Glass Ionomers

Question 1

What are the properties of glass ionomers?

Answer 1

• contain fluoro-alumino-silicate
• adheres directly to enamel and dentine
• ? cariostatic properties from fluoride release
• brittle and relatively poor resistance to abrasion

Question 2

What is the setting reaction of GI?

Answer 2

1. acid from liquid component attacks glass
2. surface of glass reacts releasing cations (calcium and aluminium) and fluoride ions
3. cations cross-link polyacid molecules giving salt matrix and unreacted glass cores

Question 3

What are the advantages of glass ionomer?

Answer 3

• tooth coloured and translucent (glass cores)
• bonds directly to enamel and dentine, no adhesion system required
• easy to mix and manipulate
• fluoride release and uptake
• can be resin-modified to increase strength of material

Question 4

Disadvantages of GI cement?

Answer 4

• wear resistance and compressive strength significantly lower than that of composite
• poorer aesthetic results for anterior teeth
• finite working time, not command set

Question 5

What are the clinical indications of GI?

Answer 5

• abrasion and erosion cavities
• restoration of deciduous teeth
• class III and V restorations
• tunnel preparations
• temporary restorations
• ART
• root caries
• luting cement

Question 6

What are contraindications of GI?

Answer 6

• class I, II cavities in permanent dentition - wear resistance and strength a problem
• class III and IV unless no alternative

Question 7

What are the clinical indications of RMGIC?
What clinical considerations are there for GI?

Answer 7

• lining over calcium hydroxide
• has strength to withstand amalgam condensing
  GI clinical considerations:
• not fully set for 24 hours so final polishing after 24 hours
• material is sensitive to moisture for first 24 hours, place varnish or petroleum jelly