mineral trioxide aggregate

1. MINERAL TRIOXIDE AGGREGATE
(MTA)
NORTH BENGAL DENTAL
COLLEGE & HOSPITAL
DEPARTMENT OF OPERATIVE
DENTISTRY

2. INTRODUCTION
Mineral trioxide aggregate (MTA) was developed for use as a dental
root repair material by Dr. Mahmoud Torabinejad, (MTA) is the most
commonly recommended material for sealing communications
between the root canal system and the periodontium and was
formulated from commercial Portland cement combined with bismuth
oxide powder for radiopacity.

3. MTA COMPOSITION
MTA is comprised primarily of Portland cement 75 wt% Portland
cement, 20 wt% bismuth oxide (Bi2O3), and 5 wt% calcium sulfate
dihydrate or gypsum (CaSO4 ∙ 2H2O). Additional minor trace
elements may also be present .

5. Mixing MTA
• Prepared immediately before use. Kept always in closed
containers or free from moisture.
• Powder: Water = 3: 1.
• Glass or paper slab used for mixing with – plastic /
metal spatula. It requires moisture to set. Once the mix
is dry sandy form its ready for application.

6. MTA Placement

7. MECHANISM OF ACTION:
From the time that MTA is placed in direct contact with human
tissues, it appears that the material does the following:
I. Creates an antibacterial environment by its alkaline pH
II. Modulates cytokine production
III. Encourages differentiation and migration of hard tissue-
producing cells and
IV. Forms HA (or carbonated apatite) on the MTA surface and
provides a biologic seal.

8. Characteristics of MTA :
1. Biocompatible with periradicular tissues
2. Non cytotoxic to cells, but antimicrobial to bacteria
3. Non-resorbable
4. Minimal leakage around the margins.
5. Very basic AKA alkaline initial pH: 10.2 initially and it
rose to 12.5 after 3 hours .
6. MTA powder contains fine hydrophilic particles that set
in the presence of moisture
7. Compressive strength develops over a period of 28
days, similar to Portland cement. Strengths of more
than 133 MPa .
8. MTA displays low or nearly no solubility
9. Radio opaque

9. Setting Time
MTA powder consists of fine hydrophilic particles. Hydration of MTA
powder results in a colloidal gel that solidifies to a hard structure in ~ 4 hrs
which has a long setting time.
It is generally considered that a potential root end filling material should set
as soon as placed in root end cavity without significant shrinkage.
This condition would allow the dimensional stability of the material after
placement and less time for an unset material to be in contact with vital tissues.
In general, quicker a material sets more it shrinks.
But MTA has long setting time with less shrinkage

10. Solubility
Lack of solubility is an ideal characteristic of MTA as a root end filling
material.
Despite of some advantages of controlled long term clinical studies, because of its long
setting time, the recommended methods of ISO (6) or ADAS # 30 (7), the test solubility
of MTA had to be modified.
Biocompatibility
Clinically MTA is a biocompatible material with good sealing ability should
generate little or no inflammatory response in periradicular tissues, and encourage
the formation of fibrous connective tissue and / or cementum covering the entire
root end.
Calcium & Phosphorus are the main ions present in this material, which are the
principle components of dental tissues, hence MTA proved to be biocompatible
when used in contact with cells and tissues.

11. Radio Opacity
Bismuth oxide added for radio opacity and it is more radio opaque than its
surrounding structures.
Shah et al in 1995 showed that the MTA is less radio opaque than Kalzinol- (7.97) and
more radio opaque than GP (6.14), IRM (5.30), Super EBA (5.16), Dentin- (0.70).
More radio opaque than GP & dentin are very much distinguishable on radiographs

12. pH
• MTA has a high pH of 12.5 similar to calcium hydroxide cement, which
prevents the bacterial growth and maintains the long lasting bactericidal
potential.
• Induction of hard tissue formation / barrier in Apexification procedures and
root end filling would minimize the interaction between material and host
tissues

13. Physical Property
Compressive Strength is an important factor to be considered when a filling
material is placed in a cavity that bears occlusal pressure. As a root end filling
material do not bear direct pressure, the Compressive strength of this material
is not as significant as materials used to repair defects in occlusal surfaces.
Compressive strength in 21days ≈70 Mpa.
Mechanical wear, an important factor in coronal restoration, MTA is not used
as coronal restoration or not placed in functional areas.

14. •Rapid cell growth promotion in vitro
•Greater ability to maintain the integrity of pulp tissue
•Thicker dentinal bridge, less inflammation, less hyperemia and
less pulpal necrosis
•Induce the formation of a dentin bridge at a faster rate
•High ability to resist the penetration of microorganisms
•Limited antibacterial effect
MTA advantages over calcium hydroxide

15. • Antimicrobial Activity
• MicroLeakage
• Cementoconductive
• Non toxic
• Non-mutagenic
• Cell adherence & growth
• Alkaline phosphotase/ osteocalcin
• Interleukin production
• Periodontal ligament attachment to
cementum growth
• Dentinal bridge formation
• More difficult to manipulate
• Longer setting time
• To preserve pulp vitality
• Prevent pathological changes in the
periradicular tissues
• Mechanical pulp exposures
• Carious pulp exposures with immature apices.
•Irreversible pulpitis
ADVANTAGES DISADVANTAGES
INDICATIONS
CONTRAINDICATIONS

17. Direct Pulp Capping
• In Exposed pulps, to preserve the pulpal vitality, MTA is used as a pulp
capping material. It prevents Bacterial leakage with a high level of
biocompatibility.
• MTA stimulates dentin bridge formation adjacent to dental pulp.
Dentinogenesis of MTA due to its sealing ability, biocompatibility, alkalinity
and other properties associated with this material. Dentin bridge
formation that promotes healing. It formed a complete barrier at exposure
site with free of inflammations.
• Reparative dentin formed by MTA does not originate from severely
damaged odontoblasts, but from undifferentiated cells that migrated from
deep regions of pulp, which replaced the degenerated odontoblasts.
Reparative dentin formed is regular and odontoblasts remain intact.

18. Apical Plug
MTA indicated for Necrotic pulps and With open apices. MTA can be
used as a material of choice for apical plug and placed 3- 4mm in the apical
plug. It creates a hard tissue formation or as an apical plug to prevent the
extrusion of filling material during obturation of the canal with open apices.

19. Root-end Filling after Apicoectomy
In root canal therapy where an apical infection is persistent, an
apicoectomy may be required. Flap is raised over the tooth and the
root tip is resected and a cavity created (3–4 mm) in the root tip
removed. Retrograde application of MTA to the root tip cavity is
completed.

20. Retrograde Filling
Jordan in 1998 ,MTA was tried as retro grade filling material.
It was found that it Inhibits dye penetration with a Good sealing
ability.
-Nicholson et al: BDJ 2000
Resorptive Defects
MTA used for repairing the resorptive defects. There will not be
inflammation surrounding it with continuous cementum
formation.
It forms a hard tissue bridges also with reduced ostoeclastic
activity.

21. Internal & external root resorption & obturation
In internal resorption, root canal therapy is performed, a putty
mixture of MTA is inserted in the canal using pluggers to the level of
the defect. Gutta percha and root canal sealer are placed above the
defect to complete the root canal treatment. In direct cases, the
canal may be completely obturated with MTA. The MTA will provide
structure and strength to the tooth by replacing the resorbed tooth
structure. In external resorption, after root canal therapy is
performed, the flap is raised over the tooth and the defect removed
from the root surface with a round bur. Retrograde application of
MTA to the root surface is then completed.

22. Root Perforations
Root perforations can occur during root canal treatment, post space
preparation or as a consequence of internal resorption.
MTA can be placed in the repair area as a reparative material. Repair can be
achieved by Intracoronal / Extracoronal placement.
-Lee etal, 1993, found to have less leakage with least overfilling
-Nataka, 1997, found that there was least bacterial leakage than amalgam
-Pittford, 1995, found that perforated area had non-inflamed surroundings
with cementum formation over MTA.

23. Apexification (Necrotic pulp)
When the root is incompletely formed in adolescents and an
infection occurs, apexification can be performed to maintain the
tooth in position as the roots develop. In case of non-vital pulp: 1.
Isolate the tooth with a rubber dam 2. perform root canal
treatment. 3. Mix MTA and insert it to the apex of the tooth,
creating a 3 mm thickness of plug. 5. Fill the canal with sealer and
gutta percha. Alternatively, revascularization techniques are being
used where an antibiotic is locally administered. Later a blood clot
is formed in the canal and a coronal plug of MTA is placed.

24. Apexogenesis (Vital pulp)
The process of maintaining pulp vitality during pulpal treatment to
allow continued development of the entire root (apical closure
occurs approximately 3 years after eruption). 1. Isolate the tooth
with a rubber dam 2. Perform a pulpotomy procedure. 3. Place the
MTA material over the pulp and close the tooth with temporary
cement until the apex is completely formed.
MTA can be used in a one step or a two step approach. It can be
used as a powder or a Wet Mix. However a study found that all
these approaches have shown to be equally effective

25. Clinical applications of MTA described

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