Glass ionomer cement & its recent advances

Jagadeesh k1st yr p.gDept. of conservative dentistry & endodontcsG.D.C.H,VIJAYAWADA

CONTENTS

• INTRODUCTION• DEFINITION• HISTORY• COMPOSITION • CLASSIFICATION• SETTING REACTION• INDICATIONS• MODIFICATIONS OF GIC• RECENT ADVANCES IN GIC• RFERENCES

INTRODUCTION

DEFINITION of 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 ed)

• Glass ionomer cement is a water based cement

• ADA specification number: 96

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.

History

•1965 –A.D Wilson mixed dental silicate glass powder & aqueous solutions of various organic acids including poly acrylic acid Set cement is sluggish Not reported or published.• 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,added tartaric acid.• ASPA III- Methyl alcohol was added.• First marketable material, ASPA IV in 1973• Luting agent ASPA IVa in 1975 by Crisp and Abel

•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.

• 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, 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

Other names

• Glass ionomer-term coined by wilson & kent glass-alumino silicate glass particles ionomer-poly carboxylic acid.• ISO terminology- poly alkenoate cement.

• Since its extensive usage to replace the dentin ,has given different names Dentin substitute Man made dentin Artificial dentin

•Introduced into u.s as ASPA-Alumno silicate polyacrylate

Composition• The glass ionomer powder is an acid soluble calcium fluoroalumino silicate glass- ion leachable glass.

• Composition of two commercial glass ionomers

Compound Composition A(wt%) Composition B(wt%)

SiO2 41.9 35.2

Al2O3 28.6 20.1

AlF3 1.6 2.4

CaF2 15.6 20.1

NaF 9.3 3.6

AlPO4 3.8 12.8

• The raw materials are fused to a uniform glass by heating them to a temp.of 1100 °C- 1500°C.• Lanthanum,strontium,barium or zinc oxide additions provide radio opacity.• The glass is ground into a powder having particles in the range of 15-50 µm. •ROLE OF COMPONENTS IN POWDER

•The role of Al2O3 & SiO2 of the glass is crucial and is required to be of 1:2 or more by mass for cement formation.

•CaF2-Supplemented by the addition of cryolite (Na3AIF6). •This flux -reduces the temperature at which the glass will fuse -increases the translucency of the set cement.

• Fluoride is an essential constituent which

- Lowers fusion temp., acts as flux

- improves working characteristics & strength

- improves translucency

- improves therapeutic value of the cement by

releasing fluoride over a prolonged period

• Al3PO4-Improves translucency. Apparently adds body to the cement paste

•LIQUID• Polyacrylic acid --- 45 %• Water --- 50 %• Modifiers Itaconic acid --- 05 %

maleic acid tricarballylic acid viscosity ,inhibits gelation , shelf life. • Tartaric acid --- Working Time & setting time.

• The liquid is an aqueous solution of polymers andcopolymers of acrylic acid.• In most of the current cements,the acid in the form of a coploymer with itaconic ,maleic ,or tricarboxylic acids.• polyacrylic acid-is the most important acid contributing to formation of the cement matrix.• Water- • It is reaction medium.• It serves to hydrate the siliceous hydrogel and the metal salts formed.• It is essential part of the cement structure. If water is lost from the cement by desiccation while it is setting, the cement-forming reactions will stop.

•Glass ionomer cements are water-based materials •Plays a role in transporting calcium and aluminium ions to react with poly acids.

•Types: - Lossely bound water -Tightly bound water

•With the aging of cement, the ratio of tightly bound to loosely bound water increases •Accompanied by an increase in strength, modulus of elasticity and decrease in plasticity •Cement is only stable in an atmosphere of 80% relative humidity

• In higher humidities the cement absorbs water and the consequent hygroscopic expansion can exceed the setting shrinkage.

• Cement can lose water under drying conditions, however leading to shrinking and crazing.

• Susceptibility to desiccation decreases as the cement ages

• This is prevented if protected for about 10 to 30 mins (depends on manufacturer).

• ITACONIC ACID• Itaconic acid promotes reactivity between the glass and the liquid.

• It also prevents gelation of the liquid which can result from hydrogen bonding between two polyacrylic acid chains

• A stronger acid than polyacrylic acid • Causes the cement to harden and lose its moisture sensitivity faster.• More carboxyl (COOH) groups which lead to more rapid polycarboxylate crosslinking

Maleic acid

• Tartaric acid• The 5% optically active dextro-isomer of tataric acid is incorporated.• It is also hardener that controls the PH of the set cement during setting process, which in turn controls the rate of dissolution of the glass.• It facilitates extraction of ions from the glass.• It typically increases the working time and also aids in snap test.

CLASSIFICATION

A.ACCORDING TO A.D. WILSON AND J.W.McLEAN IN

1988

Type I --- luting cements

Type II --- restorative cements

a.Restorative aesthetic

b.Restorative reinforced

B. ACCORDING TO SKINNERSType I – LutingType II- RestorativeType III- Liner and base

C. 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

D. ACCORDING TO J.W.McLEAN et al IN 1994 - Glass ionomer cement (traditional) -Resin modified glass ionomer cement -Poly acid modified composite resins

E. ACCORDING TO INTENDED APPLICATIONS

• Type I – Luting • Type II – Restorative• Type III – Liner/base• Type IV – Pit & fissure sealant• Type V – Luting for orthodontic purpose• Type VI – Core buildup material• Type VII – High fluoride releasing command set • Type VIII – Atraumatic restorative treatment• Type IX − Pediatric Glass Ionomer cements

F. NEWER CLASSIFICATION• Traditional glass ionomer a. Type I --- Luting cement b. Type II --- Restorative cements c. Type III --- Liners&Bases• Metal modified Glass Ionomer a. Miracle mix b. Cermet cement • Light cure Glass Ionomer 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

Cement placement

Conditioning the Tooth Surface

• Dentin conditioning prior to placement of a GIC is done primarily

to remove the smear layer.

• GIC is better able to wet the dentin surface.

• Promotes ion exchange.

• Chemically cleans dentin.

• Increases surface energy.

Agents usedSurface treatment Time of application(sec)

Citric acid, 50% aq 30

Citric acid, 2% aq/alc 30

Poly (acrylic acid), 25% aq 30

Tannic acid, 25% aq 60

Surface-active solution 60

Dodicin, 0.9% aq 60

Na2EDTA, 2% aq 30

Na2EDTA, 15% aq 30

Sodium flouride, 3% aq 30

Ferric chloride, 2% aq/alc 30

Mixing of the cement

Full spoon, no excess

Tip liquid bottle to side, then invert completely If water / tartaric acid, only 1 drop used.

Liquid should not stay on paper pad longer than 1minute (some of it may soak into it)

Don’t mix beyond 30 secondsThe objective is – only wet the particle – no dissolving it.

First half folded into liquid in 10-15seconds

Second half incorporated in 15 secondsSmall mixing area

Loss of gloss/ slump test

GIC --- 60 – 90 sec

Resin-modified GIC --3 – 3.5 min

Working time & setting time

• It sets rapidly in the mouth that is within 3-5 min 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

• Film thickness should not exceed 20µm for luting agents

Mixing capsules

• To activate capsule apply pressure 3-4 seconds before placing in machine

• Ultrahigh speed machine : 4000 cycles/minute

• (< 3000 cycles/minute – not desirable)

Finishing technique

• Best surface –cement allowed to set under matrix•Carving the cement external to the cavity margins with sharp knives or scalers•Finest abrasive should be used to minimize tearing•Finishing with rotary instruments should be done at subsequent visit

Setting reaction

•1. acid-base reaction•2. light activated polymerisation• ACID – BASE REACTION• GIC formed by the reaction of three materials Fluoro alumino silicate glass powder Poly acrylic acid Water• An acid – base reaction occurs between the glass powder and the ionic polymer.• Water is essential because that is the medium through which ion transfer takes place

• Chemistry of cement forming reaction from initial mixing occurs in various stages

• The glass particles are attacked at the surface by poly acid which

leads to withdrawal of the cations thus the glass network breaks down

to silicic acid.

• Principally Al3+, Ca2+, F-, are released and migrate into aqueous

phase of cement and form complexes

Decomposition of glass & migration of ions

• Initially calcium complexes predominate but later Aluminium

complexes are more.

• pH and viscosity increases

• 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

Gelation and vulnerability to water

• 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.

• 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

Hardening and slow maturation

•Increase in strength and rigidity are associated with slow increase

in cross linking.

Mechanism of adhesion• Polyalkenoic acid attacks dentine and enamel: displaces PO4,Ca ions• Migrate into cement and develop an ion enriched layer firmly attached to tooth structure. • The bond strength to enamel is always higher than that to dentin because of the greater inorganic content & greater homogenity.

MECHANISM• Smith – chelation of calcium(1968)• Beech – interaction between apatite and poly acrylic acid polyacrylate ions

Ionic bonds with calcium ions in enamel and dentin

• Acc. to Wilson(1974)• Initial adhesion is by hydrogen bonding from free carboxylic groups• Progressively these bonds are replaced by ionic bonds• Polymeric polar chains of acids bridge the interface between cement and substrate

• Acc. to Wilson, Prosser and Powis(1983)• Polyacrylate displaces and replaces surface phosphate and calcium from hydroxyapatite • An intermediate layer of Ca and Al phosphates and polyacrylates is formed.

Properties of Glass Ionomer cement

luting cement 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

Restorative cements

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.Knoop hardness(KHN)

48 39 40

4.Solubility(ANSI/ ADA Test)

0.4 - -

5.Pulp response mild mild mild

•Biocompatibility

• Resistance to plaque because presence of F

• Pulp response to GIC is favorable

• Freshly mixed --- acidic pH 0.9 – 1.6 -- mild inflammation resolve

10 -20 days

* used to protect mech / traumatic exposure of healthy pulp

• 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)

• 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 and not the total fluoride content

of the glass.

Fluoride release

Fluoride recharge

• Glass ionomers may have synergistic effects when used with extrinsic fluorides

• In the presence of an inverse fluoride concentration gradient, glass ionomers may absorb fluoride from the environment and release it again under specific conditions

• topical APF (acidulated phosphate fluoride), with fluoride rinses and fluoridated dentifrices recharging takes place

• Thermal Properties:•The thermal diffusivity value of GIC is close to that for dentin. • The material has an adequate thermal insulating effect on the pulp and helps to protect it from thermal trauma• Solubility & disintegration lower than ----Zn phosphate Zn polycarboxylate In water --- less than Silicate cement Resin-modified GIC is less resistant to solubility

• Compressive strength < silicate cement• Tensile strength --- higher -- silicates • Hardness < silicates • Wear resistance < composites • ESTHETICS

• Glass ionomer cement has got a degree of translucency

because of its glass filler

• Unlike composite resins, glass ionomer cement will

not be affected by oral fluids

• 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 -.90 (for optimum aesthetics

it is between 0.35 – 0.90 )

DurabilityAffected by the factors

• Inadequate preparation of the cement

• Inadequate protection of restoration

• Variable conditions of mouth

Failure rate is more a measure of clinician’s skill than inherent

quality of the material

• One of the longest observation periods for the conventional glass

ionomers in non-carious cervical lesions showed retention in the

order of 90% after 10 yrs for KetacFil

• Some other properties

• Low exothermic reaction

• Adheres chemically to the tooth structure

• Less shrinkage than polymerizing resins

• Dimensional stability at high humidity

• F release discourages microbial infiltration

• Early moisture sensitive --- requires protection

• Poor abrasion resistance

• Average esthetic

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

2. Fast setting lining cement and bases:

• Lining of all types of cavities where a biological seal and cariostatic action are required

• replacement of carious dentin the attachment of composite resins using the acid etch technique

• Sealing and filling of occlusal fissures showing

early signs of caries.

3. Luting cement: • Fine grain versions of the glass ionomer Cements are used.• Useful in patients with high caries index

Pit & Fissure sealant

• A cariostatic action is essential for caries preventive material

GIC is recommended as a P and F sealant where the orifices

of the fissure are patent .

• The size of the fissure should allow sharp explorer tip to

enter the crevice which should be > 100 µ wide. Otherwise,

GIC can get lost through erosion due to its low wear

resistance and solubility

Core buildup• 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.

Sandwich technique• Devolped by Mclean,• To combine the beneficial properties of GIC & composite.

Clinical steps:-•After cavity preparation,condition the cavity to develop good adhesion with GIC.•Place Type III GIC into prepared cavity.•After setting, etch the enamel & GIC with orthophosphoric acid for 15 seconds.•This will improve micromechanical bond to composite resin.

•Apply a thin layer of low viscosity dentin bonding agent & finally place the composite resin over GIC & light cure it.

Advantages• Polymerisation shrinkage is less,due to reduced bulk

of composite. • Favorable pulpal response.• Chemical bond to the tooth.• Anticariogenic property.• Better strength,finishing,esthetics of overlying

composite resin.• Microleakage is reduced• Minimization of no. of composite increments, therefore time is saved

GIC IN ENDODONTICSThey are used for: • Sealing root canals orthogradely , retrogradely• Restoring pulp chamber • Perforation repair• Sometimes for repairing vertical fracture

GIC was used because of :• Its capacity to bond which enhances seal & reinforce the tooth • Its good bio compatibility, which would minimize irritation to

peri radicular tissues• Its F release, which imports an anti microbial effect to combat

root canal infection

Contra indications

• Class IV carious lesions or fractured incisors.

• Lesions involving large 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.

Modifications of GIC

Water settable glass ionomer cement :-• Liquid is delivered in a freeze dried form ,which is

incorporated into the powder.

• Liquid used is clean water.

METAL MODIFIED GIC

MIRACLE MIX / SILVER ALLOY ADMIX GIC• 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 µm

• 5%titanium dioxide is added to improve aesthetics

• It has excellent handling characteristics

Indications • Core build –up material • Root caps of teeth under over dentures• class I cavities in primary teeth • Lining for class SAF• 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

incorporartion

Radiopacity:

silver cermet radio opacity is equal to that of dental amalgam

Fluoride release Type II cermet miracle mix• 2 weeks 440 ug 200 ug 3350ug• 1 months 650 ug 300 ug 4040 ug

RESIN MODIFIED GLASS IONOMER CEMENTS

Conventional

GIC

Resins &

Photo initiato

rs

RMGIC

RESIN MODIFIED GLASS IONOMER CEMENTS

• developed by Antonucci, Mc Kinney and SB Mitra.

• Addition of polymerizable resins to the formulation to import

additional curing process to the original acid base reactions.

Definition: RMGIC can be defined as a hybrid cement that sets via

an acid base reaction and partly via a photo- chemical

polymerization reaction.

Eg:Fuji II LC, Vitrebond, Photac –Fil, Vitremer, FujiV.

Composition

• Powder: Ion leachable glass and initiators for light /

chemical / both types of curing

• Liquid : water + Polyacrylic acid modified with MA and

HEMA monomers.

• 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

Setting reaction

2 distinct setting reactions occur

• Acid base neutralization

• Free radicle MA cure. This can occur purely via light

cure or by a combination of LC and chemical cure.

• Thus a cement can be termed

- dual cure if cross linking is via acid base + LC or

- tri cure if its via acid base + Light cure + chemical

cure

polyalkenoic acids + calcium fluoroalumino silicate glass + methacrylate copolymer

Siliceous hydrogel

Glasscore

Tooth structure

Ca2+

Al3+

F-

F-

F-

F-

F-

Ca2+

Ca2+

Ca2+

Al3+

Al3+

Al3+Al3+

CO-O-

CO-O-

CO-O-

CO-O-

CO-O-

CO-O-

CO-O-

CO-O-

-O-CO

CO-O-

-O-CO

CO-O-

CO-O-

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+

PO43-

PO43-

PO43-

PO43-

CO-O-

Siliceous hydrogel

Ca/Al polyacrylate matrix

methacrylate copolymer

(resin-modified GI)

methacrylate copolymer

(resin-modified GI)

Conventional GIs (Acid-based reaction)

Ca2+ = initial set (minutes)

Al3+ = final set (days, weeks, months)

Resin-modified GIsLight initiated or autocure (set w/o light)

properties• Esthetics: According to the Phillips’ science of dental

materials 12th ed, 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 non-polymerized functional groups within the RMGIC

• Micro leakage: A higher degree of Microleakage is seen due to polymerization shrinkage

• also due to reduced water and carboxylic acid content and reduces its wetting capacity

• Water sensitivity is considerably reduced.

• The biocompatibility is controversial and precautions

such as placing Ca (OH)2 in deep preparations should

be taken. The transient temp. rise during setting is also a

concern

INDICATIONS• Luting cement esp. 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

• DRAWBACKS

• Of course some drawbacks still need to be tackled such as

increased shrinkage with concurrent microleakage Low wear resistance as compared to composites

Its controversial biocompatibility

Two-bottle powder liquid system.

Photac Fil Quick Aplicap GC Fuji Plus Capsule Ketac Nano; a paste-paste system using static mixing.

Recent advances in Glass ionomer cement

Polyacid modified GIC / Compomer

Self hardening GIC

Low viscosity / flowable GIC

Condensable GIC / High Viscosity GIC

New fluoride releasing GIC

Fluoride charged GIC

Low pH ‘SMART’ MATERIALS

Bioactive glass

Fibre-reinforced GIC

Giomer

Hainomer

Amalgomer

Proline containing GIC

CPP-ACP containing GIC

Zirconia cotaining GIC

Nano Bio ceramic modified GIC

Chlorhexidine impregnated GIC

Calcium Aluminate GIC

POLYACID MODIFIED RESIN COMPOSITE / COMPOMER

COMPOMER

FLUORIDE RELEASING

CAPABILITY OF GIC

DURABILITY OF COMPOSITES

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.

• 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 where by water from

the saliva gets absorbed and initiates a slow acid base

reaction with formation of hydrogels within the resin and

low level fluoride release.

• 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 a type of GIC, it became apparent

that terms in of clinical use and performance it is best

considered as a composite

PROPERTIES

• ADHESION: to tooth requires acid –etching as acid base reaction

for ion exchange which requires water 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.

INDICATIONS • P& F sealant

• Restoration of primary teeth, class III and V lesions along

with cervical abrasions and erosions and intermediate

restorations

• Bases for composites, liners

• Small core build ups

• Filling of pot holes & undercuts in old crown

preparations

• 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, Poly acrylic acid, water and

activators. These set via light chemical polymer as well acid base

reaction.

• To summarize the differences between the three types of materials:

• Fluoride Release and Rechargability GICs>RMGICs>PAMCRs• Wear Resistance PAMCRs>GICs>RMGICs• Strength PAMCRs>RMGICs>GICs• Ease of Handling PAMCRs>RMGICs>GICs• Polishability and Esthetics PAMCRs>RMGICs>GICs

• 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 paediatric dentistry for

cementation of stainless steel crowns,space

maintainers, bands and brackets

Condensable / Self hardening GIC

• According to j Leirskar et al 2001, the high viscosity occurs to the material by adding poly acrylic acid to the powder and finer grain size distribution.

Advantages over conventional GIC’s ( A Castro & R F Feigal,2001)

• Packable + Condensable• Easy placement • Non sticky• Rapid finishing can be carried out• Improved wear resistance• Solubility in oral fluids is very low

Indications • As a final restorative material in class I and Class II primary teeth

• Geriatric restorative material for class I,II,III,IV cavities and cervical erosion

• Final restorative material in permanent teeth in non stress bearing areas

• Intermediate restorative material in class I and class II cavities

• Sandwich restoration

• Core build up material

• Fissure sealing material for permanent teeth

Ketac Molar Aplicap GCFuji IX Capsule

The low viscosity/flowable GIC –

• For lining, pit and fissure sealing • endodontic sealers • for sealing of hypersensitive cervical areas• These had a low P:L ratio and possessed increase

flow. eg: Fuji lining LC, Fuji III and IV, Ketac – Endo.

1. Fluoride charged materials: This is a 2 part material

comprising of

• A restorative part and

• A charge part

• The restorative part is used is the usual way. When

the first burst of fluoride is expended, the material is

given a fluoride charge using the second part

2.Low pH “Smart” Material

• developed to enable release fluoride when the

oral pH is low.

• Aptly called “Smart” materials, the F release is

episodic and not continuous which helps to

prolong the therapeutic usefulness of the

material

THE BIOACTIVE GLASS

• This idea was developed by Hench and co in 1973.

• It takes into account the fact that on acid dissolution

of glass, there is formation of a layer rich in Ca and

PO4 around the glass

• such a glass can form intimate bioactive bonds with

the bone cells and get fully integrated with the bone.

It is being used experimentally as

• Bone cement

• Retrograde filling material

• For perforation repair

• Augmentation of alveolar ridges in edentulous ridges

• implant cementation

• Infra- bony pocket correction

FIBER REINFORCED GIC• 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

ADVANTAGES

•Due to the ceramic fibers there is increased depth of cure as

light conduction and penetration is enhanced.

•Polymerization shrinkage is reduced as resin is confined

within the chambers.

•There is also improved wear resistance Increase in flexural

strength.

GIOMER

• Developed by Shofu

• 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 = reaction of Full / entire glass

S- PRG = Surface of glass

Eg: Beautiful, Reactmer

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

HAINOMERS

• These are newer bioactive materials developed by

incorporating hydroxyapatite within glass ionomer powder.

• These are mainly being used as bone cements in oral

maxillofacial surgery and may 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

CHLORHEXIDINE IMPREGNATED GIC

• To increase the anticariogenic action of GIC

• Still under experimental stage.

• Experiments conducted on cariogenic

organisms

PROLINE CONTAINING GLASS IONOMER CEMENT

J Prosthet Dent. 2013 Nov;110(5):408-13. doi: 10.1016/j.prosdent.2013.04.009. Epub 2013 Aug 30.ANSARI et al.

• An amino acid-containing GIC had better surface hardness properties than commercial Fuji IX GIC.

• This formulation of fast-set glass ionomer showed increased water sorption without adversely affecting the amount of fluoride release.

• Considering its biocompatibility, this material shows promise not only as a dental restorative material but also as a bone cement with low cytotoxicity

CPP – ACP CONTAINING GIC• Incorporation of casein phosphopeptide-amorphous calcium phosphate into a glass-ionomer cement. Mazzaoui SA et al. J DENT RES 2003 NOV 82(11)

• Incorporation of 1.56% w/w CPP-ACP into the GIC significantly increased microtensile bond strength (33%) and compressive strength (23%) and significantly enhanced the release of calcium, phosphate, and fluoride ions at neutral and acidic pH.

• MALDI mass spectrometry also showed casein phosphopeptides from the CPP-ACP nanocomplexes to be released.

• The release of CPP-ACP and fluoride from the CPP-ACP-containing GIC was associated with enhanced protection of the adjacent dentin during acid challenge in vitro.

ZIRCONIA CONTAINING GIC

• Scripta Materialia volume 52, issue 2. Y.W. Gu et al. • Zirconia containing GIC – A potential substitute for miracle mix.

• The diametral tensile strength of zirconia containing GIC significantly Greater than that of Miracle mix due to better interfacial bonding Between the particles and matrix.

NANO BIOCERAMIC MODIFIED GIC

• Acta biometerialia volume4 issue2 march 2008 MOSHAVERINIA et al

• Nano hydroxyapaptite / fluorapatite particles added to FUJI II GC

• The experimental cements also exhibited higher bond strength to dentin after 7 and 30 days of storage in distilled water.

• It was concluded that glass ionomer cements containing nanobioceramics are promising restorative dental materials with both improved mechanical properties and improved bond strength to dentin.

• nanohydroxyapatite/fluoroapatite added cements exhibited higher compressive strength (177–179 MPa), higher diametral tensile strength (19–20 MPa) andhigher biaxial flexural strength (26–28 MPa) as compared with the control group (160 MPa in CS, 14 MPa in DTS and 18 MPa in biaxial flexural strength).

Calcium Aluminate GIC•A hybrid product with a composition between that of calcium aluminate and GIC, designed for luting fixed prostheses.

•The calcium aluminate component is made by sintering a mixture of high-purity Al2O3 and CaO (approximately 1 : 1 molar ratio) to create monocalcium aluminate.

•The main ingredients in the powder of this hybrid cementare calcium aluminate, polyacrylic acid, tartaric acid,strontium-fluoro-alumino-glass, and strontium fluoride. The liquid component contains 99.6% water and 0.4% additivesfor controlling setting.

•The calcium aluminate contributesto a basic pH during curing, reduction in microleakage,excellent biocompatibility, and long-term stability andstrength.

calcium aluminate GIC.

• References• Glass ionomer cement by Alan D.Wilson and John W. Mclean

• Philips science of dental materials, 11th ed & 12th ed

• Sturdevant’s Art and science of operative dentistry, Fifth edition

• Craig’s Restorative dental materials, Twelfth edition

• G J Mount and R W Hume Text book of Minimal intervention dentistry

• Advances in Glass ionomer cement , Carel L. Davidson, J Minim Interv

Dent 2009; 2 (1)

• Clinical evaluation of glass-ionomer Cement restorations, Martin

John TYAS J Appl Oral Sci. 2006;14(sp.issue):10-3

• Scripta Materialia volume 52, issue 2. Y.W. Gu et al

• Acta biometerialia volume4 issue2 march 2008 MOSHAVERINIA et al