GLASS IONOMER CEMENT Dr.linda maher

GICs tooth colored fluoride releasing materials that bond to tooth structure without an additional bonding agent.

composition 1\POWDER Acid soluble calcium fluroalumino silicate glass. Alumina - 28.6% Aluminum fluoride - 1.6% Calcium fluoride - 15.7% Sodium fluoride - 9.3% Aluminum phosphate - 3.8%

2\LIQUID 1.Polyacrylic acid. 2.Tartaric acid. 3.Water.

MIXING

The powder/liquid mixing ratios are identified by the manufacturer There is difference in mixing ratio according to the use of cement (restorative cement is thicker) After proportioning the liquid and powder , mixing is done with plastic instrument (the spatula) in paper pad

SETTING REACTION ACID BASE REACTION occurs when mixing powder and liquid The acid is neutralized by the base , and fluoride and other ions released

Hence these cements must be protected by application of varnish. SETTING TIME: 6-8 minutes After hardening, fresh cement is extremely prone to the cracking, due to drying of loosely bound water. Hence these cements must be protected by application of varnish.

TYPES OF GIC 1\TRADITIONAL GIC TYPE 1 : luting (cementation ) agent TYPE 2 : restorative material TYPE3 : liners and bases for cavity preparation. Materials in these three types are similar in chemical composition , but differ in: 1\size of powder particles 2\ratios of powder to liquid

Type I luting Type II restorative Type III liners and bases

2\METAL MODIFIED GIC 1\ miracle mix 2\ cermet cement This is made by mixing of spherical silver amalgam alloy powder with glass ionomer powder. 3\HYBRID(RESIN MODIFIED)GIC conventional GIC with addition of a resin monomer and photo initiator It is light cured

SUPPLIED IN THREE FORMS 1\hand-mixed powder and liquid 2\encapsulated powder and liquid 3\two paste system

Properties of GICs 1\BIOCOMPATIBILITY: biocompatible to pulp and surrounding tissue 2\BOND TO TOOTH STRUCTURE: they make chemical bonding with tooth structure without intermediate bonding agent Bonding to enamel is stronger than to dentine 3\SOLUBILITY They are highly soluble in water during the first 24 hours of placement and must be covered with a protective varnish.

4\COMPRESSIVE STRENGTH: relatively low in strength(weaker than composites) 5\WEAR RESISTANCE: Wear faster than composite resin 6\THERMAL CONDUCTION: They are good thermal insulators

7\FLUORIDE RELEASE: GICs contains fluoride as one of their compositions They release an initial high level of fluoride for the first few days ,then the level falls down. They can absorb fluoride from in-office applications , fluoride rinses ,toothpastes and re-release it , thereby acting as a fluoride reservoir This can help in prevention of dental caries

MANIPULATION 1.Preparation of tooth surface : 2.Proportioning & mixing : 3.Filling: 4. Finishing : 5.Protection of cement after setting

ADVANTAGES of GIC Inherent adhesion to the tooth surface. Anti-cariogenic property. Biocompatibility

DISADVANTAGES Low fracture resistance. Low wear resistance. Water sensitive during setting phase . Less esthetic compared to composite.

INDICATIONS Anterior esthetic restoration material for class III & V restorations. For luting As an orthodontic bracket adhesive. As restoration for deciduous teeth. Used in Sandwich technique.

SANDWITCH TECHNIQUE Developed by Mclean. To combine the beneficial properties of GIC and composite

After cavity preparation, condition the cavity to develop good adhesion with GIC. Place Type III GIC into prepared cavity. After setting, etch the enamel & GIC with phosphoric acid for 15 seconds. This will improve micromechanical bond to composite resin

Apply a thin layer of low viscosity enamel bonding agent & finally place the composite resin over GIC & light cure it

ADVANTAGES OF SANDWITCH TECH. Favorable pulpal response of GIC Better strength, finishing, esthetics of overlying composite resin.

Thank you .