Glass ionomer cement

GLASS IONOMER CEMENT

DR. ABHIJIT. PALLEWAR

1st Year MDS Dept of conservative dentistry & endodontics

CONTENTS • INTRODUCTION• HISTORY• CLASSIFICATION• INDICATIONS &

CONTRAINDICATIONS• COMPOSITION• CLINICAL PROCEDURES• SETTING REACTION• PROPERTIES• FEW APPLICATIONS OF GIC• MODIFICATIONS OF GIC• RECENT ADVANCES• CONCLUSION

INTRODUCTION

• 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

• Glass ionomer is a water based cement

• 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.

• Great strides in dental research have led 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.

• The glass ionomer cements are one of the products developed in this

direction.

• Glass ionomer cement are described as a hybrid of dental silicate cements

and zinc polycarboxylates.

• Glass ionomer cements, are materials made of calcium, strontium

aluminosilicate glass powder (base) combined with a water-soluble

polymer (acid).

•

DEFINITIONS

“Glass-ionomer is the generic name of a group of materials that use silicate glass powder and aqueous solution of polyacrylic acid” - Kenneth J Anusavice

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

• GIC Acquired its name from its composition of glass particles and an

ionomer that contains carboxylic acid.

• Extensive use of this cement to replace dentin , has given it different

names:

1) Dentin substitute

2) Man made dentin

3) Artificial dentin

4) Alumino Silicate Polyacrylic Acid(ASPA)

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.

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

SiO2 –30.1%

Al2O3 –19.9%

AlF3 –2.6%

CaF2 –34.5%

NaF2 –3.7%

AlPO4 –10.0%

POWDER

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.

Calcium fluoride (Ca F2)

- Increase opacity

- Acts as flux

Aluminium phosphates

- Decrease melting temp.

- Increase translucency

Cryolite (Na3 Al F6)


- Acts as flux

Alumina (Al2 O3)

- Increase opacity

Silica (SiO2)

- Increase Translucency

Fluoride: Its has 5

functions

- Decrease fusion temp.

- Anticariogenecity


- Increase working time

- Increase strength

Glass ionomer cements in dentistry : a review International journal of plant, animal and environmental sciences 2011;1(1)

LIQUID

• 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.

- POLY ACRYLIC ACID - 40% TO 50%

- ITACONIC ACID

- MALEIC ACID

- TRICARBOXYLIC ACID

- TARTARIC ACID

- WATER

Tartaric acid

- Increases WT

- Increases translucency

- Improves manipulability

- Increases strength

5-15% of optically active isomer of TA is added.

Polyphosphates: extends Working Time.

Metal oxides: accelerates Setting Time.

Glass ionomer cements in dentistry : a review International journal of plant, animal and environmental sciences 2011;1(1)

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.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 SKINNERSType I – LutingType II- RestorativeType 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

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

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

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.

INDICATIONS

• 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.

• 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.

2. Fast setting lining cement and bases:

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 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.

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

CLINICAL PROCEDURE FOR PLACEMENT

1. Select the appropriate shade of the cement.

2. Isolate the tooth with rubber dam where there is any risk of gingival

seepage or bleeding.

3. Prepare the cavity- erosion/abrasion lesion:-clean only with pumice

slurry

-Carious lesion: conventional instrumentation to remove caries and

provide some mechanical retention.

4. Where there is less than 0.5mm of remaining dentin , line the cavity

with a fast setting Ca(OH)2

5.Apply a surface conditioner to the cavity to remove the smear layer and

improve the adhesion.

6. Dispense the cement on a cooled glass slab and mix quickly (30 secs for

hand mixing and 10 secs for machine mixing). Alternatively a paper

pad can be used. The mix should have a glossy appearance

Full spoon, no excess

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

Hand dispensing

Hand mixing

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

First half folded into liquid in 10-15seconds

Second half incorporated in 15 secondsSmall mixing area

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

Correct consistency for hand mixed

Type I : Luting : string up to 3-4cm from slab

Type II : string 1cm + gloss

Type III : As lining for amalgam : 1.5:1

P/L ratio 3-4 cm string

As a base for composite : 3:1 P/L

ratio 1-1.5 cm string

Mixing of capsules

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

• Ultrahigh speed machine : 4000 cycles/minute

• (< 3000 cycles/minute – not desirable)

7. Wash and lightly dry the cavity. The surface should be dried but not

desiccated as this tends to reduce the wettability. Insert the cement

using a spatula or a syringe

8. Place a preshaped matrix wherever possible.

9. Allow to set.

10.Remove the matrix and immediately apply varnish or bonding agent.

11. Trim any excess, external to the cavity with scalpel blade.

12. Reapply varnish or bonding agent.

13. The final polishing should be delayed till the next appointment or at least

24hours.

14. Reapply varnish or bonding agent after polishing.

- Best surface finish obtained – if 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.

FINISHING OF GIC

SETTING REACTION

• IT IS AN ACID BASE REACTION BETWEEN ACIDIC POLYELECTROLYTE AND BASIC GLASS POWDER.

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.

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

DECOMPOSITION ---DECOMPOSITION OF GLASS POWDER BY ACID RESULTING IN RELEASE OF IONS.

STAGES OF SETTING REACTION

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

Initially calcium complexes predominate but later aluminium complexes are

more.

pH and viscosity increases

DECOMPOSTION OF GLASS AND MIGRATION OF IONS

• 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..

• Cored filler is bound together by a hydrogel of Ca and Al poly acrylates that

contain fluorine :- FLUORO ALUMINO CALCIUM POLYACRYLATE

CEMENT STRUCTURE

WORKING TIME AND 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

CONSISTENCY AND FILM THICKNESS:

• Film thickness should not exceed 20µm for luting

agents

• It is similar to or less than zinc phosphate cement

and is suitable for cementation.

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

Plays an important role in setting reacton and structure of

cement.

Acts as reaction medium

Hydrates the siliceous microgel and metal poly

acrylate salts.

THE ROLE OF WATER

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 ionsCRACK IN UNPROTECTED GIC

• Water present in set cement can be classified in to two forms:

a) loosely bound water

b) tightly 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.

LOOSELY 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).

TIGHTLY BOUND WATER

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 post-

hardening.

Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ulrich lohbauer Materials 2010,3,76-96

• 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, as shown in Figure 6



AESTHETICS

BIOCOMPATIBILTY

ANTICARIOGENIC PROPERTIES

ADHESION

THERMAL COMPATIBILITY

WEAR AND FATIGUE

LINEAR ELASTIC MECHANICAL PROPERTIES

PROPERTIES

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 and one year after mixing .

• When exposed to aqueous solutions of varying pH, GIC exhibited a high

acid erosion resistance compared to other restorative materials.



Dental Glass Ionomer Cements As Permanent Filling Materials – Properties ,Limitations And Future Tends – ULRICH LOHBAUER et al Materials 2010,3,76-96

Properties Of Restorative Gic

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

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

Properties Of Luting Gic

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 100 months was reported.


• 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 he form of hydrogels that allow chemical

equilibrium with an ion movement between GIC and the oral cavity &

surrounding tooth structures.

FLUORIDE RELEASE

• 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 fluoride.

.

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.

Because of slow hydration reactions glass ionomer cements take at least 24

hrs to fully mature & develop translucency.

Early contamination with water reduces translucency.

AESTHETICS

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 )

• 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.

ADHESION

Mechanism Of Adhesion According To Different Authors:

.

1.Chelation (Smith)

2. Hydrogen Bonding Followed By Ionic Bond (Wilson)

3. Hydroxyapatite & Polyacrylic Acid Interaction (Beech)

4. Hydrogen Bonding With Dentin Collagen (Akinmade )

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.

IMPROVING ADHESION

• Tensile bond strength to enamel- 2.6 to 9.6 MPa

dentin- 1.1 to 4.5 Mpa

Surface Conditioning

• Smoothing of surface irregularities

1) Prevent air entrapment

2) Minimizes areas of stress concentration

3) Improves bond strength esp. to dentin

Agents used

Surface 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 60Na2EDTA, 2% aq 30Na2EDTA, 15% aq 30

Sodium flouride, 3% aq 30

Ferric chloride, 2% aq/alc 30

SEM of dentin without surface conditioning

SEM of dentine after treatment with citric acid

• 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

EROSION

GIC

Marginal seal

Fluoride release

Bio active

No secondary

caries

BIOCOMPATABILITY

• 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 and Wilson, 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 wjich 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. Reference book :Glass Ionomer Cement :Alan D Wilson/ john w.McLean chapter 8 page no.126

CLASS III RESTORATIONS

CORE BUILD UP

TUNNEL PREPARARTIONS

PIT AND FISSURE SEALENTS

SANDWICH TECHNIQUE

FEW APPLICATIONS OF GIC IN

RESTORATIVE DENTISTRY

• 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.

SANDWICH TECHNIQUE

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.

Close sandwich technique

Open sandwich technique

• 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.

PIT AND FISSURE SEALANTS

• 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.

CORE BUILD UP

TUNNEL PREPARATION• First described in 1963

• Conservative alternative cavity preparation in primary molars.

• Indication:- Small proximal caries with out involvement of marginal ridges.

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.

GIC IN ENDODONTICS

Clincal application of glass ionomers in endodontics: a review – zahed mohammadi at al International dental journal 2012;62:244-250

METAL MODIFIED GIC

RESIN MODIFIED GIC

MODIFICATIONS OF GIC

• 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.

RESIN MODIFIED GIC

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

Powder Liquid Purpose for their inclusion

Barium, strontium or aluminosilicate glass

Improved strengthImparts radiopacity

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

COMPOSITION

• 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.

The sequence of the two setting reactions in a dual-cured resin modified glass ionomer cement. The boxes coloured in pink indicate the glass ionomer cement reaction, while those in blue indicate the resin polymerization reaction initiated by light.

SETTING REACTION OF RMGIC

SETTING REACTION OF TRICURE RMGIC

Tri-cured: acid-base reaction + light activation + dark redox.

PROPERTIES:

• 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 non-

polymerized 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.

• The biocompatibility is controversial and precautions such as placing

Ca (OH)2 in deep preparations should be taken and the transient t0 rise during

setting is also a concern.

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

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.

MIRACLE MIX / SILVER CERMET• 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%

METAL MODIFIED GIC

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.

Indications

Core build –up material

Root caps of teeth under over dentures

class I cavities in 10 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.

• 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.

RECENT ADVANCES IN GIC

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)

IMPROVED TRADITIONAL GIC

Polyacrylic acid is made to finer grain size so that higher powder

liquid ratio can be used.

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, Hi-Fi, Fuji VIII and IX

.

• CC bonifac et al conducted a study between six commercially available GIC and

the aim of there study was to investigate the mechanical properties of GICs used

for ART i.e Wear resistance, flexural and compressive strength and Knoop hardness

were evaluated.

• They concluded that Ketac Molar Easymix and Fuji IX presented the best

performance in all the tests.

Physical-mechanical properties of glass ionomer cements indicated for atraumatic restorative treatment - CC Bonifac et al Australian Dental Journal 2009; 54: 233–237

• Letícia Busanello et al conducted a study to compare & evaluate compressive

strength of glass ionomer cements used for atraumatic restorative treatment.

• The found that among all Fuji IX presented the best results after 1 hour.

• Following 24-hour storage, Fuji IX, Ketac Molar, and Vitro Molar had similar

performance.

• Except for Fuji IX, all materials presented higher compressive strength values after

24 hours than after 1 hour.

Compressive strength of glass ionomer cements used for atraumatic restorative treatment - Letícia Busanello et al Rev. odonto ciênc 2009;24(3):295-298

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.

FLUORIDE

RELEASING

CAPABILITY OF

GIC

DURABILITY

OF COMPOSITES

COMPO

MER

POLYACID MODIFIED GIC /COMPOMER

• 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 evaluation of tensile bond strength and microleakage of conventional glass ionomer cement, resin modified glass ionomer cement and compomer: An in vitro study C. Vishnu Rekha et al Contemporary Clinical Dentistry2012;3(4)

INDICATIONS

1. P& F sealant

2. Restoration of 10 teeth, 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

ADVANTAGES

Superior working characteristics to RMGIC

Ease of use

Easily adapts to the tooth

Good esthetics

CONTRAINDICATIONS

Class IV lesions

Conventional class II cavities

Lost cusp areas

Restorations involving large labial surface

• 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.

• 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.

SELF HARDENING RMGIC

ADVANTAGES

Its advantages include:

• Ease of handling

• No post- cementation sensitivity

• Fluoride release

• Higher compressive strength

• No additional step of light activation

• 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.

BIO ACTIVE GLASS

• 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 remineralise 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.

FIBRE 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 as resin is confined within the

chambers.

• There is also 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

.

• Recently single application bonding system that combine the function of

self etching primer and bonding agent have been developed.

• Reactmer ( shofu,japan) bond is a single application bonding agent ,it’s a

glass ionomer based all-in-one filled adhesive based on PRG technology.

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

• Beautifil II is a second generation giomer introduced into market claiming

better optical properties than RMGIC.

• Jyothi KN et al compared and evaluated giomer and RMGIC in class V

noncarious cervical lesions in an in vivo study and they found that giomer

restorations exhibited superior surface finish and greater color stability

when compared to that of RMGIC.

• They also conclude both mechanical properties of RMGIC and GIOMER

are similar.

Clinical evaluation of giomer and resin modified glass ionomer cement in class V noncariousLesions: An in vivo study jyothi et al JCD2011;14(4)

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

• 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

AMALGOMERS

• 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)

• 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

HAINOMERS

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

New Fluoride Releasing GIC’s

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.

• To increase the anticariogenic action of GIC

• Still under experimental stage.

• Experiments conducted on cariogenic

organisms

CHLORHEXIDINE IMPEGRENATED GIC

GIC’s have come a long ways since its modest beginning in 1969.

Even though research can boast of substantial improvements, certain

essential properties still seem to be wanting and further clinical trials are

warranted for a majority of these developments.

At this point of time, we are left wondering if GIC will ever be able to

dominate tomorrow’s restorative scene or will it go into total oblivion.

Let us wish GIC all the best for the coming years

conclusion

REFERENCES

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

Education

Glass ionomer cement