CSA tooth coloured materials 2 GIC Flashcards by Zackee Chughtai

What are the types of cements?

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

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What is GIC?

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

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What can GIC be formed by?

o Liquid acid + powdered glass

o Freeze dried acid, powdered glass & water

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What is the composition of acid and base

Fluoro-aluminio-phospho-silicate (base)

* Polyacid e.g. Polyacrylic acid or polymaelic acid

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How to change setting of GIC?

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

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What are the advantages of GIC?

Very adhesive & sticks to tooth surface easily

- Cariostatic – releases fluoride

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What are the disadvantages of GIC?

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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What is the setting reaction ?

polyacid and base gives polysalt and water

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What are the stages of setting reaction ?

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

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What is decomposition in setting reaction?

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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What is Migration in setting reaction?

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

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What is Gelation in setting reaction?

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

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What is post set hardening

• continues as more cations diffuse from gel to polymer chains

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What is maturation in setting reaction?

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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What happesn when Formation of polysalts keeps occurring:

o Hydration of polysalts

o Expanded gel structure

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What does fluoride do in matrix?

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

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What does GIC reduce at margins?

risk of secondary caries

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What is the role of GIC?

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

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What does excess water do ?

Contamination >Increases opacity, decreases strength + harness

What does loss of water do ?

Desiccation >Increases crazing/cracking

How is bonding to tooth structure via GIC ?

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

* chemical bond to enamel structure – seals against bacterial ingress

How does GIC bond to dentine?

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

What does GIC release?

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

What does biocompatibility describe?

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

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

lead to a mild inflammatory pulpal response

What promotes dentine bridge formation ?

o Direct pulp capping material

Indications of GIC?

* 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

What are cemerts?

* Silver particles fused with glass * poor aesthetics * Mechanical properties are worse

What are indications of cemerts ?

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

What is alternative cements?

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

Viscous GICs like Fuji IX, ketc?

- increased powder: liquid ratio • Decreased water content • Smaller glass particles • increased strength

What is the survival time of GIC?

6 years

What is Kic?

measures fracture toughness

What is RMGIC?

•GIC with addition of a small quantity of resin components

What mods. are done to RMGIC?

1. Water replaced by water/HEMA mix. (vitremer) | 2. Mod. of polyacid side chains that polymerise by light curing mechanism (fuji II + Photac-fil)

What is hydroxy ethyl methacrylate

* Polymerises when exposed to light | * irritating and can be allergic to acrylate resins

How are side chains modified in RMGIC?

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

What are the advantages of RMGIC?

* 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

What are indications of RMGIC?

* Cervical + root caries * Base for composite/amalgam * Abfraction lesions >TSL occurs along gingival margin

What is compounds of RMGIC?

* BisGMA/UDMA are monomer, TEGMA/EDGMA are diluent monomers * Silane coupling agent * Inorganic fillers present * UV Stabilisers * Inhibitors

What is compomer ?

Polyacid modified resin cement):

What is compomer

• Acid-base functionality added to resin monomers

What is composition of compomer ?

* UDMA resin * TCB resin – contains C=C + COOH groups * Strontium fluorosilicate glass * Initiators & stabilisers

What is setting mechanism of compomer?

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

What are advantages of compomers ?

* Good handling properties * Good strength * Command set

What are disadvantages of compomers?

* Poor adhesion * Requires bonding agent? * Less fluoride release – * not used as much

What is chemfil rock-advanced GIC?

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