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- DR SNEHA RATNANI

Mineral Trioxide Aggregate

Introduction

Mineral trioxide aggregate (MTA) was developed at Loma Linda University (Loma Linda, California, USA)

First described in the dental scientific literature in 1993 by Lee et al.

The chemical composition of MTA was determined by Torabinejad et al.

It received US Food and Drug Administration approval in 1998 and is commercially available as Pro-Root MTA by Dentsply International .

Initially recommended as a root-end filling material, it is currently being used for pulp capping, pulpotomy, apexogenesis and apexification, apical barrier formation, repair of root perforations and resorptive defects, and as a root canal and root-end filling material.

Endodontic failures may occur as a result of leakage of irritants into the periapical tissues. Therefore, an ideal orthograde and/or retrograde filling material should seal the pathways of communication between the root canal system and its surrounding tissues; thus, this material should be biocompatible and dimensionally stable. This led to the development of mineral trioxide aggregate (MTA) materials possessing these ideal characteristics.

COMPOSITION

MTA is a cement composed ofMTA is a cement composed of

Portland Cement

)75%(• Tricalc ium si l icate• Dicalc ium si l icate• Tricalc ium aluminate • Tetracalc ium aluminoferr ite

Gypsum

(Calcium Sulphate)

)5%(

Bismuth Oxide

)20%(

MTA = Portland 's Cement + Bismuth Oxide + Gypsum = Radio-opacity and Good Setting Properties

Sarkar et al JOE 31 (2) Feb. 2005

-It also contains trace amounts of

Silica,calcium oxide, magnesium oxide , potassium sulphate, and sodium sulphate.

Difference between

White White MTAMTA

Secondary electron image EDAX analysis

Calcium Silicon Bismuth Oxygen

Grey Grey MTAMTA Secondary electron imageSecondary electron image

EDAX analysisEDAX analysisCalciumCalciumSiliconSiliconBismuthBismuthOxygenOxygenAluminumAluminumIronIron

Camilleri et al -Dental Materials (2005) 21, 297–303

WMTAWMTA GMTAGMTA

ElementElement Wt% conc.Wt% conc. Wt% conc.Wt% conc.CaOCaO 44.2344.23 40.4540.45

SiOSiO22 21.2021.20 17.0017.00

BiOBiO22 16.2316.23 15.9015.90

AlAl22OO33 1.921.92 4.264.26

MgOMgO 1.351.35 3.103.10

SOSO33 0.530.53 0.510.51

ClCl 0.430.43 0.430.43

FeOFeO 0.400.40 4.394.39

PP22OO55 0.210.21 0.180.18

TiOTiO22 0.110.11 0.060.06

HH22O+COO+CO22 14.4914.49 13.7213.72

Composition of MTA

MTA is essentially Portland cement (used in the building industry as a binder in concrete) with 4:1 proportions of bismuth oxide added for radiopacity.

However Camilleri and co-workers have shown that MTA is composed primarily of tricalcium and dicalcium silicate, the main constituent elements of Portland cement, which on hydration produce a silicate hydrate gel and calcium hydroxide, not calcium phosphate as claimed by Torabinejad.

MTA powder is Hydrophilic .

It consists of two phases – Crystalline material is essential calcium oxide and amorphous – Calcium phosphate.

Hydration of MTA powder result in the formation of a colloidal gel that hardens.

The Crystalline material has prisms that have

87% Ca , 2.47% Silica, and remainder oxygen.

Amorphous material 33% calcium , 2% Carbon ,3% Chloride, & 6% silica 49% phosphate.

Calcium oxide (50-75%) + Silicone dioxide(15-25%)+ Aluminum oxide

Tricalcium Silicate + Dicalcium Silicate + Tricalcium Aluminate

+ (Tetracalcium Aluminoferrite)(Tetracalcium Aluminoferrite)

Calcium silicate hydrated gel(Hardens on setting)

Calcium Hydroxide contained in a silicate Calcium Hydroxide contained in a silicate matrixmatrix

(Camilleri et al -(Camilleri et al -Dental Materials (2005) 21, Dental Materials (2005) 21, 297–303)297–303)

Clinkered in a Kiln

On mixing with water

Kiln

MTA is available either as a box of five 1-gram single-use packets or as premeasured water packs for easy manipulation and application.

ProRoot liquid microampules (sterile water) and a carrier are also provided with the packet.

It should be stored in closed sealed containers away from moisture.

The powder is mixed with supplied sterile water in a 3:1 powder/liquid ratio.

A paper pad or a glass slab and a plastic or a metal spatula is used to mix the material to obtain a putty-like consistency.

MIXING OF MTA

MIXINGMIXING

The mixing time should be less than 4 minutes, as prolonged mixing can cause dehydration of the mixture.

The mixture can be carried with a plastic or metal carrier. The unused portion of MTA powder can be stored in sterilized empty film canisters.

MTA is uninhibited by blood or water, as moisture is required for a better setting of the material.

The required hydration for setting is provided by a moist cotton pellet placed temporarily (until the next appointment) in direct contact and/or on the surrounding tissues.

MESSING GUN / AMALGAM CARRIER WEST PERF REPAIR

INSTRUMENT

FLAT END OF SPOON EXCAVATOR

AMALGAM CARRIERSPINE TAP NEEDLE

Carriers Of MTA

Different types of Carrier for placement of MTADifferent types of Carrier for placement of MTA

Small plastic amalgam type

carrier .Small Spoon excavator.

Amalgam pistolAmalgam pistol

Messing gun

Dovgan Carriers

The hydration reaction during setting occurs between tricalcium silicate (3CaO SiO2) and ·dicalcium silicate (2CaO SiO2) to form a calcium ·hydroxide and calcium silicate hydrate gel, producing an alkaline pH.

The released calcium ions diffuse through dentinal tubules, and increase their concentration over time as the material cures.

Upon hydration, the poorly crystallized and porous solid gel (hydrated forms of components) that is formed solidifies to a hard structure in approximately 3 to 4 hours (initial set), with mean setting time of 165 ± 5 minutes.

Although moisture is needed for setting of the material, excess moisture can result in a soupy mix that is difficult to use

A study comparing white MTA (White MTA, Dentsply; Tulsa Dental Products) to white Portland cement showed the cements to have similar constituent elements except for the bismuth oxide in the MTA.

MTA had less gypsum. Decreased gypsum causes a reduction in setting time

of the cement. Higher level of toxic heavy metals and aluminium in

Portland cement

Difference in the particle size distribution. Portland cement exhibited a wide range of

sizes whereas MTA showed a uniform and smaller particle size.

Both MTA (Pro-Root) and Portland cement (Quikrete, Columbus, OH,USA) had similar physical, chemical and biological properties, and the biocompatibility of both materials was due to the similarity in constituents

Results from characterization studies have indicated PC cannot be recommended as a suitable substitute of MTA for the following reasons:

• The quality and composition is difficult to predict. Studies have shown that the arsenic content of PC is 6 times the amount of arsenic in GMTA.

• The high solubility can lead to release of a toxic element and early degradation of the material, jeopardizing the long-term safety of PC.

• Carbon dioxide in inflamed tissues readily reacts with available water to form carbonic acid, which reacts with the cement to form calcium hydrogen carbonate. This carbonation decreases the tensile strength and resiliency of the material, leading to crack formation and buckling under high stress. The compressive strength of some types of PC is also observed to be lower than MTA.

• As opposed to PC, MTA is manufactured in laboratories as a medical material and is approved by the U.S. Food and Drug Administration for use in humans.

Although MTA is considered a refined form of PC material (parent compound), substitution with PC for MTA is discouraged for clinical purposes.

Generally, researchers do not suggest that MTA and PC have the same clinical, biologic, and mechanical properties and do not co nsider PC to be a suitable replacement for MTA as an endodontic material

PROPERTIES

PHYSICAL STATE - solid (powder)

COLOR - grey/white

ODOR - no specific odor

BOILING POINT - >1000ºC

SETTING TIME : 2 hours 45 min – 4 hours

COMPRESSIVE STRENGTH: immediately after setting - 40 Mpa 21 days after setting - 70 Mpa

pH :10.2 at start of mix rises to 12.5 after 3 hours. In experimental setting MTA is capable of maintaining high ph for long time. The high pH of MTA could be of clinical significance when used in apical barrier technique since alkalinity creates a favourable environment for cell division and matrix formation. Due to high ph MTA shows antibacterial action similar to calcium hydroxide.

Solubility

MTA displays low or nearly no solubility, which is attributable to addition of the bismuth oxide.

 Chemical analysis and x-ray diffraction have demonstrated insolubility of 18.8% in water.

Although MTA forms a porous matrix characterized by internal capillaries and water channels with increased liquid/powder ratio—which can increase the porosity and the solubility further—the solubility levels of GMTA have been shown to be stable over time.

Antibacterial properties

Results showed that the freshly mixed MTA was effective in killing the tested fungi after 1 day of contact, whereas the 24-h set MTA was effective after 3 days of incubation. It was concluded that MTA (freshly mixed and 24-h set) was effective against C. albicans.

Nazhan-Al Saad et al Nazhan-Al Saad et al

Nine facultative bacteria and seven strict anaerobes. MTA was found to have an antibacterial effect on five of nine facultative bacteria but no effect on any of the strict anaerobes.

Torabinejad M et al Torabinejad M et al

Periradicular reaction

As a root-end filling in vivo, less periradicular inflammation was reported compared with amalgam (Torabinejad et al.)

In addition, the presence of cementum on the surface of MTA (Loma Linda University) was a frequent finding.

It induced apical hard tissue formation with significantly greater consistency, but not quantity.

MTA (ProRoot) supported almost complete regeneration of the periradicular periodontium when used as a root end filling material on noninfected teeth

BIOCOMPATIBILITY

Some studies considered that the biocompatibility of MTA is attributable to the release of hydroxyl ions and formation of calcium hydroxide during the hydration process. 

Other reports had observed the formation of a white interfacial material (precipitates) between GMTA and tooth structure within 1 to 2 hours when exposed to physiologic fluids (phosphate-buffered physiologic solution) in vivo or with simulated body fluids in vitro. 

SEM and x-ray diffraction (XRD) analysis of these precipitates revealed the presence of chemically and structurally similar hydroxyapatite (HA)-like structure with a chemical composition of oxygen, calcium, and phosphorus, along with trace amounts of bismuth, silicon, and aluminum. 

However, the calcium-to-phosphorus ratios reportedly differed from that of natural hydroxyapatite. This HA-like structure can release calcium and phosphorus continuously, promoting the regeneration and remineralization of hard tissues and increasing the sealing ability of MTA.

Regenerative Potential and Biological Activity

MTA has the capacity to induce bone, dentin, and cementum formation and regeneration of periapical tissues (periodontal ligament and cementum).

MTA provides a good biological seal and can act as a scaffold for the formation and/or regeneration of hard tissue (periapical).

It is an osteoconductive, osteoinductive, and cementogenic (cementoconductive and cementoinductive) agent.

MTA stimulates immune cells to release lymphokines and bone coupling factors required for the repair and regeneration of cementum and healing of osseous periapical defects

Radiopacity

MTA has a mean radiopacity of 7.17 mm of equivalent thickness of aluminum, which is less than that of IRM, super EBA, amalgam, or gutta-percha. 

It has a similar radiodensity to zinc oxide eugenol and slightly greater radiopacity than dentin.

Direct pulp capping

Pulp capping is indicated for teeth with immature apices when the dental pulp is exposed & there are no signs of irreversible pulpitis .

In such cases ,the maintenance of pulp vitality is extremely important , & MTA is preferred to calcium hydroxide .

Recent studies have shown that MTA stimulates dentin bridge formation adjacent to the dental pulp ,

Dentinogenesis of MTA can be due to its sealing ability, biocompatibility and alkalinity.

Similarly to calcium hydroxide , initially causes necrosis by coagulation in contact with pulp connective tissue .

This reaction may occur due to the products high alkalinity, as the Ph is 10.2 during manipulation and 12.5 after 3 hours.

Holland et al demonstrated the presence of calcite crystals in contact with MTA implanted in rat subcutaneous tissue.

Those calcite crystals attract fibronectin which is responsible for cellular adhesion & differentiation.

Therefore it is believed that MTA mechanism of action is similar to that of calcium hydroxide , but in addition ,MTA provides a superior seal against bacteria.

Operative Sequence for Pulp capping

Anaesthesia isolation with a rubberdam the exposesd pulp is irrigated with sodium

hypochlorite to control bleeding. MTA powder is mixed with sterile water & the

mixture is placed in contact with the exposure using a dovgan carrier.

Compress the mixture against the exposure site with a moist cotton pellet.

Place a moist cotton pellet over the MTA & fill the rest of the cavity with a temporary filling material .

After 4 hours the patient is seen again, the rubber dam is positioned the temporary filling material and cotton are removed , the set of the material is assessed.

Then , the tooth can be restored.

Pulp Capping

Pulp Capping

Pulp Capping

Verification of the setting of MTA at 48 h.

Disinfection of exposure site by rinsing with 5.25%sodium hypochlorite.

Pulp exposure presenting with moderate bleeding.

Immediate postoperative periapical radiograph showingpulp capping with MTA, cotton and temporary filling material.

Follow-up periapical radiograph at 11 months showingmaturogenesis of the root.

Final coronal restoration with composite.

Follow-up periapical radiograph at 4 months presentingwith continued root development.

Pulpotomy agent

MTA has been proposed as a potential medicament for pulpotomy procedures as well as capping of pulps with reversible pulpitis.

MTA was tested in dog s teeth as a pulp ′capping material and produced favorable pulp responses.

There are reports of complete dentine bridge formation when MTA was used as a pulp capping agent.

Hard tissue bridge deposition next to MTA may occur because of its sealing properties, biocompatibility, alkalinity and other properties

All irrigation should be performed before the material is placed because irrigation after placement will cause significant wash out of the material.

MTA was less cytotoxic and non-mutagenic. This further supports the superiority of MTA over formocresol as a pulpotomy medicament.

Pulpotomy

Pulpotomy

Pulpotomy

Pulpotomy Procedure

Anaesthesia Isolation with a rubber dam. Caries should be removed using a

caries detector with a slow speed round burs & spoon excavators.

Once caries has been entirely removed, irrigate with 5.25% naocl for 5-10 minutes to achieve homeostasis and ensure complete debridement.

Rinse out naocl and ensure that the chamber is debris free.

Place a 1-1.5 mm thick layer of freshly mixed MTA directly over the exposed pulp.

Place a wet ,thinned ,flattened cotton pellet over the MTA.

The cotton pellet provides the moisture MTA requires for a proper set.

Temporize with either light cured Photocure ,IRM or other suitable material.

Recall after a week

Once proper setting of MTA has been ascertained , the tooth can be restored

Apexification

Although MTA & Calcium hydroxide both exhibit similar alkaline Ph levels, MTA also shows excellent marginal adaptability & is non-resorbable.

MTA allow apexification cases to be restored after approximately 2 weeks as opposed to traditional Calcium hydroxide therapy, where apexification may require many months .

Apexification

Apexification

Apexification

Rubber dam isolation Extirpate the pulp and clean the root canal

system using endodontic instruments and 5.25% Naocl irrigation.

Place calcium hydroxide paste in the root canal system for one week to fully disinfect the canal system.

When the patient returns in one week rinse ca(oh)2 paste from the root canal system with naocl irrigation and dry with paper points.

ProceduProcedure:re:

Place MTA in the canals and condense to the apical end of the root canal to create a 3-4mm apical plug .

Radiographically, check the extension & quality of fill .

Place a moist cotton pellet or wet paper point in the canal & close the access cavity with IRM or Cavit .

The patient can return in one week for obturation rest of the canal or the final obturation delayed until healing completed

Apexification

Preoperative radiograph of the maxillary left central incisor.

The patient is 55-years-old and this tooth (with an open apex) hasnot responded to previous therapywith calcium hydroxide

Intraoperative film with the Dovgan carrier in place

Three millimeters of MTA have been positioned at the foramen to form the apical

barrier

After the MTA is set, the thermoplastic gutta-percha

has been used to obturate the root canal.

Perforation Repair with MTA

Mta can today be considered the ideal material to seal perforations .

Cementum has been shown to grow over mta allowing normal attachment of the periodontal ligament .

Furthermore, mta dosen’t require a barrier & is not affected by moisture or blood contamination & seals better than any other material in use today.( Amalgam, super EBA ,IRM ,composite resins )

INTERNAL MATRIX CONCEPTINTERNAL MATRIX CONCEPT MODIFIED MATRIX CONCEPTMODIFIED MATRIX CONCEPT

LEMON 1992LEMON 1992 C.BARGHOLZ 2004C.BARGHOLZ 2004

PROCEDURE :-PROCEDURE :- CLEANINGCLEANING 0.5% NaOCl 0.5% NaOCl WORKING LENGTH DETERMINATIONWORKING LENGTH DETERMINATION

COLLACOTE MATERIALCOLLACOTE MATERIAL

RESTORATIVE MATERIALRESTORATIVE MATERIAL

OVER INTERNAL MATRIX CONCEPTOVER INTERNAL MATRIX CONCEPT

NO PRESSURE REQUIREDNO PRESSURE REQUIRED

WET FIELDWET FIELD

BETTER SEALINGBETTER SEALING

CEMENTOGENESISCEMENTOGENESIS

GRANULATION TISSUEGRANULATION TISSUE

COLLAGEN MATRIXCOLLAGEN MATRIX

MTA APPLIED ALONG THE COLLAGENMTA APPLIED ALONG THE COLLAGEN

HEALING OF PERFORATIONHEALING OF PERFORATION

IMPORTANCE OF COLLGENIMPORTANCE OF COLLGEN

•HIGH DEGREE OF COMPATIBILITYHIGH DEGREE OF COMPATIBILITY (KEISER et al-2000)(KEISER et al-2000)

•ROUGH SURFACE OF MTAROUGH SURFACE OF MTA (FRID LAND & ROSADO 2003)(FRID LAND & ROSADO 2003)

•MTA IS NOT A HARD MATERIALMTA IS NOT A HARD MATERIAL (TORABINEJAD et al-1995)(TORABINEJAD et al-1995)

Operative Sequence

First visitFirst visit Isolation with a rubber dam .Cleansing of the perforation site.In case of bacterial contamination ,

application of calcium hydroxide for 1 week .

Application of 2 to 3 mm of MTA .Radiographs to check the correct

positioning of the materials.Application of a small , wet cotton pellet in

contact with MTA.Temporary cement.

Second visitSecond visit After 24 hours , removal of temporary

cement to check if MTA is set.Completion of therapy

Furcal repair

FurcationPerforation

FurcationPerforation

FurcationPerforation Repair

Use of paper point to locate the perforation.

LATERAL PERFORATION AND STRIP LATERAL PERFORATION AND STRIP

PERFORATIONPERFORATION

RadicularPerforation

Prep for Extra-RadicularPerforation Repair

Extra-RadicularPerforation Repair

Accidental Perforation

1 month Follow Up

ROOT END FILLING

Establish a seal between the root canal space and periapical tissues.

Acc to Gartner and DornAcc to Gartner and Dorn 1) able to prevent leakage of bacteria & their

byproducts into the periradicular tissues.2) nontoxic3)noncarcinogenic.4)biocompatible.5)insoluble in tissue fluids.6)dimensionally stable.7)unaffected by moisture during setting.8)easy to use.9)radiopaque.10)should not stain tissue (tattoo)

Cements and sealers such as ZnOE, IRM, Super EBA, cavit, zincpolycarboxylate, zinc phosphate and glass Ionomer cements, mineral trioxide aggregate, calcium phosphate cement and bone cement have also been employed for retro-fillings.

Other commonly used materials are - composite resin (with and without bonding agent) and gutta-percha.

The less commonly used materials are laser, citric acid demineralization, ceramic inlay, teflon, mixture of powdered dentin & sulfathiazole and cynoacrylates

The use of MTA as a root-end filling material was identified because the material is a hydraulic cement that sets in the presence of water.

MTA provides superior seal when compared with Amalgam, IRM and Super EBA. and

Most characteristic tissue reaction of MTA was the presence of connective tissue after the first postoperative week.

Studies have shown that osteoblasts have favorable response to MTA as compared to IRM and amalgam.

MTA Angelus (120 days). H.E. 40 X. Presence

of odontoblasts

With longer duration, new cementum was found of the surface of the material.

In a two year follow-up study with MTA as root-end filling material resulted in a high success rate.

Such studies support further development of MTA to reduce the long setting time and difficulty in manipulation for use as a root-end filling material.

Studies evaluating MTA as a retrofilling material have shown less periapical inflammation, presence of a fibrous capsule and formation of new cementum layer in contact with the material surface in many cases.

MTA was able to induce apical healing even when placed in infected canals.

It may be assumed that neoformed cementum deposition on the entire material surface (biological sealing), as observed with MTA,was an important histopathologic event to be considered because it isolated the content remaining within the intracanal space and root-end filling material from the apical tissues.

Root- end fillings

Costa et al JOE 2003 Marthickness of 4 mm is most adequate for the use of MTA as a root-

end fi l l ing material.

Treatment of Internal & external Root resorption

Moisture present in these preparations turns the ‘MTA’ soupy & difficult to condense.

Moisture can be drawn out of the MTA after placement with a dry paper point or cotton pellet

MTA is often pressed into the desired location & not condensed.

All irrigation should be performed before the MTA is placed .

Any irrigation after placement will cause significant washout of the material

The preparation or resorptive defect does not have to be perfectly dry, but most of the fluid has to be removed.

If MTA is placed from inside the tooth , a moist cotton pellet or paper point should be placed against it, because the presence of moisture is essential for the material to set.

The access cavity is then closed .

Most internal repairs with MTA requires a second visit to complete the root canal therapy or restoration.

Root Resorption

The patient was referred with a large resorptive lesion in the root of his maxillary right central

incisor. A pulpectomy was performed and progressive

débridement of granulation tissue was accomplished by

monthly irrigation with sodium hypochlorite and placement of calcium hydroxide.

After three months, débridement of the lesion wascomplete. The calcium hydroxide was removed, the

canal was dried and the resorptive defect was repaired internally with MTA. The clinician placed

a post that extended apically to the resorptive defect

and restored the tooth with resin composite in preparation

for placement of a crown.

Internal Resorption

ROOT RESORPTIONROOT RESORPTION

Internal Resorption

Internal ResorptionRepair

Prophylactic treatment of Dens in Dente

Clinical view of the crown of the maxillary right central incisor

Preoperative radiograph. Note the periapical radiolucency, the unusual anatomy, and the wide open apex.

Intraoperative radiograph. Note the thickness of MTA without any

overfilling. Postoperative radiograph Two-year recall.

A comparative study of selected properties of ProRoot mineral trioxide aggregate and two Portland cements G. Danesh IEJ 2006

Aim To compare solubility, microhardness and radiopacity of ProRoot MTA with two Portland cements (PC: CEM I and CEM II).

Methodology Solubility: for standardized samples (n ¼

12/group) ring moulds were filled with the cements. These samples were immersed in double distilled water for 1 min, 10 min, 1 h, 24 h, 72 h, and 28 days.

Mean loss of weight was determined.

Microhardness: five samples of each cement were produced.

All samples were loaded with a diamond indenter point with a weight of 100 g for 30 s.

Radiopacity:

Five samples per cement were produced.

These samples were tested according to the ISO standards to compare their radiodensity to that of an aluminium step wedge (1–9 mm).

Differences between the three materials with respect to their solubility, microhardness and radiopacity were analysed using anova and Student– Newman–Keuls.

Results After 28 days MTA was of low solubility(0.78%)

compared with CEM I (31.38%) and CEM II (33.33%). At exposure times >1 min the two PCs were

significantly more soluble than MTA (P < 0.05). The microhardness for MTA was significantly higher

(39.99 HV; P < 0.001) compared with the two PC (CEM I: 16.32 HV; CEM II: 13.51 HV).

MTA was significantly more radiopaque (5.34 mm Al) than CEMI (3.32 mm Al) and CEM II (2.52 mm Al) (P < 0.05),whereas CEM I was significantly more radiopaque than CEM II (P < 0.05).

Conclusions Mineral trioxide aggregate displayed superior material

properties than both Portland cements.

The effect of mineral trioxide aggregate on theapexification and periapical healing of teeth withincomplete root formation. W. T. Felippe,IEJ 2006

Aim To evaluate the influence of mineral trioxide

aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA.

Methodology Twenty premolars from two 6-month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedstrom files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals two premolars in each dog were left

empty (control group)

The other eight teeth in each animal were divided into two experimental groups.

The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide–propylene glycol paste.

After 1 week, the paste was removed and the apical third was filled with MTA.

All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam.

The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing.

The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTAextrusion, and microorganisms.

Results Significant differences (P < 0.05) were found in

relation to the position of barrier formation and MTA extrusion.

The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only.

In group 2, it was formed beyond the limits of the canal walls in 75% of the roots.

MTA extrusion occurred mainly inroots from group 2.

There was similarity between the groups for the other parameters.

Conclusions Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls.

Effect of mineral trioxide aggregate on proliferationof cultured human dental pulp cellsT. Takita IEJ2006

To investigate the effect of mineral trioxide aggregate (MTA) on the proliferation of human dental pulp (HDP) cells ex-vivo.

Methodology Humandental pulp cells were cultured with

MTA or calcium hydroxide-containing cement (Dycal) using culture plate inserts. Control cells were cultured with culture plate inserts only.

Cell proliferation was measured for up to 14 days using a Cell Counting kit, and the concentration of calcium ions released fromthe tested materials was assessed using a Calcium E-test kit.

To confirm that the effect of MTA was attributable to released calcium ions, cell proliferation was measured in the presence of exogenous calcium chloride as a source of calcium ions while in the absence of MTA.

Effect of mineral trioxide aggregate on proliferationof cultured human dental pulp cells.T. Takita IEJ2006

To investigate the effect of mineral trioxide aggregate (MTA) on the proliferation of human dental pulp (HDP) cells ex-vivo.

Methodology Humandental pulp cells were cultured with

MTA or calcium hydroxide-containing cement (Dycal) using culture plate inserts. Control cells were cultured with culture plate inserts only.

Cell proliferation was measured for up to 14 days using a Cell Counting kit, and the concentration of calcium ions released fromthe tested materials was assessed using a Calcium E-test kit.

To confirm that the effect of MTA was attributable to released calcium ions, cell proliferation was measured in the presence of exogenous calcium chloride as a source of calcium ions while in the absence of MTA.

Results Mineral trioxide aggregate significantly

stimulated cell proliferation after 12 days, whereas Dycal had no such effect.

The number of calcium ions released from MTA was significantly higher than that released from Dycal.

Following the addition of calcium chloride, cell proliferation increased in a dose-dependent manner after 12 days.

Moreover, cell proliferation showed a similar pattern whether a given concentration of calcium ions was produced by calcium chloride or by release from MTA.

Conclusions In this ex-vivo study, the elution components

such as calcium ions from MTA had higher proliferation ability of HDP cells than control and Dycal.

Ex vivo biocompatibility tests of regular and whiteforms of mineral trioxide aggregateD. A. Ribeiro,IEJ 2006

Aim To examine the genotoxicity and cytotoxicity

of regular and white mineral trioxide aggregate (MTA) ex vivo by the single-cell gel (comet) assay and trypan blue exclusion test, respectively.

Methodology Aliquots of 1 104 Chinese hamster ovary ·

cells were incubated at 37 C for 3 h with grey and white forms of MTA at final concentrations ranging from 1 to 1000 lg mL)1.

The negative control group was treated with vehicle control phosphate buffer solution for 3 h at 37 C and the positive control group was treated with methyl metasulfonate (at 1 lg mL)1) for 1 h at 37 C.

After incubation, the cells were centrifuged at 180 g for 5 min and washed twice with fresh medium

and resuspended with fresh medium. Each individual treatment was repeated three times

consecutively to ensure reproducibility. Parameters from single-cell gel (comet) and cytotoxicity assays were assessed by the Kruskal–Wallis nonparametric test.

Results Neither compounds produced genotoxic effects with

respect to the single-cell gel (comet) assay in all concentrations evaluated.

In the same way, the dose–response relationships of all compounds tested at concentrations ranging from 1 to 1000 lg mL)1 on cell viability assessed by the trypan blue assay displayed no statistically significant differences (P > 0.05) for either endodontic material.

Conclusions Regular (grey) and white MTA are not genotoxins and

do not induce cellular death.

Biological response of pulps submitted to different capping materialsAndre briso 2006

ABSTRACT: Pulp capping is a procedure that comprises adequate

protection of the pulp tissue exposed to the oral environment, aiming at the preservation of its vitality and functions.

This study evaluated the response of the dental pulps of dog teeth to capping with mineral trioxide aggregate (MTA) or calcium hydroxide .

For that purpose, 37 teeth were divided into two groups, according to the capping material employed.

Two dogs were anesthetized and, after placement of a rubber dam, their pulps were exposed in a standardized manner and protected with the experimental capping materials.

The cavities were then sealed with resin-modified glass ionomer cement and restored with composite resin.

After sixty days, the animals were killed and the specimens were processed in order to be analyzed with optic microscopy.

It was observed that MTA presented a higher success rate compared to calcium hydroxide, presenting a lower occurrence of infection and pulp necrosis.

conclusion

Collect ively, these studies have shown that MTA is a biocompatible mater ial .

Mineral Trioxide Aggregate is a new mater ial that possesses numerous excit ing possibi l it ies for pulpal therapy.

It is a promising material with an expanding foundation of research.

MTA, with an excel lent long term prognosis , re lative ease at which it can be used and with its numerous excit ing c l inical appl ications promises to be one of the most versati le materials of this century in the f ie ld of dentistry.

Thank you