Dental CementsSilas M. Toka

BDS III, 2010 (UoN)8th October, 2010

IntroductionDef: A dental cement is a biomaterial

composed of but not limited to an acid and a basic component that react to set into a rigid material.

Dental cements may also be polymeric i.e. set through polymerization reactions.

Applications of Dental CementsDental Cements have both temporary and

permanent applications:i. Luting ii. Liningiii. Cementing Orthodontic appliancesiv. Fissure sealantsv. Root filling materialsvi. Temporary fillingsvii. Permanent fillingsviii. Core build-up

Dental Cements 1. Silicate Cements2. Zinc phosphate Cement3. Zinc polycarboxylate Cement4. Glass Ionomer Cement5. Zinc oxide Eugenol Cements6. Calcium hydroxide Cement7. Resin Cements8. Mineral Trioxide Aggregate

Polyacrylic acid (aq.)

Phosphoric acid (aq.)

Zinc Oxide

Alumino-silicate glass

Glass Ionomer Cements

Zinc Polycarboxylate . cements

Zinc phosphate cements

Silicate cementsDental Cements as acid + base formulations.

Eugenol

Zinc OxideEugenol

1. Silicate Cements

Based on fluoroaluminosilicate glass and aq. phosphoric acid.

Also called silicophosphate cements. First tooth colored filling material (1870). Not in use today.

Drawbacks of Silicate CementsAcidic (Phosphoric acid)Soluble in the mouthLow wear resistanceStaining at the marginsShort lasting fillings

The fluoroaluminosilicate glass of Silicate cements formed the basis for the modern day Glass ionomer cements.

2. Zinc phosphate Cements

One of the oldest cements (the oldest luting cement).

Powder: 90% ZnO, 10% MgO. MgO serves to whiten the powder. Small quantities of oxides and fluorides. SiO2 1.4% - Calcination aid. BiO3 0.1% - Smoothens powder.

Zinc phosphate Cements (cont’d) Liquid: 60-70% aq. Phosphoric acid.Zn or Aluminium phosphate (achieved by

dissolving Zn 7.1% or Al 2.5% in the liquid).

They buffer the liquid thus partially neutralizing/reducing the reactivity of the P & L.

The water in the acid controls the ionization thereby affecting P/L (acid/base) rxn.

Note on the liquid:Not to be dispensed on the slab until

mixing is to be initiated because water will be lost to air by evaporation.

Bottle should thus also be carefully stoppered;Evaporation lowers pH of the Phosphoric acid:- Issues with biocomp’t.

- Ions needed for rxn.Cloudy liquid is totally acidic and should

be discarded.Loss or gain of water in H3PO4 both

compresssive&tensile strength of cement.

Zinc phosphate Cements (cont’d)ManipulationP:L ratio dependent on clinical application.A high P:L ratio gives a stronger set

material(so use max. powder possible even when thin mix such as for luting is needed).

Thinner mix – Low viscosity(used in luting; more soluble& weaker mechanically).

Mix on a cold glass slab 1 – 1.5 mins.Small increments added.

Brisk spatulation;mix over wide area,each increment for 15-20 sec before adding.

Complete mixing in 1.5 – 2mins.For luting, low viscosity mandatory.Seat prosthesis immediately before matrix

formation occurs and hold it under pressure until cement sets.

Keep field of operation dry.Remove excessive cement after set.Apply varnish or non-permeable coat on

edges to give time to mature and develop resistance to dissolution in oral fluid.

Luting

Setting ReactionZnO+2H3PO4 Zn(H2PO4)2+H20

ZnO+Zn(H2PO4)4+2H2O Crystalline [Hopoeit]Unreacted core of ZnO remains.Set Cement Matrix of Zinc aluminophosphate

Rxn is exothermic;Cement sets in 5-9mins.

ZnO

Factors Affecting Setting RxnHigher P:L ratio.Increase in temp.Moisture.Faster rate of adding powder increments

to the liquid.Finer particles increase rate of rxn.Too acidic liquids slow down setting rxn.

Biological PropertiesFreshly mixed cement has a pH of btwn

1.6-3.6;pH of 5.5 at 24hrs.Cement should only be placed on fresh

dentine with a subliner e.g. varnish, Ca(OH)2, or ZnOE.

Is a good thermal insulator – can be used to protect pulp.

Radio-opaque.

Mechanical PropertiesNo chemical adhesion; bonding by

mechanical interlocking at interfaces.Compressive strength of 104MPa for luting

cements,but a diametral tensile strength of only 5.5MPa.

Modulus of Elasticity=13.5GPa, therefore quite stiff and resistant to deformation even when used as a luting cement in high masticatory stress areas.

Recommended P:L ratio=1.4g powder:0.5mL liquid.

Applications1. Permanent luting(of crowns&bridges).2. Lining, but only with a subliner.3. Temporary filling, with a protective layer.Advantagesi. Cement better than ZnOE;TF would last

longer.ii. Good thermal insulator.iii. Cheaper cf other luting materials. (Resin cement kit about KSh.18,000)

Zinc phosphate Cements (cont’d)Brand namesTenetHavardDe Trey’s Zinc

3. Zinc polycarboxylate Cements Synonym: Zinc polyacrelate Cements. First chemically adhesive dental material

to be developed. Presented in P:L formulation. May be capsulated. Anhydrous,where the liquid is freeze

dried and incorporated in the powder.Brand NamesDurelonCarboco

Powder: (Similar to ZnPO4 Cement; Both in composition & in manufacturing):

90% ZnO, 10% MgO. MgO serves to whiten the powder. Stannic oxide may be substite MgO. Small quantities of oxides and fluorides. SiO2 1.4% - Calcination aid. BiO3 0.1% - Smoothens powder.

One preparation contains alumina in 43% of the powder.

Stannous fluoride in small quantities. Note on Stannous FluorideModifies setting time.Enhances manipulative properties. Increases strength.However fluoride release is only 10–15 %

that released by GIC’s.

LiquidAq. Soln. of Polyacrylic acid, orA copolymer of polyacrylic acid with other

carboxylic acids such as itaconic acid.Mol. wt. of the polyacids is in the 30,000 –

50,000 range(Viscous acids).Hence the freeze dried formulation.Acid concentration varies from 32-42% by

weight.

In the freeze dried preparation, the liquid is water.

ManipulationP:L = 3:1 by volume.With the non freeze-dried preparation, the

P:L varies from different brands;range of 1 – 5 parts of powder:1part liquid by wt.Mixing done on a cold glass slab;advantage

over paperpads since it can be cooled&does not absorb liquid.

Do not dispense the liquid until it is time for the mix to be made.

Cool glass slab,but by no means refrigerate the liqud!!

Powder incorporated into the liquid in large quantities.

Viscosity increases steadily.Apply to dry tooth before cement loses

gloss in order to achieve good bonding.Gloss indicates presence of free carboxylic

groups on the surface of the mixture that are vital for bonding to the calcium in the tooth surface.

When the viscosity is changing,and lifted cement forms a streak (“cob web”), discard the material.

Setting ReactionParticle surface dissolution by the acid to

release Zn, Mg and Sn ions,which bind to the polymer chains via carboxyl groups.

These ions react with carboxyl groups of adjacent polyacid chains, so that a crosslinked salt is formed as the cement sets.

The hardened cement consists of an amorphous gel matrix in which unreacted particles are dispersed.

The microstructure resembles that of zinc phosphate in apperance.

Binding to Tooth StructurePolyacrylic acid is believed to react with

Ca2+ ions via carboxyl groups on the surface of enamel or dentine.

Thus the bond strength to enamel is greater than that to dentine.

Film ThicknessThe material is pseudoplastic and

undergoes thinning at an increased shear rate.

Spatulation can produce a film thickness of 25µm or less.

Biological ConsiderationsProduce minimal irritation to the pulp; the

liquid’s acidity is rapidly neutralized by the powder.

Biocompartibility with pulp compares well with Zinc oxide Eugenol Cements.

It is postulated that the Polyacrylic acid molecule is larger in size than the Phosphoric acid of Zinc phospahate cements.

This limits diffusion through dentine tubules.

Working TimeMuch shorter than for zinc phosphate

cements i.e. 2.5min cf 5min for ZnPO4.Lowering the temperature of the glass

slab can increase the working time, but can also cause the polyacid to thicken hence making the mixing difficult.

It is suggested that only the powder be refrigerated before mixing.

The rationale for this is that the reaction occurs on the surface and the cool temp. retards it without thickening the PAA.

Setting Time6-9 mins (Acceptable for a luting cement).

Mechanical PropertiesCompressive strength: 55-67MPa [inferior

to ZnPO4 (104MPa)].Modulus of elasticity 2.4-2.4 GPa(half that

of ZnPO4 = 13.5GPa), therefore is not as stiff, and also not as brittle.

Has a plastic deformation potential and so difficult to remove excess after set.

Avoid removing cement during the rubbery stage when luting a prosthesis as there is a danger of the cement pulling out from under the prosthesis leaving a void.

Can either start removing the cement immediately after placing the prothesis, or wait until set.

Coat the outer surface of the prosthesis with a separating medium to avoid excess cement adhering to the surface.

SolubilityLow solubility in water.Increased solubility in organic acid of pH

less than 4.5. (e.g in poor OH patients).Reduction of P:L ratio also increases

solubility hence increased disintegration in the oral cavity.

ApplicationsLuting (currently overtaken by GIC’s).Lining.Temporary fillings.

4. Glass Ionomer Cements

Materials based on the reaction between silicate glass powder and polyacrylic acid.

Developed in 1971 by Wilson and Kent and has properties that supersede those of Zinc polycarboxylate and Silicate cements.

Are an aesthetic tooth colored material with the 3 salient properties of:

Biocompartibility, Chemical adhesion to the tooth, and Fluoride release and re-release.

GIC Fillings

GIC Brands

GIC Brands

GIC’s and Related Materials

1. Conventional GIC’s/Traditional GIC’s.2. Resin Modified GIC’s.3. Metal Modified GIC’s.4. Phosphonate Modified GIC’s.5. Advanced/Highly Viscous/Condensable

GIC’s/A.R.T. materials.6. Giomers.7. Compomers.

GIC’s in EndodonticsKetac-EndoEndodontic sealer cement based on GIC

chemistry.Disadvantage is that GIC is hard to

remove, making retreatment almost impossible.

May be used without Gutta percha cones.Currently, chloroform, hand instruments

and ultrasonics are used in an attempt at removal.

Fissure Sealant Application of GIC’sTraditional GIC’s are viscous which

prevents penetration to depth of fissures.

Less viscous formulations of GIC’s are now available for fissure sealant therapy.

5. Zinc oxide Eugenol CementsZinc oxide is the major component of the

cement.Presented as Zinc oxide powder and

Eugenol liquid, or sometimes as 2 pastes.The higher the P:L ratio, the faster the

material sets.Powder particle size affects strength; the

smaller the size, the stronger the set.Compressive strength ranges from 3-55

MPa depending on ZOE formulation.

Manipulation

Mixing done on glass slab or oil-impervious paper-pad.

Cooling a glass slab slows down the reaction until dew point; water incorporated after dew point hastens the reaction.

Mix in increments until desired consistency is attained.

P:L Ratio = 5.5:1 for TF or Lining.P:L Ratio = 4:1 for luting.

Manipulation (cont’d)Mixing time: 60 seconds.Working time: 3 minutes.Setting time: 3.5 – 4.5 minutes.

The pH is approx. 7 at the time of placement, which makes ZOE the least irritating of all dental materials.

A TF lasts approximately 3 months (Zinc phosphate performs better).

Setting ReactionConsists of Zinc oxide hydrolysis and a

subsequent reaction between Zinc hydroxide and Eugenol to form a chelate.

Water is needed to initiate the reaction and is also a by-product, hence the rxn proceed faster in humid environments.

Zinc oxide + Eugenol Zinc Eugenolate

Characteristics of ZOE CementsSoluble in oral fluids and so if left for a

long time, the filling crumbles and desintergrates.

Has a palliative/soothing/optudent effect to the pulp (manages hypersensitivity).

However, effect only when placed on dentine; should never be placed on the pulp – causes necrosis.

Potential allergen to some patients.Irritation to soft tissue (therefore, handle

with gloves)

Characteristics of ZOE Cements (cont’d)

Plasticizes and interferes with polymerization reaction of tooth colored filling materials.

Therefore contraindicated in lining under resin composites and compomers.

Have a characteristic smell (of Eugenol) and clinics will smell of it if not thoroughly cleaned.

Formulation ModificationsPlain unmodified ZOE will set very slowly;Therefore, modifications:Zinc acetate dihydrate is much more

soluble than Zn(OH)2 and will supply zinc ions more rapidly.

Acetic acid catalyses the reaction faster than water does because it increases the formation rate of Zn(OH)2.

Applications of ZOE Cements4 types (ANSI/ADA Specification No.30):1) Type I: For temporary cementation e.g of

provisional acrylic crown or bridge.2) Type II: For long-term cementation of fixed

prosthesis (not so desirable cf GIC).

Applications of ZOE Cements3) Type III: For temporary fillings (lasts a

few wks), and thermal insulating bases.

Applications of ZOE Cements

4) Type IV: For intermediate restorations (can last up to 1 year).

Applications of ZOE Cements5) Variety of ZOE cements also serve as

root canal sealers, and 6) Periodontal dressings.

Applications of ZOE Cements7. Zinc oxide Eugenol Sealer CementsPresented as powder+ liquid.

i. Grossman’s sealer CompositionPowder/ pellet Zinc oxide – 42% Staybellite resin – 27% Bismuth – 15% Barium sulphate – 15% Sodium borate – 1% Liquid: Oil of cloves

Manipulation of Grossman SealerMixing is done on a sterile glass slab with

sterile spatula.After mixing, the cement is carried into

the canal on a sterile smooth broach and coated around canal walls.

Cement sets hard on the slab from 6 – 8 minutes; Begins to set in the root canal in about 10 minutes and achieves a final set in 90minutes.

The cement is tolerated relatively well by periapical tissues and is also germicidal.

ii. Paste-Paste ZOE Sealer Cement Preparation

Base Paste Zinc oxide Oleo resins Bismuth trioxide Thymol iodide Oil and waxesCatalyst Paste: Eugenol Polymerized resin Annidalin

ManipulationTwo pastes of equal lengths are dispensed

onto a dry glass slab and mixed to obtain homogeneity.

It sets within 5 minutes on the slab and in 20 minutes in the root canal.

A commonly used brand is Tubliseal.

Other ZOE Based BrandsRickert’s Formula.Wach’s Sealer.N2.Endomethasone N.

“N”: Contain Formaldehyde, hence risk of toxicity; Brands not used much.

Properties of ZOE Sealer Cements

AdvantagesEasy manipulation.No dimensional changes.Radiopacity.Germicidal.Ample WT.Non-staining.DisadvantagesNot resorbed if excess periapically.Some degree of solubility.Fluid ingress.

Modifications of ZOE Cements1. Resin Modification Hydrogenated resin (29%) is added to the

powder. 10% polystyrene is added to the liquid. Other cements have 20% PMMA added

[Intermediate Restorative Material (IRM)].

2. Rosin A natural resin from tropical pines. Light-brown in color. 29% is added to Zinc oxide. Ground to a fine powder. Reduces brittleness. Reduces solubility. Smoother mix with better consistency. Adds compressive strength from 15MPa –

38 Mpa. Reduces WT and ST. All modern ZOE’s contain rosin.

3. Ethoxybenzoic Acid (EBA) Modified ZOE

Substitutes a part of Eugenol liquid with orthoethoxybenzoic acid:

37.5% Eugenol : 62.5 % EBA Fused quartz/alumina is added to ZnO. Purpose: higher compressive strength

(90MPa) and abrasion resistance. For strong cement set, P:L Ratio = 7:1. Lower solubility. Can also be used for permanent luting.

Examples:

4) Eugenol Free ZnO Cements Especially for patients allergic to

Eugenol, or For use as lining under

composites/compomers. May contain vanilate esters in place of

the Eugenol component.

Freegenol (GC) Nogenol (COE) Temp Bond (Kerr) ZONE

5. Other Modifications Formulation containing powder made of

of 20 wt% to 40 wt% of fine polymer particles and Zinc oxide particles that have been treated with carboxylic acid.

The rationale is also to improve strength and abrasion resistance.

The liquid used in this system is Eugenol.

Zinc oxide Eugenol Brands

Zinc oxide Eugenol Brands

Kalzinol™ by Dentsply (a resin bonded ZOE)

Zinc oxide Eugenol Brands

6. Calcium hydroxide CementsPresented either as 2 paste system with

radio-opaque fillers, or as,

A 1 component light-curable base: by addition of urethane dimethacrylate.

Light cured presentation has superior properties:

80MPa Compressive strength. 10MPa Tensile strength.

Composition

Base paste: - 1,3 butylin glycol disalicylate.- Titanium dioxide (inert filler and pigment).- Calcium tungstate. - Barium sulphate.

Brown in color.

Confer Radio-opacity

Composition

Accelerator Paste Calcium hydroxide. Zinc oxide: Reactant but not a principal

participator. Zinc stearate: Accelerator. Ethylene toluine sulphonamine:

antibacterial agent. Oils: Make it into a paste form.

White in color.

Setting ReactionThe setting reaction occurs between

Calcium hydroxide and disalicylate yielding Calcium disalicylate.

The Calcium hydroxide is present in stoichiometric excess.

ManipulationEqual amount of base and catalyst

dispensed on an oil impervious paper-pad.Using a ball-ended instrument, mix to

homogenous color.Apply on dentine as a lining.

Mixing time: 5-10 secondsWorking time: 30 secondsSetting time: 1 minute

PropertiesBasic cement; pH : 11 – 12; used to

neutralize acidic cements, Thus, used as sub-liner under cements

like Zinc phosphate. Ideal to inhibit microbes esp. those found

in carious dentine. Poor mechanical strength: Compressive = 6 – 10 MgN/m2. Tensile = Very low (almost 0).

High solubility in water.

Properties (cont’d)Stimulates formation of reparative dentine

and so is applied in instances of pulpal exposure (direct pulp-capping), or near pulpal exposure (indirect pulp-capping).

Due to its high pH, it causes irritation to the pulp.

Necrosis of cells adjacent to the cement, and transformation of mesenchymal cell into odontoblasts which start laying down reparative dentine.

Procedure not always successful.

Application as Cavity LinerCa(OH)2 used as a liner is suspended in a

solvent carrier with a thickening agent.When placed on the pulpal floor, the solvent

evaporates leaving a thin film of Ca(OH)2.The liner does not contain significant

strength or thermal insulation capability.But it can neutralize acids that migrate

towards the pulp, and in the process, can induce the formation of reparative dentine.

Can be used as a direct pulp-capping material.

Applications1. Used principally as cavity liners and

bases.

Applications2. Subliner.3. Pulp-capping.4. Apexification.5. Temporary luting cement.6. Non-setting Ca(OH)2 for root canal

dressing.7. Endodontic sealer cement.

Non-setting Calcium hydroxide

Used in root canals as intra-canal dressing material between endodontic appointments, – eliminate microbes, then later washed off.

Also for managing root resoption.

Usual formulation: Ca(OH)2 and some binders e.g. Methyl cellulose.

Other formulation: Powder mix with distilled water.

Ca(OH)2 Based Sealer Cements

Used in endodontics.Favoured due to their ability to :-i. Induce apical closure.ii. Inhibit root resorption.iii. Create as good a seal as ZOE.iv. Less toxic than ZOE sealers.

Ca(OH)2 Based Sealer Cements (cont’d)

They are presented as paste/paste.They set via a reaction between calcium

hydroxide and a salicylate ester-aldehyde.The base paste mainly has 35%calcium

hydroxide while the reactor paste is 25% ethyl salicylate and fillers making up the remaining bit.

Ca(OH)2 has a pH of 12.5 and is radiopaque.It has been recognized for being antibacterial

due to the high pH and its ability to stimulate bone healing and root formation.

Ca(OH)2 Based Sealer Cements (cont’d)

Besides being used as an adjunct root canal filling materials, it has also been employed for:

- Apexification: Cement is placed in root canal’s apex.

- Apexogenesis: Histological analysis later shows apex formed is a mixture of hard tissues:dentine, cementum and bone.

Calcium hydroxide BrandsSetting: DycalCalcimolCavitecPrisma Dycal (light cured)Sealer Cements: - Apexit - Metapex. - SealapexNon-Setting:UltracalPD Calcium hydroxide

Calcium hydroxide Brands

Calcium hydroxide Brands

Calcium hydroxide Brands

PRISMA VLC DYCAL™ – Light Curing

7. Resin CementsPolymeric cements that set via polymerization

reactions.Resin cements are essentially flowable

composites of low viscosity. ApplicationsCementation of: Crowns. Resin bonded bridges. Inlays and onlays. Orthodontic brackets. Veneers. Posts and Cores.

Applications of Resin CementsResin bonded bridges

A Maryland Bridge

Applications of Resin CementsCementing Orthodontic Appliances

Composition and ChemistrySimilar to that of resin based composite filling

material: resin matrix with silane-treated inorganic fillers.

Fillers: silica or glass particles &/or colloidal silica used in micro-filled composites.

Require a dentine bonding agent in most instances to promote adhesion to tooth structure e.g in luting a crown.

Only exception is in anterior veneer tooth preparation which is usually only enamel deep.

The adhesive monomer incorporated into the resin monomer and cements include:

i. HEMAii. 4 – META(Methacryloxyethyl trimetillic

anhydride): a liquid adhesive that acquires cement consistency by incorporating polymer beads.

No separate bonding agent is needed.iii. An organophosphate e.g. MDP (10-

methacryloxydecamethylene phosphoric acid).

PolymerizationBy conventional chemical cure system

with an organic peroxide e.g. BPO as an initiator.

Light activation; addition of an alpha diketone and an aliphatic amine: applied where curing is practical e.g. through thin porcelain veneers (like Porcelite), resin based prostheses that are less than 1.5mm in thickness, and plastic and ceramic orthodontic appliances.

Dual cure.

Properties of Resin CementsInsoluble in oral fluids.Monomer is a pulp irritant, thus line with

Ca(OH)2 or GIC if dentine thickness ≈ 0.5mm or less.

Compressive strength: 180-265MPa.Tensile strength: 30-63MPa.Viscosity: Low to high.Film thickness: 13-20 μm.Shear bond strength to enamel: 15-

35MPa.To dentine: 5-35MPa.

ManipulationEnsure clean, dry area of tooth surface.Condition with etchant.Prime.Bond.Remove excess cement immediately after

prosthesis is seated.Light cure if indicated, usually for no less

than 40 seconds.The dual cure should not be used for any

light transmitting prosthesis thicker than 2.5mm (use chemical cure for such).

Metallic Prosthesis

Roughened by grit blasting with 30-50pm alumina particles at an air pressure of 0.4-0.7MPa, or by electrochemical etching.

Surface oxide layers contribute to bonding in base metals when MDP or 4-META based resin is used.

Electrochemical coating of tin (≈0.5pm) on noble metals is done to achieve this oxide.

A silica coating can be used to achieve the same bonding strength values to noble metals and base metal alloys as grit blasting and electrochemical etching.

Orthodontic BracketsEnsure proper isolation and etching of

enamel.Apply a bonding agent on the enamel.Metallic bracket has a mesh for mechanical

retention.Etch ceramic brackets and coat with an

organosilane analogous to the coupling agent of fillers to resin matrix of composites.

Prime plastic brackets in a solvent containing methylmethacrylate monomer.

Advantages

i. Only cement that is insoluble in oral fluids.

ii. High strength.iii. Viscosity suitable for luting.iv. Various shades; color can be matched to

the tooth.v. Dual cure.vi. Radio-opaque.vii. Easy to manipulate.

Disadvantages

i. Disintegrates if used as a gap filler.ii. Self cured form is difficult to trim.iii. Expensive.iv. Irritation to pulp.v. Stains.vi. Poor wear if not highly filled.

… and finally

Université délLöMA LINDA

8. Mineral Trioxide AggregateDeveloped as a root end filing material in the

1990’s.Commercially available as Pro root MTA in

either grey or white form; their difference being the conc. of Al, Mg and Fe cmpds.

Grey MTA contain the tricalcium alluminoferrite phase that is lacking in White.

ConstituentsMTA is a silicate cement.50-75% by wt Ca(OH)2.15-25% silicon dioxide.

When these raw material materials are blended they produce:

i. Tricalcium silicate.ii. Dicalcium silicate.iii. Tricalcium aluminate.iv. Tetracalcium aluminoferrite.v. Calcium sulphate.vi. Bismurth oxide.

On addition of water the cement hydrates to form silicate hydrate gel.

PropertiesCompressive strength of 40-70MPa(equal

to IRM&Super EBA,but lees than AgF).pH of 12.5.ST = 2-4 hrs.Sets in moist environments.Low solubility.Resists marginal leakage and bacterial

invasion.EXCELLENT biocompatibility.

Packaged in 2gm pellets and sterile water.

ManipulationMix to obtain a grainy, sandy mixture and

the apply with a messing gun.Requires moisture to set; desiccation is

contraindicated.Might even have to place wet cotton pellet

in contact with the MTA to facilitate setting.Takes 4 hours to set; this may limit its use

in endo.

Applications1. Root end filling.2. Pulpotomy.3. Apexification.4. Perforation repair.5. Pulp capping.6. Repair of resorption.

Disadvantages Expensive. Difficult to remove. Technique sensitive. Long setting time. Grey colored cannot be used in anterior teeth.

Comparison with Portland Cement.

MTA Portland Cement

•Presence of Bismuth oxide •Bismuth oxide absent

•Less gypsum •More gypsum

•Shorter setting time •Longer setting time

•Less aluminum and heavy metals; less toxicity.

•More aluminum and heavy metal ions; more toxicity.

•Smaller uniform particle size. •Range of particle size distribution.

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