material aspect of glass ionomer cement

1. FINAL YEAR BDS
GLASS IONOMER CEMENT
MATERIAL ASPECT OF

2. CONTENTS
1.DEFINITION
2.CLASSIFICATION
3.COMPOSITION
4.SETTING REACTION
5.PROPERTIES
6.INDICATIONS
7CONTRAINDICATIONS
8.ADVANTAGES
9.DISADVANTAGES
10.USES

3. DEFINITION
Glass-ionomer is the generic name of a group of materials that
use silicate glass powder and aqueous solution of polyacrylic
acid” -Kenneth J Anusavice
Glass ionomer is a basic glass & an acidic polymer which
sets by an acid –base reaction between these components.
-JW MCLEAN, LW NICHOLSON, AD WILSON
Glass ionomer is a water based material that hardens
following an acid-base reaction between fluroaluminosilicate
glass particle & an aqueous solution of polyacid.
-DAVIDSON & MAJOR
A non metallic material used for luting, filling permanent or
temporary restorative purposes,made by mixing components
into a plastic mass that sets or as an adherent sealer in
attaching various dental restoration in or on the tooth. ---
According to CRAIG

4. CLASSIFICATION
A.ACCORDING TO A.D. WILSON AND J.W.McLEAN IN 1988
Type I --- luting cements
Type II --- restorative cements
a.Restorative aesthetic
b.Restorative reinforced
B. ACCORDING TO SKINNERS
Type I – Luting
Type II- Restorative
Type III- Liner and base
C. ACC.TO CHARACTERISTICS SPECIFIED BY MANUFACTURER
• Type I --- Luting cement
• Type II --- Restorative material
• Type III --- a. Bases & liners
• Type IV --- Admixture

5. D. ACCORDING TO J.W.McLEAN et al IN 1994
- Glass ionomer cement (traditional)
-Resin modified glass ionomer
cement
-Poly acid modified composite
resins
E. ACCORDING TO INTENDED APPLICATIONS
• Type I – Luting
• Type II – Restorative
• Type III – Liner/base
• Type IV – Pit & fissure sealant
• Type V – Luting for orthodontic purpose
• Type VI – Core buildup material
• Type VII – High fluoride releasing command set
• Type VIII – Atraumatic restorative treatment
• Type IX − Pediatric Glass Ionomer cements

6. F. NEWER CLASSIFICATION
• Traditional glass ionomer
a. Type I --- Luting cement
b. Type II --- Restorative cements
c. Type III --- Liners&Bases
• Metal modified Glass Ionomer
a. Miracle mix
b. Cermet cement
• Light cure Glass Ionomer
Hybrid Glass Ionomer/resin modified Glass Ionomer
a.Composite resin in which fillers
substituted with glass ionomer particles
b.Precured glasses blended into composites

7. COMPOSITION
COMPONENT WEIGHT%
SiO2 [Quartz] 41.9%
Al2O3 [Alumina] 28.6%
CaF2 [ Calcium fluoride] 15.7%
NaF[Sodium flouride] 9.3%
AlF3[Aluminum fluoride] 1.6%
:
The composition of the powder is an acid soluble calcium fluoroaluminosilicate
glass.
Formed by fusing silica[Sio2], alumina [Al2O3], calcium fluoride / fluorite(CaF2),
metal oxides and metal phosphates at 11000C to 15000C temperature.

8. •LIQUID
•Polyacrylic acid --- 45 %
•Water --- 50 %
•Modifiers Iticonic acid --- 05 %
maleic acid
tricarballylic acid
•Tartaric acid
•The liquid was an aqueous solution of in a
concentration of about 50%.
•The liquid was quite viscous and tended to gel over time.
•Hence, acrylic acid was copolymerised with other acids such
as iticonic ,maleic and tricarballylic acid.

9. The use of copolymer :
- Decrease the viscosity of the liquid
- Reduces the tendency for gelation and thus
improving storage
- Increases the reactivity of the liquid
•It is one of the most important
constituents of glass ionomer cement.
•It is the reaction medium

10. Setting reaction

11. 1.Leaching:
THE POWDER & LIQUID ARE MIXED TOGETHER
THE ACIDS ATTACKS THE GLASS PARTICLES
CALCIUM ,ALUMINUM,SODIUM & FLUORIDE IONS
LEACH OUT INTO THE AQUEOUS MEDIUM
2.Calcium cross links:
After initial set occurs
Calcium ions then binds with
the polyacrylic acid chains &
forms a solid mass
3.Aluminum cross
links:
In next phase ,the aluminum
also begins to binds with the
polyacrylic acids chain.
Process of setting reaction

12. 4.Sodium & fluorine ions: Theses ions are not take part in the cross linking
.Some of the sodium ions may replace the hydrogen ions in the carboxylic
groups. The rest combine with fluorine to form sodium fluoride which is
uniformly distributed within the cement.
5.Hydration : Water plays a very important role in the cement.initially it
serves as the medium.Later it slowly hydrates the matrix , adding to
the strength of the cement.
6.Silica gel sheath: The unreacted glass powder particle is covered by
a silica gel. It is formed by the leaching of the ions[ Ca, Al, Na, F]
from the outer portion of the glass particle.
• Complete process of setting
reaction

13. PROPERTY GlassIonomer [Type I] VALUES
1.Setting time(min) 7.0
2.Film thickness(µm) 24
3.24 hr compressive strength(MPA) 86
4.24 hr diametrical tensile
strength(MPA)
6.2
5.Elastic modulus(GPA) 7.3
6.Solubility in water(Wt%) 1.25
7.Pulp response Mild to moderate
PROPERTY GLASS IONOMER Type II [values]
1.Compressive strength(MPA) 150
2.Diametrcal tensile strength(MPA) 6.6
3.Knoop hardness(KHN) 48
4.Pulp response mild
PROPERTIES
1.MECHANICAL
PROPERTIES

14. PHYSICAL PROPERTIES
1 BIOCOMPATIBILITY
The glass ionomer cements are therapeutic materials. Their adhesion
to tooth material ensures that they provide an excellent and enduring
marginal seal, thus eliminating secondary caries while sustained
release of fluoride confers resistance to caries on adjacent tooth
material (i.e. there is a reduction in ‘contact’ caries).
These cements are not only biocompatible they are bio-active,
because when they are used as bone cements they promote bone-
healing .
Type II glass ionomer cement is more biocompatible than type I glass
ionomer cement.
2 SOLUBILITY AND DISINTEGRATION
The initial solubility is high due leaching of intermediate
products.The complete setting reaction takes place in 24 hours;
therefore the cement should be protected from saliva in the
mouth during this period.Glass ionomer cements are more
resistant to attack by organic acids.
1.Solubility in water for Type I -1.25% wt.
2.Solubility in water for Type II- 0.4% wt.

15. 3 Anticariogenic effect:
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.

16. The influence of fluoride action is seen of at least 3 mm around
the glass ionomer restoration
Released for a sustained period of 18 months (Wilson et al
1985)
Thickly mixed cements release more fluoride than thinly mixed
ones.
Fluoride release is restricted by sodium and to some extent by
calcium content and not the total fluoride content of the glass.
Fluoride release
Glass ionomers may have synergistic effects when used with
extrinsic fluorides
In the presence of an inverse fluoride concentration gradient,
glass ionomers may absorb fluoride from the environment and
release it again under specific conditions

17. 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.

18. 4 ADHESION
GIC adheres well to enamel & dentin.
Shear bond strength ranges from 3-5
MPA.
MECHANISM OF ADHESION : Glass
ionomer bonds chemically to tooth
structure.The bonding is due to the
reaction between the carboxyl groups
of the polyacids & the calcium in the
enamel & dentin . The bond to enamel is
always higher than that to dentin ,
probably due to greater inorganic
content of enamel & its greater
homogeneity.
5 ESTHETICS
1. Glass ionomer cement has got lack of translucency because of its glass
filler.
2. Unlike composite resins, glass ionomer cement will not be affected by
oral fluids.
3.Available as in different shades.
4.The luting cement [type I ] is more opaque than the restorative
cement [type ii].

19. The thermal value of glass
Ionomer cement ions is
close to that for dentin.
Hence the material has an
adequate thermal
insulating effect on the
pulp and helps to protect it
from thermal trauma
6 Thermal Properties:
7 Durability
Affected by the following factors::
Inadequate preparation of the cement
Inadequate protection of restoration
Variable conditions of mouth

20. 1. Restorative materials:
•Restoring of erosion/ abrasion lesions without cavity preparation.
• Sealing and filling of occlusal pits and fissures
• Restoration of deciduous teeth.
• Restoration of class III lesions, preferably using a lingual approach with
labial plate intact.
•Repair of defective margins in restorations
•Minimal cavity preparations – proximal lesions, Buccal and Occlusal approach
(tunnel preparation)
•Core build-up.
TUNNEL PREPARATION
Indications

21. 2. Fast setting lining cement and bases:
Lining of all types of cavities where a biological seal and cariostatic action are
required
• Replacement of carious dentin the attachment of composite resins using the
acid etch technique
• Sealing and filling of occlusal fissures showing
early signs of caries.
3. Luting cement:
Fine grain versions of the glass ionomer Cements are used.
Useful in patients with high caries index.
CONTRAINDICATIONS:
 Class IV carious lesions of fractured incisors.
 Lesions involving large areas of labial crown portion where esthetics is of
major importance.
 Class II carious lesions where conventional cavities are prepared;
replacement of existing amalgam restorations.
 Lost cusp areas.

22. Advantages
Inherent adhesion
to the tooth
surface.
Good marginal seal.
Anticariogenic
property.
Biocompatibilty
Minimal cavity
preparation
required.
♦Low fracture
resistance.
♦Low wear
resistance.
♦Water sensitive
during setting
phase .
♦Less esthetic
compared to
composite.
Disadvantages
Little shrinkage

23. EROSION / ABRASION LESIONS
CLASS V CARIOUS LESIONS
CLASS III CARIES
MNIMAL CAVITY PREPARATIONS
Uses of glass ionomer cement

24. Pits and fissures caries
Primary Teeth restorations
Bracket Bonding
LINER
BASE