Luting Agents Flashcards

1
Q

what does the viscosity of a luting agent depend of

A

the size of the powder or filler particle in the material

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2
Q

what should the viscosity of a luting agent be

A

low to allow seating of the restoration without interference

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3
Q

why is it important for luting agents to be radiopaque

A

ceramic crowns are radiolucent which makes it easier to see marginal breakdown

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4
Q

what mechanical properties should a luting agent have

A

high compressive strength
high tensile strength
high hardness value

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5
Q

what are the two types of dental cement used for luting agents

A

zinc phosphate
zinc polycarboxylate

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6
Q

what are the two glass ionomer cements used for luting agents

A

conventional
resin modified

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7
Q

what reaction takes place in the zinc phosphate luting agents

A

acid-base reaction initially
then a hydration reaction

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8
Q

what is the powder aspect of zinc phosphate

A

zinc oxide
magnesium dioxide
alumina and silica

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9
Q

what is the liquid aspect of zinc phosphate

A

aqueous solution of phosphoric acid

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10
Q

what are some problems with zinc phosphate

A

low initial pH - pulpal irritation
exothermic setting reaction
not adhesive to tooth or restoration

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11
Q

what is the difference between zinc phosphate and zinc polycarboxylate cement

A

the phosphoric acid is replaced with polyacrylic acid

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12
Q

what is an advantage of zinc polycarboxylate cement

A

bonds to tooth surface in a similar way to glass ionomer cements

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13
Q

what are some problems with zinc polycarboxylate

A

difficult to mix
difficult to manipulate
soluble in oral environment at low pH
opaque

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14
Q

what is the reaction of glass ionomer cement

A

silica glass, aluminium oxide and calcium fluoride

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15
Q

what stages of reaction does glass ionomer go through

A

dissolution
gelation
hardening

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16
Q

how does glass ionomer bond to tooth surface

A

ion exchange with calcium in enamel and dentine
hydrogen bonding with the collagen in the dentine

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17
Q

what are some advantages of glass ionomer cements

A

low shrinkage
long term stability
aesthetically better than zinc phosphate
fluoride release
cheap

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18
Q

what is the reaction of resin modified glass ionomer

A

light activation causes polymerisation of the HEMA and copolymers in the material leading to initial rapid set

19
Q

what does the secondary cure of RMGIC occur due to

A

a redox reaction

20
Q

what does the secondary cure redox reaction allow for

A

dark curing - where the material is not exposed to light but will still cure

21
Q

what does the incorporation of resin improve

A

shorter setting time
longer working time
higher compressive strength and tensile strength
higher bond strength to tooth
decreased solubility

22
Q

what are disadvantages of RMGIC

A

HEMA is cytotoxic
HEMA swells - cannot be used with porcelain
no bond to indirect restoration

23
Q

what must composite luting agents be used in conjunction with

A

suitable DBA

24
Q

what is the trouble that occurs when trying to bond to porcelain

A

porcelain is brittle and its surface is smooth and unretentive so it needs a surface wetting agent

25
what surface wetting agent is used with porcelain
silane coupling agent gamma-methacryoxypropyltrimothoxysilane
26
what end of the silane coupling agent reacts with the composite luting resin
C-C double bond end
27
what end of the silane coupling agent reacts with the composite luting resin
C-C double bond end
28
what end of the silane coupling agent reacts with the porcelain
the oxide group side
29
how can we bond luting agents to metal
the metal surface needs to be roughened by etching or sandblasting
30
how does etching a metal's surface occur
electrolytes etching removes the different phases of the alloy at different rates
31
how would you bond to non-precious metal
4-META and MDP acidic end of the molecule reacts with the metal oxide
32
when bonding to metal why must you use a dual curing material
light will not penetrate the metal
33
how do you bond to precious metal
the metal coupling agent is incorporated into the composite resin
34
what is Panavia
a composite resin with metal coupling agent which is an anaerobic self cured material
35
what indirect restoration can GIC be used to bond
MCC metal posts zirconia crowns gold restorations
36
what indirect restorations can light cure composite and DBA used to bond
veneers
37
what indirect restorations can dual cure composite and DBA be used to bond
fibre post composite inlay porcelain inlays
38
what indirect restoration can anaerobic cure composite be used to bond
adhesive bridge
39
what are temporary cements
made to cement temporary restorations into place while permanent restoration is fabricated
40
how are the temporary cements supplied
2 pastes
41
what does the base of a temporary cement of
XnO, starch and mineral oil
42
what are the two main types of temporary luting agents
with eugenol withou
43
when should eugenol containing cements not be used to cement the provisional restoration
when the permanent restoration will be cemented with a resin cement
44
why should you not cement a temp with a eugenol containing material when the permanent will be cemented with a resin cement
any residual eugenol may interfere with the setting of the luting agent