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BDS2.5 Dental Materials - operative dentistry > Glass Ionomer Cement 2 > Flashcards

Glass Ionomer Cement 2 Flashcards

1
Q

What are the 2 mechanisms which GIC bind to the tooth tissue?

A
  1. polyacrylic acid displaces surface phosphate and calcium an enters the hydroxyapatite structure and forming a calcium polyacrylate salt
  2. Intermediate layer of calcium and aluminium phosphates and polyacrylates are formed at the tooth/restoration interface
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2
Q

What is the bond strength like?

A

low, but good enough

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3
Q

Can the bond reform if broken?

A

YES, there is evidence

it is considered dynamic

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4
Q

Why can the material and tooth tissue rebond?

A

due to the polyacrylate and calcium ions being in close proximity to each other

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5
Q

What can improve the reliability of the bond?

A

preconditioning surface of the tooth by an acid conditioner

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6
Q

What is an example of an acid conditioner?

A

citric and polyacrylic acids

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7
Q

What does the acid conditioner do to the tooth?

A

primarily removes the smear layer and debris form the surface of the tooth

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8
Q

Between polyacrylic acid and citric acid, what one is favoured for acid conditioning?

A

polyacrylic acid

it is not so highly mineralised

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9
Q

Is the ability of GIC to seal good or bad?

A

pretty good - get little leakage

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10
Q

Does GIC dimensionally change?

A

little or no change

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11
Q

Is the bond between restoration and tooth stressed or unstressed?

A

unstressed

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12
Q

When are fluoride ion released form the glass?

A

during setting reaction

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13
Q

Where do the fluoride ions sit in the material?

A

within the matrix and free to migrate

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14
Q

What does the rate of release of fluoride ions depend on?

A
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15
Q

When are the most fluoride ions relased?

A

during maturation phase and slows and follow a normal diffusion pattern

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16
Q

How long are fluoride ions released from GIC?

A

YEARS

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17
Q

When can GIC take up fluoride ions?

A

if the eternal concentration is higher than that in the surface

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18
Q

How can you ‘recharge’ the GIC?

A

FLUORIDE TOOTHPASTE OR GEL

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19
Q

When does the GIC release the fluoride ions?

A

When the external fluoride conc drops aka fluoride sink

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20
Q

What can fluoride ion release prevent?

A

inhibit bacterial growth and plaque build up

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21
Q

When does rapid wear occur of GIC?

A

first 10 days then slows

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22
Q

What can happen to the GIC before maturation?

A

washout by saliva

23
Q

Why does wear occur of GIC?

A

due to loss of glass particles from the matrix particularly in load-bearing areas

24
Q

Can low ph erode GIC?

A

YES, if maintained for long periods of time

25
Q

What are the advantages of GIC?

A
26
Q

What are the disadvantages of GIC?

A
27
Q

When would you use GIC?

A

Atraumatic restorative technique (ART)

deciduous teeth

Tunnel preparations

class III

class V (especially non-carious tooth loss)

inter-visit endodontic access cavity restorations (especially with respect to resin composite)

long-term intermediate restoration

as a base layer or liner

dressings

fissure sealants

luting of crown and bridge retainers / orthodontic cements

28
Q

What cavities would you use GIC?

A

Class III and class V (especially non-carious tooth decay)

29
Q

What is luting?

A

a technique used to secure indirect dental restorations e.gf. crowns, bridges etc

30
Q

What should have a higher viscosity GIC, luting or restoration?

A

direct restoration - increased mechanical properties

31
Q

What is the downside to having a higher viscous GIC?

A

less liquid, so less acid, not going to get as good a bond

32
Q

When would you not use GIC?

A

Where high load is anticipated - class I or II)

large posterior cavities

cores where little or no tooth is remaining to support the material

where aesthetics are a primary concern

33
Q

Do you want a round or sharp cavity prep?

A

round - no sharp edges

34
Q

Do you need extensive retentive features in the cavity?

A

no need

35
Q

How does GIC appear after thoroughly drying?

A

whiter than tooth tissue

36
Q

What is the aim of conditioning the tooth?

A

clearing out the smear layer and cleaning the surface as well

37
Q

What do you use to condition the tooth?

A

a 25% solution of polyacrylic acid

38
Q

How long do you condition the tooth for?

A

15-30 seconds

39
Q

Do you cure of rinse off the conditioning solution?

A

wash off and gently dry

40
Q

What are the 2 methods to mix the GIC materials together?

A
  1. by hand
  2. encapsulation
41
Q

When would you mix GIC by hand?

A

to vary the materials consistency to suit application e.g. non-ideal crown

42
Q

What decreases when you increase the powder ratio of GIC?

A

The ability to form chemical bonds decreases (the cement must adequality wet the tooth surface)

rapid decline in mechanical properties also result because solid particles of glass are not wetted sufficiently by the acid to start setting reaction

setting time

43
Q

What increases when you increase the powder ratio?

A

compressive strength

44
Q

What is the scoop to drop ratio?

A

2:2

45
Q

What type of spatula is used?

A

agate

46
Q

What is the most common glass ionomer lute cement on the market?

A

aquaCem

47
Q

What has a higher powder to liquid ratio; hand or encapsulated?

A

in general the powder: liquid ratio of encapsulated materials is less than the recommended powder to liquid ratio for their hand mixed counterparts

48
Q

What is used when placing GIC for a class V?

A

cervical matrices

49
Q

For a class V restoration using GIC, when do you remove the tweezers from the surface of the cement?

A

until material has fully set

50
Q

How long do you wait before finishing?

A

at least 3 minutes

some up to 6 minutes

51
Q

How do you cause the least damage during finishing?

A

under fine water spray

don’t use petroleum jelly

52
Q

How long is water protection essential for?

A

at least an hour

53
Q

How do you protect the outer surface of the restoration from water?

A
  1. petroleum jelly
  2. copalite varnish
  3. fuji varnish (GC)
  4. RESINS

BDS2.5 Dental Materials - operative dentistry (22 decks)

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