Clinical aspects of GICs Flashcards
which materials developed GICs
- silicate cements
- glass powder
- poly acrylic acid
briefly describe the structure of GICS
- glass particles are surrounded by poly acid chains in water
- long poly acid chains when glass ionomers first mixed
what are 3 stages in setting reaction
- dissolution
- gelation/hardening
- maturation
what occurs in the dissolution stage?
- in the dissolution phase, the poly acid is mixed with water and hydrogen ions are liberated
- leaving negatively charged carboxyl groups
- The hydrogen ions attack the glass causing calcium, fluoride and aluminium to be released
- since the poly acid chains have a lots go negative charge they bond to more than one chain causing the material to become solid
- there is also the release of fluoride ions which can move about within her material even after it has set
describe the hardening process of GICs
since the poly acid chains have a lots go negative charge they bond to more than one chain causing the material to become solid
- there is also the release of fluoride ions which can move about within her material even after it has set
Describe maturation of GICs
- Harder material as it matures
- fluoride can swim around fairly quickly
- During maturation, more and more Ca and Al ions cross link acid chains - but this takes time
- until they are cross linked however, they may be lost form the material into he saliva if the restoration gets wet- leaving it weak
- A coating og varnish or bonding resin will prevent this
- Initial set material is quite soft and brittle and takes a few days to become strong
why should a varnish be applied during maturation phase
- keeps the water balance in the material correct
- if it is not protected then it will lose calcium and aluminium ions that have not yet formed bonds
- If they are lost they will leave the material weaker
- improves wear resistance
Name 3 benefits of glass ionomer
- easy to use - doesn’t need bond, tolerates moisture
- chemically bonds to enamel and dentine
-released fluoride
describe what is used to condition the dentine and what dentine conditioning does
- 10% poly acrylic acid
- paint on, wash off after 20s and dry
- clean the tooth surface prior to placing glass ionomer
- It is a good idea to clear the smear layer off the surface of a cut cavity to improve bonding
What is a large factor of failure of GICS
- 50% if 790 GIC retsoraiton are removed due to secondary caries
What are the benefits of fluoride release GICs
- greater caries inhibition seen than amalgam
- significantly greater caries preventive effect than composite
- significantly fewer deminerlaised restoration margins in class II restorations in deciduous teeth
- GIC can be replenished with fluoride by topical flruodie application and even toothbrushing
what re disadvantages of GICs
- weak compared to other materials
-poor aeshtetics compared to composite - not as good as composite - poorer survival time compared to other materials
what glass ionomer was new in 1989
material more like composite by adding a resin to mix
- called RMGIC
describe propeorties of RMGICs
- better aesthetics
- command set
- more resistant to losing ions during maturation
- stronger
- stop acting like a GIC when cured
-lower flruodie release - polymerisation shrinkage
Describe RMGIC setting reaction
- prevents ions form being able to freely move
- no longer releasing fluoride as they are locked
- the stoppage of ions moving, means good aspects of GIC are reduced such as bonding to tooth and release of fluroide
- this only happens after light curing though
- advocated that dentist delays light curing as long as possible
What was the adaptation to GIC in mid 1990s?
- keep traditional GIC but change filler to give strength
- smaller glass particles
- high density materials are better and can make permanent restorations in small cavities posteriorly
- popular with peadiatric dentists due to tolerance of mositure and easy of use.
what is chemfil rock
- bonds to enamel
- bonds to dentine
-Bons to NPM - no conditioning
- no varnish required
- ideal for compromised clincal situations
- Inject, pack, remove excess, set
- not aesthetic
Problems with current GIs
weak (fracture easily, wear is high)
- complicated to use (conditioning and coating rewired)
- waiting time - sticky at first, short workable time
- resin modified materials cease to act like GIC once light cured
what are clinical indications to use GIC
traditional GIC- temporisation as contrasting colour helps removal without damaging structure
- simple to use
- stepwise excavation - preserve lie of tooth
- fissure sealant
- cervcial cavities
deserve clinical usage and indications for Zinc reinforced GICs (Chemfil rock)
Clinical usage
- no conditioner
- no varnish
Indications
- long term restoration
- caries management
- Fissure sealant
Describe clinical usage and indications for traditional GIC (fuji triage, fuji Ix, Chemfil)
- 10% poly acrylic acid
- varnish as soon as finished
indications
- subgingival restorations
- temporary restorations
- stepwise excavation
Describe the clinical stage and Indicatiosn for resin modified GIC (Fuji II)
- condition 10% poly acrylic acid
- light cure
- no varnish
Indications
- non load bearing restorations
- bonded amalgams
