GLASS IONOMER CEMENT Dr.linda maher
Dec 23, 2015
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.
Silica - 41.9%Alumina - 28.6%Aluminum fluoride - 1.6%Calcium fluoride - 15.7%Sodium fluoride - 9.3%Aluminum phosphate - 3.8%
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
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 GIC1\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
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.
INDICATIONS1. Anterior esthetic restoration
material for class III & V restorations.
2. For luting
3. As an orthodontic bracket adhesive.
4. As restoration for deciduous teeth.
5. Used in Sandwich technique.
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.