GIC Flashcards
What is the glass filler made from?
Silica and alumina in a CaF flux
SiO2 and al2o3
Minor SAF and CAP
Sodium and aluminium fluoride
Calcium and aluminium phosphate
What are the four major components of GIC?
Filler
Water
Poly acid
Tartaric acid
What is a flux?
This has a lower melting point that the other components which means to when the mixture is ground up and heated the flux melts first and bing
SS the other components together
What’s the purpose of the minor fillers?
They act as fluoride sources and fluxes
How are the glass fillers produced?
Fused at a high temp and the fluxes then melt and bong the other particles together they are then shock cooled to a fine powder
T/F the filler does not the part in the setting of GIC
F
It is reactive and provides the strength, colour, reduce crack propagation, radiopacities
What size part files are available?
Depends on the intention to use
Less then 50 microns is for fillings less than 20 microns is for outing and lining cements
What is type of polya acid is most commonly used?
Poly acrylic acid
May be a co polymer of acrylic and maleic or acrylic and itaconic acid
Carbon backbone with COOH pendant groups
What is the name of the stronger poly acid used?
Poly vinylohosphonic acid which claimed to be a stronger acid there for he GIC cents harder stronger and faster
What is the purposive of the tartaric acid?
This gives the GIC a snap set
What is the purpose of water?
The GIC sets in an aqueous environment
What are the phase of GIC set?
- Dissolution: water attacks poly acid which contain COOH groups, this then causes the COOH to break down and H ions are released. These H ions attack the glass particles and cause them to release NA, Ca, F and Al particles and a layer of silica gel
- Gelation: Ca ions join together the polyacid
- Tartaric acid chelates the Ca ions to enable…
- ….Hardeing: this is where Al ions for the trivalent bonds with the COO atoms
How long does it take GIC to fully set?
Slow
Up to 7 days
What can happen to the GIC during the setting phase? How can you prevent this?
It can desiccate or be contaminated with excess moisture
Place a suitable varnish
What are the properties of GIC?
- Fluoride release. Initial burst of fluoride which can then be recharged
- Adhesion to enamel and dentine
How does GIC adhere to enamel?
Via PAIRS of calcium bond to the HAP
How does GIC bond to dentine?
Via H bonding to collagen and pairs of calcium bonds to HAP
T/F there is an intermediate layer of polyacrylate, free Ca and PO4 ions
T
What is the bond strength of GIC to enamel and dentine?
2-7MPa
Where does the bond failure usually occur with GIC?
Usually due to a cohesive failure within the material,rather than at the tooth interface
What type of setting reaction do GIC’s set via?
Acid base
Which materials can release fluorides?
RMGIC
GIC
Compomer
How does fluoride react with tooth?
- Forms FAP which forms a layer around the HAP and is mor acid resistant
- CaF is formed and acts as a reservoir this enables FAP to form during an acid attack
Where is most of the evidence for showing the effectiveness of fluoride release in enamel and dentine?
In vitro studies
Where is it likely that fluoride release is more effective, enamel or dentine?
Dentine (small evidence)
In vitro, enamel demin adjacent to GIC has been shown to be reduced compared to composite?
T
T/F
In vitro studies it has been shown that fluoride release can reduce artificial caries?
T
By how much is the demin inhibited by from the edge of the restoration?
7mm
What did the in vivo study show with regards to hyper mineralisation with GIC?
This was seen in dentine and not enamel and only with GIC and not composite or amalgam
Where are GIC used?
In cavities
Wear cavities
Lining material
Luting material
What is meant by snap set?
Longer working time and short set time
What is a chelator?
Molecule that can sequester metal ions removing them from other reactions
