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1. Glass Ionomer Cements
By: Abbas Naseem
abbas_naseem@yahoo.com
Oct 17, 2010

2. INTRODUCTION
Glass ionomer cement is a tooth coloured material, introduced by Wilson &
Kent in 1972.
Material was based on reaction between silicate glass powder & polyacrylic
acid.
They bond chemically to tooth structure & release fluoride for relatively long
period.
GLASS IONOMER CEMENTS
(a.k.a. glass polyalkenoate)
Silicate Cement Polycarboxylate
fluoride release Cement
tooth color adhesion to tooth
translucency
structure
Glass Ionomer Cement

3. CLASSIFICATION

4. CLASSIFICATION
Type I. For luting
Type II. For restoration
Type II.1 Restorative esthetic
Type II.2 Restorative reinforced
Type III. For liner & bases
Type IV. Fissure & sealent
Type V. As Orthodontic cement
Type VI. For core build up

5. Physical Properties
1. Low solubility
2. Coefficient of thermal expansion similar to dentin
3. Fluoride release and fluoride recharge
4. High compressive strengths
5. Bonds to tooth structure
6. Low flexural strength
7. Low shear strength
8. Dimensional change (slight expansion) (shrinks on setting,
expands with water sorption)
9. Brittle
10.Lacks translucency
11.Rough surface texture

6. •Indications for use of Type II glass ionomer cements
1) non-stress bearing areas
2) class III and V restorations in adults
3) class I and II restorations in primary dentition
4) temporary or “caries control” restorations
5) crown margin repairs
6) cement base under amalgam, resin, ceramics, direct and indirect gold
7) core buildups when at least 3 walls of tooth are remaining (after crown preparation)
•Contraindications
1) high stress applications
I. class IV and class II restorations
II. cusp replacement
III. core build-ups with less than 3 sound walls remaining

7. COMPOSITION

8. SETTING REACTION
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.

9. Setting Reaction
a) Acid-Base Reaction (metal + acid = salt)
b) Water is critical for the reaction to occur
c) If the material does not have this reaction, it is not a true glass ionomer. In
other words, if you do not have to mix anything, the material is not a glass
ionomer.
Reaction Steps
1. Acid soluble glass is attacked by the polyacids releasing Ca++, Al+++, Na+, and
F -.
2. Initially calcium, and later, aluminum replaces the hydrogens on the
carboxyl groups of the polyacids to make calcium and aluminum polysalts
3. The salts hydrate to form a gel matrix while the unreacted portion of the
glass particles are surrounded by silica gel that arises from the loss of the
surface cations.
4. The set cement consists of unreacted glass surrounded by silica gel bound
together by a matrix of hydrated calcium and aluminum polysalts.
5. Notice that fluoride is not an integral part of the matrix
formation, therefore it is available for release without compromising the
structural integrety of the restoration.

10. Reactions notes:
1. Water is what hydrates the salts and allows them to crosslink. Too much water
dilutes the metal ions resulting in an opaque restoration that lacks strength and
hardness. If water is lost during setting, the maturation of the cement will be
disrupted resulting in cracking and crazing of the material. Initially, water is loosely
bound and the material will dessicate quite readily.
2. At the initial set, calcium polysalts dominate the matrix and the cement is rather
opaque. As post-set maturation progresses, aluminum polysalts become the
dominate component and opacity decreases.

11. ROLE OF WATER
Reaction medium into which the cement forming cations are leached and transported
to react with poly acid to form a matrix
Hydrates siliceous hydrogel and metal polyacrylate salts formed.
Water can be of two forms:
1. Loosely bound water – Readily removed by Dessication
2. Tightly bound water- cannot be removed and is associated with the hydration shell
of the cation- polyacryate bond, particularly that of aluminium and some silica gel
water.
With aging, tightly bound water increases, increasing the strength, modulus of
elasticity and decreasing the plasticity.
Cement is stable in an atmosphere of 80% relative humidity
High humidity absorbs water hygroscopic expansion
Dry conditions loses water shrinking and crazing
Loss of water also retards cement formation.

12. Factors affecting the rate or setting
1. Glass composition:
Higher Alumina – Silica ratio, faster set and shorter working time.
2. Particle Size: finer the powder, faster the set.
3. Addition of Tartaric Acid:-
Sharpens set without shortening the working time.
4. Relative proportions of the constituents: Greater the proportion of
glass and lower the proportion of water, the faster the set.
5. Temperature

13. CEMENT STRUCTURE
• Cored filler is bound together by a hydrogel of calcium and
aluminium polyacrylates that contains fluorine as
fluoroaluminium polyacrylate.
• Filler particles contain a glassy core pitted by a siliceous
hydrogel.

14. GLASS IONOMERS
HYBRID = SC [Powder] and PCC [Liquid] = A.S.P.A.
H2O Si+4
PAA
SiO2, in Al+3
SiO2,
Al2O3, H2O Na+
Al2O3,
Na, Ca, Ca+2
Na, Ca,
F F-
F
PAA
Residual Glass Particle
SiO2,
POLYACRYLATE HYDROGEL
Al2O3, (initially Ca polyacrylate gel
Na, Ca, and later Al polyacrylate gel)
F
Si+4, Al+3, Ca+2, Na+, F- Ions

15. SETTING STEPS
Calcium poly salts are formed first, then followed by aluminum poly salts which cross
link with poly anion chain.
Set cement consist of unreacted powder particle surrounded by silica gel in amorphous
matrix of hydrated calcium & aluminum poly salts.
Calcium poly salts are responsible for initial set.
Aluminum poly salts form the dominant phase.
 Water plays an important role in structure of cement.
 After hardening, fresh cement is extremely prone to the cracking &
crazing, due to drying of loosely bound water .
 Hence these cements must be protected by application of varnish.
SETTING TIME
Type I 4 - 5 minutes
Type II 7 minutes

16. STAGES IN SETTING REACTION
(Based on the work of Crisp and Wilson 1972-1974)
1. Decomposition: of glass and release of cement forming metal ions
(A13+ and Ca2+)
2. Migration: of these metal ions into the aqueous phase of the cement.
3. Gelation: of the polyacid by metal ions leading to set.
4. Post set hardening: when metal ions become increasingly bound to
the polyacid chain. (continues for 24 hrs)
5. Further Slow Maturation: takes place even after 24 hrs. Translucency
develops further as does resistance of desiccation and acid attack.

17. PROPERTIES
Adhesion :-
☻ Glass ionomer cement bonds chemically to the tooth structure.
☻ Bonding is due to reaction occur between carboxyl group of poly acid & calcium of hydroxyl
apatite.
☻ Bonding with enamel is higher than that of dentin ,due to greater inorganic content.
1. Primarily chemical (calcium – carboxyl groups)
2. Micromechanical
3. Bond to enamel better than bond to dentin
4. Barriers to adhesion
i. smear layer not removed
ii. contamination (blood, saliva, too much water)
iii. setting reaction too far advanced before application (cement must
have a glossy surface when applying to tooth.)
Esthetics :-
GIC is tooth coloured material & available in different
shades.
Inferior to composites.
They lack translucency & rough surface texture.
Potential for discolouration & staining.

18. Biocompatibilty :-
• Pulpal response to glass ionomer cement is favorable.
• 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.
a) Pulp reaction – ZOE < Glass Ionomer < Zinc Phosphate
b) Powder:liquid ratio influences acidity
c) Manufacturer recommends using a Ca(OH)2 liner when within 0.5
mm’s of the dental pulp
Solubility & Disintegration:-
Initial solubility is high due to leaching of intermediate products.
The complete setting reaction takes place in 24 hrs, cement should be protected
from saliva during this period.

19. Anticariogenic properties :-
•Fluoride is released from glass ionomer at the time of mixing & lies with in matrix.
Fluoride can be released out without affecting the physical properties of cement.
Initial release is high. But declines after 3
months.
After this, fluoride release continuous for a
long period.
Fluoride can also be taken up into the
cement during topical fluoride treatment
and released again ,thus GIC act as fluoride
reservoir.

20. Fluoride Release
1. derived from flux used during glass fusion
2. fluoride release is not part of the structural matrix of the material
3. fluoride released in form of NaF
4. initial high fluoride release (1 – 2 day burst) followed by low sustained
release, constant release occurs at about 3 weeks
5. fluoride release requires water movement
6. more fluoride is released from Type II glass ionomers than from liners or luting
cements
7. applying varnish or resin to the surface of the restoration decreases fluoride release
until abrasion removes the coating.
8. restorations with larger surface area release more fluoride
9. materials must be recharged in order to provide fluoride levels necessary to
remineralize tooth structure.
10. most recharged fluoride released again in 24 hours
11. application of acidic fluorides should be avoided with glass ionomer restorations as
the acid will cause surface deterioration of the restoration.
12. higher fluoride releasing materials are more effective at reducing recurrent caries
than are low fluoride releasing materials.

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

22. MANIPULATION
1.Preparation of tooth surface :-
The enamel & dentin are first cleaned with pumice slurry
followed by swabbing with polyacrylic acid for 5 sec.
After conditioning & rinsing ,tooth surface should isolate
& dry.
2.Proportioning & mixing :-
 Powder & liquid ratio is 3.6:1 bywt. Powder & liquid is
dispensed just prior to mixing.
 First increment is incorporated rapidly to produce a
homogenous milky consistency.
 Mixing done in folding method to preserves gel structure.
 Finished mix should have a glossy surface.

23. 3. Protection of cement during setting :-
• Glass ionomer cement is extremely sensitive to
air & water during setting.
• Immediately after placement into
cavity, preshaped matrix is applied to it.
4. Finishing :-
Excess material should be trimmed from margins.
Hand instruments are preferred to rotary tools to
avoid ditching.
Further finishing is done after 24hrs.

24. 5.Protection of cement after setting :-
• Before dismissing the patient ,restoration is
again coated with the protective agent to protect
trimmed area.
• Failure to protect for first 24hrs results in
weaken cement.

25. Advantages of glass ionomer Disadvantages of glass ionomer
1. bonds to enamel and dentin 1. opacity higher than resin
2. significant fluoride release, can be 2. less polishability than resin
recharged 3. poor wear resistance
4. brittle, poor tensile strength
3. coefficient of thermal expansion similar to 5. poor longevity in xerostomic
tooth structure patients
4. tooth colored
5. low thermal conductivity ♦ Low fracture resistance.
6. 10 year clinical studies (conventional GI) ♦ Low wear resistance.
♦ Water sensitive during setting
♣ Inherent adhesion to the tooth surface. phase .
♣ Good marginal seal. ♦ Less esthetic compared to
composite.
♣ Anticariogenic property.
♣ Biocompatibilty
♣ Minimal cavity preparation required.

26. Uses :-
1. Anterior esthetic restoration material for class
III & V restorations.
2. For luting.
3. For core build up.
4. For eroded area .
5. For atraumatic restorative treatment.
6. As an orthodontic bracket adhesive.
7. As restoration for deciduous teeth.
8. Used in lamination/ Sandwich technique.

28. SANDWICH TECHNIQUE
Devolped by Mclean,
To combine the beneficial properties of
GIC & composite.
Clinical steps:-
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 orthophosphoric 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.

29. MODIFICATIONS
Modifications in the powder:
• Dried Poly Acrylic Acid (Anhydrous GIC)
• Silver-Tin Alloy (Miracle Mix)
• Silver-Palladium/ Titanium (Cermet cement)
• BisGMA, TEGDMA, HEMA (Light cure/Dual cure GIC)
Modifications in the liquid:
• Only water and tartaric acid (Anhydrous GIC)
• HEMA (Light cure components)

30. MODIFICATIONS
1.Water settable glass ionomer cement :-
• Liquid is delivered in a freeze dried form ,which is
incorporated into the powder.
• Liquid used is clean water.
2.Resin modified glass ionomer cement :-
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.

31. • Resin Modified Glass Ionomer
– Also known as:
• Visible Light Cure Glass Ionomers (VLC)
• Hybrid Glass Ionomers
– Composition
• Liquid
– Polyacrylic acid copolymer
– Tartaric acid
– Methacrylate groups (HEMA)
– Photoinitiator
• Powder
– Same powder as chemical cure glass ionomer
– Photosensitizer
• Setting Reaction
– Polymerization of resin + normal glass ionomer acid-base reaction
– If not supplied in two components, not a glass ionomer

32. •Requirements to be a Resin Modified Glass Ionomer Cement
i. Acid-base reaction critical to setting
ii. Have a pH change & formation of carboxylate salt
iii. Material must contain fluoroaluminosilicate glass, a polymeric
carboxylic acid and water
•Comparison to Conventional Glass Ionomer
I. Generally improved physical properties
II. Improved shades and translucency
III. Water sensitivity reduced
IV. Can be finished almost immediately
V. Slightly less fluoride release
VI. Fluoride can still be recharged
VII. Slight increase in thermal expansion
VIII. Can be dual or tri-cure
•Precautions
I. Must be light cured to achieve good bond
II. Fill in increments of 2 mm’s or less
III. Bond to dentin highly dependent on surface conditioning

33. 3.Metal modified glass ionomer cement:-
• Glass ionomer have been modified by addition of filler particles ,to improve
strength ,fracture toughness & resistance to wear.
Silver alloy admix / miracle mix:-
• This is made by mixing of spherical silver amalgam alloy powder with glass
ionomer powder.
Cerment:-
• Bonding of silver particles to glass ionomer particles by fusion through high
temperature sintering.
a) Strength Silver alloy admix (silver amalgam alloy particles mixed with glass particles)
b) Cermet (glass sintered with silver)
a) Physical Properties compared to conventional glass ionomer cement
a) Strength>> Same
b) Fracture Toughness>> Same
c) Wear Resistance>> Increased slightly
d) Fluoride release >> reduced with Cermet, same or slightly increased with admix

34. 4.Compomer :- ( POLYACID MODIFIED COMPOSITE RESINS )
1. Compomer is a composite resin that uses an ionomer glass which is the
major component of glass ionomer as the filler.
2. Small quantity of dehydrated polyalkenoic acid incorporated with filler
particles,
3. Setting reaction is light activated.
4. Adhesive system used with compomer is based on acid etch found with all
composite resin.
 Combination of composites (comp) and glass ionomers (omers).
 Compomer is a one-paste material consisting of fillers and a matrix that is similar
to that of composite resin.
 contains fluoroaluminosilicate glass powder as filler to release fluoride.
 Contains dimethacrylate monomer and carboxylic groups along with ion leachable
glass.
 There is no water in the composition
 Glass particles are partially silanated to ensure some bonding with the matrix.
 contains strontium or some other metal to make the material radiopaque

35. Giomers
•A recent addition to the continuum of hybrid materials is a class of anhydrous resin-
based restoratives that utilizes prereacted glass ionomer technology (PRG).
•E.g. Beautiful (Shofu); Reactmer paste (Shofu).
•Known as “giomers” in Japanese market, these materials incorporate fillers that are
produced from the complete or partial reaction of ion-leachable glasses with
polyalkenoic acid.
•giomers may contiain either fully prereacted (F-PRG) or surface prereacted (S-PRG)
fillers as part of the total filler composition.
•Unlike compomers, immediate fluoride release may occur from the PRG fillers
without the need for in-situ acid-base reaction via water sorption.

36. Conventional Resin- Compomers Fluoride Composite
Glass Modified Releasing Resin
Ionomer Glass Ionomer Resin
Typical Ketac-fil Fuji II LC, Dyract AP, GeriStore, Herculite XRV,
Products Fuji II, Fuji Photac-fil Elan, F2000, Variglass, Prisma TPH,
IX, *Ketac- Quik, Vitremer Compoglass Resinomer, Heliomolar,
silver, F Hytac Tetric Ceram,
Miracle Mix Solitaire,
SureFil
Fluoride High High Medium Low Lowest
Release (*Ketac-silver
medium)
Fluoride High High Some Very Low None
Recharge
Thermal Lowest Medium Highest
Expansion
Translucency Lowest Highest
Tensile Lowest Highest
Strength &
Fracture
Toughness

37. THANK YOU
Abbas Naseem(BDS)
Dated: Oct 17, 2010
abbas_naseem@yahoo.com