GLASS IONOMER CEMENT

GLASS IONOMER CEMENT
By Dr.LilavantiVaghela
MDSin Pediatrics And Preventive Dentistry

• Contents
❑ Introduction
❑ History
❑ Classification
❑ Indications & Contraindications
❑ Composition
❑ Clinical Procedures
❑ Setting Reaction
❑ Properties
❑ Few Applications Of Gic
❑ Modifications Of Gic
❑ Recent Advances
❑ Conclusion

Introduction
• Cement
• A cement is a substance that hardens to act as a base , liner ,filling material or adhesive to
bind devices or prosthesis to the tooth structure or to each other. (philips’ science of dental
materials 12th edition)
• ADA specification number: 96
• During the last decades, an increasing variety of dental restorative materials have
conquered the market.
• Gold and ceramics are the main standard material used for indirect restorations, and until
the late seventies amalgam was used for direct restorations.
• Today, the decreased number of amalgam fillings is also influenced by a high demand for
tooth-colored and biocompatible restorations.
An atlas of glass ionomer cement- A clinician's guide 3rd edi by Graham J Mount glass
ionomer cement by Alan wilson and john kent

• Great strides in dental research have lead to a variety of alternatives to amalgam one of
which is Glass Ionomer Cement
• In dentistry adhesion of restorative materials to tooth substance is an important
objective.
• It is believed that a restorative material should resemble the tooth in all respects.
“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

• Definition
“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
“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
An atlas of glass ionomer cement- A clinician's guide 3rd edi by Graham J Mount
glass ionomer cement by Alan wilson and john kent

History
• Scientific development:
• D.C. smith in 1968 used poly acrylic acid in zinc polycarboxylate cement
• The invention of glass ionomer cement was done in 1969.first reported by Wilson and
Kent in 1971.(ASPA I)
• First practical material: ASPA II in1972 by Crisp and Wilson
• First marketable material, ASPA IV in 1973 Luting agent ASPA IVa in 1975
• Metal reinforced cements in 1977 by Sced and Wilson
• Cermet ionomer cements in 1978 by Mc Lean and Glasser
• Improved traslucency, ASPA X by Crisp, Abel,Wilson in 1979
• Water activated cements, ASPA V in 1982 by Prosser et al.
An atlas of glass ionomer cement- A clinician's guide 3rd edi by Graham J
Mount glass ionomer cement by Alan wilson and john kent

• Clinical development:
• First clinical trials in 1970 by Mc Lean
• Class I restorations, fissure sealing and preventive dentistry in 1974 by Mc Lean and
Wilson
• Erosion lesions, deciduous teeth, lining, luting, composite/ ionomer laminates in 1977 by J.
W. Mclean & A. D. Wilson.
• Improved clinical techniques between 1976-77 by G.J.Mount & Makinson,1978
• Approximal lesions and minimal cavity preparation in 1980 by Mc Lean
• Water activated luting cements in 1984 by Mc Lean et al
• Tunnel class I and II preparations by Hunt and Knight in 1984
• Double etch ionomer /composite resin laminates,1985,Mc Lean

• Composition
• POWDER
• SiO2 –30.1%
• Al2O3 –19.9%
• AlF3 –2.6%
• CaF2 –34.5%
• NaF2 –3.7%
• AlPO4 –10.0%
• Basic component is a calcium alumino silicate containing fluoride.
• Glasses are prepared by fusing the components between 11000c - 15000 c then pouring
the melt onto a metal plate or into water.
• The glass is then ground to a fine powder, size ranging between 20μ for luting to 50μ for
restoration.
• They get decomposed by acids due to the presence Al +3 ions which can easily enter the
silica network.
• It is this property that enables cement formation.

Alumina (Al2 O3)
- Increase opacity
Silica (SiO2)
- Increase Translucency
Fluoride: Its has 5 functions
- Decrease fusion temp.
- Anticariogenecity
- Increase translucency
- Increase working time
- Increase strength
Calcium fluoride (Ca F2)
- Increase opacity
- Acts as flux
Aluminium phosphates
- Decrease melting temp.
Cryolite (Na3 Al F6)
- Acts as flux

LIQUID
- Poly Acrylic Acid 40% To 50%
- Itaconic Acid
- Maleic Acid
- Tricarboxylic Acid
- Tartaric Acid
- Water
• water is an important constituent of GIC, It is the reaction medium and helps in hydrating
the matrix.
• The three acids itaconic ,maleic and tricarboxylic acid decrease viscosity of liquid , Promote
reactivity, prevent gelation of liquid

Tartaric acid
- Increases WT
- Increases translucency
- Improves manipulability
Increases strength
5-15% of optically active isomer of TA is added.

A.ACCORDING TO A.D. WILSON AND J.W.McLEAN IN 1988
Type I --- luting and bonding cements
Type II --- restorative cements
a.Restorative aesthetic
b.Restorative reinforced
Type III –lining or base cement
B.ACC.TO CHARACTERISTICS SPECIFIED BY MANUFACTURER
Type I --- Luting cement eg. Fuji I, KETAC
Type II --- Restorative material eg. Ketacfil, Fuji II, fuji IX
Type III --- a. Bases & liners --weak with less acidic
b. Bases & liners --stronger but more acidic
c. Bases & liners --strong even in thin layer
Type IV --- Admixture eg. Ketac silver, miracle mix

C. ACCORDING TO SKINNERS
Type I – Luting
Type II- Restorative
Type III- Liner and base
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 USES:
• 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
An atlas of glass ionomer cement- A clinician's guide 3rd edi by
Graham J Mount glass ionomer cement by Alan wilson and john kent

MODE OF SUPPLY
Powder, liquid
Pre proportioned capsules
ANHYDROUS CEMENT
• Anhydrous cement was introduced in order to avoid increased viscosity due to Increasing
molecular weight of polyacids.
• In this freeze dried polyacid powder and glass powder are placed in the same bottle
• Liquid is water or water with tartaric acid
• Also called as water settable cement
• Facilitates mixing and extends shelf life
An atlas of glass ionomer cement- A clinician's
guide 3rd edi by Graham J Mount glass

Dispensing
• Capsulated material is recommended
• Cost effectiveness
• The only caution ---capsule is fully activated before placing in to mixing machine
• Hand mixing
An atlas of glass ionomer cement- A clinician's guide 3rd edi by Graham
J Mount glass ionomer cement by Alan wilson and john kent

Variation in dispensing
Two paste system packaged in a twin syringe apparatus
presentation available only for resin modified luting cements
main attraction----dispense variable quantities with the correct ratio all the time
utilize fine powder particle
film thickness under 5um
setting time around 3 mins

Mixing of capsules
Mixing
• Care must be taken to see the
correct timing
• 10 to 15 sec with 4000cycle/min
• Old cycle- 3000cycle/min
• Estimation of effective working
time determined by loss of gloss
test

Loss of gloss test

Hand mixing
Liquid should not stay on paper pad
longer than 1minute.
Don’t mix beyond 30 seconds
The objective is – only wet the particle
– no dissolving it.
First half folded into liquid in 10-15seconds
Second half incorporated in 15 seconds
Small mixing area

Porosity
• Degree of porosity is incorporated in material, which is unavoidable.
• Because they are two part materials which require mixing
• Larger voids—hand mixing
• Smaller voids—machine mixing
• Main hazard of porosity---reduce compressive and tensile strength because void may
promote crake propagation

Correct consistency for hand mixed
• For luting and lining strings up to 3-4cm from mixing pad
• for restorative strings up to 1 cm from mixing pad.

Setting reaction
Showing extraction of ions from the glass, migration into aqueous
phase, & subsequent precipitation as polyanion hydrogels

SETTING REACTION
it is an acid base reaction between acidic polyelectrolyte and basic glass powder.
decomposition ---decomposition of glass powder by acid
resulting in release of ions
migration ---these ions migrate into aqueous medium
gelation ---caused by multivalent aluminium and calcium
ions displacing various spheres of hydration that
interpose themselves between cation-anion ion pairs
post set hardening and slow maturation ---hardening
and precipitation continue for about 24 hrs
accompanied by slight expansion under conditions of
high humidity and development of translucency.

STAGES OF SETTING REACTION
Unattacked
glass
particles
dispersed
in polyacid
liquid
Outer layer of glass
particles is depleted
of metal ions &
degraded to silica
gel.
Metal ions migrate to
liquid, where they
remian in soluble
form
(red dots)
Initial gelation
Soluble metal
ions remain ..
The cement is
still vulnerable
to moisture
Fully hardened glass
ionomer in an
insoluble form
Cement is no longer
vulnerable to attack
by moisture

• Stage 1 : Decomposition of glass & migration of metal ions (Dissolution)
• • 20-30% of glass is attacked by polyacid
• • Surface of the glass particles decompose
• • Releasing metal ions (Al 3+ , Ca 2+ )
• • Glass network breaks down into silicic acid which polymerises at surface of the glass
powder
• • As pH of aqueous phase increases, polyacrylic acid will ionize & create electrostatic field
that will aid the migration of liberated cations into the aqueous phase
• • The ions thus migrate into the aqueous phase
• • As the negative charge increases, polymer chains unwind, viscosity increases

• Stage 2 : Precipitation of salts; gelation & hardening
• • At a critical pH & ionic concentration, precipitation of insoluble polyacrylates begins
• • Ca 2+ &Al 3+ bind to polyanions via carboxylate groups
• • The initial set is achieved by the cross-linking of the more readily available Ca 2+ (forming
clinically hard surface within 4minutes of start of mix)
• • Maturation occurs over the next 24hours when the less mobile Al 3+ become bound within
the cement matrix, leading to more rigid crosslinking between poly (alkenoic acid) chains
• • Aluminium polyacrylate ultimately predominates in the matrix

• At critical pH and ionic conc. Precipitation of insoluble poly acrylates takes place.
• Initial set occurs due to calcium polyacrylate but hardening of cement is due to slow formation
of aluminium polyacrylate
• When cement is not fully hardened Al, Ca, F and polyacrylate ions may leach out leading to
irretrievable loss of cement matrix
• Calcium acrylate is more vulnerable to water. So the freshly set cements are to be protected
Gelation and vulnerability to water

Hardening and slow maturation
• This process continues for about 24 hrs
• Undergoes slight expansion and increase in translucency
• Cement becomes resistant to dessication and strength also increases for at least a year.
• Increase in strength and rigidity are associated with slow increase in cross linking.

CEMENT STRUCTURE
• Cored filler is bound together by a hydrogel of Ca and Al poly acrylates that
contain fluorine :- FLUORO ALUMINO CALCIUM POLYACRYLATE

SETTING TIME :
• It sets rapidly in the mouth and hardens to form a body having translucency that
matches enamel
• Setting time for type I –GIC – 5 -7 min
• Setting time for type II–GIC --10 min

THE ROLE OF WATER
• Plays an important role in setting reaction and structure of cement.
• Acts as reaction medium
• Hydrates the siliceous microgel and metal poly acrylate salts.

Early contamination
• Loss of calcium polyacrylate chains
• Loss of translucency
• Loss of physical properties
• Leaves cement susceptible to erosion
Dehydration
• Cracking & fissuring of cement
• Softening of surface
• Loss of matrix-forming ions
crack in unprotected gic

Water present in set cement can be classified in to two forms:
• a) loosely bound water
• b) tightly bound water
• LOOSELY BOUND WATER
• Its is the water which is readily removed by desiccation .
• Water is easily lost and gained by the cement as the loosely bound water is labile.
• TIGHTLY BOUND WATER
• Its is the water which cannot be removed .
• Its is associated with the hydration shell of cation-polyacrylate bond.
• As the cement ages the degree of of hydration ↑ that is the ratio of tightly bound to loosely
bound water increases which in turn increases strength and modulus of elasticity and
decrease plasticity (according to wilson et al 1981).

Factors affecting setting characteristics
• Role of fluoride
• Effect of tartaric acid
Factors affecting rate of setting
• Glass composition
• Particle size
• Addition of tartaric acid
• Relative proportions of constituents
• Temperature of mixing

Role of fluoride
Fluoride forms metal complexes
They retard the binding of cation to
anion sites on polyacrylate chain
Delays gelation & prolongs working
time
Release of H+
Acidity of paste increases
Delays pH dependant gelation

Role of tartaric acid
• Tartaric acid is stronger than polyacrylic acid Forms stronger complex with Al Therefore increases
extraction of Al from glass
• Initially tartaric acid alone complexes cations As neutalisation proceeds & pH ~ 3 Polyacrylic acid
becomes neutralised by metal ions until cement sets at pH ~ 5-5.5
• Also ionization of polyacrylic acid is suppressed & unwinding of the chain is retarded, resulting in
decrease in viscosity & delaying gelation
• Once gelation occurs, tartaric acid accelerates hardening
• Tartaric acid & calcium react preferentially therefore initial set may be due to formation of
calcium tartarate
• Tartaric acid controls initial setting of cement

Factors affecting rate of setting
1. Glass composition : increase in Al/Si ratio – faster set
2. Particle size : finer – faster set
3. Tartaric acid – sharpens set without shortening working time
4. Relative proportion of constituents – Powder : Liquid
5. Temperature of mixing – increase – faster set
Among these the factors within the province of the clinician are
Temperature of mixing
Powder : Liquid

Factors within the province of the clinician
1. Temperature of mixing
• Chilling powder & mixing pad – increases working time up to 25% (Mc
Lean 1970)
• Increase in working time occurs without loss of physical properties
(Makinson 1978)
• Increase in humidity & temperature below dew point – weakens the cement
2. Powder : Liquid
• Increase in powder – faster set
• But insufficient liquid – decrease in translucency of the set cement

Setting reaction of light initiated auto cure material
• Involves enhancing speed of acid-base reaction by utilizing a simple physical principle
• No resin is added
• The glass ionomer is colored (Eg. red) ; on irradiation with a blue halogen activator light , acid-
base reaction will take place more rapidly
• Setting time is reduced dramatically
• No heat generation
• Physical properties not downgraded
• Highly bactericidal
• Flows easily
• Easily identified

RESIN COATING(protection of cement)
Water plays a key role for proper maturation of GIC.
• water contamination and dehydration during the initial setting stages can compromise the
physical properties of the restoration.
• It is recommended to strictly exclude water during the vulnerable setting stage, which is
reported to last for atleast one hour until even two weeks after placement.
• Petroleum jelly, cocoa butter, waterproof varnishes, and even nail varnishes have been
recommended as suitable surface coating agents.
• Coatings are lost by oral masticative wear, but by this time the cements become more
resistant to variations in water balance due to their posthardening.

• Among the coating strategies, light-polymerized resin coatings have been considered the
optimal surface protecting agent.
• Hotta et al. found, that the use of light-polymerized bonding or glazing agents are able to
limit water movement across the setting cement surface.
• Recently, a new restorative concept has been marketed (Equia®, GC Europe, Leuven,
Belgium), a system application consisting of a posterior restorative GIC combined with a novel
nanofilled coating material.
• This self-adhesive, nanofilled resin coating that provides a high hydrophilicity combined with
an extremely low viscosity, accounts for a perfect seal of a GIC surface

Indications
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 – Approximal lesions, Buccal and Occlusal approach (tunnel
preparation)
• Core build-up
• Provisional restorations where future veneer crowns are contemplated
• Sealing of root surfaces for overdentures.

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 and 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 cement are used.
• Useful in patients with high caries index

CONTRAINDICATIONS
• Class IV carious lesions or fractured incisors.
• Lesions involving larger areas of labial enamel where esthetics is of major importance
• class II carious lesions where conventional cavities are prepared.
• Replacement of existing amalgam restorations.
• Lost cusp areas.

bonding ability of paste-paste glass ionomer
system to tooth structure :in vivo study,2015

CLINICAL PROCEDURE FOR PLACEMENT
To ensure successful Glass Ionomer restoration following parameters
are to considered:-
1.Preparation of tooth surface
2.Proportioning & mixing
3. Protection of cement during setting
4. Finishing
5.Protection of cement after setting

• Routine procedure for placement of any glass ionomer cement:
1. Prepare the cavity as smooth as possible.
2. Clean the tooth surface gently, where access permits, using a slury of plain pumice and water
3. Apply a libral coat of 10% ployacrylic acid for 10 secs.
4. Wash vigorously with water for 10 secs.
5. Dry lightly but do not dehydrate tooth surface.
6. Place GIC
7. Positive support with matrix band
8. Remove excess material
9. Immediately cover the cement with protective agent
10. Polishing of restoration.

Sensitivity to luting cement
• GIC can be the cause of post operative sensitivity when used as luting agent under full
crown(vital tooth)
• Pulp is already inflamed because of previous trauma and this may further enhanced by crown
preparation
• Do not remove the smear layer by conditioning
• Seal the dentine tubules by applying mineralizing solution or resin dentine bond that contain
maleic acid
• Vent a crown prior to cementation to reduce internal pressure.

Finishing and Polishing methods
Type II.1 – Restorative esthetic ----1)resin modified
2)auto cure
2) Auto cure
• Because of slow setting chemistry, do not attempt to contour or polish at least for 24hrs
• Use a sharp blade only to reduce gross contour at the time of insertaion.
• After 24hrs, gross contoured can be achived with very fine sintered diamonds under air/water
spray at 20,000revs/min
• Refine the surface with graded rubber polishing points and cups at 5000revs/min
• Finish to a gloss with graded polishing disc at 3000revs/min
• seal with a low viscosity resin glaze.

Type II.2 restorative
• Because of the rapid setting chemistry, contoured and polishing can be done in beginning at 6
mins from the start of mix.
• Gross contour and refine the surface same as auto cure cement
• Interproximal surface can be contoured and polished with the profin directional system
equipment using diamond or polishing blades

• Properties
❑ Linear Elastic Mechanical Properties
❑ Wear And Fatigue
❑ Thermal Compatibility
❑ Adhesion
❑ Anticariogenic Properties
❑ Biocompatibilty
❑ Aesthetics

Linear-Elastic Mechanical Properties
• The compressive strength of GIC is commonly measured after 24 hours wet storage.
• Compressive strength ranges between 60 and 300 Mpa and flexural strength up to 50 Mpa .
• GIC exhibit a significant increase (approximately 100%) in flexural as well as in compressive
strength when exposed to water in the period between 24 hours.
• When exposed to aqueous solutions of varying pH, GIC exhibited a high acid erosion resistance
compared to other restorative materials.

FS: flexural strength; CS: compressive strength; 3-PB: three-point-bending; 4-PB: four-point-bending; BB:
biaxial bending; ws: wet storage; as: air storage; wc: wet cyclic.
Dental Glass Ionomer Cements as Permanent Filling Materials—Properties, Limitations and Future Trends
Ulrich Lohbaue, 2010 by ulrich lobbauer

Dental Glass Ionomer Cements as Permanent Filling Materials—Properties, Limitations and Future Trends
Ulrich Lohbaue

PROPERTY GLASS
IONOMER II
CERMET HYBRID
IONOMER
1.Compressive
strength(Mpa)
150 150 105
2.Diametrcal
Tensile
strength(Mpa)
6.6 6.7 20
3.Solubility 0.4 - -
4.Pulp response mild mild mild
Properties Of Restorative Gic
phillips's science of dental material by Annusavise, 11th edi

Properties Of Luting Gic
PROPERTY 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

WEAR AND FATIGUE
• Deterioration is described in general terms of wear, marginal breakdown and fatigue
fracture due to cyclic loading.
• Braem et al.proposed average human chewing stresses between 5 MPa and 20 MPa at a
chewing frequency of approximately 2 Hz.
• The number of occlusal contacts per day at medium chewing forces was estimated to range
between 300 to 700 cycles.
• In dentistry, the loss of material due to non-antagonistic contacts have been defined as
occlusal contact free area (CFA) wear.

• Occlusal contact area (OCA) wear has been designated as material loss by direct interaction of
an antagonist with the restorative material.
• GIC exhibit a CFA wear five times higher than amalgam and three times higher than resin
composite materials.
• Failure mechanisms such as void nucleation, crack propagation and detachment of particles or
sudden, subcritical failure are common features in wear and fatigue.

THERMAL COMPATIBILITY
• The tooth structure and restorative materials in the mouth will expand upon heating by hot
foods and beverages but will contract when exposed to cold substances.
• Such expansions and contractions may break the marginal seal of an inlay or other fillings in
the tooth, particularly if the difference in coefficient of thermal expansion (CTE) is great
between the tooth and the restorative material.
• practically relevant temperature range between 20 °C and 60 °C, materials such as resinous
composites and amalgam expand more than the tooth tissue, whereas porcelain and glass
ionomer cements are well adapted to the tooth tissue.

ANTICARIOGENIC PROPERTIES
• Fluoride is the most effective agent in caries prevention.
• The metabolism of the bacteria that cause caries is inhibited and the resistance of enamel and
dentin is increased due to the remineralization of porous or softened enamel and dentin.
• Sustained, long-term fluoride release especially in marginal gaps between filling material and
tooth help prevent secondary caries of the dental tissues.
• For conventional GIC, an initial release of up to 10 ppm and a constant long-term release of 1
to 3 ppm over 10-15months was reported.

Fluoride release
• 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 flouride than thinly mixed ones.
• Fluoride release is restricted by sodium and to some,extent by calcium content.
• Water plays a critical role in the fluoride release of GIC , the aqueous phases of the set GIC
exist in the form of hydrogels that allow chemical equilibrium with an ion movement between
GIC and the oral cavity & surrounding tooth structures.

• GIC is also described as ‘smart” restorative material because apart from releasing fluoride to
surrounding tooth structure, they can also “recharge” themselves by fluorides.
• This is also referred to “reservoir effect”.
• From saliva there is an ion exchange of fluoride ions diffusing from GIC
(area of high conc.) to the tooth (area of low fl conc.)
• Released fluoride is incorporated in to hydroxyapatite crystals of the enamel and dentin over
an area of approx. 1-3 mm surrounding the restoration forming hydroxyfluorapatite.
• Fluoride containing oral care products including topical fluoride gel applications,
tooth pastes and mouth rinses can recharge the GIC restoration with flouride

AESTHETICS
• Glass ionomer cement has got a degree of translucency because of its glass filler .
• Because of slow hydration reactions glass ionomer cements take at least 24 hrs to fully
mature & develop translucency.
• Early contamination with water reduces translucency.
• Dark shades are less translucent .

▪ The esthetic quotient depends upon:-
1.Refractive index of glass particles and matrix
2.particle size
3.translucency of glass particles
▪ Specification limits of GIC 0.35 - 0.90 (for optimum aesthetics it is between 0.35 – 0.90 )

ADHESION
• Glass ionomers bond permanently to tooth structure and also to other polar
substrates such as base metals.
• Barriers of adhesion 1) water
2) dynamic nature of tooth material.

Mechanism Of Adhesion According To Different Authors:
1.Chelation (Smith)
3. Hydroxyapatite & Polyacrylic Acid Interaction
(Beech)
4. Hydrogen Bonding With Dentin Collagen
(Akinmade )
1.Chelation (Smith)
2. Hydrogen Bonding Followed By Ionic Bond
(Wilson)
3. Hydroxyapatite & Polyacrylic Acid Interaction
(Beech)
4. Hydrogen Bonding With Dentin Collagen
(Akinmade )

IMPROVING ADHESION
• Tensile bond strength to enamel- 2.6 to 9.6 Mpa dentin- 1.1 to 4.5 Mpa
Surface Conditioning
1)Smoothing of surface irregularities
2) Prevent air entrapment
3) Minimizes areas of stress concentration
4) Improves bond strength esp. to dentin
SEM of dentin without surface conditioning
SEM of dentine after treatment with citric acid

Erosion
• Erosion is as a result of chemical attack and mechanical wear
• Chemical erosion is due to acids generated by dental plaque,or contained in food and
beverages
• Acid erosion –glass ionomer < silicate < zinc phosphate < poly carboxylate
Silicate cement Glass ionomer cement

Biocompalibility
Glass ionomer cement showed greater inflammatory response than ZOE but less than Zn
phosphate cement, other cements but it resolved in 30 days (Garcia et al, 1981).
• Reasons for blandness (Mc Lean andWilson, 1974) -
1.poly acrylic acid is weak acid
2.Tendency of acid to dissociate in to H+ and polyacrylate ions is reduced after partial
neutralization which makes the acid weaker.
3.Acid is readily neutralized by Ca2+ ions in tubules.
4. Because of its higher molecular weight and chain entanglement there is
unlikely of diffusion of polyacid in to dentinal tubules.

FEW APPLICATIONS OF GIC IN RESTORATIVE DENTISTRY
• class iii restorations
• core build up
• tunnel preparartions
• pit and fissure sealents
• sandwich technique

SANDWICH TECHNIQUE
• First described By Mc Lean & Wilson In 1977.
The procedure involves :-
• Placing GIC as base of cavity .
• Etching with 37% phosphoric acid for 1 min causes surface roughness
• Dentin bonding agent is applied.
• Placing composite restoration.

Advantages included:
• GIC acts as a dentin substitute
• The high contraction stresses produced (2.8 – 3.9 Mpa) by the polymerization shrinkage are
reduced as the amount of composite is reduced .
• Microleakage is reduced.
• Minimization of no. of composite increments, therefore time is saved.

GIC in pit and fissure sealant
• Conventional glass ionomer – bonds chemically
• Classified as---high viscosity GI sealant
---low viscosity GI sealant
The Use of Pit and Fissure Sealants—A Literature Review
Reem Naaman A,. El-Housseiny , and Najlaa Alamoudi ,2017

• Low viscocity GI sealent
• eg, Fuji III
• It has now been replaced with a later generation--Fuji Triage (VII)
is designed to release a higher amount of ﬂuoride

• High viscosity GI sealent
• Eg, Ketac Molar Easymix, Fuji IX
➢ RMGI has also been used as a pit and ﬁssure sealant material
➢ Its resin component has improved its physical characteristics, compared to conventional GI
➢ In fact, when compared to conventional GI, RMGI has less sensitivity to water and a
longer working-time

• Advantage of RMGIC as pit and fissure sealent
• Continuous fluoride release and the fluoride recharging ability
• preventive effect
• moisture-friendly
• easier to place
• can be used as a transitional sealant when resin-based sealants cannot be used due to
difficult moisture control

Core build up
• The metal reinforced glass ionomer cements are used for this purpose
• Glass ionomer cements reinforce the teeth &prevent root fracture when root canals are over
widened.

TUNNEL PREPARATION
• First described in 1963
• Conservative alternative cavity preparation in primary molars.
• Indication:- Small proximal caries with out involvement of marginal ridges.

GIC IN ENDODONTICS
They are used for:
• Root end fillngs
• Root canal sealer
• Perforation repair
• Intraorifice barriers
• Temporary coronal restorations
GIC is used because of :
• Its capacity to bond which enhances seal & reinforce the tooth
• Its good biocompatibility, which would minimize irritation to peri radicular tissues
• Its F release ability, which imparts an antimicrobial effect to combat root canal infection.

MODIFICATIONS OF GIC
➢ Resin modified gic
➢ Metal modified gic

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
HEMA added to liquid
• Hybrid Glass Ionomer/resin modified Glass Ionomer
a.Composite resin in which fillers substituted with glass ionomer particles
b.Precured glasses blended into composites

RESIN MODIFIED GIC
DEFINITION: RMGIC can be defined as a hybrid cement that sets via an acidbbase
reaction and partly via a photo- chemical polymerization reaction.
Eg: Fuji II LC, Vitrebond, Photac –Fil, Vitremer, FujiV
• Developed by Antonucci, Mc Kinney and SB mitra.
• It was developed in between late 1980s and early 1990s .
• Resin modification of glass ionomer cement was designed to produce favourable physical
properties similar to those of resin composites while maintaining basic features of
conventional GIC.

COMPOSITION
Powder Liquid Purpose for their inclusion
Barium, strontium or Improved strengthImparts radiopacity
aluminosilicate glass
Vacuum-dried polyacrylic acid Polyacrylic acid Reacts with the glass to form the poly salt
matrix
Potassium persulphate Redox catalyst system to provide the
methacrylate (dark) cure
Ascorbic acid
Pigments Varies shade
HEMA Water miscible resin
Polyacrylic acid with
pendant methacrylates
(copolymer)
Ability to undergo both acid–base and
polymerization reactions Helps form
interpenetrating network
Tartaric acid Sharpens the acid–base reaction set
Water Permits reaction between the polyacid and
the glass
Photo-initiators Achieves light curing

• Addition of polymerizable resins to the formulation is done to import additional curing process to
the original acid base reactions.
• The HEMA content is around 15-25% and water content is low to accommodate the
polymerizable ingredients.
• It is a powder : liquid system with P:L = 3:1
• These products are considered to be dual –cure cements if only one polymerization mechanism is
used , if both mechanisms are used they are considered to be tri-cure cements.

Setting reaction of resin-modified light cured materials
2 distinct mechanisms :
• The original acid – base setting reaction
• Vinyl polymerisation of acrylate groups that can be activated through the presence of photo
initiators such as camphorquinone

When mixed, original acid base reaction appears to continue without interruption
Resin component activation
Some degree of cross linking may be present between 2 matrices ;
both reactions may proceed without interference
Over time, any remaining resin not affected by light - activation may
undergo further chemical setting reaction
A “Dark – cure reaction”
Lead to the term “Tricure” or “Triple-cure”

• Importance of depth of cure
• 1. Lack of water inhibition of acid-base reaction
• 2. Residual HEMA in lower levels, closest to pulp
• 3. Fully light activated restoration is notably superior in physical properties
• Therefore, depth of cure is important ;
• incremental build up recommended Unless, a mechanism for chemical curing of methacrylate
groups is incorporated “Redox” catalyst
• Allows for continuing polymerisation in absence of light activation, thus ensuring activation of any
remaining HEMA
• Micro – encapsulated potassium persulphate & ascorbic acid

2 distinct types of setting reaction occur :
➢ Acid-base neutralisation reaction
➢ Free-radical metharylate cure
Relationship between the 2 reactions may take one of 2 forms
➢ Formation of 2 separate matrices
Ionomer salt hydrogel
Poly-HEMA matrix
➢ Multiple cross-linking pendant methacrylate groups may replace a small fraction of carboxylate
groups of polyacrylic acid, thus preventing separation of 2 potential Matrices

Cross – linking of polymer chains may take place through 1/more of the following reactions:
➢ Acid – base reaction
➢ Light – cure mechanism
➢ Oxidation – reduction reaction
➢ Full physical properties are not achieved till acid – base reaction continues for some
days

Setting reaction of resin – modified auto cure material
• Mixing of powder + liquid
• Usual acid base reaction initiated
• Catalyst in powder will initiate polymeristaion of HEMA & cross-linkable monomers
• Ultimately, there will be cross-linking between 2 systems & the entire mass will set hard with
uniform physical properties

• Properties
• Esthetic
• Flouride release
• Strength
• Adhesion
• Micro leakage
• Water sensitivity
• Biocompatibility

• Esthetics:
According to the Skinners, there is a definite improvement in translucency as the monomer brings
the refractive index of the liquid close to that of the glass particle.
• Fluoride release:
is same as that of the conventional but the lining version shows higher F release
• Strength:
The diametrical tensile strength is much higher but compressive
strength and hardness is lesser.

• Adhesion:
to tooth is reduced. This is expected because of reduction in carboxylic acid in the liquid and
interruption of chemical bonding due to the resin matrix.
-Adhesion to composites is increased due to the presence of residual nonpolymerized
functional groups within the RMGIC
• Micro leakage:
A higher degree of Microleakage is seen due to polymerization shrinkage
• Due to reduced water and carboxylic acid content , reduces its wetting
Capacity
• Water sensitivity
is considerably reduced.

INDICATIONS:-
➢ Luting cement in orthodontics
➢ Liner and base
➢ Pit and fissure sealant
➢ Core build up material
➢ For amalgam repair

ADVANTAGES
• Long Working time and Snap setting
• Early water sensitivity is reduced
• Rapid development of early strength
• No etching is needed either to tooth for adhesion or for the material if composite
lamination is to be done.
• Bonding to composite is higher.
• Finishing can be done immediately.
• F release .
• Diametrical tensile strength is higher

• Contour and polish immediately after light activation
• Begin with fine polishing diamonds at intermediate speed
• Continue with finer diamond with slow speed under air/water spray
• Finally complete using aluminium oxide graded polishing disc at slow speed under air water spray
• Seal with low viscosity resin glase.
Finishing and polishing

DRAWBACKS
– Increased shrinkage with concurrent microleakage.
– Low wear resistance as compared to composites.
− Its controversial biocompatibility.

METAL MODIFIED GIC
• Silver cermet was introduced by Simmons in year 1983.
• Sced and Wilson in 1980 incorporated spherical silver amalgam alloy into
Type II GIC powder in a ratio of 7:1.
Powder
• Glass –17.5%
• Silver –82.5%
Particle size of silver is 3 – 4μm
Liquid
• Aqueous solution of copolymer of acrylic acid and
or maleic acid—37%
• Tartaric acid 9%

Disadvantages
• Poor resistance to abrasion
• Resistant to burnishing
• Poor aesthetics

Glass cermet
• Also called as cermet ionomer cements
• McLean and Gasser in 1985 first developed
• Fusing the glass powder to silver particles through sintering that can be made to react with
polyacid to form the cement
• Sintering is done at high pressure more than 300MPa and at a temperature of 8000C which is
ground to fine powder particle size of 3.5 μ
• 5% titanium dioxide is added as whitening agent to improve aesthetics.
• It has excellent handling characteristics.
IOSR Journal of Dental and Medical Sciences (IOSR-JDMS)
e-ISSN: 2279-0853, p-ISSN: 2279-0861.Volume 15, Issue 11 Ver. III (November. 2016), PP 124-126
www.iosrjournals.org

Indications
➢ Core build –up material
➢ Root caps of teeth under over dentures
➢ Preventive restoration
➢ Temporary posterior restoration
Contraindications
➢ Anterior restorations.
➢ Areas subjected to high occlusal loading

PROPERTIES
Strength-
• Both tensile and compressive strength is greater than conventional glass ionomer cement
Modulus of elasticity-
• Tends to be relatively lower than conventional gic
Abrasion resistance-
• Greater than conventional gic due to silver particle in-corporartion
Radiopacity:
silver cermet radio opacity is equal to that of dental amalgam.

• According to a study conducted By Sinha S.P et al they found photomicrographs of
scanning electron microscope (500x) of silver amalgam showed more marginal gap than
glass ionomer and cermet ionomer cements.
• In this study cermet glass ionomer showed the least microleakage and the best sealing
ability among other retrograde filling materials.

❑ Improved traditional gic :
➢ - highly viscous/ packable gic
➢ - Low viscosity gic
❑ Polyacid modified gic /compomer
❑ Self hardening gic
❑ New fluoride releasing gic:
A) fluoride charged gic
B) low ph ‘smart’ materials
❑ Bioactive glass
❑ Fibre-reinforced gic
❑ Giomer
❑ Zirconomer
❑ Hainomer
❑ Amalgomer
❑ Chlorhexidine impregnated gic

i) Highly viscous/ packable / condensable GIC
➢ alternative to amalgam in posterior preventive restoration.
➢ Fast setting Auto cure cement.
➢ 10-15% better physical properties than resin modified glass ionomer
➢ Available as “normal set” or “fast set”
➢ Particularly useful as transitional restoration
➢ Changes :powder particle size
particle size distribution
Heat history of glass (improvement in surface reactivity of powder)
➢ Polyacrylic acid is made to finer grain size so that higher powder liquid ratio can be used.
IMPROVED TRADITIONAL GIC

SIGNIFICANT FACTORS
➢ P/L ratio:3:1 to 4:1
➢ Resistance to water uptake/ loss as soon as set.
➢ Adhesion is stronger.
➢ Release of ions: similar to other types of autocure , therefore useful for root
surface caries, tunnels.

PHYSICAL PROPERTIES:
• Tensile strength & fracture resistance substantially better than autocure, marginally better
than resin modified glass ionomer
• Abrasion resistance – as they mature they match that of amalgam,composite resin
• Radioopacity – adequate
Used in
- ART procedure
- Restorations for deciduous teeth.
- Intermediate restoration
- core build- up materials
Eg. Ketac molar, Fuji VIII and IX

ii) The low viscosity/flowable GIC –
• For lining, pit and fissure sealing
• endodontic sealers
• for sealing of hypersensitive cervical areas These have a low P:L ratio and
posses increase flow.
eg: Fuji lining LC, Fuji III and IV, Ketac – Endo.

POLYACID MODIFIED GIC /COMPOMER
OF COMPOMER
COMPOSITES
Definition: Compomer can be defined as a material that contains both the
essential components of GIC but at levels insufficient to promote the acid –
base curing reaction in the dark .
• Compomer is a combination of the word ‘comp’ for composite “omer” for ionomer.
• Though introduced as type of GIC, it became apparent that terms in of
clinical use and performance it is best considered as a composite.

COMPOSITION
• Compomers are essentially a one – paste system containing ion leachable glass &
polymerizable acidic monomers with functional groups of polyacrylic acid & methacrylates in 1
molecule.
• NaF and some other fillers are also present for additional F release and
Radio opacity.
• There is no water in the formulation.
• Glass particles are partially silanated to ensure bonding

SETTING REACTION
Setting reaction occurs in 2 stages
• Stage 1:
In contrast to RMGIC, a typical composite resin network around
filler particles forms on light activation .
• Stage II :
occurs over 2-3 months when the water from the saliva gets absorbed and initiates a
slow acid base reaction with formation of hydro gels within the resin and low level
fluoride release.

PROPERTIES
• ADHESION: to tooth requires acid –etching because acid base reaction for ion exchange
requires water which does not occur for some time after placement.
• Bond strengths achieved usually approach the typical resin bonding systems.
It is = 18-24Mpa
• FLUORIDE RELEASE: is limited. It is significantly less than Type II or RMGIC. F release usually
starts after about 2-3 months; it peaks initially and then falls rapidly.
• PHYSICAL PROPERTIES: fracture toughness, flexural strength and
wear resistance are better than GIC but less than composite.

• The in vitro study conducted by vishnu et al found that the highest tensile bond strength for
compomers and the least tensile bond strength for chemically cured glass ionomer cement.
• They concluded that the tensile bond strength of Compoglass (compomer) is significantly
greater than Fuji IX GP and Fuji II LC(RMGIC) Comparative

INDICATIONS
1. P& F sealant
2. class III and V lesions along with cervical abrasions and erosions and intermediate
restorations.
3. Bases for composites, liners
4. Small core build ups
5. Filling of pot holes & undercuts in old crown preparations
6. Root surface sealing

CONTRAINDICATIONS
• Class IV lesions
• Conventional class II cavities
• Lost cusp areas
• Restorations involving large labial surface

ADVANTAGES
➢ Superior working characteristics to RMGIC
➢ Ease of use
➢ Easily adapts to the tooth
➢ Good esthetics

Recently, a 2 component compomer is being marketed as a P: L system or
2 paste system meant exclusively for luting.
• These are self adhesive due to the presence of water which starts off the
acid base reaction.
• The powder contains the glasses, fluoride & chemical / light initiators.
• liquid contains the monomers, Polyacrylic acid, water and activators. These set via light
chemical polymer as well acid base reaction.

Advantage of RMGIC as pit and fissure sealent
• Continuous fluoride release and the fluoride recharging ability
• preventive effect
• moisture-friendly
• easier to place
• can be used as a transitional sealant when resin-based sealants cannot be used due to
difficult moisture control

SELF HARDENING RMGIC
• These are basically, purely chemically activated RMGIC with no light activation at all.
• Developed mainly for luting purposes, they contain monomers and chemical initiatiors such a
the benzoyl peroxide and t- amines to allow self polymerization.
• It is used mainly in pediatric dentistry for cementation of stainless steel
crowns, space maintainers, bands and brackets.

ADVANTAGES
• Ease of handling
• No post- cementation sensitivity
• Fluoride release
• Higher compressive strength
• No additional step of light activation

BIO ACTIVE GLASS
• Hench -1969 and various studies were performed to ensure that bioactive glasses are safe for
clinical applications , Wilson et al (1981) reviewed these studies & proposed that this are safe for
clinical use.
• Bioactive glass can form intimate bioactive bonds with the bone cells and get fully integrated
with the bone.
• Bio-active glass (BAG) can act as a source of a large amount of CaO and P2O5 in a Na2O–SiO2
matrix with a rapid dissolution rate and high ionic concentration.

• BAG 45S5 exhibits a high bioactivity index (IB = 12.5) compared to other bio-active materials
such as hydroxyapatite (IB = 3), and therefore it has the potential to remineralize enamel white
spot lesions with an increased rate of HA formation.
• According to study conducted by hussam et al they found that BAG exhibited a potential of
remineralisation of white spot lesions to an extent and further modification has a potential to
promote entire mineral gain of treated lesions.
Enamel white spot lesions can remineralise using bio-active glass and polyacrylic
acid-modified bio-active glass powders hussam mily et al JCD 2014;14

It is being used experimentally as
• Bone cement
• Air abrasive powder in MID.
• Retrograde filling material
• For perforation repair
• Augmentation of alveolar ridges in edentulous ridges.
• implant cementation
• Infra- bony pocket correction

• Incorporation of alumina fibres into the glass powder to improve upon its flexural
strength
• This technology called the Polymeric Rigid Inorganic Matrix Material or PRIMM
developed by Dr. Lars Ehrnsford
• It involves incorporation of a continuous network / scaffold of alumina and SiO2
ceramic fibres.
FIBER REINFORCED GIC

ADVANTAGES
• Due to the ceramic fibers there is increased depth of cure as light conduction and
penetration is enhanced.
• Polymerization shrinkage is reduced
• Improved wear resistance
• Increase in flexural strength.

• Developed by Shofu
• Recently ,a new category of hybrid aesthetic restorative material,which differs from
both resin modified GICs and compomers has been introduced known as GIOMERS
• Giomers are available in market as one paste form and these are light polymerizing and
require bonding agents for adhesion to tooth structure.
• Commercially available as Reactmer(shofu,japan), beautifil (shofu,japan) & beautifil II
(shofu ,japan).
GIOMER

Chemical Nature
• Giomer utilizes the hybridization of GIC and composite by using a unique technology
called the pre-reacted glass ionomer technology.
• The fluoro aluminosilicate glass is reacted with polyalkenoic acid to yield a stable phase
of GIC this pre reacted glass is then mixed with the resin.
• Depending on the amount of glass which is reacted, the PRG technology can be 2 types:
F- PRG = Full reaction type / entire glass
S- PRG = Surface reaction type

INDICATIONS
• Restoration of root caries
• Non carious cervical lesions
• Class v cavities
• Caries deciduous teeth.
ADVANTAGES
• Fluoride release
• Fluoride recharging
• Biocompatibility
• Smooth surface finish & esthetics
• Excellent bonding
• Clinical stability

ZIRCONOMER
• Zirconomer defines a new class of restorative glass ionomer that promises the strength and
durability of amalgam with the protective benefits of glass ionomer while completely eliminating
the hazard of mercury.
• Its is also called as “WHITE AMALGAM”.
• The inclusion of zirconia fillers in the glass component of Zirconomer reinforces the structural
integrity of the restoration and imparts superior mechanical properties for the restoration of
posterior load bearing areas where the conventional restorative of choice is amalgam.

• Combination of outstanding strength, durability and sustained fluoride
protection deems it ideal for permanent posterior restoration in patients
with high caries incidence as well as cases where strong structural cores
and bases are required.

Ideal for Restoration of
• Class I & II cavities
• Structural base in sandwich restorations
• All classes of cavities where radiopacity is a prime requirement
• Core build-up under indirect restorations
• Root surfaces where overdentures rest
• Pediatric and Geriatric restorations
• Long-term temporary replacement for fractured cusps
• Fractured amalgam restoration
• Suitable for ART techniques

Zirconomer Benefits
• Reinforced with special zirconia fillers to match the strength and durability of amalgam.
• Sustained high fluoride release for anti-cariogenic benefits especially in cases
with high caries risk.
• Packable and condensable like amalgam without the hazard of mercury, the
risk of corrosion, expansion and thermal conductivity.
• High flexural modulus and compressive strength ensures longevity in stress
bearing areas.

• Chemically bonds to enamel/dentin and has tooth-like co-efficient of thermal expansion
resulting in low interfacial stresses and long-lasting restorations.
• Ceramic fillers impart remarkable radiopacity for accurate follow up and diagnosis
• Adequate working time with snap-set reaction
• Easy mixing and handling characteristics minimize chair time and enables ease of bulk
placement
• Excellent resistance to abrasion and erosion

AMALGOMERS
• These are restoratives which are glass ionomer based but with the strength of amalgam.
• They also provide F- release, natural adhesion to tooth structure, good compatibility and
prevent shrinkage, creep, corrosion or thermal conductivity problems associated with other
filling materials
• They have been found to have exceptional wear characteristics, along with other
advantages of GIC

• According to bahadure et al conducted a study to estimate fluoride release of six
different dental restorative materials namely Amalgomer CR, Fuji II, Fuji IX, Beautifil II,
Dyract extra, and Coltene Synergy.
• They concluded Amalgomer CR was found to have significantly highest fluoride
releasing capacity among the all experimental dental restorative materials.
An estimation of fluoride release from various dental restorative materials at different pH:
In vitro study Bahadure, et al JOURNAL OF INDIAN SOCIETY OF PEDODONTICS AND PREVENTIVE DENTISTRY 2012 ;30(2)

HAINOMERS
• These are newer bioactive materials developed by incorporating hydroxyapatite
within glass ionomer powder.
• These are mainly being used as bone cements in ora maxillofacial surgery and
may have a future role as retrograde filling material.
• Studies have shown that they have a role in bonding directly to bone and affect
its growth and developement

Calcium Aluminate GIC/Ceramir
• luting cement
• Hybrid composition of calcium aluminate and glass ionomer.
• Glass ionomer component contributes to:
improved flow and setting characteristics
early adhesive properties to tooth structure
early strength properties
• Calcium aluminate component in the cement contribute to:
increased strength and retention over time
biocompatibility
better sealing of tooth-material interface
bioactive
lack of solubility/degradation

CHLORHEXIDINE IMPEGRENATED GIC
• To increase the anticariogenic action of GIC
• Still under experimental stage.
• Experiments conducted on cariogenic organisms

REFERENCES
❖ An atlas of glass ionomer cement- A clinician's guide 3rd edi by Graham J Mount
❖ Glass ionomer cement by Alan D.Wilson and John W. Mclean
❖ Philips science of dental materials, Eleventh edition
❖ Sturdevant’s Art and science of operative dentistry,Fifth edition
❖ Craig’s Restorative dental materials, Twelfth edition

GLASS IONOMER CEMENT

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