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
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
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
