Summary cards Flashcards

(58 cards)

1
Q

What is the composition of dental amaglam?

A

50% mercury
50% metal alloy

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2
Q

what is in dental amalgam alloy?

A

silver, tin, copper, zinc

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3
Q

what is silver and coppers properties in dental amalgam?

A

strength

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4
Q

what is tins properties in dental amalgam?

A

corrosion

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5
Q

what is zincs properties in dental amalgam?

A

deoxidiser - prevents oxidisation of other metals in the alloy

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6
Q

what happens to zinc in dental amalgam is contaminated with moisture?

A

it can expand

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7
Q

what is it called when amalgam is mixed?

A

trituration

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8
Q

what components are involved in the setting reaction of dental amalgam?

A

mercury and silver

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9
Q

what does dental amalgam setting reaction involve in?

A

3 phases:
Y
Y1
Y2

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10
Q

What is the Y phase of dental amalgam setting?

A

unreacted silver-tin alloy

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11
Q

what is the Y1 phase of dental amalgam setting?

A

strong silver-mercury matrix

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12
Q

what is the Y2 phase of dental amalgam setting?

A

weak tin-mercury

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13
Q

why is the Y2 phase of dental amalgam setting weak?

A

susceptible to corrosion and creep

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14
Q

what is creep?

A

deformation of amalgam under compressive stress

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15
Q

on trituration what are the dimensional changes?

A

30mins shrinkage
30-60mins

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16
Q

what is an advantage of corrosion products?

A

margin seal

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17
Q

when does dental amalgam reach its peak strength?

A

24 hours

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18
Q

what are the 2 alloy types for dental amalgam?

A

conventional
high copper

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19
Q

what percentage of copper differentiates types of amalgam alloys?

A

12%

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20
Q

why is high copper alloy better for dental amalgam?

A

doesnt result in Y2 phase = less corrosion and creep

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21
Q

what are the 2 types of dental amalgam alloy particles?

A

spherical and admixed (spherical and lathe-cut)

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22
Q

what are 3 advantages of a spherical alloy for dental amalgam?

A

easier to condense
stronger
sets faster

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23
Q

what is an advantage of an admixed alloy particle for dental amalgam?

A

better proximal contact

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24
Q

what minimum depth should amalgam be placed in?

25
how should dental amalgam be placed and filled?
in 2mm increments overpack carve back mercury layer
26
are enamel or dentin bonds weaker?
dentine
27
why are enamel bonds stronger than dentine?
enamel has more mineral content enamel rods are parallel and more etchable
28
why has dentine got weaker bonds than enamel?
more organic matter and water collagen fibres that are maze like dentinal fluid smear layer
29
what is used for acid etching?
30-40% phosphoric acid
30
how long do you leave acid etch on for?
15 seconds
31
what does acid etching do?
cleans surface debris and removes smear layer widens dentinal tubules
32
what does enamel look like after it has been etched?
frosty white
33
what component of primer allows for a good bond?
HEMA
34
How does HEMA allow for a good bond?
infiltrates enamel prisms and dentinal tubules and WETS dentine to prevent collagen collapsing
35
what are the contraindications of HEMA in primers?
can cause allergic reaction on skin - contact dermatitis
36
What is the component of bond/ adhesive?
Bis-GMA
37
What does bond/ adhesive do?
chemically bonds to underlying primer and overlying composite resin
38
what is the key to great bond strength?
hybrid layer
39
what does the hybrid layer create?
mechanical interface between tooth and adhesive
40
what are resin tags?
extensions of primer into dentinal tubules
41
what is resin composite made of?
resin matrix (Bis-GMA) and glass filler particles (silica)
42
what is in resin composite that promotes adhesion between resin matrix and filler?
coupling agent
43
what does coupling agent do in resin composites?
coats filler particles to promote adhesion between resin matrix and filler
44
what makes resin composite radioopaque?
filler
45
what setting reaction does resin composite undergo?
polymerisation
46
what are the 2 pastes involved in self curing composite?
benzoyl peroxide (initiator) tertiary amine (activator)
47
what component allows composite to be light cured?
camphorquione (photo initiator)
48
how strong does light need to be to initiate polymerisation?
468nm
49
What makes up a glass ionomer?
acid (polyacrylic acid) base (aluminosilicate glass)
50
what are the good properties of glass ionomer?
self-adhesion to tooth fluoride release less overall shrinkage
51
what process makes glass ionomer self adhesive?
chelation
52
what are the bad properties of glass ionomer?
weaker longer setting time lack of control when setting
53
adding light curing resin to glass ionomer makes it a?
resin-modified glass ionomer
54
what setting reactions do resin-modified glass ionomers undergo?
acid base free radical addition polymerisation
55
what ways can resin-modified glass ionomers be set?
light and/or chemical
56
what is vitrebond??
resin-modified glass ionomer liner
57
what are good properties of resin modified glass ionomers?
more rapid polymerisation fluoride release
58
if a cavity is deep to pulp what would you use before vitrebond and why?
dycal as vitrebond is an irritant to pulp