GIC and RMGIC Flashcards Preview

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Flashcards in GIC and RMGIC Deck (30)
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1
Q

What bonding does GIC use?

A

Chemical

2
Q

What are the applications of GIC?

A
  • Restorations
  • Luting
  • Bonding/conditioning
  • Protection
  • Fissure sealing
  • Protection of root surfaces against caries
3
Q

What are the two components of GIC?

A

Acid = poly acylic acid

Glass = calcium fluoroalumosilicate glass

4
Q

What component of GIC acts as the base?

A

Calcium fluoroaluminosilicate glass

5
Q

What shape does the GIC molecule have?

A

Tetrahedral shape

6
Q

What additives do we have to enhance the basic properties?

A

Sodium, calcium and strontium

7
Q

What acids do we use in GIC?

A

Polyalkenoic acid

such as polyacrylic acid and polyitaconic acid.

8
Q

Why is tartaric acid used in GICs?

A
  • It improves handling, extends the working time and sharpens the setting characteristics
9
Q

What does tartaric acid interact with in the GIC

A

It interacts with glass particles, liberating the aluminium ions which can then interact with the polymeric acid.

10
Q

How is GIC mixed on the pad?

A
  • Bottle containing powder and the liquid in dispensed in the squeezing bottle. Spoon is what measures out the powder.
  • Can see the mixing of the cement here, polymer mixing pad. 1 scoop of powder to 2 drops of liquid in this example. The drops of liquid need to come out as proper drops with no air bubbles.

Then mixing can be carried out by spatulating the liquid with the powder until a smooth mix is achieved.

11
Q

How long does GIC take to set?

A

2-3mins

12
Q

What are the 3 stages of GIC setting reaction?

A

1) Dissolution: powder is mixed with liquid and the acid attacks the outer part of the glass particles

2) Initiation gelation and hardening: the polymeric acid molecules upon ionisation adopt a more linear form which makes the carboxylic acid more accessible.
- The ions then released on the interaction of the polymeric acid with the glass then interact with the poly acid molecules to form ionic cross-links which causes gelation

3) Hydration of salts: the aluminium ions become more involved and aluminium polyacrylates are formed - maturation is progressive via hydration of matrix salts

13
Q

How are GICs mixed?

A
  • Usually powder and liquid

- Ratio of powder to liquid is important and manual mixing is susceptible to operator induced variability

14
Q

What are the two forms that GIC is dispensed in?

A
  • Powder and liquid phase

- Powder and aic (freeze died) and water

15
Q

What is the importance of the aqueous systems?

A
  • Provides ion transport
  • Acid-base setting reaction
  • Fluoride release
  • Bound into the set cement
  • Affects ultimate stability
16
Q

Why do we water in GIC?

A

To make it an aqueous system.
Water allows for ion transport, allowing for H+ ions to be released to attack the basic glass to start setting.
Without water, no setting can occur.

17
Q

Why do we need to get the level of water corect in GIC?

A

Too much moisture = can lead to loss of the polyacrylate chains.
Excess water causes sub-optimal properties of the cement leading to loss of physical properties and translucency.

Too little moisture = the cement will get cracked. The surface will be soft and there is a lot of the matrix forming ion.

18
Q

What are the 2 theories of how GIC adheres to the tooth?

A

One theory:

  • Polymeric acid molecules collate with the calcium in enamel.
  • Formation on calcium poly-alkenoic salts then occurs forming the bond

Another theory:

  • Adhesion is due to hydrophilic nature of GIC
  • Adhesion occurs through hydrogen bonding between the free carboxylic acid group of cement and the bound water on the surface of the tooth
19
Q

Why do we condition the tooth before placing GIC?

A
  • Removal of smear layer
  • Partial demineralisation of tooth surface
  • Increasing the SA
  • Allowing for micro-mechanical bonding (as well as the chemical)
20
Q

What governs the physical properties of GIC?

A
  • The powder to liquid ratio
21
Q

What does GIC appear like in the mouth?

A

Dense and opaque, tooth coloured.

22
Q

What bioactive property does GIC have?

A
  • It can release fluoride
23
Q

What are the minimum requirements for GIC for:

a) setting time
b) compressive strength
c) opacity

A

a) 2-6mins
b) 100mPa
c) 0.35-0.9

24
Q

What are the main + and - of GIC?

A

+ Fluoride release
+ Adheres to tooth via chemical bonding
+ Acceptable aesthetics
+ Low solubility after full maturation

  • Low fracture resistance
  • Susceptible to early water contamination
  • Short working time
  • Long setting time
25
Q

What is additionally added into RMGIC?

A

Hema molecules.

  • This is a molecule with a C=C bond that can be polymerised under light cure
  • It is a methacrylate molecule
26
Q

What is the main setting reaction in RMGIC?

A
  • Acid-base reaction

- Rapid set is due to polymerisation of 2-HEMA as another reaction

27
Q

What is the suggested main benefit of RMGIC over GIC?

A
  • Compressive, tensile and shear bond strength are higher
28
Q

What are the clinical considerations of RMGIC and GIC?

A
  • Adhesion to tooth so conservative cavity preparation
  • Isolation of GIC in early stages is advocated due to water uptake leading to staining
  • RMGIC has a low pH so in a deep cavity we need to use a lining material to prevent necrosis to pulp.
29
Q

What are giomers composed of?

Why were they deverlpoed?

A

Composites with glass ionomer cement filler particles.

To try and give a bioactive element to composites.

30
Q

What is the main advantage that GIC has over composites?

A

The ability to chemical bond to the tooth (no adhesive needed).