DMS Flashcards
What are the components of conventional glass ionomer cement?
Tartaric acid, Polyacrylic acid, silica, aluminium dioxide, calcium fluoride, aluminium phosphate and sodium fluoride
What are the 3 stages of the setting reaction for GIC?
Dissolution, Gelation and Hardening
What happens during the Gelation Phase when GIC is setting?
crosslinking between bivalent calcium ions and poly acrylic acid form calcium polyacrylate
What happens during the dissolution phase when GOC is setting?
The H+ ions from the acid attack the surface of the glass, which results in Ca, Al, Na and F ions being released
What are the advantages of conventional glass ionomer as a restorative material?
Good bond to enamel and dentine without the need of an intermediate material
Good sealing ability
similar thermal expansion to dentine
no setting contraction
fluoride releasing
What are the disadvantages of glass ionomer cement?
Low bond strength compared to composite
poor tensile strength
poor wear resistance
higher solubility than composite
poor aesthetics - lack translucency
What is the function of Potassium Persuphate in RMGIC?
It is a redox catalyst
Explain the process of trigger-curing in relation to the setting of RMGIC
- on mixing the acid base reaction begins in the same way as conventional GIC
- the redox reaction also begins and continues for around 5 minutes after the initial mixing
- on light activation a free radical methacrylate reaction occurs, forming a resin matrix
- the hardening of the acid base reaction continues within the resin matrix
What are the advantages of RMGIC?
- Bonds to enamel and dentine
- better physical properties than conventional GIC
- fluoride releasing
- better translucency and aesthetics than conventional GIC
What are some disadvantages of RMGIC?
- HEMA is toxic so must be completely polymerised
- exothermic setting reaction - can irritate pulp
- swelling due to uptake of water - HEMA=hydrophilic
- polymerisation contraction
What are the advantages of Zinc Oxide Eugenol
- Adequate working time
- radiopaque
- fast setting
what are the disadvantages of ZOE?
low thermal conductivity
low strength
high solubility
What are the components of composite resin?
Filler particles, resin, camphorquinone, silane coupling agent, low weight dimethacrylates
What are the advantages of composite resin?
Good aesthetics
high compressive strength
on-command setting
low thermal conductivity
low thermal diffusivity
radiopaque
What are some disadvantages of composite resin?
High thermal expansion coefficient - higher than dentine
polymerisation shrinkage
doesn’t bond directly to tooth surface
