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CSA Dental materials > CSA tooth coloured materials 2 GIC > Flashcards

CSA tooth coloured materials 2 GIC Flashcards

1
Q

What are the types of cements?

A

• Light cured GIC Resin modified glass polyalkenoate (hydrophilic)
• Compomer
- Polyacid modified resin cement (hydrophobic)
• Composite
- Composite (Hydrophobic)

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2
Q

What is GIC?

A

formed by acid-base reaction between fluoride (F) containing glass & polyacid

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3
Q

What can GIC be formed by?

A

o Liquid acid + powdered glass

o Freeze dried acid, powdered glass & water

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4
Q

What is the composition of acid and base

A
  • Fluoro-aluminio-phospho-silicate (base)

* Polyacid e.g. Polyacrylic acid or polymaelic acid

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5
Q

How to change setting of GIC?

A

o Change molecular weight of polyacid
o Change conc. of acid
o Control activity of glass

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6
Q

What are the advantages of GIC?

A
  • Very adhesive & sticks to tooth surface easily

- Cariostatic – releases fluoride

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7
Q

What are the disadvantages of GIC?

A
  • Technique sensitive
  • Moisture sensitive
  • not placed in stress bearing areas
  • Low tensile & fracture toughness
  • Poor wear resistance (Not for posterior fillings)
  • can pick up stain
  • Not command set so need to work quickly
  • appearance/strength change over time
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8
Q

What is the setting reaction ?

A

polyacid and base gives polysalt and water

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9
Q

What are the stages of setting reaction ?

A 
Stage 1 – Decomposition
Stage 2 – Migration
Stage 3 – Gelation
Stage 4 – post set hardening
Stage 5 – Maturation
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10
Q

What is decomposition in setting reaction?

A
  • Acid dissolves in water – forms viscos solution with glass spread
  • H+ ions dissociate from COOH groups on polyacid + displace cations on surface of glass
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11
Q

What is Migration in setting reaction?

A

• (Ca2+ / Al3+) migrate to neg charged ions in dissolved polyacid

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12
Q

What is Gelation in setting reaction?

A

• Cations form cross links in polymer chains > longer polysalts form, modified glass surface becomes a silica gel

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13
Q

What is post set hardening

A

• continues as more cations diffuse from gel to polymer chains

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14
Q

What is maturation in setting reaction?

A
  • Al3+ ions bound in cement matrix + precipitate
  • Ca2+ ions precipitate over 24 hours as well
  • setting is very slow
  • Formation of polysalts keeps occurring:
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15
Q

What happesn when Formation of polysalts keeps occurring:

A

o Hydration of polysalts

o Expanded gel structure

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16
Q

What does fluoride do in matrix?

A

• free to move & released from matrix w/o affecting structure of cement

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17
Q

What does GIC reduce at margins?

A

risk of secondary caries

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18
Q

What is the role of GIC?

A

• Slowly hydrates polysalts in mature cross linked matrix
o Increases strength
o Improves translucency
o Increases resistance to desiccation

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19
Q

What does excess water do ?

A

Contamination >Increases opacity, decreases strength + harness

20
Q

What does loss of water do ?

A

Desiccation >Increases crazing/cracking

21
Q

How is bonding to tooth structure via GIC ?

A
  • Ca2+ ions present in HAP, form cross links with PA chain

* chemical bond to enamel structure – seals against bacterial ingress

22
Q

How does GIC bond to dentine?

A

polyacid chains bond to collagen in dentine via carboxyl/amine groups via Hydrogen bond

23
Q

What does GIC release?

A
  • Fluoride released from glass by acid attack (polyacrylic)
    o Ions =free to move
    o Ions contribute to biocompatibility of material + capacity to inhibit recurrent caries
24
Q

What does biocompatibility describe?

A

materials property of being compatible with living tissue
o Plaque can’t thrive on GIC surface
o S. Mutans growth is inhibited by restorations

25
Q

What can the freshly mixed cement of pH 0.9-1.6 lead to ?

A

lead to a mild inflammatory pulpal response

26
Q

What promotes dentine bridge formation ?

A

o Direct pulp capping material

27
Q

Indications of GIC?

A
  • Cementation of rigid restorations e.g. bridges/veneers
  • Restorations of primary teeth
  • Class III/V carious lesions
  • Crown margin repair
  • Forms a base under amalgam/composite
  • Temporary restorations – carious cavities/ fractured tooth
28
Q

What are cemerts?

A
  • Silver particles fused with glass
  • poor aesthetics
  • Mechanical properties are worse
29
Q

What are indications of cemerts ?

A

•Core build up
o Low C of TE
o Good adhesion
o Brittle

30
Q

What is alternative cements?

A

• DiamondCarve + Diamond 90-(sets in 90 seconds)
o Based on glass & co polymer of
- Polyvinylphosphoric acid
- Polyacrylic acid

31
Q

Viscous GICs like Fuji IX, ketc?

A
  • increased powder: liquid ratio
    • Decreased water content
    • Smaller glass particles
    • increased strength
32
Q

What is the survival time of GIC?

A

6 years

33
Q

What is Kic?

A

measures fracture toughness

34
Q

What is RMGIC?

A

•GIC with addition of a small quantity of resin components

35
Q

What mods. are done to RMGIC?

A
  1. Water replaced by water/HEMA mix. (vitremer)

2. Mod. of polyacid side chains that polymerise by light curing mechanism (fuji II + Photac-fil)

36
Q

What is hydroxy ethyl methacrylate

A
  • Polymerises when exposed to light

* irritating and can be allergic to acrylate resins

37
Q

How are side chains modified in RMGIC?

A

• C=C bonds added to part of polymer chain >polymerisable functional groups

38
Q

What are the advantages of RMGIC?

A
  • Tooth coloured
  • Shorter setting
  • Sets on command
  • Less moisture sensitive
  • Increased tensile strength
  • Better wear characteristics
  • Easier to use
  • F release is moderate and can recharge – Acts as fluoride reservoir
  • Easier USE
  • Increased bond strength to composite
  • no bonding system
39
Q

What are indications of RMGIC?

A
  • Cervical + root caries
  • Base for composite/amalgam
  • Abfraction lesions >TSL occurs along gingival margin
40
Q

What is compounds of RMGIC?

A
  • BisGMA/UDMA are monomer, TEGMA/EDGMA are diluent monomers
  • Silane coupling agent
  • Inorganic fillers present
  • UV Stabilisers
  • Inhibitors
41
Q

What is compomer ?

A

Polyacid modified resin cement):

42
Q

What is compomer

A

• Acid-base functionality added to resin monomers

43
Q

What is composition of compomer ?

A
  • UDMA resin
  • TCB resin – contains C=C + COOH groups
  • Strontium fluorosilicate glass
  • Initiators & stabilisers
44
Q

What is setting mechanism of compomer?

A

1) light curing – induces polymerisation of resins
2) – Water uptake (from saliva/drinks etc.) = causes acid base reaction to take place & results in cross linking of matrix

45
Q

What are advantages of compomers ?

A
  • Good handling properties
  • Good strength
  • Command set
46
Q

What are disadvantages of compomers?

A
  • Poor adhesion
  • Requires bonding agent?
  • Less fluoride release –
  • not used as much
47
Q

What is chemfil rock-advanced GIC?

A
  • Added zinc makes stronger/tougher –
  • No conditioning cavity (less steps)
  • No varnish/Vaseline (like regular GIC’s)
  • used for temp restorations

CSA Dental materials (7 decks)

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