Gic

By;Mhmood M.H. Radhi

BDSFinal year

• Glass ionomer cement is a tooth Glass ionomer cement is a tooth colored material, introduced by colored material, introduced by Wilson et al in 1970.Wilson et al in 1970.

• It can be used as luting cements It can be used as luting cements or lining under another or lining under another restoration or as restorative restoration or as restorative material.material.

I. For lutingII. For restoration

III. For liner & bases

Type II.1 Restorative esthetic

Type II.2 Restorative reinforced

TypeType

Type

Powder :-It is an acid soluble calcium fluroalumino

silicate glass.

Silica - 41.9%Alumina - 28.6%Aluminum fluoride - 1.6%Calcium fluoride - 15.7%Sodium fluoride - 9.3%Aluminum phosphate - 3.8%

Liquid :-Liquid :-1.Polyacrylic acid in the form co-polymer with

itaconic acid & malic acid .2.Tartaric acid: improves handling

characteristic & increase working time.3.Water : Medium of reaction & hydrates the reaction products

When the powder & liquid are mixed, Surface of glass particles are attacked by acid. then Ca, Al, sodium, & fluoride ions are leached into aqueous medium.

Calcium ion cross-link the poly acrylic acid chains, This forms a solid mass.In next phase, aluminum also begins to cross-link with poly acrylic acids chains. Water plays an important role in structure of cement. Initially it serves as the medium, later it slowly hydrates the matrix.The unreacted glass(powder) particle is covered by a silica gel.

The set cements consists of agglomeration of unreacted powder particles surrounded by a silica gel sheath and embedded in a matrix of hydrated calcium and aluminum cross-liked poly acrylic gel.

The exposure of cement to water before hardening is complete, leads to loss of cations and anions which form a matrix as they can be dissolved.

Thus it is very important to protect the cement surface after its placed in the mouth e.g. by applying a varnish

Initial solubility is high due to leaching of Initial solubility is high due to leaching of intermediate products.intermediate products.

The complete setting reaction takes place The complete setting reaction takes place in 24 hrs, cement should be protected in 24 hrs, cement should be protected from saliva during this period.from saliva during this period.

Adhesion :-Adhesion :-☻ It adheres well to enamel and dentine.It adheres well to enamel and dentine.☻ Glass ionomer cement bonds chemically to Glass ionomer cement bonds chemically to

the tooth structure.the tooth structure.Esthetics :-Esthetics :-GIC is tooth colored material & available in

differentshades. Inferior to composites. They lack translucency & rough surface

texture. It may be stain with time.

Biocompatibility :-Biocompatibility :- The GIC show high degree of compatibility with

living tissue. Pulpal response is mild due to - High buffering capacity of hydroxy apatite. - Large molecular weight of the polyacrylic

acid ,which prevents entry into dentinal

tubules.

Anticariogenic properties :-Anticariogenic properties :-•Fluoride is released from glass ionomer at the time of mixing & lies with in matrix.

1.Preparation of tooth surface :-2.Proportioning & mixing :- Powder & liquid ratio is 3:1 by wt. Powder

& liquid is dispensed just prior to mixing. First increment is incorporated rapidly

into the mix with stiff bladed spatula. Mixing done in folding method to

preserves gel structure. Finished mix should have a glossy surface. Stiff mixing spatula is preferred.

3. 3. Protection of cement during setting :-Protection of cement during setting :- GIC is extremely sensitive to air and water GIC is extremely sensitive to air and water

during setting.during setting. It should be protected from moisture as It should be protected from moisture as

well as drying during setting for few days. well as drying during setting for few days.

4. 4. Finishing :-Finishing :- Excess material should be trimmed from

margins. Hand instruments are preferred to rotary

tools to avoid ditching. Further finishing is done after 24hrs.

5.5.Protection of cement after Protection of cement after setting :-setting :-

Before dismissing the patient ,restoration Before dismissing the patient ,restoration is again coated with the protective agent is again coated with the protective agent to protect trimmed area.to protect trimmed area.

Failure to protect for first 24hrs results in Failure to protect for first 24hrs results in weaken cement.weaken cement.

♣ Adhesive Adhesive ♣ EstheticEsthetic♣ Fluoride releasingFluoride releasing

DisadvantagesDisadvantages:-:-♦ Susceptible to erosion and wearSusceptible to erosion and wear♦ brittlebrittle

1.1.Anhydrous GIC :-Anhydrous GIC :- Liquid is delivered in a freeze dried

form ,which is incorporated into the powder.

Liquid used is clean water.2.Resin modified GIC2.Resin modified GIC:- Powder component consist of ion leachable

fluroalumino silicate glass particles & initator for light curing.

Liquid component consist of water & poly acrylic acid with methacrylate & hydroxyl ethyl methacrylate monomer.

33.Metal modified GIC .Metal modified GIC :-:- Glass ionomer have been modified by Glass ionomer have been modified by

addition of filler particles ,to improve addition of filler particles ,to improve strength ,fracture toughness & resistance strength ,fracture toughness & resistance to wear.to wear.

Silver alloy admix :- This is made by mixing of spherical silver This is made by mixing of spherical silver

amalgam alloy powder with type II GIC amalgam alloy powder with type II GIC powder.powder.

Cermet:-Cermet:- Bonding of silver particles to glass Bonding of silver particles to glass

ionomer particles by fusion through high ionomer particles by fusion through high temperature sintering.temperature sintering.

4.4.Compomer Compomer :-:- Compomer is a composite resin that uses

an ionomer glass which is the major component of glass ionomer as the filler.

Small quantity of dehydrated polyalkenoic acid incorporated with filler particles,

Setting reaction is light activated. Adhesive system used with compomer is

based on acid etch found with all composite resin.

Resistance to fracture is one of the main limitation of using GIC. It is generally quite satisfactory for one-surface lesion but a two surface lesion is always at risk.

Resistance to abrasion and wear is little less than composite resin.

They also remain susceptible to dehydration through out lifespan, so that pt. with dry mouth should not have restoration with GIC.

Text book of pedodontics, Shoba Tandon, 2nd edition .

Dental material book, John J.M. 3rd edition.

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