Glass ionomer cement was developed in the 1970s as a dental restorative material. It consists of a powder made of glass particles containing fluoride and an acidic liquid such as polyacrylic acid. The powder and liquid react via an acid-base reaction during setting to form the cement. The cement releases fluoride over time and bonds chemically to tooth structure. It has advantages such as fluoride release, adhesion to tooth, and biocompatibility, though it is more brittle than dental composites. Many variations of glass ionomer cement have since been developed.

1. GLASS IONOMER CEMENT
BY
DR
V.VASUNDHARA

2. DEFINITIONDEFINITION
INTRODUCTIONINTRODUCTION
HISTORY AND EVOLUTIONHISTORY AND EVOLUTION
CLASSIFICATIONCLASSIFICATION
COMPOSITIONCOMPOSITION
CHEMISTRY OF SETTINGCHEMISTRY OF SETTING
FLUORIDE RELEASEFLUORIDE RELEASE
PROPERTIESPROPERTIES
MECHANISM OF ADHESIONMECHANISM OF ADHESION
CONTENTS

3. INDICATIONS
CONTRAINDICATIONS
ADVANTAGES
DISADVANTAGES
USES OF GIC
MANIPULATION
RECENT ADVANCES
NEWER ADAVANCEMENT
CONCLUSION

4. 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 cement is a basic glass and an acidic
polymer which sets by an acid- base reaction between
these components”
JW McLean, LW Nicholson. AD Wilson

5. “Glass ionomer is a water- based material that hardens
following an acid-base reaction between
fluroaluminosilicate glass particles and an aqueous
solution of polyacid.”
(Davidson and Mjor)
“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
restorations in or on the tooth”
( Acc to CRAIG)

6. Glass ionomer cement was developed by Wilson and Kent in the British
Laboratory of the Government Chemist, England in the early 1970’s
INTRODUCTION
The design of the original glass-ionomer cements was a hybrid
formulation of silicate and polycarboxylate cements. Glass ionomers used
the aluminosilicate powder from silicates and the polyacrylic acid liquid of
polycarboxylates. The earliest commercial product was named using the
acronym for this hybrid formulation and was called aluminosilicate
polyacrylic acid (ASPA).
Alumino-Silicate Polyacrylic Acid (ASPA); Glass Ionomer Cements (GIC);
Polyalkeonate cement; Glass polyalkeonate cement. Glass Ionomer
Cements or GIC is the popular name for this cement. Because of the
extensive use of this cement as a dentin replacement material it has also
been referred to as “Manmade Dentin” or “Dentin Substitute”.

7. Originally, the cement was intended for aesthetic restoration of anterior
teeth and it was recommended for use in restroring teeth with class III
and class V cavity preparation. Because of its adhesive bond to tooth
structure and its caries prevention potential, the types of glass ionomers
have expanded to include their use as luting agent, orthodontic bracket
adhesives, pit and fissure sealants, liners and bases, core buildups, and
intermediate restorations.
The original polyacrylic acid in the liquid component was modified by
copolymerization with different amounts of maleic acid, itaconic acid, and/or
tartaric acid to increase the stability of the liquid and modify its reactivity.
Powder particles were reduced in size and modified by incorporating
additional types of powder particles for reinforcement.
Ag-Sn particles (amalgam alloy particles) were admixed in some
formulations to produce an amalgam substitute. This combination became
known as the "miracle mixture"

8. History And EvolutionHistory And Evolution
 The development of amalgam, gold, and porcelain restorative materials
in the mid-1800s stimulated the creation of dental cements.
 In 1855, Sorel introduced zinc oxychloride cement, the first popular
dental cement.
 In 1871- T. Fletcher introduced the first tooth colored filling material,
silicate cement. It lost its popularity due to its high degree of acidity and
solubility
 The work of Ames and Fleck established the modern-day zinc
phosphate cement.
 In 1870, Pierce introduced zinc oxide–phosphoric acid cement, which
replaced oxychloride and oxysulfate cements, because it caused less
irritation to the pulp and had greater durability.

9.  In 1951 swiss chemist DR OSCAR HAGGER was the first to
demonstrate adhesion
 In 1955 BUONCORE defined the principles of acid etch technique for
micro mechanical adhesion
 In 1956 BOWEN defined conventional composite resin
 In 1966, D.C. Smith introduced yet another class of cement, in which the liquid of
the zinc phosphate cement was replaced by aqueous polyacrylic acid. This so-
called carboxylate cement opened up new prospects for self-adhesive dental
materials.

10.  In 1972 Wilson and Kent developed a new translucent cement-
Aluminium Silicate Poly Acrylate (ASPA), which later became popular
as Glass Ionomer Cement (GIC).
 It was B E KENT who coined the term GLASS IONOMER
 1972 Wilson & Crisp found that tartaric acid improves manipulative
properties
 1974 Mc. Lean & Wilson proposed clinical use of GIC
 In 1974 they discovered ASPA 3 which had methyl alcohol added to poly
acrylic acid but used to get stained

11.  In1975 they discovered ASPA 4 which contained co polymers of acrylic
acid and itaconic acid
 FORSTEN studied the pattern of fluoride release from GIC
 CRISP ABEL AND WILSON in 1979 discovered ASPA-X which had
excellent translucency
 AD WILSON AND SIMMONS [1983]developed ‘Miracle Mix’ cement by
incorporating metal oxide metal alloy filler in gic for improving strength
 Prosser et al in 1984 developed ASPA 5 which contained poly acrylic acid
in dry powder form blended with glass powder mixed with water /tartaric
acid

12.  The tunnel preparation for class 2 was suggested for GIC by HUNT AND
KNIGHT in 1984
 In 1985 MCLEAN et al developed lamination ‘sandwich technique’ now
called as bilayer technique
 In 1985 MCLEAN and GASSER developed ‘cermet’ ionomer cement by
fusing silver particles
 ANTONUCCI AND MCKINNEY IN 1986 added polymerizable free
radically active methacrylate monomers and pre polymers and coined the
term ‘resin modified gic’

13.  MC LEAN et al in 1994 termed the word ‘Polyacid Modified Composite
Resin’
 Atraumatic Restorative Therapy was presented for first time by WHO
 In 2002 SHAFER company developed ‘giomers’
 In 1989 Mitra developed Resin Modified GIC

14. Classification
According to clinical use as:
Type I- Luting
TYPE II- Restorative
Type III-Fast setting Liner/ Base
Type IV- Pit & Fissure Sealant
Type V- Luting for Orthodontic Purpose
Type VI- Core build up material
Type VII- High fluoride releasing command set GIC
Type VIII-GIC for ART
Type IX- Geriatric & Paediatric GIC

15. According to characteristics specified by the
manufactures :
1. Type I - Luting Cement
Eg: Fuji 1, Ketac cement
2. Type II - Restorative material
Eg: Ketac Fil, Fuji II, Fuji IX
3. Type III:
a. Bases and Liners - Weak with low acidity
Eg: AC lining cement, Shofu liner
b. Bases and Liners - strong but more acidic
Eg: Ketac Bond, Shofu base, GC Dental Cement
c. Bases and Liners - strong even in thin layer light
Eg: Vitrebond
4. Type IV- Admixtures
Eg: Ketac Silver, Miracle mix.

16. According to Philips
Type I – Luting
Type II - Restorative
Type III - Liner & base

17.  According to Davidson and Mjor:
1. Conventional/ Traditional
Glass Ionomer for direct restorations
Metal reinforced GIC
High viscosity GIC
Low viscosity GIC
Base/Liner
Luting

18. 2. Resin modified GIC
Restorative
Base/Liner
Pit & fissure sealant
Luting
Orthodontic cementation material
3. Polyacid modified resin Composites/Compomers

19.  According to GJ Mount:
1. Glass ionomer cements:
a. (i) Glass Polyalkeonates
(ii) Glass polyphosphonates
b. Rein modified GIC
c. Polyacid modified composite resin
2. a. Auto-cure
b. Dual Cure
c. Tri cure

20. 3. a. Type I – Luting
b. Type II – Restorative
Type II.1. Restorative aesthetic
Type II.2. Restorative reinforced
c. Type III – Lining or Base

21.  According to Sturdvent:
1. Traditional or conventional
2. Metal modified GIC
a. Ceremets
b. Miracle Mix
3. Light cured GIC
4. Hybrid (Resin modified GIC)
5. Polyacid modified resin composites or Compomer

22.  According to Wilson & McLean (1998)
1. Type I Luting
2. Type II
a. Aesthetic filling material
b.Bis-reinforced filling material (includes ceremets)
3. Type III – Lining, base and fissure sealant

23.  According to McLean, Nicholson &
Wilson (1994):
1. Glass Ionomer cement
a. Glass polyalkeonates
b. Glass Polyphosphonates
2. Resin modified GIC
3. Polyacid modified GIC

24.  NEWER CLASSIFICATION
1.TRADITIONAL GLASS IONOMER
A.TYPE I – LUTING CEMENT
B. TYPE II – RESTORATIVE CEMENTS
C. TYPE III – LINERS AND BASES
2. METAL MODIFIED GLASS IONOMER
A. MIRACLE MIX
B. CERMET CEMENT
3. LIGHT CURE GLASS IONOMER HEMA ADDED TO LIQUID
4. HYBRID GLASS IONOMER
A. COMPOSITE RESIN IN WHICH FILLER SUBSTITUTED
WITH GLASS IONOMER PARTICLES.
B. PRE-CURED GLASSES BLENDED INTO COMPOSITES

25. Powder Is basically an acid soluble calcium
aluminosilicate glass containing fluoride. It is
formed by fusing silica + alumina + calcium fluorite,
metal oxides and metal phosphates at 11000
-15000
C and then pouring the melt onto a metal plate / into
water. The glass formed is crushed, milled and
ground to a form powder of 20 – 50 µm size
depending on what it’s going to be used for. They
get decomposed by acids due to the presence Al +3
ions which can easily enter the silica network. It this
property that enables cement formation.

26. POWDER
SILICA (SIO2) – 35.2--41.9%
ALUMINA (AL2O3) – 20.1--28.6%
ALUMINIUM FLOURIDE – (ALF3) 1.6 – 2.4 %
CALCIUM FLUORIDE (CAF2) – 15-20 %
SODIUM FLUORIDE (NAF) – 3.6--9.3 %
ALUMINIUM PHOSPHATE (ALPO4) – 3.8 – 12 %
LANTHANUM, STRONTIUM, BARIUM IN TRACES
( FLUORIDES ACT AS CERAMIC FLUX )

27. Alumina :
It forms the skeletal structure of the glass. It also increases the opacity of the
glass.
Silica :
It forms the skeletal structure of the glass and increases the transparency of
the glass
Aluminium Fluoride :
It partially replaces silicon in the glass network providing negative sites,
which are vulnerable to acid attack by H+ leading to decomposition of glass
and providing cement potential.
FUNCTIONS OF COMPONENTS :

28. Fluoride :
It contributes to therapeutic value by releasing fluoride over a prolonged
period of time. It helps to lower the fusion temperature. It enhances
translucency and improves the working characteristics. It also helps to
increase the strength of set cement
Calcium Fluoride :
It acts as a flux and provides opacity to the set cement
Phosphate :
It lowers the melting temperature and modifies the setting characteristics
of the cement.
Lanthanum, Strontium, Barium :
It provides radio - opacity to the cement

29. Na+ Ca+2, Sr+2
Works as modifying ions and induce high reactivity of glass with polyacid.
Cryolite (Na3 AIF6)
It acts as a flux and increases the translucency of the cement
Aluminum phosphate :
It helps to add body to cement and improve the translucency of the
cement.

30. Liquid: Originally, the liquid for GIC was an
aqueous solution of PAA in a concentration of about
50%. This was quite viscous and tended to gel over time.
Thus, PAA was co- polymerized with other acids such as
itaconic, maleic and tricarboxylic acids. This
polyelectrolytic liquid of GIC is, thus, also called as
polyalkenoic acids. Recently polyvinyl phosphoric acid
has also been introduced to this system.
A typical liquid of GIC contains 40-55% of 2:1
polyacrylic : itaconic acid co- polymer and water.

31. The basic functions of these co–polymers include:
the co- polymeric acids are more irregularly arranged than the homo
polymer. This reduces H- bonding between acid molecules and reduces degree
of gelling
decrease the viscosity
reduce tendency for gelation,hence, improves storage.
Increase the reactivity of liquid

32. LIQUID
POLYACRYLIC ACID – 45%
ITACONIC ACID – 5%
MALEIC ACID – 5%
TRICARBOXYLYLIC ACID – 5%
TARTARIC ACID – TRACES
WATER – 50% (HYDRATES REACTION PRODUCT)

33. Additives:
1.Tartaric acid
- Increases working time
- Increases translucency
- Improves manipubality
- Increases strength
2.Polyphosphates: extends working time
3.Metal oxides: accelerates setting time

34. Modifications in liquid
- Only water and tartaric acid[anhydrous cement]
-Hema [light cure components]
Recently polyvinyl phosphonic acid has been added
Modifications in Powder
* Dried Poly Acrylic Acid (anhydrous GIC).
* Silver-Tin alloy (Miracle Mix).
* Silver-Palladium/Titanium (Cermet cement).
* BiSGMA, TEGDMA and HEMA (Light/Dual cure GIC).

35. Bulk of powder and liquid for hand mix version.
Pre-proportioned capsules form for mixing in
mechanical mixers.
Anhydrous glass ionomer cements are supplied as
powder that may be mixed with water or water with
tartaric acid.
Compomers that are polyacid modified resins are
supplied as single pastes in bulk as tubes or
compules (cavifils) for single use.
DISPENSING

36. SETTING REACTION OF
CONVENTIONAL GLASS IONOMER
The material are supplied in two part powder-liquid systems that require
mixing.
Following are the essential components
Polycarboxylic acid
Fluoroaluminosilicate (FAS) glass
Water
Tartaric acid
The polymeric matrix of most glass ionomers is a copolymer of acrylic acid
and itaconic acid or maleicacid. Tartaric acid is added to control the working
and setting characteristics of the material. The powder consists of an acid-
reactive comminuted FAS glass and has ions such as calcium, strontium,
and lanthanum.

37. When heavy metal ions are used, the set material is radiopaque to x-rays.
When the powder and liquid are mixed, an acid
base setting reaction begins between tha FAS
glass and polyacrylic acid. The acid etches the
surface of the glass particles and calcium,
aluminium, sodium and fluorine ions are leached
into the aqueous medium.
An initial set is achieved within 3 to 4 minutes, but
the ionic reaction continues for atleast 24 hours
or more so that maturation is achieved much later
Maturation time has been improved in newer
formulations to allow finishing after 15 minutes of
placement of mix.
Silica gel
Glass core
Ca2
+
Al3
+
F-
Polyacid liquid

38. Stage 2- The hydrated proton attacks the surface of the glass particles
releasing calcium and aluminium ions. The carboxylate ions from the polymer
react with these metallic ions to form a salt bridge, resulting in gelation and
setting
Stage 3- During the initial setting, calcium ions are more rapidly bound to
polyacrylate chains; binding to the aluminium ions occurs at later stage. The
strength of the cement builds with time
Stage 4- silicic acid is initially formed when the glass breaks down, but rapidly
polymerizes to form silica hydrogel
Stage 1 - In an acid base reaction, all carboxylic acids have common organic
functional group denoted COOH. In the presence of water, the COOH group
undergoes partial ionization to yield a carboxylate anion COO and a hydrated
proton, H3O.

40. The set cement is constituted by hydrogel of calcium, aluminium, and
fluoroaluminum polyacrylates involving the unreacted glass particles
sheathed by weakly bonded siliceous hydrogel layer.
About 20% to 30% of the glass is dissolved in the reaction. Smaller glass
particle may be entirely dissolved and replaced by siliceous hydrogel
particles containing fluorite crystallites.
The stability of matrix is given by an association of chain entanglement,
weak ionic cross-linking and hydrogen bonding

42. WORKING TIME AND
SETTING TIME OF GIC
Fuji I :
Mixing time = 30 sec.
Working time = 60-90 sec.
Fuji II :
Mixing time 45 –60 sec or 30 sec. (first half 15 sec. & other half
15 sec)
Working time = 60-90 sec.
Setting time = 2min 40 sec.
RMGIC:
Mixing time = 10 sec (in a capsule form, 20-25 sec manually)
Working time = 3 min.

43. Fuji III :
Mixing time = 10 sec
Working time = 1 min 40 sec.
Setting time = 2min 45 sec.
Miracle mix :
Mixing time = 10 sec (in a capsule form, 20-25 sec manually)
Setting time = 4 min
Fuji VII :
Setting time = 1 min
Mixing time = 20-25 sec.

44. Fuji IX :
Working time = 2 min
Setting time = 2.5min, 4.5 min from the start of mix.
Fuji IX GP fast:
Mixing time = Less than 30 sec.
Setting time = initial set is 3 min 35 sec. Final finishing after 6
min

46. Factors Affecting setting:
1. Glass composition : If the Al2O3 / SiO2 and fluoride content are
higher in ratio faster the set and shorter the working time
2. Particle size of the glass powder: Finer the powder, faster the set
and shorter the working time.
3. Addition of tartaric acid: Sharpens the set without shortening
the working time.

47. FLUORIDE RELEASEFLUORIDE RELEASE

48. • The fluoride ions from the glass matrix is sustained and occurs a long period
of time. The fluoride release is result of setting reactions and the ion
exchange process in the cement
• In this process the fluoride from the glass is being replaced by carboxylates
and water
Initial
dissolution
for
starting
reaction
ALUMINO-SILICATE
PARTICLE
CEMENT
MATRIX
rapid early
F release
from matrix Slow long term
F release
by diffusion
from particle
F-1
,
Ca+2
, Al+3
, Si+4

49. Importance of water
1.It provides ion transport needed for the acid base setting reaction and
fluoride release.
2.It is chemicaly bound in the set complex and provides stability to the
restorative material
3.Provides plasticity during manipulative stage
Water present in the set cement can be arbitrarily classified as:
- loosely bound water which can get readily removed by dessication. This is
associated with Ca+2
during the initial reaction
- tightly bound water is the one which hydrates the matrix as setting
continuous and cannot be removed by dessication. This is associated with
Al+3
and is critical in yielding a stable gel structure and building the strength of
the cement.

50. Although the clinical set is completed within a few minutes, a continuing
‘maturation’ phase occurs over subsequent months.
This is predominantly due to the slow reaction of the aluminium ions, and is the
cause of the set material’s sensitivity to water balance.
The set material needs to be protected from salivary contamination for several
hours, otherwise the surface becomes weak and opaque.
From water loss for several months, otherwise the material shrinks and cracks
and may debond.

51. SURFACE PROTECTION
Certain materials are applied on the GIC restoration surface
immediately after removal of matrix in order to prevent
excessive imbibition or desiccation of the cement, these are
Petroleum jelly Cocoa Butter
Dentin Bonding agents Dental Varnish.

52. PROPERTIES
Properties of GIC can be divided into two group:
Physical properties.
Biological properties.
Physical properties of glass ionomer cement
Traditional GIC Glass cermet Light cure GIC Compomer
Compressive strength
16000-22000 psi
150mpa
27500 psi 23200 psi 29000 psi
Tensile strength
900-960 psi
6.6 mpa
950-1000 psi 2000-3000 psi 2000-3000 psi
Modulus of elasticity 2900000 psi - 906175 psi 1217900 psi
Coefficient of Thermal expansion/0
C lO x lO-6
15 X 10-6
18 X lO-6
18 X lO-6
Solubility 0.3-0.5% 0.1% 0.08% 0.08%
Opacity 90% 95% 85% 80%
Hardness (KHN) 48 39 40 38
Film thickness (μm) 22-25 - 30-40 30-40
Physical properties:

53. DENTAL MATERIAL COMPRESSIVE STRENGTH (MPA)
1. Silicate cement 180
2. Glass Ionomer Cement (Type II) 150
3. Cement 150
4. Hybrid Ionomer 105
5. Unfilled resins 70
6. Traditional composite 250-300
7. Hybrid Composite 350-400
8. Dental Amalgam 300-550
COMPRESSIVE STRENGTH :

54. Dental Material Tensile Strength ( MPa)
Silicate 3.5
GIC (type II ) 6.6
Cement 6.7
Hybrid Inomer 20
Unfilled resins 24
Traditional composite 50-65
Hybrid Composite 75-90
Dental Amalgam 45-65
TENSILE STRENGTH

55. Material KHN
Silicate Cement 70
GIC type II 48
Cement 39
Hybrid Ionomer 40
Zinc Phosphate 50-60
HARDNESS

56. Solubility and disintegration
The surface of gic can be damaged in presence of low ph, like
application of topical fluoride
 in cases of people having xerostomia due to lack of buffering the
glass ionomer may disintegrate in faster time
 resin modified glass ionomers are more resistant to solubility
Physical properties
Dimensional changes
Gic which have been manipulated correctly and protected from early
exposure to moisture show a volumetric contraction of 3% at
humidities.
 Protection can be given by applying varnish
 the Resin modified glass ionomer restorative materials contain less
than 5% of additional resin and show very small initial shrinkage
 in contrast light cured composite resins show immediate shrinkage
with development of considerable stress at tooth interface

57. Resistance to fracture
The disadvantage of gic is its susceptibility to brittle fracture
they should be avoided in areas of heavy occlusal loading
Abrasion resistance
Immediately after placement are less resistant to abrasion than
composite resins but improves with maturation
In cermet the presence of silver particles improves abrasion resistance
Radio-opacity
These cements can be made radio opaque by addition of radio
opacifiers like barium sulfate or metals like silver

58. • the Glass ionomer cement is an aesthetic filling material because it has
glass as its filler material
• A degree of translucency exists for GIC due to the glass fillers. Its
translucency depends on its formation.
• It should be noted that because of slow hydration reaction glass
ionomers take 24 hrs to fully mature and develop full translucency
• Early contamination of cement surface with moisture adversely affects
translucency
• Resistance to stain is largely dependent on obtaining a good surface
finish
Aesthetics

59. ADHESION
1. Chelation (Smith)
2. Hydrogen bonding followed by ionic bond (Wilson)
3. Hydroxyapatite & polyacrylic acid interaction
(Beech)
4. Hydrogen bonding with dentin collagen
(Akinmade)
Mechanism of adhesion

60. • Polyacid co- polymer liquids are thought to bond by an ionic interaction
between the negatively charged polyacid chain of the ionomer matrix
and the positively charged calcium on tooth surface.
• Polyacid also form hydrogen bonds and undergo ion exchange in the
collagen and in organic components of the tooth structure, particularly to
calcium carboxylate and phosphate
• They chemically bond to the restorative material and tooth structure.
• The bond strength to enamel is always higher than that to dentin
because of the greater inorganic content of enamel and its greater
homogenicity from a morphological standpoint
• Adhesion of conventional GIC to enamel and dentine only produces
bond strength in the range of 6-12 Mpa

61. Polymerization of the
Poly acid

62. • Most GICs are aqueous systems that wet tooth structure very well
because they are Hydrophilic.
• However GIC tends to have high viscosity and therefore do not flow and
adapt to micro-mechanical spaces very readily
Adhesion can be improved by usage of surface conditioners which helps
to eliminate the wide variation found after cutting better, wetting and inter
facial contact will occur, if a smooth surface is attained
• Bond strength
Enamel- 2.6 to 9.6 Mpa
Dentin – 1.1 to 4.5 Mpa
CONDITIONER helps to
• Remove the smear layer
• Increase surface energy of tooth
• increase wettability and therefore decrease contact angle

63. Mechanical Properties
STRENGTH:
 Mechanical mixing using capsules containing pre proportioned amounts
of the components will statistically improve the performance of any Glass
Ionomer Cement
 major limitaions of GIC:
 susceptibility to brittle fracture as compared to composite and
amalgam
 weak
 lack rigidity
 weakness appears to be in the matrix, which is prone to crack
propagation
 Since glass ionomer cement is a hybrid of silicate cement and zinc poly
carboxylate cement, it has mechanical properties that are in between
these cements.
 silicate cement is a hard (70 KHN) but brittle material
 the glass ionomer cement is less hard (48 KHN) and less brittle than the
silicate cement

64.  The strength of GIC is increased as
 the filler contents is increased
 the water content is reduced
 using phase separated glass
 increasing the molecular weight of the polyacid
 increased strength is accompanied by an acceleration of setting and loss of
workability.
 Increasing in molecular weight also increases fracture toughness and
resistance to erosion but at the same time reduces the workability of the
cement due to high viscosity of the liquid.
 phase separated glasses appeared to yield stronger cement than clear
glasses.
 Reinforced fillers such as Alumina and Lathe cut silver tin alloy has been
used successfully to increase the flexure strength GIC.
 However these strengths are still less than those for posterior filling material.

65. Different Conditioners used are :
1.PAA : Is the conditioner of choice as it is a part of the cement forming acid. It
alters the surface energy, exposing highly mineralized tooth surface to diffusion
of acid and ion exchange. This enhances adaptation of cement (10%, 10sec)
2.50% citric acid, 5 sec
3.25% tannic acid, 30 s
4.2% Ferric chloride
5.NaF
6.EDTA
7.Mineralising solution –ITS solution, Levine solution

66.  Compressive Strength :compressive strength is 150-200 MPa
.Compressive strength is increased by increasing alumina content. The
finer the particles the more will be the compressive strength.
 Tensile Strength :It has a higher tensile strength when compared with
silicates tensile strength 6.5 MPa - 17.4 MPa.
 Flexure Strength :GIC are relatively brittle having a flexure strength of
only 15-20 MPa and cannot be considered suitable as general purpose
filling material for permanent teeth.
 Hardness :
It is less than that of silicates the value is 48 KHN.
 Fracture Toughness :
Glass ionomer cements are much inferior to composites

67. Thermal Properties :The thermal diffusivity value for glass ionomer
cement ions is close to that dentin. Hence the material has an adequate
thermal insulating effect on the pulp and helps to protect it from thermal
trauma.
The co efficient of thermal expansion values of glass ionomer is
10.8x10 -6/degree centigrade and that of the tooth structure is 11.4x 10 -6/
degree centigrade thus the values of GIC and tooth structure are similar
which means that the tooth structure and glass ionomer cemnts will
expand and contrct at similar rates

68. The two main biologic properties of GIC are:
1. Anticariogenic potential due to release of fluoride.
2. Biocompatibility.
BIOLOGIC
PROPERTIES
Fluoride Release
- One of the important properties GIC shares with silicate cement is
the release of fluoride ions throughout the life of the restoration
(Forsten 1994).
- This fluoride release provides for the cariostatic effect of GIC.
- The influence of fluoride is found in a zone of resistance to
demineralization which is at least 3mm thick around a GIC
restoration (Kidd et al 1978).

69. Fluoride ions released from the restorative material becomes incorporated
in hydroxyapatite crytals of adjacent tooth structure to form in a structure
such as fluroapatite that is more resistant to acid mediated decalcification.
The fluoride originates from that used in preparing the alumina silicate
glass which can contain upto 23% fluoride
Before it was found that the fluoride is released as sodium fluoride but
recent studies have shown that some calcium too is released with fluoride
Large amount of fluorides are released during the first few days after
placement after which it gradually declines during the first week and
stabilizes after 2-3 months and continues for a long time that is 8 years
after placement

70. BIOCOMPATIBILITY
• Bio compatibility is defined as the ability of a material to perfom with an
appropriate host response in a specific application
• GIC are generally biocompatible with oral tissues and as restorative
materials results in only mild pulpal irritation at a level similar to that
produced by zinc polycarboxylate or zinc phosphate cements
• This can be attributed to polykenoic acid which is a weak acid and also
has high molecular weight (30,000-50,000) of liquid and larger molecular
size of acid thus it is not able to penetrate the dentinal tubules
• Setting reaction is min exothermic, rapidly neutralizes after mixing, slow
release of ion which are biologically beneficial
• It gets readily precipitated by the calcium ions in the tubules
• Dissociated H+ remains near the chains due to electrostatic attractions
• Their adhesion to tooth structure ensures that they provide an excellent
marginal seal and prevent microleakage the traditional GICs are very
acidic at times of initial mixing and have potential to produce post-
operative sentivity and pulp irritation.

71. As the reaction proceeds the PH increases from initial value to 1 to the range
of 4 to 5. As the setting reaction nears completion the final PH value reaches
6.7 to 7
In deep cavities pulp protection is needed either by placing ca(OH)2.
Post-operative sensitivity
Post-operative sensitivity is usually associated with poor manipulation
and/or poor powder/liquid ratio. This is also related with moisture
contamination during setting of the cement leading to hydraulic effect on
dentinal fluid. However, the menace of post-operative sensitivity is less
affected with light cure glass ionomers and compomers.

72. INDICATIO
NS
I] As a Restorative Material
a.Restoration of erosion / abrasion lesion – Class V lesion.
b.Anterior restorations.
c.Sealing and filling of occlusal pits and fissures.
d.Restoration of Class III carious lesions, preferably using a lingual
approach.
e.Restoration of deciduous teeth Class I and Class II.
f.Repair of defective margins in restoration or temporary coverage of
fractured teeth

73. a. Core build-up.
b. Provision restorations where future veneer crowns are contemplated.
c. Sealing of root surfaces for overdentures.
II] Fast Setting lining cements and base
a.Lining of all types of cavities where a biological seal and cariostatic
action are required.
b.Dentine substitute in laminate techniques.
c.Sealing and filling of occlusal fissures showing early signs of caries.

74. Luting Cements (Fine grain version of GIC)
a.Useful in patients with rampant caries and as well as multiple carious lesions.
b.In exposed porcelain margins used for cosmetic reasons, because of its increased
translucency.
c.Crown and prosthesis cementation. Because:
i) Its ability to release F ions into underlying dentine. This is of great value as
secondary caries is a common cause of failure for cementation prosthesis.
ii) Chemical bonding.

75. CONTRAINDICATIO
NS
1.Class IV carious lesions or fractured incisors.
2.Lesions involved large areas of labial enamel where esthetics is of
major importance.
3.Class II carious lesions where conventional cavities are prepared;
replacement of existing amalgam.
4.Lost cusp area.

76. ADVANTAGES
1. Anticariogenic – Because of fluoride ions they can alleviate sensitivity
and reduces recurrent caries.
2. Biocompatible – Least irritant to pulp.
3. Chemical bond to enamel / dentine – thus provide good marginal seal.
4. Minimal setting shrinkage.
5. Coefficient of thermal expansion similar to tooth structure (i.e. dentine)
thus it prevents microleakage because as the coefficient of thermal
expansion increases, microleakage increases (JADA vol. 124, Sept.
1993).
6. Relatively resistant to acid and wear.

77. DISADVANTAGES
1. Brittle material.
2. Low tensile strength thus used in bulk and low stress – bearing area.
3. Esthetically less pleasing than composite restorations.
4. Relatively opaque and lack polishability thus poor surface finish.
5. Technique sensitive (But lesser than composite).
6. Lack of toughness.
7. Because of powder liquid, formulations alterations.
- Post operative sensitivity.
- Reduced physical and mechanical properties.

78. Water contamination during early stages of setting reaction (15 seconds to
1 minute) can cause porosity, gazing and later staining and solubility. Thus,
GIC should be covered with varnish / DBA.
Poor edge strength, GIC do not perform well in saucer shaped lesions (QI
vol. 19, No. 12; 1988).

79. 1)Restoration of permanent teeth :
•Class V and Class III cavities
•Abrasion / Erosion lesion
•Root caries
2) Restoration of deciduous teeth
•Class I – Class VI cavities
•Rampant caries, nursing bottle caries
3) Luting or cementing
•Metal restorations viz. inlays, onlays, crowns
•Non-metal restorations viz composite inlays
and onlays
•Veneers
•Pins and posts
•Orthodontic bands and brackets
Uses of GIC

80. Preventive restorations
•Tunnel preparation
•Pit and fissure sealant
5) Protective liner under composite and
amalgam
6) Core build up
7) Splinting of periodontally weak teeth
8) Glazing (Fuji Coat LC )
•Glazing of traditional GIC filling
•Improving aesthetics of old GIC filling
•Protection of new GIC filling

81. 9) Other restorative technique
•Sandwich technique / Layered restorations/ Laminated restorations /
Bilayered restorations
•Atraumatic restorative treatment (Fuji VIII and Fuji IX).
•Co-cure technique
•Bonded restorations
10) Endodontics
•Repair of external root resorption
•Repair of perforation
•Retrograde filling

82. MANIPULATIO
N
 Isolation
 Tooth preparation/ Conditioning of the
tooth surface
 Cement placement
 Finishing & polishing
 Surace protection

83. ISOLATION
• Saliva control is an essential step in the restoration of glass ionomer
cement.
• The cement is very sensitive for water loss as well as contamination.
• Saliva, sulcular fluid and gingival haemorrhage, have to be controlled
during the restoration procedure.
• Rubber dam, retraction cords and cotton rolls with saliva ejectors are
generally used and are rather mandatory in the restoration of lesions
close to the gingival margins of the tooth.

84. TOOTH PREPARATION
To achieve long lasting restorations, the
following conditions must be satisfied:
Surface of the tooth must be clean &
dry
Consistency of the cement must allow
complete coating of the surfaces
irregularities
Surface must be finished without
excessive drying
Surface protection must be done
properly.

85.  Tooth surface cleaned – With pumice slurry
 Conditioning – With (34% to 37%) phosphoric acid or an organic
acid like polyacrylic acid (10 to 20%) for 10 to 20 seconds,
followed by a 20 to 30 sec of water rinsing.
 Drying by gentle air blow
 Excessive air blow causing desiccation should be avoided.
 Any further contamination with saliva or blood impairs bonding.
SURFACE PREPARATION

86. POSTCONDITIONING
SURFACE
PRECONDITIONING
SURFACE

87. P/L ratio recommended
by the manufacturer
should be followed
( usually 4 :1)
PREPARATION OF THE
MATERIAL
Mixing is usually done
on plastic crafted paper
pad.

88. Plastic spatula is most
commonly used.
Powder incorporated
rapidly in the liquid.
Mixing done for 45 to 60
Seconds

89. • Mix should be glossy at this time which indicates unreacted polyacid
on the surface. This residual acid on the surface is critical for bonding
to the tooth.
• A dull appearance indicates inadequacy of free acid for bonding.
• Preproportioned capsule of GIC are also available.
• They are used with amalgamators or specialy designed triturators.
• The preproportioned capsules have nozzles so that the mixed material
can directly be injected in the prepared cavity.
• Advantages of mechanical mixing are
• Convenience
• Consistent control over P/L ratio
• Elimination of variation associated with
hand spatulation.

90.  Cement is placed using a plastic instrument or injected into cavity
Cavities are slightly overfilled & surface immediately covered by
using plastic matrix at least for 5 minutes.
 Excess is trimmed off.
 Surface protection is done immediately.
 Further finishing procedure if needed should be delayed for at
least 24 hrs.
PLACEMENT OF
RESTORATION & REMOVAL
OF EXCESS

91. FINISHING & POLISHING

92. PREOPERATIVE VIEW
POSTOPERATIVE VIEW

93. The GIC has come a long way since it was first introduced its properties
have improved and there are now many versions for various applications.
Amongst the recent development are:
1.Metal reinforced ionomer cements.
2.New fast setting lining cements.
3.Water hardening luting agents.
4.Dual cure system which include:
- Resin modified GIC.
- Poly acid modified resin / compomer.
5.Packable GIC.
RECENT
ADVANCES

94. 6. Self hardening resin GIC.
7. Smart materials / fluoride charged materials.
8.Bioactive GIC.
9.giomers

95. HIGH VISCOSITY GIC
Developed as an alternative to amalgam.
Packable / condensable glass ionomer cements
Composition: Powder: Ca,La,Al fluorosilicate glass
Liquid: PA,TA,water and benzoic acid
INDICATIONS: Molar restoration of primary teeth
Intermediate restoration
Core build up material
For A R T
ADVANTAGES: Packable or condensable
Improved wear resistance
Easy to use
Low solubility
Rapid finishing possible
Decrease moisture sensitivity
DISADVANTAGES: Limited life
Moderately polishable
Not esthetic

96. LOW VISCOSITY GIC
1. Also called as Flowable GIC
2. Low P:L ratio thus increase flow.
3. Use for lining, pit and fisure sealer, endodontic
sealer and for sealing hyper sensitive cervical
area.
Eg fuji lining LC, Ketac – endo etc.
Fuji lining LC Ketac-Endo

97. The main shortcoming of GIC that limits its use in stress bearing
areas is its lack of fracture toughness. To improve upon it metal
reinforced GICs were developed.
They are mainly of two types:
1. Miracle Mix
2. Cermets
METAL MODIFIED GIC
Miracle mix Ketac Silver

98. • Seed & Wilson (1980) invented miracle mix: Spherical silver amalgam alloy+Type II
G I C in ratio 7:1
• Mc lean & Gasser (1985) invented ceremet: Glass powder sintered to metal fillers
(<5%) at 800°C. Minimal improvement in mechanical property
• Compressive strength – 150 Mpa
• Modulus of elasticity is slightly lower
• KHN – 39
• Tensile strength – slightly more 6.7 Mpa
• Slight increase in wear resistance.
• Fluoride release
• Max for miracle mix (3350µg, 4040µg)
• And min for cermets (200µg, 300µg)

99. • Indications:
• Class I cavities in primary teeth
• Core build up material
• Lining of class II amalgam restorations
• Root caps for teeth under over dentures
• As a preventive restoration
• Contraindications:
• Anterior restoration
• In areas of high occlusal loading

100. Advantages:
•Ease for placement
•Adhesion to tooth structure and anticariogenic
potential
•Crown cutting can be done immediately
•Increased wear resistance
Disadvantages:
•Esthetically poor
•Tooth discoloration
•Rough surface
•Reduced W.L and S.T

101. RESIN MODIFIED GIC
• To overcome low early strength and moisture sensitivity
• Defined as HYBRID CEMENT that sets partly by acid base reaction
and partly by polymerisation reaction (Mc Lean)
• Materials that are modified by the inclusion of resin, generally to
make the them more photo curable (Nicholson)
• Powder – Ion leachable glass and initiators
• liquid – water, Poly acrylic acid, HEMA (15-25%), methacrylate
monomers.
• Setting reaction: - Dual cure
- Tricure

102. PROPERTIES
• Esthetic – Superior than conventional GIC
• Fluoride release:
• Conventional
• 440µgF after 14 days
• 650 µgF after 30 days
• RMGIC-1200 µgF after 14 days
• 1600 µgF after 30 days
• Strength: Diametral strength
• Conventional
• G I C: 6.6Mpa
• RMGIC: 20 Mpa

103. • Compressive strength
• Conventional G I C:150Mpa
• RMGIC: 105Mpa
• Hardness:
• Conventional GIC:48KHN
• RMGIC:40KHN
• Shear bond strength: lesser than conventional GIC (Acc to skinner)
• Marginal adaptation: poor compare to conventional GIC
• Biocompatibility: Transient rise in Temperature

104. Advantages
• Long working time due to photo curing
• Improved setting characteristics
• Decrease sensitivity to water (but not significantly, Journal of
Conservative Dentistry, June 2005)
• Increase early strength
• Finishing & polishing can be done immediately
• Improved tensile strength.
• Better adhesion to composite restoration
• Increase fluoride release.
• Repairable.

105. Disadvantage
• Biocompatibility is controversial
• More setting shrinkage leading increase microleakage and
poor marginal adaptation

106. Uses
As a luting cement (FUJI PLUS Ketac-cem 3M ESPE, Fuji Cem)

107. As a liner and bases
(Fuji LC)
As a pit and fissure
(Vitre Bond)
Core build up material
(Fuji I LC)
Retrograde filling material

108. POLYACID MODIFIED
COMPOSITE RESIN
• Also called as COMPOMER
• Defined as : material that contain both the essential components of
GIC but in an amount insufficient to carry out acid base reaction in
dark.
• They are developed to combine fluoride release of GIC and
durability of composite

109. Composition: one paste system containing ion leach able glass, sodium
fluoride, polyacid modified monomer but no water
Recently 2 paste or powder liquid system is introduced.
Powder:
Strontium aluminium flurosilicate glass particles, metal oxides,and
intiators
Liquid:
Polymerizable methacrylate/caboxylic acidic monomers multi functional
acrylate monomers and water ;

110. Setting reaction
1. Initially light curing forms resin network around the glass
2. After 2 to 3 month there is water uptake which initiates slow acid
base reaction and fluoride release.

111. Properties
• Adhesion –Micromechanical, absence of water thus no self
adhesion
• Fluoride release minimal.
• Physical properties better than conventional GIC but less than
composite.
• Optical properties superior to conventional GIC.

112. Uses
• Pit and fissure sealant
• Restoration of primary teeth
• Liners and bases
• Core build up material
• For class III & V lesions
• Cervical erosion / abrasion
• Repair of defective margins in restorations
• Sealing of root surfaces for over dentures
• Reterograde filling material.

113. Contraindications
• Class IV carious lesions
• Large areas of labial surfaces
• Class II cavities where conventional
cavity is prepared
• Lost cusp areas
• Under full crown or PFM crowns.

114. Advantages
• Ease of use
• Easy adaptation to the tooth
• Good esthetics
• More working time than RM GIC

115. Commercial Products
Compoglass F
Compoglass Flow
Principle

116. Bioactive glass
• Introduce by Hench in 1973
• Acid dissolution of glass forms calcium and phosphate rich
layers
• The glass can form bioactive bonds with bone cells
• Better than hydroxyapatite
• Can grow calcium and phosphate rich layer in presence of
calcium and phosphate saturated saliva.
• They are less abrasive than feldspathic porcelain to opposing
teeth
•

117. Uses
• Bone cement
• Retrograde filling material
• For perforation repair
• Augmentation of resorbed alveolar
ridge
• Implant cementation
• Infra bony pocket correction
• Bio glass ceramic crown.

118. Fiber-reinforced Glass Ionomer
Cements
Al and Sio2 fibers added to glass powder (PRIMM)
Diameter of fiber is 2µm.
Advantages:
• Increased wear resistance.
• Improved handling characteristics
• Increased depth of cure
• Reduction of polymerization shrinkage
• Improved flexure strength(50Mpa)

119. GIOMERS
True hybridization of GIC and composite
Combine fluoride release and fluoride recharge of GIC with esthetic
easy polishability and strength of composite
Two types
G- PRG : (Fully pre reacted giomers)
S-PRG: (Surface pre reacted giomers)
INDICATIONS
• Class I, II, III, IV, and Class V cavities
• Restoration of cervical erosion and Root caries
• Laminates and core build up
• Restoration of primary teeth.
• Repair of fracture of porcelain and composites
BEAUTIFUL (SHOFU)

120. Advantages
• Increase wear resistance
• Increase Radiopacity (glass filler)
• Ideal shade match (improved light diffusion and fluorescence)
• High and sustained fluoride release and recharge
• Provide almost complete seal against bacterial microleakage
• Little mechanical and chemical pulp irritation
• Inhibit demineralization

121. Amino-acid modified GICs
- introduced to improve the strength of the
glass ionomer so as to make it suitable for
restoring high stress sites such as class I and
II cavities.
- Examples for amino acids used in GICs
include:
• N- acryloyl - glutamic acid (AGA)
• N -acryloyl - 6- aminocaproic acid (AACA)
• N- Methacryloyl glutamic acid (MGA)

122. NEWER ADVANCEMENTS

123. • Many modifications to the inorganic component of glass-ionomer
cements have been attempted.
• Metals, fibers and other nonreactive fillers have been evaluated in
an attempt to improve the mechanical properties of GICs without
compromising the handling or biological characteristics.
• In most cases, the bonding between the reinforcing agent and the
cement matrix has proven challenging.
• Additionally, modifications to the chemistry of the basic glass have
been attempted to strengthen the cement.

124. • The first attempt to increase the strength of conventional
glassionomer cements by addition of reinforcing fillers were
reported by Simmons in 1983
• he added amalgam alloy powder to GIC powder composition
• One of the commercially available products resulting from this
innovation was Miracle Mix (MM, GC Corporation, Japan)
• due to metal–carboxylate matrix interface failure, the simple
addition of amalgam powder did not exhibit promising results

125. • McLean and Gasser fused and sintered amalgam powders to basic
glass particles (cermet-ionomer cements)
• The resulting cermet particles exhibited strong bonding between the
metallic and glass particles.
• Cermet–ionomer cements showed increased resistance to abrasion
when compared with glass–ionomer cements and their flexural
strength was also higher. However, their strength is still not enough
to replace amalgam restoration for posterior teeth

126. • Kerby et al. prepared stainless-steel glass-ionomer cements by combining
atomized stainless-steel powder with an average particle size of 9 mm with a
commercially available glass-ionomer powder
• one hour after curing
• the mechanical strengths of stainless steel reinforced glass-ionomers were
more than 40% greater than commercially available glass-ionomer cements
• more than 50% greater in compressive strength and more than 60% greater
in diametral tensile strength
• These values continued to increased after 24 h, resulting in 50% and 100%
increases in compressive and tensile strength respectively of stainless steel
glass-ionomers compared to commercial controls
• stainless steel cements provided the most desirable physical properties that
include high compressive and tensile strength, favorable working and setting
times and low acid solubility
• disadvantage of the stainless steel GIC is the grayish color which makes it not a
suitable choice for anterior tooth restoration
STAINLESS-STEEL GLASS-IONOMER CEMENTS

127. REACTIVE GLASS FIBERS: FIBER REINFORCED GLASS-IONOMER CEMENTS
• Lohbauer et al. reported that a reactive glass fiber (the composition of the glass
fibers was SiO2: 33.3, Al2O3: 16.7, CaO: 14, NaF: 3.3, AlF3: 3.3, Na3AlF6:
16.2%) with 20 vol% of fiber loading (fiber length ¼ 254 nm)
• had the ability to increase the fracture toughness of glass-ionomer cements
• Yli-Urpo et al. added bioactive glass particles (particle size: less than 45 mm),
with a composition of: SiO2 53%, Na2O 23%, CaO 20%, and P2O5 4%, into the
composition of GIC powder
• Bioactive glasses are known to promote healing and incorporate into hard tissue
• decreased the compressive strength of the cement on average by 54%.
• This phenomenon suggested that BAG particles might be only loosely attached
to the glass-ionomer matrix

128. INCORPORATION OF HYDROXYAPATITE (HA) AND HA/ZrO2 IN GICS
• Lucas et al. in their studies added 0.3–50 µm spherical HA particles to the
powder of a capsulated GIC (Fuji IX GP) with a particle size of 0.3–200 µm
• HA-ionomers are promising filling dental materials and the incorporation of HA
particles into the powder of glass-ionomer cements increased the mechanical
properties of the set cement
• addition of HA did not impede sustained fluoride release and also maintained
long-term bond strength to dentine.
• However Gu et al. found that the substitution of GIC glass with crystalline HA did
not affect compressive strength significantly.
• They also found that the substitution of the glassionomer glass with HA did not
affect diametral tensile strength.
• In addition, they reported that the addition of HA in the glassionomer powder
composition in higher amounts than had adverse effects on the mechanical
properties of the glassionomers.

129. • In a recent study, Moshaverinia et al. synthesized nanohydroxy- and
fluoroapatite using an ethanol based sol–gel technique and
incorporated the synthesized nanoparticles into commercial glass-
ionomer powder (Fuji II GC).
• Compressive, diametral tensile and biaxial flexural strengths of the
modified glass-ionomer cements were evaluated.
•
• Results of their studies showed that after 24 h and one week of setting,
the nanohydroxyapatite/ fluoroapatite added cements exhibited
• higher compressive strength (177–179 MPa),
• higher diametral tensile strength (19–20MPa)
• higher biaxial flexural strength (26–28 MPa) as compared to the control
group (160 MPa in CS, 14 Mpa in diametral tensile strength and 18 MPa
in biaxial flexural strength).

130. • Gu et al. in their studies added a mixture of HA/ZrO2 (4–40% by
volume) to glassionomer powder (Fuji IX GP) and then measured
the mechanical properties of the resulting cement
• As a result, the mechanical properties of HA/ZrO2 were significantly
improved compared to HA-GICs
• The main disadvantage of incorporation of ZrO2/HA, as shown by
high magnification SEM, is the propagation of the cracks around the
glass and HA/ZrO2 particles rather than through the particles

131. GICS CONTAINING YBF3 (ytterbium) AND BASO4
• In the study carried out by Prentice et al., nanoparticles of YbF3(25 nm)
and BaSO4 (less than 10 nm) were added to conventional glass-ionomer
cement powder
• The BaSO4 was incorporated to increase the radiopacity of the cement
and the YbF3 was a fluoride source that can modify both setting and
working times
• addition of BaSO4 and YbF3 nanoparticles reduced the working time and
the initial setting time, However, the effect was reversed at higher
concentrations.
• significantly reduced 24 h compressive and surface hardness of glass-
ionomers
• Finally, they concluded that YbF3 accelerated the glass-ionomer curing
reaction, as did low concentrations of BaSO4, but higher amounts of
BaSO4 had opposite effects

132. YTTRIA STABILIZED ZrO2-GICS
• Gu et al. added nano-sized yttrium stabilized ZrO2 (YSZ) powders and
Y2O3 stabilized ZrO2 powders to the glass-ionomer cement powder
• YSZ containing GICs are promising restorative materials only if the
appropriate particle size distribution is used

133. NIOBIUM SILICATE GICS
• In order to investigate the effect of addition of other glass compositions to
conventional GIC glasses, Bertolini et al. used the following composition
as the powder for glass-ionomer cements: 4.5 SiO2 : 3Al2O3 : xNb2O3
(niobium) 2CaO (0.1 < x < 2.0).
• setting time of the cement pastes increased significantly for Nb
containing GIC samples
• micro hardness and DTS of the experimental glass-ionomer were
decreased

134. ZINC BASED GLASS-IONOMER CEMENTS
• Boyd et al.84 investigated the effect of incorporation of Zn in the
composition of glass-ionomer cements
• Mechanical testing results demonstrated that Zn based GIC had
approximately one quarter the strength of their aluminium silicate glass
counterparts after 30 days of maturation
• the flexural strength of these cements was comparable to the flexural
strength of conventional GICs

135. BORIC ACID CONTAINING GLASS-IONOMER CEMENTS
• Prentice et al., incorporated boric acid (H3BO3) into the glass powder of
a glass-ionomer cement in order to evaluate the effect of this acid on the
mechanical properties of the glass-ionomer cements
• indicated that the incorporation of boric acid was followed by a significant
reduction in the compressive strength of the GIC
• indicated that the incorporation of boric acid was followed by a significant
reduction in the compressive strength of the GIC

136. SrO ADDED GLASS-IONOMER CEMENTS
• The effect of strontium oxide on the mechanical properties of GICs was
studied by Deb et al.
• an increase in the amount of SrO led to increases in both working and
setting times, indicating that SrO retarded the rate of reaction
• The compressive strength of SrO modified cement was increased
significantly by (0–5% m/m) SrO addition

137. GLASS-IONOMERS CONTAINING SPHERICAL SILICA FILLER (SSF)
• Tjandrawinata et al. incorporated silica fillers into GIC compositions, and
evaluated the various properties of the resulting material, such as 24 h
compressive strength, modulus of elasticity, water uptake, and immediate
setting shrinkage of conventional glass-ionomer (Fuji II GC).
• The result of their study demonstrated that the addition of SSF
• increased the compressive strength value by 1.1 times
• increase of modulus of elasticity was 1.10 to 1.35 times
• Decreased the 24 h water uptake to 80–90% and reduced the immediate
setting shrinkage to 70–79% of the original material.

138. SIC ADDED GLASS-IONOMER CEMENTS
• It has been reported that by adding silicone carbide whiskers containing a
coating and followed by silanization, the polymeric matrix was bonded
more tightly to the whiskers due to the coating on their surfaces
• The results indicated the SiC added GIC exhibited improved transverse
strength, enhanced fatigue resistance and improved the long term bond to
enamel, while not inhibiting fluoride release and forming a thicker
intermediate layer.
• The main disadvantage of SiC added GIC is the risk of SiC particles
migrating to vital organs since they do not bond to the matrix of GIC and
therefore they can be potentially hazardous to human health

139. • the current literature demonstrates that the mechanical properties of
the glass-ionomer cements can not be enhanced by merely adding
reinforcing particles and fillers such as bioactive glass fillers, spherical
silica fillers and SiC.
• For instance, in the glass-ionomers modified with SiC there are no
bonds between the added fillers and the organic/inorganic matrix of
the glass-ionomer; therefore, there is a risk of filler migration to vital
organs and so this modified GIC is contra-indicated.
• By incorporation of ceramic fillers such as ZrO2 into GIC powder
composition, mechanical properties of conventional GIC can be
increased.
• However, the optimum amount of filler should be added in order not
to deteriorate other physical properties of the modified GIC.

140. • For hydroxyapatite modified GICs, the main problem is the poor
mechanical properties of the HA itself. However, it has the ability to
react with PAA and bond to tooth structure
• . The addition of stainless steel particles to the composition of
glassionomer cements causes an apparent increase in mechanical
properties
• the main disadvantages of these kinds of materials are the grayish-like
color of the set cement and also the probability of the toxicity of the
released ions from the stainless steel particles.
• Adding niobium oxide could be a successful method, since they
made the same structure as the aluminosilicate glasses. However,
niobium oxide containing GICs showed decreased mechanical
properties.

141. • Addition of cations like Fe3+(ferrous) and Fe2+(ferric), which have
the same charge and polarity as Al3+ and Ca2+, does not deteriorate
the aesthetics of the glass-ionomer and is a good way of enhancing
the mechanical properties of conventional GICs.
• These ions should not be toxic for the vital tissues and organs
within the human body
• By incorporation of reinforcing materials into glass-ionomer cement
powders, such as hydroxyapatite and metallic nanofillers, it may be
possible to use glass-ionomer cements as the primary material for
tooth restoration and as a bone grafting material in stress bearing
areas. In order to achieve these goals new powder combinations
should be developed with the ability to improve the strength of the
inorganic/organic matrix within the glassionomer cements.

142. CONCLUSION
 For the poor mechanical properties the GIC has good thermal,
adhesive and biologic properties.
 With the current level of intensive research on glass ionomers, the
deficiencies that exist seem certain to be eliminated, or at least
reduced, resulting in an ever improving range of materials of this
type.
 It is apparent that the whole family of glass ionomers is growing
rapidly and areas of application are expanding along with further
refinement.

143. • Art And Science Of Operative Dentistry, Sturdevent..5th Edition
• Phillips’ Science of Dental Materials, 11th
edition, Anusavice KJ; WB Saunders
Company
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