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Operative 2 > Current Adhesives and Composite Bonding > Flashcards

Current Adhesives and Composite Bonding Flashcards

1
Q

Cohesion:

A

attraction between similar molecules or atoms
a. Cohesive failure

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2
Q

Adhesion:

A

attraction between unlike molecules, attraction between two contacting
surfaces
a. Adhesive Failure

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3
Q

Adherend:

A

material bonded to another material by means of an adhesive

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4
Q

Adhesive:

A

substance that promotes adhesion

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5
Q

Adhesive Bonding:

A

joining two materials by means of an adhesive

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6
Q

Physical Bonding

A

◦ Very weak
◦ Ex. van der Waals forces

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7
Q

Chemical Bonding

A

◦ Very limited with dissimilar materials

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8
Q

Mechanical Bonding
(3)

A

◦Interlocking
◦Adhesive interlocks into surface irregularities
◦THIS IS THE DENTAL ADHESION MECHANISM

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9
Q

Microscopically intimate interface=

A

improved interlocking

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10
Q

Surface wetting-

A

the ability of a liquid to maintain intermolecular contact with
a solid surface

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11
Q

Improved surface wetting=

A

increased surface energy

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12
Q

Improved surface wetting= increased surface energy
◦ HOW?
(2)

A

◦ INCREASE SURFACE AVAILABLE FOR BONDING BY ETCHING
◦ Etching transforms smooth enamel into an IRREGULAR surface

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13
Q

Enamel Bonding=

A

very predictable
◦~25-30 MPa

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14
Q

Dentin Bonding=

A

more challenging
◦ Bond strengths vary

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15
Q

Type I-

A

“honeycomb” from dissolution of prism CORES

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16
Q

Type II-

A

“cobblestone” from dissolution of prism PERIPHERIES

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17
Q

TYPES I and II are found in

A

occlusal and middle thirds of teeth
BEST BONDS ACHIEVED TO TYPE I AND II

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18
Q

Type III-

A

combination of I and II

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19
Q

Type IV-

A

“pitted”

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20
Q

Type V-

A

“prismless” (flat and smooth)

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21
Q

Acid Etching Enamel

A

Chemical “drilling”

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22
Q

—% phosphoric acid is most effective for enamel retention

A

30-40

◦ Different types of acid used to etch different materials (nitric for metal, hydrofluoric for feldspathic porcelain)

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23
Q

◦ Removes about – microns enamel

A

10

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24
Q

◦ Place for — seconds prior to rinsing

A

15

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25
Q

Creates porous layer — microns deep

A

5-50

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26
Q

RINSE with water for – seconds after etching

A

10

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27
Q

RINSE with water for 10 seconds after etching
◦ To…
◦ — minimum water is necessary

A

◦ To remove acid and leave enamel surface clean for bonding
◦ 25mL

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28
Q

Etching increases (2)

A

wettability and surface area of the enamel

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29
Q

Etching raises the surface free energy to — the surface tension of bonding
material
◦ = (2)

A

EXCEED
◦ = produces spaces where resin can penetrate to form resin tags
◦ = mechanical interlocking that we are trying to achieve

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30
Q

After etching, apply —
(2)

A

resin (low viscosity)
◦ FLOWS into microporosities
◦ Polymerizes to MICROMECHANICAL BOND

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31
Q

LOCATION OF ADHESION MATTERS

A

Incisal third and middle third enamel
◦Predictable, strong

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32
Q

Cervical enamel
(2)

A

◦Shorter and fewer enamel tags (compared to middle and incisal thirds)
◦Less prism delineation (de to presence of prismless enamel, found in cervical third of 70% of teeth)

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33
Q

Bevels and Adhesive Dentistry
(3)

A

Reduce microleakage at cervical and ascending walls in Class II
preparations
Bevel gingival floor of prep
NECESSARY in enamel!

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34
Q

Additionally, enamel prepared with a bur
(bevelled) — better

A

etches
◦Reveals underlying prismatic enamel

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35
Q

When do we NOT bevel?

A

Deep preparations
◦So little enamel remains that a bevel would remove it all OR
◦Gingival floor is on cementum or dentin

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36
Q

The goal of adhesive dentistry with composite resin
◦In enamel-
◦In dentin-

A

interlocking with etched enamel rods
interlocking with etched dentin collagen

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37
Q

Enamel is great
◦—% inorganic matter by weight
◦—% hydroxyapatite by volume
◦—% organic matter by weight
◦—% water weight

A

95-98
90-92
1-2
4

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38
Q

Bond strength to perpendicular
Enamel (ENDS of rods)=
Bond strength to parallel
enamel (SIDES of rods)=

A

25MPa
7-10MPa

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39
Q

PERPENDICULAR oriented enamel (3)

A

◦Cavosurface margins of class I preparations
◦Bevels of class II preparations
◦ENDS of enamel rods

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40
Q

PARALLEL oriented enamel (3)

A

◦Internal walls of occlusal preparations
◦Gingival floor of box of class II preparations (see bevelling)
◦SIDES of enamel rods

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41
Q

Enamel Bonding, summarized

A

Etch surface
◦ Increased surface area and surface energy
◦ Allows wetting by hydrophobic adhesive resin
◦ Remember- enamel has MINIMAL water (3%)
Resin tags interlock◦ Macro and micro tags into surface irregularities
Micromechanical bonding!
Enamel- Adhesive- Composite Bond!◦ 20-25MPa
◦ Clinically Acceptable!

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42
Q

Dentin is very heterogenous
◦—% mineral by volume
◦—% collagen
◦—% water
Compare this to enamel- —% inorganic matter and —% water

A

55
30
15

97
1-2

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43
Q

Tubules

A

◦Fluid filled

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44
Q

Peritubular Dentin

A

◦Very INorganic

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45
Q

Intertubular dentin
(2)

A

◦Very ORGANIC
◦Collagen rich

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46
Q

Dentin tubules
◦ Diameter:

A

0.5 μm near DEJ, 2.5 μm near pulp

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47
Q

Dentin tubules
◦ Distribution

A

◦ 20,000/mm2 near DEJ
◦ 45,000/mm2 near pulp

48
Q

Deeper dentin (2)

A

◦more & wider tubules
◦ = more fluid
◦less intertubular dentin

49
Q

Smear Layer-

A

mixture of tooth debris, often contaminated with saliva, blood
cells, and bacteria

50
Q

DO NOT BOND TO

A

SMEAR LAYER
◦ Bond strength- 7.4MPa

51
Q

Remove smear layer with

A

acid etch

52
Q

Hybrid Layer-

A

intermingled layer of collagen and resin
*What we WANT to form when bonding to dentin

53
Q

Forming the Hybrid Layer
What happens when done properly
Steps:
(5)

A

1.Acid Etch 15 seconds dentin
2.Wash and LIGHTLY dry
= Hydroxyapatite removed, water remains to support collagen fibers
3.Apply primer
4. Apply adhesive
5. Light cure
Hybrid layer forms!
upon light curing, the unfilled resin sets within the collagen fibril network

54
Q

OVERETCHING results in

A

underfilled restorations

55
Q

OVERDRYING results in

A

lower bond strengths

56
Q

UNDERDRYING results in

A

collagen that is too wet

57
Q

Bonding Systems
(4)

A

Initial Bonding Agents
Etch-and-Rinse Bonding Agents
Self-Etching Primers
Universal Adhesives

58
Q

Initial Bonding Agents

A

◦ No longer used, first three generations of bond agents

59
Q

Etch-and-Rinse Bonding Agents (2)

A

◦Previously “Total Etch”
◦2 or 3 bottle system

60
Q

Self-Etching Primers
(2)

A

◦Eliminate a step
◦ 1 or 2 bottle system

61
Q

Development of Etch Systems
First:

A

No etch, adhesive resin only
◦ Pretty awful, 4-6MPa bond strength
◦ Bonds to smear layer

62
Q

Development of Etch Systems
Second:

A

Etch, adhesive resin only
◦ 10-12MPa bond strength

63
Q

Development of Etch Systems
Third:

A

Etch, primer, adhesive
◦ Now we’re talking!
◦ 20-30MPa bond strength

64
Q

Disadvantages of bonding systems
(3)

A

Too many steps
Or insufficient penetration of smear layer
Delicate treatment of dentin necessary

65
Q

Bonding System Components
(4)

A

Etchant
Primer
Adhesive Bonding Resin/Agent
Filler

66
Q

Etchant

A

◦ Phosphoric acid gel (30-40%)

67
Q

Primer
(2)

A

◦ HYDROPHILIC monomers in HEMA solvent
◦ Acetone, ethanol/water, water

68
Q

Adhesive Bonding Resin/Agent
(4)

A

◦ HYDROPHOBIC dimethacrylate monomers (BisGMA)
◦ Initiators and Activators
◦ Camphorquinone in light activated systems
◦ Benzoyl Peroxide (BPO) Tertiary amine in chemical and dual cure systems

69
Q

Filler

A

◦ Most unfilled, some 0.5-40 % by weight

70
Q

Adhesive/primer monomers–> polymers

A

◦Chemical reaction

71
Q

Activator
(3)

A

◦Converts Initiator (chemical) into a free radical
◦Free radical starts polymerization reaction
◦Light or chemical

72
Q

◦ Light
(2)

A

◦ Blue light (~47-nm)
◦ Camphorquinone→free radical→polymerization reaction

73
Q

◦ Chemical (tertiary amine)
(1)

A

◦ Benzoyl peroxide (initiator)→free radical→polymerization reaction

74
Q

Bonding Procedure
steps (6)

A

Step 1. Acid etch
◦ 15 seconds
Step 2. Rinse
◦ 10 seconds
◦ GENTLY dry- enamel should be dry, dentin should be slightly moist
Step 3. Apply Primer
Step 4. Apply Bond
Step 5. Light cure (= polymerize)
(Step 6. Place composite)

75
Q

Dentin Bonding Mechanism
(4)

A
  1. Acid-etched,
    demineralized collagen fibrils
    (~2-5 m deep)
  2. Water supports collagen
    network
  3. Hydrophilic Primer
    applied
  4. Hydrophobic Dentin Bond
    agent
    applied, polymerized
76
Q

Bonding Procedure
Step 1. Acid Etch
◦Dentin-

A

15 seconds at MOST
◦ Acid demineralizes dentin, leaving collagen

77
Q

Bonding Procedure
Step 1. Acid Etch
◦Enamel-

A

15-30 seconds
◦ Removes hydroxyapatite

78
Q

Bonding Procedure
Step 1. Acid Etch
◦Or

A

SELECTIVE ETCH
◦ Only etch enamel

79
Q

Bonding Procedure
Step 1. Acid Etch
◦Removes

A

smear layer
◦Denatured collagen, hydroxyapatite
crystals, debris from cutting tooth
~2 microns thick
Held on tooth by van der Waals forces
(4-6MPA)

80
Q

Step 2: Gently rinse and air dry
(4)

A

◦Rinse 10 seconds, air dry gently
◦DO NOT DESSICATE
◦Enamel should be dry
◦Dentin should be slightly moist

81
Q

Step 3: Apply Primer
(6)

A

◦Hydrophylic
◦Low viscosity
◦2-hydroxyethyl methacrylate (HEMA)
◦Penetrates water filled spaces in demineralized collagen network
◦Promotes bonding to dentin
- Attracts hydrophobic bond agent

82
Q

Step 4: Apply Bonding Agent Resin
(4)

A

◦Hydrophobic
◦Follows primer into spaces in demineralized collagen
◦Bisphenol A diglycidyl methacrylate (~70%)
◦Triethylene glycol dimethacrylate (~30%)

83
Q

Bisphenol A diglycidyl methacrylate (~70%)

A

◦ Bis-GMA- viscous, rigid

84
Q

Triethylene glycol dimethacrylate (~30%)
(2)

A

◦ TEGDMA- flexible, decreases viscosity
◦ Crosslinking

85
Q

Step 5- Light cure
(3)

A

◦Polymerization reaction
◦ Blue light ACTIVATES
◦ Camphorquinone INITIATES

86
Q

Step 6- Place composite resin
(2)

A

◦Incrementally
◦Light cure between increments

87
Q

Primary dentin bond mechanism is from — LAYER

A

HYBRID

88
Q

Hybrid layer-

A

micromechanical interlocking of resin with demineralized
collagen
◦ Collagen from intertubular dentin

89
Q

Factors affecting bond to dentin
(3)

A

cavity depth
caries
moist vs dry dentin

90
Q

Cavity depth

A

◦ Better bond strength in superficial dentin
\

91
Q

Caries

A

◦ Lower bond strength in carious dentin

92
Q

Moist vs. Dry dentin

A

◦ Moist is better!
◦ Overwet◦ Resin doesn’t penetrate well
◦ Decreased bond strength
◦ Collagen fibers collapse in dry dentin◦ Resin cannot penetrate
◦ Poor hybrid layer
◦ Decreased bond strength

93
Q

Factors to improve bond to dentin
(2)

A

Use extreme caution when using air/water syringe to dry
dentin
◦Use brush or cotton pellet to remove excess water on dentin

Use Rubber Dam
◦Prevents saliva contamination
◦Reduces humidity in oral cavity

94
Q

Systems previously described by ‘Generation’ number
(2)

A

a.Not a useful system
b.Describe instead by the components

95
Q

Bonding Systems
(3)

A

Phosphoric acid used to etch
Etch-and-Rinse/Total etch
Self-etch

96
Q

Etch-and-Rinse/Total etch
(2)

A

• Extra step
• Rinsed

97
Q

Self-etch
(3)

A

• No phosphoric acid-etch step
• Acid part of the primer or primer/bond agent
• Not rinsed

98
Q

Etch-and-Risne/Total Etch Bonding Systems
2 steps

A

1.3-step (2-bottle) Total Etch
a.Etchant
b.Primer
c.Bond agent
1)Example: Scotch Bond Multi-purpose

2.2-step (1-bottle) Total Etch
a.Etchant
b.Primer and bond agent combined
1)Examples
1)Prime and Bond NT, PQ 1, Peak,
Optibond Solo Plus

99
Q

Self-etching primer
(3)

A

◦2-step: acidic primer & bonding agent
◦Acidic primer partially dissolves smear layer, allows penetration of
bond resin
◦Clearfil SE Bond; Clearfil Liner Bond 2V

100
Q

Self-etching adhesive (All-in-one)

A

◦ 1-step –most variable/ least predictable
◦ Acidic primer and bond resin, one solution
◦ Many require mixing
◦ Examples: Xeno,
i-Bond, Bond Force (no mix)

101
Q

Rinse and Etch/Total Etch Systems
Advantages
(2)

A

◦More predictable, stronger bond
◦Enamel adequately prepared

102
Q

Rinse and Etch/Total Etch Systems
Disadvantages
(4)

A

◦Collagen collapse is possible*
◦Etched zone is often deeper than hybrid layer
◦ Exposed demineralized, collagen fibrils
◦ Post-operative sensitivity

103
Q

Self-etch SystemsAdvantages
(4)

A

◦No separate etch: overdried, collapsed demineralized collagen not a problem
◦Etched zone and hybrid layer comparable width; however, some exposed
collagen
◦Low post-operative sensitivity
◦Time efficiency

104
Q

Self-etch Systems
Disadvantages
(4)

A

◦Not compatible with self-cure, dual-cure composite
-Acidic monomers, low pH, “kills” the basic amine activator

◦Will not etch unprepared enamel

◦Self-etch primer systems
-Long-term bond strength?

◦Self-etch adhesives (all-in-one)
- Lower bond strength
- Long-term breakdown?
- Collagen degradation over time

105
Q

Universal adhesives

A

Can be used in total etch, self-etch or selective-etch mode (etch
enamel only with phosphoric acid)
What we’re using at UMKC
Adhese and Peak

106
Q

Universal adhesivesChemistry game changer is

A

10-MDP
◦ Methacryloyoxy-decyl-dihydrogen-phosphate (10-MDP)

107
Q

Universal adhesives
Mechanism of action : (3)

A

A monomer that chemically interacts via ionic bonding to
calcium in hydroxyapatite
Single bottle, no mix adhesive system
Monomer is a phosphate ester

108
Q

Biocompatibility of acid etchEtchant
◦ Enamel was only etched up until the late 1980’s;

A

we thought etching dentin would harm the pulp so we used to cover the dentin with CaOH before we etched a tooth.

109
Q

We now use a total etch technique of etching enamel and dentin.

A

◦ Etchant interacts with superficial dentin and there is no pulpal damage

110
Q

Direct etch of pulp?

A

bad

111
Q

Dentin adhesive
(3)

A

◦ Well tolerated by dentin
◦ Do not want to apply it directly to the pulp though
◦ Adverse pulp reaction comes primarily from bacteria remaining in
or penetrating the preparation

112
Q

Bond Strengths to Dentin Vary (8)

A

Region of tooth
◦ Superficial higher bond strength than deeper (Prati, 1992)
Flat surfaces higher than box cavities (Bouillaguet, 2001)
C-factor (Yoshikawa, 1999)
Adhesive system used (Yoshikawa, 1999)
Thickness of increment of composite resin
◦ 1 mm better than 2 mm increment
Operator (Shono, 1999)
Intrinsic wetness of tooth (Ogata, 2001)
Dryness vs wetness (Tay, 1996)

113
Q

ond to dentin collagen is influenced by

A

Matrix metalloproteinases (MMPs)
• collagen enzymes that metabolize unhybridized collagen

114
Q

MMPs are present on

A

collagen fibrils and can be seen at 100,000X on SEM

115
Q

— inhibits MMP activation

A

Chlorhexidine

116
Q

Consepsis® (Ultradent)
(2)

A

◦ 2% Chlorhexidine Antibacterial Solution
◦ Applied after acid etching

Operative 2 (12 decks)

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