategy 3)

11. DBS – dissolve smear layer with acid (strategy 2)
Three Step (3 bottle)
Conditioner
Primer
“adhesive” resin
5 μm
After treatment with acid, the smear layer has been removed and dentinal tubules are open.

12. Dentinal tubule diameter: Superficial vs. Deep Dentin
The smaller area of intertubular dentin close to the pulp could mean lower bond strengths. That’s what was observed for some DBSs.
Or maybe the tubules are the weak link? More area of tubules means weaker bonds? It is not known which factor causes the lower bond strength to deep dentin.

13. Conditioning with phosphoric acid
1 μm
demineralized
dentin
If dehydrated
will collapse
Van Meerbeak et al.
J Dent :1-20

14. DBS – dissolve smear layer with acid (strategy 2)
Three Step (3 bottle)
Conditioner
Primer
“adhesive” resin

15. Primers for enamel & dentin:
Vocabulary – adhesives vs. primers
Adhesives are applied between two materials. They adhere to each.
Primers penetrate the surface of a material, changing the character of the surface

16. Primers for enamel & dentin:
Primers penetrate the surface of a material, changing the character of the surface so that
an adhesive will adhere to the modified surface or
the second material will adhere to the modified surface without the use of an adhesive.

17. Primers for enamel & dentin:
Goal:
To modify the surface of enamel or dentin so that acrylic copolymers will copolymerize with the altered surface.

18. Primers for enamel & dentin:
Primer Mechanisms:
Penetrates a porous surface & mechanically interlocks with that surface.
Copolymerizes with acrylic polymers placed on the surface

19. Primers for enamel & dentin:
Penetration of surfaces promoted by:
Etching the surface. High-surface-energy etched surfaces react with the liquid resin, causing it to more readily wet and penetrate the porous surface.
Reducing the viscosity of the resin. Viscosity is decreased by adding diacrylate diluents to BIS-GMA. Such resins flow more easily into etched tooth structure.

20. Primers for enamel & dentin:
Penetration of surfaces promoted by:
Making the primer less hydrophobic. Adding hydrophilic moieties to an acrylic monomer will reduce its hydrophobicity, and thereby improve wetting and penetration of surfaces contaminated with aqueous fluids or surfaces within which such fluids are contained (e.g., dentin).

21. Primers for enamel & dentin:
Additional advantages of primers modified to be less hydrophobic:
damp or moist surfaces don’t interfere with wetting
resins are dissolved in low vapor pressure solvents; evaporation of the solvent results in high concen-trations of primer resin in the conditioned surface.

22. Primers for enamel & dentin:
Additional advantages of primers modified to be less hydrophilic:
as solvents evaporate they may chase fluids out of crevices thereby facilitating better penetration of the primer

23. C O H Primer resins: HEMA HEMA hydroxyethylmethacrylate 3 hydrophobic
methacrylate group C O H 3
HEMA
hydroxyethylmethacrylate
Unlike many other acrylics, HEMA and polyHEMA are soluble in water. Solutions of these will flow into hydrated demineralized dentin surfaces.
hydrophilic
hydroxyl group

24. The act of forming a hybrid layer.
hybridization:
The act of forming a hybrid layer.
A hybrid layer is a surface layer of porous dentin or enamel that is interpenetrated on a micron scale by polymer.

25. Optibond FL
hybrid
layer
2.0 μm

26. Hybrid layer
resin
between
fibriles
banded
collagen
0.20 μm

27. DBS – forming Hybrid Layer (strategy 2)
conditioned dentin: mixture of collagen & water
primer: hydrophilic acrylic resin dissolved in solvent (water, acetone, or ethanol)
primer diffuses into water incorporated in conditioned layer
solvent evaporates from primer

28. DBS – forming Hybrid Layer (strategy 2)
hydrophilic acrylic resin left behind
the hydrophilic acrylic monomer is polymerized, usually when the adhesive layer is cured.
hybrid layer: collagen embedded hydrophilic acrylic polymer

29. DBS – dissolve smear layer with acid (strategy 2)
Three Step (3 bottle)
Conditioner
Primer
“adhesive” resin
may have the advantage of protecting
hydrophilic layer from the oral
environment.

30. DBS – dissolve smear layer with acid (strategy 2)
Three Step Products:
All-Bond 2 (Bisco)
Optibond FL (Kerr)
Scotchbond Multipurpose (3M Espe)

31. DBSs – dissolve smear layer with acid (strategy 2)
resin
composite
Bond 1
(Jeneric-Pentron)
shear bond
strength MPa
adhesive
hybrid
layer
Vargas et al. Dent Mater
1997;13:
2 μm

32. DBSs - dissolve smear layer with acid (strategy 2)
Syntac Single
Component
(Ivoclar-Vivadent
America)
shear bond
strength MPa
Maybe, incomplete adhesive layer is the reason for the relatively low bond strength
Vargas et al. Dent Mater
1997;13:
2 μm

33. DBS – dissolve smear layer with acid (strategy 2)
Three Step (3 bottle)
Conditioner
Primer
“adhesive” resin
These two can be combined in one bottle. Simpler systems work initially, but there is evidence that they are not a durable

34. DBS – dissolve smear layer with acid (strategy 2)
Two Step (2 bottle)
Conditioner
Primer + adhesive resin

35. DBS – dissolve smear layer with acid (strategy 2)
Two Step Products:
One-Step (Bisco)
Optibond Solo plus (Kerr)
Prime & Bond NT (Dentsply/Caulk)
Single Bond (3M Espe)

36. DBSs - dissolve smear layer with acid (strategy 2)
Single Bond
(3M Espe)
shear bond
strength -
22.2 MPa
There is no evidence of an adhesive layer. The hybrid layer alone attracts water and may degrade. The more hydrophobic adhesive layer may offer protection to the hybrid layer.
Vargas et al. Dent Mater
1997;13:
2 μm

37. DBS: Strategy 2 - solvents
Water:
Scotchbond MP (3M-Espe)
Ethanol-Water:
Optibond FL (Kerr)
Ethanol:
Optibond Solo (Kerr)

38. DBS: Strategy 2 - solvents
Ethanol - Acetone:
All-Bond 2 (Bisco)
Acetone – Water:
Tenure Quik (Den-Mat)
Acetone
Prime&Bond NT (Dentsply)
Solid Bond (Kulzer)

39. Dealing with the smear layer - Strategies
bond primer to surface of smear layer. (strategy 1)
dissolve smear layer and demineralize near-surface dentin with an acid; treat demineralized dentin with primer. (strategy 2)
dissolve smear layer & demineralize near- surface dentin with an acidic primer. (strategy 3)

40. Primers for enamel & dentin:
Penetration of surfaces promoted by:
Making the primer acidic. Adding acidic moieties to an acrylic monomer enables it to etch tooth structure. The high energy of the etched surface is never reduced by exposure to the atmosphere or by rinsing. In principal, resin will be strongly attracted to this high energy surface thus increasing the likelihood that the resin will wet and penetrate the surface.

41. Primers for enamel & dentin:
Advantages acidic primers:
etching produces high-energy surfaces that are attracted to primer resins
the porous subsurface produced by etching can never extend deeper than the primer penetrates – that is, the primer penetrates the entire depth of the etched zone

42. O P H O O P O C C O H Comparing Phosphoric Acid & Acidic Primers:
Used for decades to etch enamel. Currently used in total etch. Below we add this group to an acrylic primer.
Phosphoric
Acid
Self-etching
Primer
(3M – Unitek) O O P O C C O H

43. Acidic primers: Successful primers are all at least mildly acidic
methacrylate group
acidic C H 2 3 O (C ) 1 P
hydrophilic
hydrophobic
10 – MDP (10 methacycloxydecyl dihydrogen phosphate) –
[the primer in Panavia]

44. Comparing Dental Primers
Primer Type
in solvent
hydrophilic
acidic
unfilled resins no
moisture insensitive
yes
mildly
self etching
useful for etched enamel only
useful on etched dentin or enamel
useful on unetched dentin or enamel

45. DBS – use acidic primer (strategy 3)
Two Step (2 bottle)
Separate enamel etch
Self-etching primer (SEP) + resin
Some products are too weak to etch enamel, so a separate enamel etch is needed.

46. DBS – use acidic primer (strategy 3)
Products:
Two bottle: 1) SEP 2) “adhesive”
Clearfil SE Bond (Kuraray)
Clearfil Protect Bond (Kuraray)
Prelude (Danville Materials)

47. DBS – use acidic primer (strategy 3)
Products:
One bottle: SEP + resin together
Xeno IV (Dentsply / Caulk) *
Optibond All-on-One (Kerr) *
Clearfil S3 Bond (Kuraray)
G-Bond (Kuraray)
* requires two applications for bonding to dentin

48. DBS – use acidic primer (strategy 3)
Products:
Two bottle: 1) SEP 2) “adhesive”
Clearfil SE Bond (Kuraray)
20% Phenyl-P + 30% HEMA + water
Phenyl-P is 2-methacryloyloxyethyl
phenyl phosphoric acid

49. DBS – advantages of SEPs
Simultaneous demineralization & resin impregnation
No post conditioning rinsing
Not sensitive to dentin wetness
Resin penetrates to the full depth of etched zone
Less post operative sensitivity ??
More

50. DBS – advantages of SEPs
Less technique sensitive
Time saving

51. DBS – disadvantages of SEPs
Little clinical research has been done
Adhesion to enamel may be low in some systems
Some systems do not form durable bond

52. Technique for Total Etch Bonding

53. Total etch dentin bonding: etching time
etching time with H3PO4 is often 15 s
extend by additional 15 s if dentin is sclerotic
more concentrated acids produce thicker hybrid layers
bond strength is independent of hybrid layer thickness
not known whether thickness affects the integrity of the H.L. (e.g., the seal)

54. Total etch dentin bonding: etching time
etching time with H3PO4 is often 15 s
careful not to over etch young dentin or deep dentin – some worry that etched dentin will not be penetrated by primers

55. Total etch dentin bonding: priming
primer is applied to moist dentin
if too dry collagen fibrils may collapse
bond strength will be low
primers that are dissolved in water will rehydrate the dentin – bond strength is regained

56. Total etch dentin bonding: priming
use air pressure for a few seconds to force the primer into the tubules
but some are concerned air pressure will increase the oxygen in the primer, which can inhibit its polymerization
danger of the above is balanced by the need to force the primer into tubules and side canals

57. Total etch dentin bonding: primers in acetone solvent
primers that are dissolved in acetone evaporate more quickly due to the low vapor pressure of the solvent
may “chase” water from between collagen fibrils

58. Total etch dentin bonding: primers in acetone solvent (2)
acetone solvent can evaporate – thickening the primer
some manufacturers mix the primer with excess solvent to prevent thickening – may require multiple layers
primers dissolved in acetone must be applied to moist dentin; water is necessary to rehydrate

59. Total etch dentin bonding: adhesives (e.g. intermediate resins)
adhesives usually contain mixture of both the hydrophilic primer mono-mers and a hydrophobic diacrylate monomers
do not use air pressure to thin this layer (some evidence of weakened bond – oxygen inhibition of poly-merization ??)

60. Pulpal compatibility of hybrid-layer-forming adhesives:
Most studies find little pulpal response
One recent exception (Subay, 2000):
some short term inflammation
some evidence of bacteria
concluded that the hybrid layer did not form a complete seal

61. Pulp Reaction beneath deep Cl V restorations
11 – 14 yr old premolars
Calcium hydroxide – Dycal sealed with ZOE
Dentin Bonding Agent – Scotchbond Multipurpose Plus
Subay et al., J Dent 2000;28:

62. Pulp Reaction beneath deep Cl V restorations
11 – 14 yr old premolars
Calcium hydroxide – Dycal sealed with ZOE
Dentin Bonding Agent – Scotchbond Multipurpose Plus
Subay et al., J Dent 2000;28:

63. Postoperative Sensitivity in Bonded Resin Composite Restorations

64. Bonding Systems for Clinical Trial of Class II Composite Restorations
Code
Product
Description
Manufacturer
3 step
Scotchbond
Multipurpose
total etch w primer & adhesive
3M Dental
2 step
Clearfil Photo Bond
etch
combined primer & adh
Kuraray
1 step
Clearfil Liner
Bond
self etching primer
Opdam et al. J Dent 1998;26:

65. Leakage along cervical margin of Cl II resin composite restorations
11 – 14 yr old premolars
cervical margin 2 mm occlusal to CEJ
one posterior resin composite used – Clearfil Ray Posterior
Opdam et al. J Dent 1998;26:

66. Leakage along occlusal margin of Cl II resin composite restorations
11 – 14 yr old premolar
Opdam et al. J Dent 1998;26:

67. Sensitivity to occlusal loading in Cl II resin composite restorations
11 – 14 yr old premolar
No restoration was sensitive when exposed to a cold stimulus
Opdam et al. J Dent 1998;26:

68. Retention of Bonded Class V Resin Composites Restorations

69. Bonded Resin Composite in Class V lesions
– smear layer dissolved – dentin weakly etched
No retention grooves
Enamel etching avoided
Van Dijken Dent Mater 1994;10:

70. Bonded Resin Composite in Class V lesions – 3-step system
No retention grooves
Enamel etching avoided
Tyas MJ. Int Dent J 1996;46:10-14.

71. Bonded Resin Composite in Class V lesions – 3-step system
All Bond 2 (Bisco)
No retention grooves
Enamel & dentin were etched
McCoy et al. J Am Dent Assoc
1998;129:

72. Bonded Resin Composite in Class V lesions – 3-step system
Clearfil Liner Bond (Kuraray)
No undercuts
Enamel etched ??
Mandras et al. Oper Dent 1997:22;

73. Bonded Resin Composite in Class V lesions – 3-step system
Gluma 2000 (Bayer)
No retention grooves
Enamel & dentin were etched with an oxalic acid containing gel
McCoy et al. J Am Dent Assoc
1998;129:

74. Bonded Resin Composite in Class V lesions – 3-step systems
No retention grooves
Enamel etching avoided
Van Meerbeek et al. Quint Int
1996;27:

75. Bonded Resin Composite in Class V lesions – 3-step systems
No retention grooves
Enamel etching avoided
Van Meerbeek et al. Quint Int
1996;27:

76. Bonded Resin Composite in Class III lesions
– 2-step system (in vivo) – in dogs
Clearfil Liner Bond II (Kuraray)
Self-etching primer
Microtensile w. area 0.7 x 1.4 mm
Sano et al. J Dent Res 1999;
78:

77. Bonded Resin Composite in Class V lesions
– 3-step system (in vivo) – Cl I in primary molars
Scotchbond MP (3M)
Microtensile w. area ??
Hashimoto et al. J Dent Res 2000;
79:509 (abstr 2924).

78. Resin Composite bonded to occlusal dentin – 3-step system - aging
Scotchbond MP (3M)
Microtensile w. area 0.5 mm2
Armstrong et al. J Dent Res 2000;
79:453 (abstr 2476).

79. Microtensile bond strength tests – higher strengths:
Notice in the last slide that the bond strengths are extremely high
Due to the tiny bonded areas used in microtensile bond strength tests

80. Fabricating microtensile bond strength specimens:

81. microtensile specimen conventional specimen
resin
composite
diameter < 1.0 mm
area less than 3.14 mm2
diameter 3 – 5 mm
area between & 78.5 mm2
dentin
1 mm
diameter
3 mm
A larger area surface area means that one is more likely to sample a defect that will reduce the bond strength
This type of specimen gives larger bond strengths.

82. typical bond strengths 40 – 80 MPa typical bond strengths 12 - 25 MPa
microtensile specimen
conventional specimen
resin
composite
typical bond
strengths
40 – 80 MPa
typical bond
strengths
MPa
dentin

83. Aging affects microtensile bond strength
three step
two step
NOTE: Protected interfaces were not in direct contact with water
De Munck et al J Dent Res 82:

84. Bonded Resin Composite on occlusal dentin
– 3-step system (in vitro) – bovine dentine
Clearfil Photo Bond (Kuraray)
Phosphoric acid etch
Tensile w. area 4 mm dia.
Burrow et al. Dent Mater 1996;
12:

85. End