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Operative II > Week 3- Tooth Bonding and Adhesives > Flashcards

Week 3- Tooth Bonding and Adhesives Flashcards

1
Q

what is adhesion

A

the state in which two surfaces are held together by interfacial forces which may consist of valence or interlocking forces or both

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2
Q

what is adhesive

A

a material, frequently a viscous fluid that joins two substrates together by solidifying and transferring a load from one surface to the other

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3
Q

what is adhesive strength

A

the measure of the load bearing capacity of an adhesive joint

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4
Q

what is failure of adhesive joints caused by

A
  • cohesive in substrate
  • cohesive within the adhesive
  • adhesive failure or at the substrate adhesive interface
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5
Q

what are the factors that affect adhesion

A
  • clean substrate
  • wetting ability of substrate
  • adhesive viscosity
  • surface roughness
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6
Q

what is wetting ability

A

ability to maintain intermolecule contact with dental surface

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7
Q

how does acid etching improve surface wetting

A

it increases surface free energuy

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8
Q

what does viscosity depend on

A

surface tension of the liquid (adhesive) and of the solid (substrate)

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9
Q

how does surface roughness affect the bonding ability

A

irregular surface increases the bonding ability
- increased area for bonding
- increased adhesive interlocking

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10
Q

how does acid etching affect surface roughness

A

increases the surface available for bonding and intermolecular contact with adhesive

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11
Q

what are the bonding mechanisms to tooth structure

A
  • mechanical
  • chemical/adsorption
  • diffusion
  • a combination of the 3
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12
Q

what does mechanical bonding do

A
  • penetration of resin adhesive and formatino of hybrid layer/ or resin tags within the tooth surface after polymerization - entanglement
  • resin tags
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13
Q

what do resin tags do

A

micromechanical interlocking within the tooth surface

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14
Q

what is chemical/adsorption bonding

A

chemical bonding to the inorganic component (hydroxyapatite) or organic components (mainly type I collagen) of tooth structure

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15
Q

what is the diffusion type of bonding

A

precipitation of substances on the tooth surfaces to which resin monomers can bond mechanically or chemically

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16
Q

what is the bond strength, origin, composition, structure, and type of substrate of ENAMEL

A
  • 20MPa to 53MPa
  • epithelial
  • 97% mineral (hydroxyapatite), 1-2% organic (amelogenin and enamelin), 2% water
  • prisms
  • homogenous
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17
Q

what is the bond strength, origin, composition, structure, and type of substrate of DENTIN

A
  • unpredictable
  • conjunctive
  • 55% mineral (hydroxyapatite), 30% organic (type I collagen), 15-20% water
  • tubular
  • very heterogenous
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18
Q

describe acid etching

A
  • introduced by buonocore through the acid etch technique
  • very predictable
  • chemical drilling
  • most effective for enamel retention (5-50 microns deep)
  • 30-40% phosphoric acid (37% is most common)
  • application 15-30 seconds, rinse for 10 seconds and 25 mL water is necessary
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19
Q

what is the role of acid etching

A
  • clean surface for bonding
  • increases wettability and SA for bonding
  • increases surface free energy to EXCEED the surface tension of the adhesive
  • micro retentions: adhesive penetration and resin tags
  • mechanical interlocking after adhesive polymerization
  • MICROMECHANICAL BOND
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20
Q

what is the fundamental mechansim of adhesion

A

micromechanical bond

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21
Q

what is the type 1 etching pattern on enamel

A
  • honeycomb
  • dissolutino of prism cores
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22
Q

what is the type 2 etching pattern on enamel

A
  • cobblestone
  • dissolutino of prism peripheries
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23
Q

what types are the best bonds achieved in enamel

A

type I and type II

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24
Q

where are type I and type II etching patterns of enamel location

A

occlusal and middel thirds of teeth

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25
Q

describe type III etching pattern of enamel

A

combination of type I and type II

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26
Q

describe type IV etching pattern

A

pitted

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27
Q

describe the type V etching pattern

A

-prismless
- flat and smooth

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28
Q

where is stronger retention and more predictable bonding performance of enamel located

A

incisal and middle third of the tooth

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29
Q

describe the bonding performance of the enamel in the cervical third of the tooth

A

prismless enamel -> fewer and shorter resin tags

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30
Q

why should you bevel the gingival floor in class II preps

A

reduce the microleakage at cervical and ascending walls

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31
Q

why is enamel prep with burs more efficient etching

A

it reveals underlying prismatic enamel

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32
Q

when do we not bevel enamel

A

-in deep class II preps where so little enamel remains that a bevel would remove it all
- gingival floor is on cementum or dentin

33
Q

describe perpendicular prisms

A

-better performance (~25MPa)
- cavosurface margins class I prep
- bevels of class II prep
- ends of enamel rods

34
Q

describe parallel oriented prisms

A
  • lower performance
  • 7-10 MPa
  • internal walls occlusal prep
  • gingival floor of box of class II prep
  • sides of enamel rods
35
Q

describe dentin tubules

A

-fluid filled
- enclose cellular extensions (odontoblasts)
- conntect pulp to DEJ

36
Q

describe intertubular dentin

A
  • higher organic content
  • collagen rich zone
37
Q

describe peritubular dentin

A
  • surrounding the tubuels
  • highly mineralized
38
Q

describe the dentin structure

A
  • tubules that connect the pulp with the DEJ
  • tubules change in distribution and diameter through the dentin depth
39
Q

how big are the dentin tubules near DEJ

A

20,000/mm^2
- 0.5 micrometer diameter

40
Q

how big are the dentin tubules near the pulp

A

45,000/MM^22
- 2.5 micrometer in diameter
- more fluids
- less intertubular dentin

41
Q

how is bond strength affected by dentin depth

A

better bonding at superficial dentin than deep dentin

42
Q

what is the smear layer

A
  • organic and inorganic residues left by burs or other instruments
  • contaminated with saliva, blood, cells, and bacteria
43
Q

what is it called when the smear layer is in the tubules

A

smear plus

44
Q

how does the smear layer affect bonding

A

it decreases it to 7.0 MPa

45
Q

how is smear layer removed

A

acid etch

46
Q

how is the hybrid layer created

A
  • after acid etching, collagen fibrils are exposed
  • adhesive penetrates and encapsulates the collagen fibrils
  • after polymerization creates an intermingled layer of collagen and resin called the hybrid layer
47
Q

what is the hybrid layer key for

A

dentin bonding
- base for all composite restorations

48
Q

what relies on the hybrid layer

A

stability/longevity of composite restorations
- stability of collagen and adhesive resin

49
Q

what are the steps in forming the hybrid layer

A
  • acid etch dentin for 15 sec: removes the smear layer and minerals surrounding collagen, rinse with water for 15 sec
  • remove the excess of water but keep dentin moist: the space previously occupied by minerals is filled with water to support collagen fibrils
  • apply adhesive or primer+ adhesive
  • light cure
50
Q

what are the factors affecting the hybrid laeyr formation

A
  • clean dentin surface and free of smear layer
  • poor adhesive infiltration
  • incomplete adhesive polymerization
51
Q

what does dentin over etching cause

A

denature dentin collaen matrix and premature bond failure

52
Q

how does dentin moisuter affect hybrid layer formation

A

avoid over wetting or drying that impacts on adhesive penetration

53
Q

how does poor adhesive infiltration affect the hybrid layer

A

collagen exposed is subjected to degradation by host derived enzymes (MMPs or CT) due to presence of water/hydrophobicity of adhesive

54
Q

what would cause incomplete adhesive polymerization

A
  • low density/energy light curing units
  • lack of evaporation before polymerization
  • premature faiure of bonding interface and premature loss of composite restorations
55
Q

what are adhesive systems

A

agents that bond micromechanically and/or chemically the restorative material to tooth substrate through an interface

56
Q

what are the current applications of adhesive systems

A
  • direct restoration technique- class 1-5 and veneers
  • indirect adhesive restorations- crowns or partial restorations to increase retention in metal crowns
  • seals pits and fissues
  • bond ortho brackets
  • desensitize noncarious cervical lesions and exposed root surfaces
  • repair existing restorations
  • bond to root canal
57
Q

what are the types of adhesive systems

A
  • three step etch and rinse
  • two step etch and rinse
  • two step self etch
  • one step self etch
  • two step etch and rinse
  • one step self etch
58
Q

what are the components of the three step etch and rinse

A

-phosphoric acid
- hydrophilic primer
- bonding resin

59
Q

what are the components of the two step etch and rinse

A
  • phosphoric acid
  • adhesive(hydrophilic primer and bonding resin)
60
Q

what are the components of the two step self etch

A

-self etching primer
- bonding resin

61
Q

what are the components of the one step self etch

A

all in one (self etch hydrophilic primer and bonding resin)

62
Q

what are the components of the two step etch and rinse/ one step self etch

A
  • phosphoric acid and hydrophilic bonding resin
  • self etch hydrophilic primer/ bonding resin
63
Q

what are the components of the adhesive systems

A
  • acid etchant: phosphoric acid gel 30-40%
  • primer: hydrophilic monomers in HEMA, solvent (acetone, ethanol/water, water)
  • adhesive bonding resin/agent: hydrophobic dimethacrylate monomers, initiators and activators, camphorquinone, or benzoyl peroxide tertiary amine, filler
64
Q

describe the polymerization process

A

-adhesive/primer: monomers to be converted into polymers- chemical reaction
- reaction: activator converts initiator into a free radical and free radical starts polymerization reaction
- light activator: blue light and initiatory- camphorquinone and DMAEMA
- chemical: tertiary amine and benzoyl peroxide-> free radical -> polymerization reaction

65
Q

describe the dentin bonding mechanism of micromechanical interlocking

A
  • acid etched, demineralized collagen fibrils, adhesive to form hybrid layer
66
Q

describe dentin bonding mechanism chemically

A

phosphate acidic monomers, phosphate monomer chemically interacts via ionic bonding to calcium in hydroxyapatite

67
Q

what is the bonding procedure at UMKC SOD

A
  • step 1: acid etch: enamel for 15-30 sec and dentin for 15 sec or SELECTIVE ETCH (enamel only)
    -step 2: rinse 10 seconds at least. air dry gently- enamel should be dry and dentin slightly moist
  • step 3: click the viva pen and apply adhesive, agitate for 20 sec, air dry until glossy immobile film layer
  • step 4: light cure for 10 s
  • step 5: place composite resin
68
Q

what are the steps in three step etch and rise

A
  • step 1: acid etch enamel for 15-30 sec and dentin 15 sec
  • step 2: rinse 15 sec and air dry
  • step 3: primer application and agitation only on dentin and air dry
  • step 4: adhesive bond application and agitation and air dry
  • step 5: polymerization for 10 sec
  • step 6: place composite
69
Q

what are the steps in two step etch and rinse

A
  • step 1: acid etch enamel 15-30 seconds and dentin 15 sec
  • step 2: rinse 15 sec and air dry
  • step 3: adhesive application and agitation and air dry
  • step 4: polymerization for 10 sec
  • step 5: place composite resin
70
Q

what are the steps to two step self etch

A

step 1: acidic primer application agitation and air dry
- step 2: adhesive application agitation and air dry
- step 3: polymerization for 10 sec
- step 4: place composite resin

71
Q

what are the steps to one step self etch

A
  • step 1: adhesive (all in one) application and agitation and air dry
  • step 2: polymerization for 10 sec
  • step 3: place composite resin
72
Q

what are the factors affecting bond to dentin

A
  • cavity depth
  • caries affected dentin
  • C factor
  • adhesive system used
  • thickness of increment of composite resin
  • operator error
  • moisture of dentin
73
Q

what are the advantages and disadvantages to etch and rinse

A

-advantages: more predictable in enamel, stronger bond in enamel, less marginal staining and marginal openings overtime. HL with more robust resin tags
- disadvantages: more clinical steps, longer tx time, hard to control dentin moisture, collagen collapse is possible, etched zone is often deeper than adhesive penetration
- post operative sensitivity

74
Q

what are the advantages and disadvantages of self etch

A
  • advantages: less clinical steps, shorter clinical time, control dentin moisture, simultaneous deminerlization and adhesive infiltration, reduced the difference between adhesive penetration and etched dentin depth, post op sensitivity, good for dentin
  • disadvantages: in enamel- weaker bond strength, more marginal staining and marginal openings overtime. not compatible with self cure, dual cure composite
75
Q

what can increased hydrophilic content affect

A
  • polymerization of adhesive
  • more susceptible to hydrolysis of adhesive
  • more degradation of the bonding interface
  • lower bond strength
  • incompatibility with chemically activated composites
76
Q

what did the presence of 10-MDP do

A

increased clinical performance of universal adhesives through retention rate, marginal staining and adaptation overtime

77
Q

why does a perfect hybrid layer not exist

A

all HL are subject to degradation overtime

78
Q

to reduce degradation in attempt to prolong the lifespan of composite restorations:

A

-increase the adhesive properties
- reduce the collagen degradation

Operative II (10 decks)

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