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Dental Materials > Lecture 8: Adhesion > Flashcards

Lecture 8: Adhesion Flashcards

1
Q

what is the definition of adhesion?

A

substance capable of strongly and permanently holding two surfaces together

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2
Q

what are the two types of adhesion in densitry?

A

-mechanical (micromechanical interlocking)
- chemical (true) adhesion

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3
Q

both mechanisms of adhesion (micromechanical and chemical) can be found _______

A

simultaneously (common with dental adhesions)

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4
Q

what are the steps for a typical composite bonding?

A

conditioning
primer
adhesive
composite

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5
Q

what are the key steps/techniques for good bonding?

A

clean adherence
good wetting
intimate adaptation
bonding
complete curing

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6
Q

what is etching/conditioning used for?

A

removal or modification of smear layer

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7
Q

what can be used for etching?

A
  • acids (37% phosphoric acid)
  • calcium chelators (EDTA)- without demineralization of dentin
  • functional monomers (10-MDP, 4-META, phenyl-P)
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8
Q

explain what enamels acid etching does?

A
  • converts smooth surface into a rough surface
  • creates micropores (5-500 um deep)
  • increases surface energy and wettability
  • prepares surface for micromechanical locking
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9
Q

explain what dentin acid etching does?

A
  • opens the dentin tubules for resin infiltration (for acid etching bonding systems)
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10
Q

explain what a smear layer is

A
  • cavity is preped and residual layer forms smear layer
  • fills dentin tubules, forming smear plugs
  • decreases dentin permeability
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11
Q

what are primers used for?

A
  • to increase the diffusion of resin into moist/ demineralized dentin after etching
  • similar to primers in paint and are usually air dried, not rinsed off
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12
Q

what are primers made of and what are common primers?

A
  • usually a solution of monomers, organic solvents (alcohol/acetone), water and stabilizers
  • common primers are HEMA and 4-META
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13
Q

what does it mean that primers are bi-functional agents?

A

contain monomers with a
- hydrophilic end with affinity for exposed collagen fibrils
- hydrophobic end with affinity for resin/adhesive

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14
Q

what is an adhesive resin?

A
  • link between primer and composite
  • solvent free (hydrophobic) low-viscosity resin that is applied over the primer that interacts and copolymerizes with the restorative material
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15
Q

what are some examples of adhesive resins?

A

unfilled or lightly filled monomers typically Bis-GMA, UDMA, TEGDMA

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16
Q

what are the three bonding strategies?

A
  • etch and rinse (total etch)
  • self etch
  • universal
17
Q

what does the etch and rise technique always use?

A

acid-etch step

18
Q

explain the etch and rinse strategy

A
  • oldest strategy
  • either 2 or 3 step process
  • etching + primer + bonding
  • etching + primer/bonding
  • wet bonding technique after acid etch
    -primary adhesion mechanism is mechanical locking
19
Q

explain the self etching strategy

A
  • no acid etching
  • primers contain functional monomers (carboxyl or phosphate) that can permeate and diffuse into dentin
  • partial demineralization
  • chemically interacts with hydroxyapatite
  • either 1 or two step process
  • acid/primer + adhesive (gold standard)
  • acid/primer/adhesive
  • primary adhesive mechanisms are mechanical locking/ chemical bond
20
Q

how are self etching strategies classified?

A

based on aggressiveness:
- strong (pH < 1)
- intermediate (pH = 1.5)
- mild (pH = 2)
- ultramild (pH > 2.5)

21
Q

what is universal/multi-mode adhesive and what is it available as?

A
  • most simple-to-use and versatile adhesive
  • available in ER (acid etching + universal bottle) mode and SE mode (universal bottle)
22
Q

what are some challenges for dental adhesion?

A
  • retention (bacteria and leaks)
  • degradation of biomaterials (bad environmental condutions)
  • technique (proper preparation)
  • handling (proper material and lamp use
23
Q

what can lack of retention cause?

A

sensitivity
failure
staining
2nd caries
inflammation

24
Q

what is the first challenge in bonding to dentin?

A
  • the presence of water and organic components lower the surface energy of dentin
  • water keeps collagen expanded and retains spaces for resin infiltration
  • dry collagen collapses and obstructs the resin from reaching the dentin
    *** presence of moist/wet dentin is needed
25
Q

what is the second challenge in bonding to dentin?

A
  • microstructure: the higher the tubule density, the lower the bond strength values of the dentin adhesives
26
Q

what is consepsis and what is its main function ?

A
  • 2% chlorhexidine gluconate solution used to clean/disinfect before bonding
  • its main function is antimicrobial activity and inhibition of metalloproteinases
27
Q

what is gluma and what is its main function?

A
  • collagen crosslinking agent with 5% glutaraldheyde, 35% HEMA, 60% water
  • cross link and stablize collagen

Dental Materials (8 decks)

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