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GLASS IONOMER CEMENTS

Traditional form powder / liquid

Proportioned capsules

Water settable cement

Polycarboxylic acid freeze dried and in such a case the liquid

may be distilled water or a diluted solution of tartaric acid

Composition:

Calcium fluoroaluminosilicate glass

Glass are three components Silica(Sio2) , Alumina( mix in flux

of sodium and calcium fluorides.The particle size of the powder depends upon the purpose for

which is used.

Barium glass may be added to give radiopacity

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CompositionLiquid:Aqueous solution

of

polyacrylic acid,itaconic acidCopolymer

with

tartaric acidnot more than 5%

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Applications

1. Cement2. Liner / Base3. Core4. Retrograde Filling Material5. P/F Sealant6. Root Caries Cervical Restoration

7. Temporary, or ART Restoration8. They are recommended for high caries risk patients

9. Cervical class V restorations in adults

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1.Direct Bond to tooth no bonding agentrequired

2.Bonds to moist tooth

3.Fluoride protection

4.Excellent marginal seal - no shrinkage

5.Thermal expansion = tooth6.Biocompatible - ideal match for dentin

Benefits of Glass Ionomer

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Setting ReactionsThe following stages on mixing

1. Dissolution

2. Migration

3. Reaction and precipitation (Hardening)

Dissolutionof the surface glass by the acid H+ attack glass to

release cation (Ca++,AL+++) and fluoride ions between 20% to30% of the glass is decomposed by acid attack.

Migration of the surface ions (Ca++,AL+++) and fluoride ions

complex into the liquid.

The divalent Ca++ will migrate first and react with carboxylicgroup to form cross linked carboxylic acid gel leading to initial

set ,followed by trivalent AL+++ the latter reaction takes longer

time 24 H and results in stronger cements so the reaction

protected from saliva with varnish.

The sodium ions form silica gel on the surface of the particles.

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Properties

Bond strength to dentin of 2 to 3 Mpa lower thancomposite.

When the dentin etched, the glass-ionomer may use 4years clinical data showed a retention rate

for glass-ionomer.

1-Cervical restoration 75% pulp reaction was mild.

2-If the thickness of dentin is less than 1mm

use calcium hydroxide Liner.The fluoride in glass-ionomer released over a period of

two years.

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Role of water in the setting reactions

1. It is serves as a reaction medium

2. It is loosely bond to the structure,

3. It is slowly hydrates the cross-link matrix

and become tightly bond.

4. It is increase strength by producing stable

gel structure if glass ionomer cement is

subjected to dryness during the initial set.5. The reaction will not complete and the

surface crack.

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Manipulation

G.I. packed in bottles and in capsules,mixing time 30 to 40 sec. is used with a

typical setting time of 4 minutes.

Placing the restorative and carving thecorrect contour should protect the

surface from saliva by applications of

varnish. Trimming and finishing had doneafter 24 H.

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Modification of glass ionomers

It have been made in order to improve the mechanicalproperties, abrasion resistance and optical

properties.

1. Metal modified glass-ionomers

A. Miracile mixture.

B. Cermet glass-ionomers.

2. Light cured (Hybrid glass-ionomers )

3, Compomer.

4. Giomer (Hybrid glass- ionomers and composite)

5. Nano-ionomer

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summary.

Cements are popular applications for GI to attach crowns andbridges to tooth structure.

Cores or foundations for fixed prosthetics:

are popular but not as durable as composite or amalgam.

Tunnel restorations are MO or DO restorations formed undermarginal ridges without breaking them.

Sandwich restorations are composites bonded over GI with the GI

exposed as surfaces in some cases for fluoride release.Retrograde filling materials are root canal fillings of teeth that areremoved, filled, and replanted.

Sealant applications have not fared well because GI tend to bebrittle.

Cervical restorations are hard to restore because of moisturecontrol challenges so traditional glass ionomers are oftenpreferred because of the ability to work in wet fields.

Temporary restorations in permanent teeth or ART restorations inprimary teeth are extremely popular.

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Three classifications of GIsa) Glass Ionomer Cements or traditional glass ionomer restorativeproducts.Consist of an acid-decomposable glass and an acidic polymer thatundergo an acid/base reaction when mixed. The reaction does not

require light to occur - the mixed material sets in the dark.Examples of these products are Ketac-Fil (ESPE) and Fuji II (GCAmerica).

b) Resin-Modified Glass-Ionomer CementsThis group can be divided into 2 subgroups : Light Cured ResinModified Glass Ionomer Base/Liners & Light Cured Resin Modified

Glass Ionomer Restoratives.Resin has been added in one form or another. In addition to the GIacid/base reaction, they also undergo a resin polymerization reactionthat is usually initiated by light exposure (these products require lightexposure to harden.) Examples are Fuji II LC (GC America), Vitremer(3M), and Photac-Fil (ESPE).

c) Polyacid Modified Composite ResinsThese are more resin than glass ionomer. They contain one or both ofthe basic glass-ionomer components These products usually do notset without light exposure or set very slowly.Examples are VariGlass VLC (Caulk), Dyract (Caulk), and Geristore(Den-Mat).

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Hytac and F2000 are compomers.

Dyract Flow is a flowable version of aresin-modified glass ionomer.

Fuji I LC is a light-cured RMGI that has

substantial quantities of glass ionomer

Vitremer is a common RMGI that is

extremely popular as a lining cementover calcium hydroxide for deep

amalgam or composite restorations.

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(RESINS MODIFIED GLASS IONOMER)

COMPOMERS

Applications

1-Used for low stress bearing

2- High caries risk patients(civically eroded teeth)

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Compositions

Supplied as one past system more related to glass-ionomer than composite, the liquid contains

monomers, polyacid and water reaction

Advantages:1.Better optical.

2.Less sensitivity to moisture after setting.

3. Superior mechanical properties.

4. They are used as anterior restorative.

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They are used as liningmaterials under composite

resin used as anteriorrestoration specially as class

V cavities

Set by acid base reaction andboth lightcured and self-

cured

Light cured (Hybrid Ionomer

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PropertiesNot need bonding agent the tooth has

conditioned (etched) with polyacrylic acidor a primer before placement of thehybrid ionomer.

More fluoride release than compomersand composite but less than glassionomer recharge when exposed to

fluoride treatment or fluoride dentifrices.

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ManipulationPackaged as powder/liquid or

encapsulated forms

Hybrid Ionomer set has immediately

when light cured and can befinished immediately.

Not need bonding agent.

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RESIN CEMENTS

There are two major

groups of resin cements

A-Unfilled acrylic resincement

B-Composite cements

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Clinical applications1. Cements are recently used

substituted the conventional resin2. They are also used for cementation

of veneers, cast ceramic crowns ,inlays, bridges

3. composite inlays and orthodontic

brackets .

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Classification of resin cements

These are based on methyl methacrylate +

compomersThe accelerator initiator system is typically amine and

peroxide

Setting occurs As a result of free radical,

polymerization characterized by heat liberation andshrinkage of polymer Supplied as powder + liquid

Used for cementation of orthodontic brackets

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II- Adhesive resin

2-Composite resin cements

Replaced the unfilled resin due to their superiorproperties

Classification according to bonding mechanism to

tooth structureConventional cure. resin cement

These types gain their retention to tooth structure

through acid etching in conjunction with enamel and

dentin bonding.

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These divided into 3 types

1-Self cured

Powder + liquid or two paste systems.Composition

Diacrylates oligomers Diluted with

dimethaerylate monomer ( low molecularweight) Silanated silica or Glass filler.

initiator accelerator system Peroxide

amine

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2- Light cured (micro filled )

Small particle (hybrid composites)

Composition:The other major past

(Bis- GMA) or( urethane

dimethaerylate) diluted withdimethacrylate monomer or

TEGDMA OrSilica or glass fillers

20-75 (or) both

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They are photo initiated in the

presence of camphorquinine

(amin system )

they are provided as a paste

which requires no mixing .

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3. Dual cured

Similar to the light

curePolymerize by the mechanisms of light or

Chemical

supplied as base + catalyst pastemust be mixed before use after mixing ,

self cure chemical reaction takes place

slowly and provided extended working timeuntil the cement is exposed to light at which

the cement solidifies rapidly.

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Adhesive Resin Cements

Phosphonate Cements

These are self-cured powder / liquid systems.

Composition: ( Methacryloxyethyl phenyl phosphate )MAOEPH.PH (or)

4- Methacryloxyethyl trimellitican hybride ( 4META )

These cements are called ( phosphonate cements )

Recently formulated as a two paste system contains

Composition: 1- Bis GMA resin.

2- It is silanated quartz fillers.

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The phosphate end of the phosphonate

react with calcium of the tooth or withmetal oxide.

the phosphonate is very sensitive tooxygen so a gel has provided to coat

the margins of a restoration until the

setting has occurred.

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Properties

The effect on the pulp:Irritating to the pulp so pulp protection via calcium

hydroxide is very important or glass ionomer

liner .If the bonding are a involves only enamelor if the remaining dentin thickness is sufficient,

The irritation not significant .

Film thickness: It is varies according to uses.

Solubility: It is insoluble in the oral fluids.

- on ng

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- on ng

1- To enamel by acid etching.

2- To dentin by dentin bonding agents

3- To restoration previously treated with

surface or chemical preparations.

) Strength5

It has high compressive strength 180-260 MPA

fracture toughness high.

) Optical6

They are translucent radiopaque types are

available to be used in the posterior teeth.