Glass Ionomer Restorative material

Question 1

Glass ionomer

Answer 1

• tooth colored material which is also known as glass polyalkenoate
• Silicate Glass Powder + Polyacrylic acid = GIC
• the powder is ion leachable glass. Calcium-Fluo-alumino-silicate. That reacts with ionomeric acid containing carboxyl group (Poly acrylic acid)

Question 2

GIC Composition

Answer 2

Powder: 1) silica
2) Alumina
3) Aluminum Fluoride
4) Calcium Fluoride
5) Sodium Fluoride
6) Aluminum phosphate

Liquid: 1) Polyacrylic acid
2) Tartaric acid
3) Water

Question 3

Different uses of GIC

Answer 3

• Luting
• restorative
• Cavity base and liner
• Pit and Fissure sealants
• Orthodontic cement
• Core Build-up

Question 4

The setting reaction

Answer 4

• When the powder and liquid are mixed, surface of the glass particles are attacked by acid. The Ca, Al, Na, and F ions are leached in to the aqueous medium
• calcium poly salts are formed first, followed by aluminum poly salts which cross link with poly anion chain.
• set cement consists of unreacted powder particle surrounded by silica gel in amorphous matrix of hydrated calcium and aluminum poly salts
• Calcium poly salts are responsible for initial set
• water plays an important role in structure of cement
• fresh cement is extremely prone to the cracking and crazing due to drying of loose bound water

Question 5

Properties of GIC

Answer 5

• Adhesion
• GIC binds chemically to the tooth structure, due to reaction between carboxyl group of poly acid and calcium hydroxyl apatite
  -Binding with enamel is higher than dentin due to higher inorganic content

Question 6

Aesthetic of GIC

Answer 6

• Aesthetics of GIC is poorer compared to composite
• they lack translucency and looks rough on the surface
• Lacks finishability of the restoration

Question 7

Biocompatibility of GIC

Answer 7

• Pulpal response to GIC is mild
• No other tissue irritation

Question 8

Anticariogenic Effect of GIC

Answer 8

• GIC is anticariogenic due to fluoride releasing property
• Initial fluoride release is high and then it declines over the time
• But GIC acts as fluoride reservoir, which means GIC replenishes the fluoride after topical application of fluoride