Glass Ionomer Flashcards
What is a use of Riva?
Restorative material- temporary material in permanent teeth and definitive restoration in deciduous teeth.
What is a use of vitrebond?
Cavity lining material.
What is a use of GI luting cement?
Cementing in MCC, metal posts and zirconia crowns.
What type of reaction occurs during setting of GI?
Acid-base reaction between poly acrylic acid and glass particles.
What happens during the dissolution phase?
Acid reacts with the gas particles- releases ions.
Leaves silica gel around unreacted glass.
What happens during the gelation phase?
Calcium ions cross link with the polyacid to form calcium polyacrylate.
Equates to the initial set of the materials.
What happens during the hardening phase?
Aluminium ions cross link with the calcium polyacrylate to form aluminium polyacrylate.
Does not start until 30 minutes after the initial set and can take up to 1 week.
Why is it important to place a protective agent over GI once it is placed in the cavity?
The material is moisture sensitive during the gelation and hardening phases.
Causes leaching of aluminium ions- which weakens the material.
What materials can be used to protect GIC after placement?
Varnishes, resins (dentine bonding agents), vaseline.
Why do you not need to etch before placing GI?
Gi bonds directly to enamel and dentine.
Chelation between carboxyl groups in the cement and hydroxyapatite on the tooth surface.
Hydrogen bonding to collagen.
Advantages of GI as a restorative material?
Similar thermal expansion to dentine
No contraction on setting
Fluoride release
Less susceptible to staining than composites.
Disadvantages of Gi asa. restorative material?
Poor tensile strength
Low compressive strength
Poor wear resistance
Soluble
Aesthetics- more opaque material.
