Week 7- fundamental concepts of enamel and dentin adhesion

Question 1

fundamental mechanism of enamel resin adhesion

Answer 1

formation of resin microtags in enamel surface

Question 2

enamel adhesion made possible by

Answer 2

acid etch which makes enamel surface irregular

Question 3

purpose of acid etch

Answer 3

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

Question 4

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

Answer 4

adhesion

Question 5

4 mechanisms of adhesion

Answer 5

mechanical 
adsorption
diffusion
electrostatic
(MADE)

Question 6

mechanical adhesion

Answer 6

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

Question 7

absorption adhesion

Answer 7

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

Question 8

diffusion adhesion

Answer 8

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

Question 9

electrostatic adhesion

Answer 9

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

Question 10

4 types of dental adhesion

Answer 10

mechanical
adsorption
diffusion
combination of the above

Question 11

microtags

Answer 11

small tags form across end of each rod

Question 12

macrotags

Answer 12

tags form between enamel rods

Question 13

what differentiates GI from resin based composite materials?

Answer 13

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

“self adhesive”

Question 14

mechanical dental adhesion

Answer 14

penetration of resin and formation of resin rags with tooth structure

Question 15

adsorption dental adhesion

Answer 15

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

Question 16

diffusion dental adhesion

Answer 16

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

Question 17

what is critical for good adhesion?

Answer 17

close contact between adhesive and substrate (enamel or dentin)

Question 18

adhesive failure

Answer 18

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

Question 19

adhesive restoration technique uses

Answer 19

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

Question 20

morphological patterns of acid etching - type I

Answer 20

dissolution of prism cores but keep prism peripheries

Question 21

morphological patterns of acid etching - type II

Answer 21

dissolution of prism peripheries but keep cores

Question 22

morphological patterns of acid etching - type III

Answer 22

not related to prism morphology

Question 23

phosphoric acid concentration for etching

Answer 23

30-40%

Question 24

etching time

Answer 24

15-60 seconds

Question 25

bond strength

Answer 25

20-50 MPa

Question 26

low end estimate of bond strength to resist contraction stresses

Answer 26

17MPa

Question 27

Dentin adhesion relies on

Answer 27

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

Question 28

what makes etching dentin difficult?

Answer 28

dentin tubules with collagen and liquid

Question 29

smear layer

Answer 29

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

Question 30

ratio between # bonded surfaces and unbonded surfaces

Answer 30

Configuration (C) factor

Question 31

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

Answer 31

C-factor

Question 32

class I restoration C-factor

Answer 32

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

Question 33

what may act to offset polymerization shrinkage effects?

Answer 33

water absorption by resin

Question 34

microleakage around dentin margins is potentiated by

Answer 34

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

Question 35

improves enamel seal:

Answer 35

extension of cavosurface bevel of enamel

Question 36

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

Answer 36

enamel bond strengths

Question 37

loading and unloading of restored teeth can lead to:

Answer 37

damage or marginal gaps

Question 38

how to remove smear layer?

Answer 38

acid etch

Question 39

options for resin-dentin bonding

Answer 39

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

Question 40

acid etch acts to

Answer 40

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

Question 41

it is desirable for substrate to have ______ surface energy

Answer 41

high

Question 42

after etching, dentin is left with ______ surface energy

Answer 42

low

Question 43

what effect does primer in 3 step process have?

Answer 43

increases surface tension of dentin

Question 44

what happens when primer and bonding resin applied?

Answer 44

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

Question 45

two step etch and rinse adhesive

Answer 45

1. etch | 2. primer and adhesive in same bottle

Question 46

water trees associated with:

Answer 46

porosities in adhesive layer

Question 47

microleakage

Answer 47

passage of bacteria and toxins between restoration margins and tooth prep walls bacteria can lead to pulpal irritation

Question 48

interfacial gap

Answer 48

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

Question 49

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

Answer 49

unchanged OR degraded by hydrolysis

Question 50

nanoleakage

Answer 50

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

Question 51

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

Answer 51

nanoleakage