Applied Dental Materials
Developed in attempt to combine the favorable
properties of silicate cement and
Was introduced in 1972 by Wilson and Kent.
The ﬁrst introduced GIC was opaque, limited
shade selections, mixing and handling
problems and technique sensitivity.
It was introduced in~1870 as direct aesthetic
restoration [historical type]
Supplied form : Powder & Liquid
Powder: Fluoro- calcium- aluminum- silicate
glass (ion leach-able glass )
Liquid: Aqueous solution of phosphoric acid
It is an acid base reaction
Base + Acid
Salt + Water
It is a surface reaction
Aesthetic [glass content]
Anticariogenic [ﬂuoride content]
[Early clinical failure].
Highly irritant to the pulp due to.
- Its high acidity.
- Arsenic impurity content.
Highly soluble in oral ﬂuids.
Inadequate mechanical properties.
Discoloration by time.
No adhesive bond between the tooth &
Ca, Na, Ph, F, O
stability) (increase shelftime)
Fluoro-aluminosilicate glass prepared with
Type II (restorative material) is generally coarser
than that of type I (Luting agent).
Glass is thermally treated to form the powder,
the quality of the setting reaction can be partially
controlled by the thermal handling.
more rapid setting rate
The major component of the liquid is water.
35-65% aqueous solution of various polyacids.
Most common polyacids, polyacrylic acid or
copolymers of acrylic, Maleic acid or acrylic and
Itatonic acid tends to reduce the viscosity,
Tartaric acid in small amount improves working
and setting characteristics.
Some manufacturers freeze or vacuum dry the
polyacids and copolymers, to incorporate them
with the cement powder rather than the liquid.
this was an attempt to ensure the accuracy of
the P/L ratio, and avoid the thickening of the
liquid with storage.
A typical acid base reaction
Metal + Acid = Salts (exothermic)
acid soluble glass reacts
with the polyacids releasing Al, Ca, Na, F ions.
Ca and Al polysalts are formed.
The salts Hydrate to form a gel matrix, while the
unreacted glass particles act as ﬁllers
surrounded by the gel.
Set cement consist of unreacted glass
surrounded by silica gel bonded together by a
matrix of hydrated Ca and Al-polysalts.
Fluoride ions are not integral part of the
matrix formation, they are available for
clinical release without compromising the
structure of the cement.
Stages of Setting
I. Decomposition: acid attack and release of metal
ions from glass.
II.Migration: ions move into the aqueous phase. at
this stage the cements has a shiny glossy
III.Gelation: Ca-poly-acrylate primary
components. the cement at this stage starts to
become rigid and has an opaque
appearance(because of the large difference in
the refractive index between the glass particle &
the matrix). clinical set, polishing and ﬁnishing
postponed 24 hrs.
at this stage the cement has to be protected from
dryness and moisture.
IV. Post-set hardening: ions become bound to
polyacid chains, Al-polyacrylate becomes
V.Maturation: increase cross-linking gives greater
physical properties, the cement becomes
resistant to acid attack and desiccation. increase
at this stage the cement can be ﬁnished &
The set G.I. appears as follows:
Role of Water
Water plays a crucial role in the setting reaction
of glass-ionomer cement.
It act as a reaction medium.
Facilitate the formation of the hydration of the
salts and enable the cross-linking to progress
Amount of available water is crucial, if it varies
the results can be catastrophic:
Excess water: contamination will dilute the
metal ions in soluble form and result in
increased opacity and decreased strength and
hardness of the ﬁnal cement.
Water loss during setting: desiccation of the
hydrogel disrupts the cement structure during
maturation resulting in crazing and cracking of
the ﬁnal cement.
The P/L ratio of GIC is critical.
P/L ratio is 3:1 by weight.
Must be mixed within 45 sec.
the resulting mix must have a surface gloss or
it will not adhere.
Pre-capsulated form is available.
Care of the liquid: In order to preserve the amount
of water inside the liquid
1)Dispense the liquid just before mixing
2)Reseal the bottle immediately
3)Discard the last third of the liquid
Use cool glass slab(not below the dew point in
order not to change the water content)
Mixing over large area (for heat dissipation) with
Isolation of the cavity
Application of calcium hydroxide liner
Conditioning of cavity wall
Bulk insertion of the G.I.
Coating of the G.I. surface with cavity varnish
G.I. is mildly irritant to the pulp due to:
Mild exothermic setting reaction
Mild acidic irritation of polycarboxylic acid
Rapid rise to neutrality within 24 hrs.
Difﬁcult penetration of the large acid molecules
inside the dentinal tubules.
Anti-cariogenic property due to
Fluoride release from G.I. to tooth
It is recommended in patients with high
Compressive strength: fairly high up to 200 MPa.
Flexural strength: fairly low 5 to 40 MPa.
Shear strength: fairly low 3 to 5 MPa.
Coefﬁcient of thermal expansion similar to tooth
Dimensional changes: shrinks on setting, expand
with water sorption.
The strength and hardness are lower than those
of the silicate cements.
low toughness and less wear resistance when
compared with resin composite.
The strength of G.I. depends on:
2)Protection of G.I. against dryness & moisture in
the initial set stage
During setting very sensitive to water but once
it sets it is characterized with a very low
solubility, the lowest of the available dental
Esthetic & Optical
Tooth colored restoration, acceptable esthetic
but not as good as the resin composite.
G.I. is radio-opaue by the addition of barium to
the glass powder.
Bonding TO Tooth
GIC share the adhesive potential of the
They appear to bond primarily to the inorganic
component (Ca) of the tooth st. by initial hydrogen
bonding, forming a metal ion bridges.
Good isolation to avoid contamination and
moisture, smear layer should be removed and the
cement should be used when its in its glossy stage.
Clinical Uses for GIC
Type I cement:
luting agent or liner
The ﬁlm thickness is 20µm.
Type II cement: Class V erosion/caries
Temporary rest (caries control)
Class II, III, IV(dentin margins)
The ﬁlm thickness is 45µm.
Type III cement: Pit & Fissure sealant.
The ﬁlm thickness is25-35µm
Type IV cement: for core build up in high stress
The ﬁlm thickness is 45µm or more
Type V cement:
for liner & bases
1 )To improve the mechanical properties
2 )To decrease the moisture sensitivity
The modiﬁcation is done either to the powder or
to the liquid.
TYPES OF MODIFICATIONS:
1)METAL G.I. MIXTURE (MIRACLE MIX):
G.I. powder +Amalgam alloy powder
It was not successful
Precious metal e.g. silver is sintered to the G.I.
Cermet can be used
1)Core build up
Properties of cermet :
Glass ionomer cement in which the acid-base
setting reaction has been supplemented by a
polymerization reaction of added resin
the following criteria must be fulﬁlled:
the acid base reaction must be critical to the
must contain ﬂuoroaluminosilicate glass,
polymeric carboxylic acid and water.
A hydrophilic monomer as HEMA is grafted to
the aqueous polycarboxylic acid copolymer
1)The monomer should be hydrophilic to
avoid separation of the resin from the liquid.
2)Initiator activator system for light & or
chemical curing of HEMA should be included.
Setting reaction:(supplied as powder&liquid)
1)Acid base reaction
2)Light polymerization of HEMA
3)Chemical polymerization of HEMA
Hybrid ionomer can be used as:
1)Lining under composite restorations
2)Anterior restorations Class III & V
( Polyacid Modiﬁed Composite Resin):
It is a modiﬁed C.R.( C.R.+G.I.)
1)Dimethacrylate oligomer with two carboxylic
2)Ion leachable glass ﬁller.
3)Partially silanated to allow for bonding of ﬁller to
matrix&leaching out of ﬂuoride from the ﬁller.
Setting reaction:( supplied as one paste)
1)Light polymerization of the oligomer(major)
2)Acid base reaction(minor;it occurs only inside the
1)High translucency as C.R.
2)Improved mechanical properties as C.R.
3)Chemical bonding to tooth but less than G.I.
It is again a mixture of C.R.+ G.I,but with surface
or fully pre-reacted glass ionomer.
Setting reaction:(supplied as one paste) light
polymerization of the oligomer
Its properties are intermediate between C.R. & G.I.