Enamel bonding Flashcards

1
Q

what is adhesion

A

force that binds two dissimilar materials together when they are brought into intimate contact

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2
Q

what does the ability of adhesive depend on to contact a substrate

A

the wet ability of the adhesive on that particular substrate

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3
Q

what is non wetting

A

hydrophobic

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4
Q

what is wetting classes as

A

hydrophilic

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5
Q

what is wetting measured by

A

the contact angle

smaller contact angle more wettable

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6
Q

enamel

A

hardest and most mineralised substance the body

once formed no blood vessels r nerves

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7
Q

composition of enamle

A
96% hydroxyapitite
1% inorganic protiens
3% water
hexagonal rods of minerals
prismatic arrangement perpendicular to tooth surface
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8
Q

what can composite bonded to enamel do

A

improve appearance of teeth
mask further discolouration
prevent further wear and tear

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9
Q

what 2 things does acid etching do

A

increase surface roughness

raises surface energy

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10
Q

how does etching increase surface roughtness

A
  • acid base reaction prompts partial dissolution of hydroxyapatite
  • structural changes: loss of enamel prism periphery and prism core constituents
  • increase the roughness/bonding area
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11
Q

how does etching raise surface energy

A
  • Acid removes pellicle and exposes underlining surface of enamel
  • Raises surface tension encouraging wetting (resin/applicant needs to have a lower surface energy than enamel, therefore acid etching increases probability of adhesion)
  • Acid removes surface contaminates
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12
Q

what is needed to enhance addition/wetting

A

surface energy of the solid should be greater than the liquid to enhance addition/wetting

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13
Q

summary of what etching does

A

makes a retentive surface
micro mechanical bonding
increase surface area and energy

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14
Q

3 things to consider to prevent clinical probelsm

A

patent selection
enamel prophylaxis
application of etchant

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15
Q

what are resins and what does this mean

A

non polar

- prevents resin adapting to enamel so poor bond

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16
Q

enamel prophylaxis effects

A

needs to bond to the enamel not the pellicle and plaque on the tooth
etch won’t completely remove the plaque and pellicle
clean with slurry pumice and water for 30 secds

17
Q

application of etch

A

apply with cotton pledgt on clean surface
dont rub etchant onto surface
- breaks the tags that resin flows into and weakens bond