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operative 2 final > Week 7- fundamental concepts of enamel and dentin adhesion > Flashcards

Week 7- fundamental concepts of enamel and dentin adhesion Flashcards

1
Q

fundamental mechanism of enamel resin adhesion

A

formation of resin microtags in enamel surface

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2
Q

enamel adhesion made possible by

A

acid etch which makes enamel surface irregular

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3
Q

purpose of acid etch

A

makes enamel surface irregular -> resin penetrates surface -> polymerize and are then attached to enamel

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4
Q

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

A

adhesion

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5
Q

4 mechanisms of adhesion

A 
mechanical 
adsorption
diffusion
electrostatic
(MADE)
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6
Q

mechanical adhesion

A

interlocking of adhesive with irregularities in surface of substrate or adherend (enamel?)

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7
Q

absorption adhesion

A

chemical bonding between adhesive and adherend forces
primary (ionic, covalent)
secondary (H bonds)
valence forces

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8
Q

diffusion adhesion

A

between mobile molecules such as adhesion of two polymers through diffusion of polymer chain ends across interface

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9
Q

electrostatic adhesion

A

electrical double layer at interface of a metal with a polymer that is part of total bonding mechanism

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10
Q

4 types of dental adhesion

A

mechanical
adsorption
diffusion
combination of the above

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11
Q

microtags

A

small tags form across end of each rod

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12
Q

macrotags

A

tags form between enamel rods

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13
Q

what differentiates GI from resin based composite materials?

A

do not need to etch enamel/dentin with phosphoric acid gel

“self adhesive”

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14
Q

mechanical dental adhesion

A

penetration of resin and formation of resin rags with tooth structure

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15
Q

adsorption dental adhesion

A

chemical bonding to inorganic component (HA) or organic components (collagen I) of tooth structure

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16
Q

diffusion dental adhesion

A

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

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17
Q

what is critical for good adhesion?

A

close contact between adhesive and substrate (enamel or dentin)

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18
Q

adhesive failure

A
  1. cohesive failure in substrate
  2. cohesive failure within adhesive
  3. adhesive failure @ interface of substrate and adhesive
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19
Q

adhesive restoration technique uses

A 
17 different things
bonding, sealing, recontouring of teeth, 
improve retention for PftM or metallic crowns
bond all ceramic restorations 
cavity restorations (class I-VI)
bond ortho brackets & perio splints
desensitize exposed root surfaces
repair existing restorations
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20
Q

morphological patterns of acid etching - type I

A

dissolution of prism cores but keep prism peripheries

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21
Q

morphological patterns of acid etching - type II

A

dissolution of prism peripheries but keep cores

22
Q

morphological patterns of acid etching - type III

A

not related to prism morphology

23
Q

phosphoric acid concentration for etching

A

30-40%

24
Q

etching time

A

15-60 seconds

25
Q

bond strength

A

20-50 MPa

26
Q

low end estimate of bond strength to resist contraction stresses

A

17MPa

27
Q

Dentin adhesion relies on

A

penetrations of adhesion monomers into collaged network left exposed by acid etching

28
Q

what makes etching dentin difficult?

A

dentin tubules with collagen and liquid

29
Q

smear layer

A

after preparing tooth structure, remaining residual organic and inorganic components form layer of debris that fills dentin tubule orifices

removal results in fluid flow into exposed dentin - interferes with adhesion

30
Q

ratio between # bonded surfaces and unbonded surfaces

A

Configuration (C) factor

31
Q

stress relief within a 3D bonded restoration is limited by its

A

C-factor

32
Q

class I restoration C-factor

A

5 ; results in stress relief due to limited flow from only one free surface

33
Q

what may act to offset polymerization shrinkage effects?

A

water absorption by resin

34
Q

microleakage around dentin margins is potentiated by

A

difference in linear coefficient of thermal expansion between substrate (tooth) and restoration

35
Q

improves enamel seal:

A

extension of cavosurface bevel of enamel

36
Q

______ usually sufficient to prevent formation of marginal gaps by polymerization contraction stresses

A

enamel bond strengths

37
Q

loading and unloading of restored teeth can lead to:

A

damage or marginal gaps

38
Q

how to remove smear layer?

A

acid etch

39
Q

options for resin-dentin bonding

A

3 step etch and rinse adhesives

  1. phosphoric acid etching gel, rinse
  2. primer containing reactive hydrophilic monomers in ethanal, acetone, or water
  3. unfilled/filled resin bonding agent
40
Q

acid etch acts to

A

remove smear layer
demineralize intertubular and peritubular dentin
expose filigree of collagen fibers

41
Q

it is desirable for substrate to have ______ surface energy

A

high

42
Q

after etching, dentin is left with ______ surface energy

A

low

43
Q

what effect does primer in 3 step process have?

A

increases surface tension of dentin

44
Q

what happens when primer and bonding resin applied?

A

penetrate intertubular dentin and form resin-dentin interfusion hybrid zone and resin tags = good bonding

45
Q

two step etch and rinse adhesive

A
  1. etch

2. primer and adhesive in same bottle

46
Q

water trees associated with:

A

porosities in adhesive layer

47
Q

microleakage

A

passage of bacteria and toxins between restoration margins and tooth prep walls

bacteria can lead to pulpal irritation

48
Q

interfacial gap

A

develops when dentin adhesive system does not adhere immediately to dentin substrate
bacteria can penetrate this gap

49
Q

when all restoration margins are in enamel, quality and integrity of the bond remain:

A

unchanged
OR
degraded by hydrolysis

50
Q

nanoleakage

A

small porosities in hybrid layer or hybrid/mineralized dentin transition layer allow penetration of little particles of silver nitrate dye

51
Q 
spotted pattern in hybrid layer 
or 
reticular pattern in adhesive layer
(the RA says SHhhh)
result from:
A

nanoleakage

operative 2 final (8 decks)

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