Glass Ionomers Flashcards
Glass ionomers are a tooth-colored restoration material composed of a ________________.
salt matrix
Glass ionomers are ___________ to tooth surfaces and rely on the chemical, calcium chelation bond formed between carboxylate groups of the glass ionomer and hydroxyapatite (tooth).
self-adhesive
chemical bond of GIs
calcium chelation bond between the carboxylate groups of the glass ionomer and hydroxyapatite (tooth)
Characteristics of GI:
- fluoride storage, released overtime within material
- weaker material
- less shrinkage
- uncontrolled and lengthier set time
GI vs composite resin
GI
- acid = polyacrylic acid, base = fluoro-alumino-silicate glass
- self-cure
- chemical bonding
- releases fluoride
- weaker
Composite resin
- matrix = bis-GMA, filler = barium silicate glass
- light or self-cure
- micromechanical bonding
- does not release fluoride
- stronger
Content of GI:
Acid- poly acrylic acid
Base- fluoro-alumino-silicate glass
How do RMGIs set?
acid-base reaction (GI) and free-radical addition polymerization (by light or chemical curing)
Characteristics of RMGI:
- free-radical initiation of resin induces more rapid polymerization
- some control over setting time with light cure
- more strength compared to conventional GI
- fluoride release (GI)
anhydrous single pastes which possesses primary elements of both CR and GI, except for water (anhydrous)
compomer (polyacid-modified resin composites)
commonly used in orthodontics as their slow polymerization provides more time to clean up excess around bands
compomers
benefit of compomers being anhydrous (no water)
Excluding water ensures that the initial setting occurs only by polymerization, which prevents untimely setting and increases setting time with proper moisture isolation.
The acid-base reaction of the GI occurs later with water absorption from the oral cavity.
set only by polymerization mechanism, but include ion-leachable glasses to release very minimal fluoride
ionomer-modified composites
