introduction to mineral trioxide

1. MINERAL TRIOXIDE AGGREGATE

2. INTRODUCTION TO MINERAL TRI-OXIDE
AGGREGATE (MTA)
DR SYED SOHAIB GILANI

3. Mineral trioxide aggregate is a new
biocompatible material with numerous exciting
clinical application in endodontics. MTA was
introduced by Torabinejad et Al at Loma Linda
university in 1993 as a root-end filling material
and for repair of lateral perforation .It has
been patented and has received approval of
FDA and is commercially available as Pro-Root
MTA by Dentsply International .Several in vitro
and in vivo studies have shown that MTA
prevents microleakage, is biocompatible and
promotes regeneration of original tissues when
placed in contact with periradicular tissues or
dental pulp.

4. Initially Gray MTA was introduced in
market. It has been shown that after
periradicular surgery and GMTA as root
end filling periapical lesion heals to almost
normal conditions over past 10-12 years.
More than 125 articles have been
published on properties and application of
MTA.
White MTA has recently been
introduced to endodontics .One of the
main reason for introducing WMTA as a
substitute for GMTA was to provide a
hue matched more closely to that of the
colour of teeth as opposed to contrasting
Gray colour of GMTA.

5. A Brazilian version of MTA was developed to
improve handling and setting properties. The
product is MTA Angelius and is claimed by
manufacturer to have an initial setting time of 10
minutes. Sealing ability , marginal adaptation and
cytotoxicity of MTA Angelus was found to be
similar to Pro-Root MTA.
Further attempts to
improve the handling properties of MTA includes
the formation of an experimental endodontic
cement which handles like a gel ,Viscosity Enhanced
Root Repair Material (VERRM). It has composition
similar to MTA with handling characteristics and
consistency similar to commercially available
material such as IRM and Super EBA.

6. COMPOSITION
MTA consists of fine hydrophilic particles. The
material is primarily derived from calcium oxide
,silicon dioxide , and aluminium oxide . These raw
materials are grind and clinkered in a kiln to
produce
•Dicalcium silicate
•Tricalcium silicate
•Tricalcium aluminate
•Tetracalcium aluminate
It also contains trace amount of silicon
dioxide ,calcium oxide, magnesium oxide,
potassium sulphate and sodium sulphate. These
oxides are almost 75% of MTA .

7. In the 75% content of oxides the various oxides are
distributed as :
•SiO2-21%
•Al2O3 -4%
•Fe2O3 -5%
•Ca O -65%
•Mg O -2%
•Alkalies (Na2O,K2O)- 0.5%

8. Bismuth oxide (20%) is also added for radio
opacity. Calcium sulphate dihydrate (gypsum)
(5%) is also present. Predominant oxides in
MTA are lime (Cao),silica (Sio2), and bismuth
oxide .
According to Torabinejad et al main
constituents of GMTA were calcium and
phosphorus, but , Saeed Asgary et al showed
by electron probe analysis that phosphorus is
close to limit of detection. Material safety
data sheet supplied by Denysply company
also does not report phosphorus as a
significant element in MTA. White MTA has
significantly lower concentration of Al2O3,
MgO, and FeO than GMTA .

9. Differences in FeO concentration is thought to
be primarily responsible for variation in colour of
WMTA (off white )in comparison to Gray MTA
GMTA was un aesthetic in
cervical area of anterior tooth . Manufacturer’s
claims that there are no changes in physical
properties but mixing it tends to be more
technique sensitive. White MTA is creamier when
mixed and a little more difficult to manipulate
but sets as hard as original grey MTA. A study by
Gary et al concluded that grey MTA
demonstrated significantly less apical dye leakage
than white MTA. He hypothesised that slight
volumetric shrinkage that occurred with WMTA
may account for increased leakage.

10. MANIPULATION
ProRoot MTA has been marketed by Dentsply Tulsa
company. Each pack of MTA comes with pre
measured unit dose of water for convenience in
mixing. To use MTA simply pour the powder onto
pad supplied ,add water and mix to working
consistency. Water powder ratio should be 3:1
according to manufacturer. Variation on part of
water powder ratio could account for increased
solubility and porosity of material. Manufacturer
also recommend not to reuse one sachet of powder
to prevent contamination and cross contamination

12. MIXING OF MTA

14. SETTING REACTION
On addition of water compound in MTA react to
produce calcium silicate hydrate gel that is
calcium hydroxide contained in a silicate matrix.
The dissolution of anhydrous phase of MTA
occurs followed by the crystallization of the
hydrate in a interlocking mass which consists of
cubic and needle like crystal. In the crystal
kinetics point of view the complexity of MTA
resulted in different nucleation rates and some
parts move rapidly than others to construct the
epitaxillary growth. According to patent of MTA
C3S is a predominant phase and play an important
role in its hydration behaviour.

15. The hydration of C3S is follows chemical
process and produces calcium silicate hydrate
and calcium hydroxide. The set MTA exhibits
both crystalline and amorphous phases. The
crystalline material is essentially calcium
oxide and amorphous phase is calcium
phosphate. MTA consists of hydrophilic
particles and sets in presence of moisture. In
clinical setting a moist cotton pellet need to
be placed over MTA to help in setting
reaction.

16. PROPERTIES
PHYSICAL STATE- solid (powder)
COLOR -grey/white
ODOR -no specific odor
BOILING POINT ->1000ºC

17. 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.

18. SOLUBILITY
MTA is capable of partially releasing its soluble
fraction to an aqueous environment over a period of
time with decreasing rate. Solubility of MTA in
water is about 0.1% -1.0%. The soluble fraction
released by MTA in aqueous environment is mainly
composed of calcium hydroxide. It has been
proposed that calcium oxide present in MTA reacts
with water to form calcium hydroxide. It has been
shown that set MTA’s solubility is a function of
water powder ratio (for optimum properties
recommended w/p ratio is 3:1) MTA is mainly
composed of a insoluble matrix of silica gel that
maintains its integrity even in contact with water.

19. For this reason operators should not be
concerned with complete solubilization in
contact with periradicular tissues .

20. SEALING ABILITY/MARGINAL ADAPTATION
The sealing ability and marginal adaptation of MTA
outperforms other material compared (amalgam,
Super EBA IRM e.t.c. ). A stable barrier to
bacterial and fluid leakage is one of the key factors
in creating clinical success of root repair material.
The sealing ability of MTA
was investigated using florescent dye and confocal
microscopy, methylene blue dye and bacterial
marker. Its marginal adaptation was assessed using
scanning electron microscopy.

21. The long tern seal was measured over a 12
week and 12 month period using different
fluid transport methods. MTA’s sealing
ability is probably due to its hydrophilic
nature, long setting time ,and slight
expansion when it is cured in moist
environment. In dye leakage study
conducted by Torabinejad et al the sealing
ability and marginal adaptation of ProRoot
MTA , amalgam and super EBA cement were
compared. The results showed that MTA
allow significantly less dye leakage and had
better adaptation than other test material.

22. Clinically a barrier of 3-5 mm should be
considered if root end surgery is a treatment
option. Recent evidence has shown that teeth
obturated with orthograde MTA and followed by
root end resection showed periradicular healing
similar to teeth with fresh MTA placed as a root
end filling material (Torabimejad et al ). If a 3mm
root end resection had to be performed after
placement of 5mm apical barrier then no root end
filling would have to be placed at the time of
surgery. This thickness of MTA is sufficient to
prevent marginal leakage and showed better
sealing than other root end filling material.

23. DELIVERY TECHNIQUE
The method of placement of MTA in apical barrier
technique is still controversial. Aminoshariae et al
obtained a more accurate adaptation of MTA by hand
compaction compared with ultrasonic condensation,
whereas Lawley et al and Matt et al showed that
ultrasonic condensation of MTA results in hardest and
most impervious barrier. Barriers placed with ultrasonic
activation demonstrated fewer voids than barriers placed
without ultrasonic energy. The ultrasonic energy helped
move the MTA apically and more completely condense the
material without dislodging.

24. STUDIES ON ADAPTATION/MICROLEAKAGE
• Fluid transport models comparing microleakage
of MTA and amalgam or EBA, amalgam and MTA
showed less microleakage with MTA
(Yasshushiri et al )
•Torabinejad et Al evaluated marginal
adaptation using SEM revealed that MTA had
better adaptation than other material.
•
•Endotoxin studies by Torabinejad et Al also
confirms superior sealing ability of MTA using
E.Faecalis to test sealing property.

25. •Study by Lawley et Al using PCR
followed by reverse blot confirms
superior sealing and adaptation of
MTA.
•Schress found that MTA did not allow
passage of strict anaerobes for
duration of 47 days. MTA also gives
seal against
S.Epidermidis,F.nucleatum,S.Marcesen
ces

26. MECHANISM
MTA’ s sealing ability and better marginal
adaptation is probably due to its hydrophilic
nature, longer setting time and slight
expansion when it is cured in moist
environment. MTA contains 5% gypsum that
expands during setting contributing to better
adaptation .

27. BIOCOMPATIBILITY/RESPONSE OF
PERIRADICULAR TISSUES
Biocompatibility is the ability of the material to
perform with an appropriate host response in a
specific application. This means that the tissue of
patient comes in contact with the material does
not suffer from any toxic , irritating,
inflammatory, allergenic and carcinogenic action.
The biocompatibility
assessment of MTA encompassed in vitro cell
culture technique using established cell lines,
primary cell culture of various combination. Apart
from variation in sensitivity of cell types used
the result showed MTA to be biocompatible.

28. Tissue response evaluated in vivo by intra osseous
and subcutaneous implantation experiment found
MTA to be well tolerated. MTA was also shown not
to have an adverse effect on connective tissue
microcirculation when assessed using an improved
rabbit ear chamber . In vivo usage tests revealed
less inflammation with MTA root end filling
material compared to amalgam in addition to
presence of new cementum formed over and
adjacent to MTA

29. The major difference among periapical tissue’s
response to amalgam EBA and MTA as root end
filling material are degree of inflammation, type
of infiltrated inflammatory cells, frequency of
fibrous capsule .formation and cementum
formation. MTA was best material overall.
Torabinejad et al compared cytotoxicity of MTA,
amalgam, EBA ,IRM using radiochromium release
method, MTA was least cytotoxic.

30. REGENERATIVE CAPABILITIES
Regeneration has been defined as the
replacement of tissue components in the
appropriate location, in the correct amount
and the correct relationship to each other.
This means reformation of the bone in the
surgical site, adjacent to fully
reconstituted PDL, attached to newly
formed cementum, over resected root end
and root end filling material.

31. MTA has the ability to encourage hard tissue
disposition and the mechanism of action may
have same similarity to that of calcium
hydroxide. Although hard tissue formation
occurs early with MTA, there was no significant
difference in the quantity of cementum or
osseous healing associated with freshly mixed
or set MTA

32. STUDIES
Investigation of why MTA appears to induce
cementogenesis found that material seemed to
offer a biologically active substrate for
osteoblasts, allowing good adherence of the
bone cells to the material while also stimulating
production of cytokines. Koh et Al found that
MTA causes an increase in production of
interleukin IL-1α, IL-1β, IL-6 an ostoecalcin.
Osteoclacin is an
abundant protein and may be an indicator or
bone matrix production. Mitchell et Al found
that set MTA induced production of IL-6, IL-
8, and macrophage colony stimulating factor

33. IL-8 promotes the development of new blood
vessels and activate precursor of osteoblasts.
Macrophage stimulating factor may have a
significant function in osteoclast development
and maturation.
The source or origin of new
cementum is not clearly understood, Two
possibilities exists, one derived form remaining
PDL or one from growing connective tissue from
bone.

34. MTA was found to stimulate extra cellular
regulated kinases, members of mitogen activated
protein kinase pathway which are involved with bone
cell proliferation, differentiation and apoptosis.
MTA also induces fibroblasts to express gene
associated with cementum formation of an
osteogenic phenotype.Sarkar et Al investigate the
physiochemical basis of biological properties of
MTA. They concluded that calciumions released
form MTA reacts with tissue phosphates yielding
hydroxyappetite matrix at dentin MTA interface.
10 Ca2+ + 6(PO4) -3 + 2(OH) -1
Ca10(PO4)6(OH) 2

35. authors concluded that MTA is not an
inert material in a simulated oral
environment, it is “BIOACTIVE”. The
success of MTA in terms of sealing
ability, biocompatibility and
dentinogenic activity is believed to be
in these physicochemical reaction.

36. DENTINOGENIC ACTIVITY
MTA is used for pulp capping / pulpotomy and
shown to have dentinogenic effect. Pulp capping is
mainly indicated for reversible pulp tissue injury
after physical or mechanical trauma on developing
or mature tooth. The ultimate goal of pulp capping
material is to induce the dentinogenic potential of
pulpal cells. The dentinogenic potential can be
induced directly as a specific biological effect of
the capping material on pulpal cells or indirectly as a
part of stereotypic wound healing mechanism in
traumatised pulp.

37. Experiments showed that pulp capping with
MTA induces cytological and functional
changes in pulpal cells resulting in formation
of fibrodentin and reparative dentin at the
surface of mechanically exposed pulp. MTA
offers a biologically active substrate for
pulpal cells and is able to regulate
dentinogenic events.

38. Reparative dentinogenesis was
clearly observed three weeks after
capping of exposed pulp with MTA.
Odontoblasts like cells elaborating
tubular matrix in predentin like
structure is seen. These data’s
confirmed similar mechanism for
initiation of reparative
dentinogenesis in capping with MTA
and calcium hydroxide based
material.

39. Regulatory effect of MTA and production of osteocalcin
or alkaline phosphatase or intereleukin 6 or 8 might be
further related to stimulation of dentinogenic activity. In
addition the importance of fibronectin rich zone which
formed on to crystalline structures along pulpal side of
MTA and possible effect of alkaline environment in the
solution of growth factors from surrounding dentin as has
been suggested for calcium hydroxide may not be
excluded

40. DISADVANTAGES OF CALCIUM HYDROXIDE
Calcium hydroxide remains the standard of
pulp capping. Subsequent to pulp capping with
calcium hydroxide the adjacent pulp tissue is
usually completely deranged and distorted
forming a zone of obliteration. A weaker
chemical effect on subjacent more apical
tissue results in a zone of coagulation
necrosis. The superiority of calcium hydroxide
is questioned because of degradation over
time ,tunnel defects through dentinal bridges
under it and poor sealing properties.

41. CALCIUM HYDROXIDE SHOWING GRANULATION TISSUE

43. ADVANTAGES OF MTA
With MTA thicker dentinal bridges are formed
and the presence of an odontoblastic layer was
a frequent finding. Hyperaemia of pulp is a less
frequent finding with MTA while hyperaemia is
seen in almost every case with calcium
hydroxide. MTA has sufficient compressive
strength to allow condensation of amalgam in
contrast to calcium hydroxide which has limited
strength

44. DENTINOGENIC ACTIVITY WITH MTA

45. ANTIBACTERIAL EFFECT
In addition to having good sealing ability and
biocompatibility root end filling material
should ideally have some antibacterial
properties to prevent bacterial growth. A
study by Torabinejad et Al concluded that
MTA has no antibacterial against anaerobes
but causes effects on facultative bacteria.
The antibacterial effect of MTA could be due
to its high ph or release of diffusible
substances.

46. White MTA in concentration of 50 mg/ml
may exert an antifungal effect against
C.albicans a period of up to 30 days.
Recently it has been suggested to mix
chlorhexidine to MTA to enhance its
antibacterial properties ,however its not
clear what effect chlorhexidine has on
physical and chemical properties of MTA.

47. Bacteria inhibiting root canal is composed
mainly of strict anaerobic bacteria, some
facultative anaerobes and usually no
aerobes. In apical portion of root canal
68% of bacteria are anaerobes. The
relative proportion of strict anaerobes
bacteria to facultative bacteria increases
with time. Although EBA, ZOE, and MTA
are ineffective against a number of
bacteria MTA is superior to others due to
its sealing ability preventing migration of
bacteria and some antibacterial activity
against facultative anaerobes.

48. CLINICAL APPLICATIONS

49. APEXIFICATION/APICAL BARRIER
One of the principal objective of non
-surgical root canal therapy is seal the
canal system from apical and coronal
leakage after cleaning and shaping. The
absence of an adequate apical constriction
is often found in cases of apical root
resorption, apical perforation, and
immature necrotic tooth. In these cases it
is critical that either a stop be developed
or an apical barrier be placed to limit
extrusion of obturation material .

50. Although apexification with calcium
hydroxide pastes has been highly successful,
an alternative treatment is the use of an
artificial barrier that allows immediate
obturation of the canal. Thus some of the
disadvantages of calcium hydroxide therapy
including increased cost and patient
compliance with multiple appointments over
6-24 months could be eliminated. Calcium
hydroxide has also been shown to decrease
the fracture resistance of tooth. Dentin
chips, freeze dried cortical bone , and
calcium phosphate also has been used, but
they do not provide well sealed environment.

52. ADVANTAGES OF MTA
MTA is superior to all other material due
to its
•Sealing ability
•Biocompatibility
• Ability to set in presence of moisture
• Induces hard tissue formation

53. TECHNIQUE
Prior to placement of MTA all necrotic debris should be
cleaned and canal bio mechanically prepared.
Manufacturer recommend medication of canal with
calcium hydroxide for 1 week with subsequent removal
using sodium hypochlorite. They also recommend a 3-5
thickness of MTA to be placed at apex.
The delivery technique is controversial, some
prefers hand condensation while others prefers
ultrasonic condensation.

54. Moisture from periapical area could be
sufficient for MTA to set but additional
moisture from a cotton pellet is crucial for the
material to establish its optimum properties. It
is recommended to place a most cotton pellet or
paper point in canal before temporising.

55. If after placement of orthograde MTA
periapical surgery can not be excluded than
even after root end resection of 3 mm
additional root end filling need not be placed as
similar healing is shown with fresh MTA or set
MTA. It is also recommended to follow two
step apexification procedure that is after
placement of apical barrier a damp cotton
pellet in canal, temporize and allow material to
set for at least 4 hours or do obturation next
day.

56. ROOT-END FILLING
 Numerous materials have been used as a root-end
filling material. The main disadvantage include their
inability to prevent egress of irritants from infected
root canal into periradicular tissues, lack of
biocompatibility, and their inability to promote
regeneration of periradicular tissues to their prede
asesed status and normalcy.
 MTA is superior to
other material as it provides “DOUBLE SEAL” that is
physical seal due to its excellent sealing property
and biological seal due to regeneration of cementum
over it.

57. The major difference between MTA and other root
end filling material on periradicular response are
degree of inflammation, extent of inflammation,
frequency of fibrous capsule and cementum
formation over MTA. Formation of fibrous
connective tissue cementum and low level of
inflammation with MTA indicates its excellent
biocompatibility.

58. TECHNIQUE
After careful debridement of apical lesion, root
end is sectioned and root end cavity prepared.
Preparation of root end cavity with ultrasonic
retro tips have shown better results than cavity
prepared with a bur. MTA is mixed according to
manufacturer’s instruction and is carried to root
end preparation with modified amalgam carrier or
other specially designed carrier. Once MTA is
micro ball burnisher and micro pluggers are used
to gently compact it. A damp cotton pellet is used
to remove any excess MTA from cavity. The
surgical area should be kept dry and care should
be taken not to wash out the filling material by
irrigation before closure.

59. MTA CARRIER

60. MICRO BALL BURNISHER AND CONDENSER

62. REPAIR OF ROOT PERFORATION
Perforations are procedural accidents that can have
adverse effect on the outcome of endodontic
treatment. The prognosis for the tooth with a
perforation depends on location of perforation, the
time the perforation is open to contamination, the
possibility of sealing the perforation and
accessibility of main canal.
MTA as a perforation
repair material has been shown to leak less than
amalgam and Super EBA and is less cytotoxicity.

63. TECHNIQUE
Before placing MTA over a perforation site the area
should be copiously irrigated with NaOcl (5% or 2.5%).
After perforation site has been soaked with NaOcl for
approximately 5 minutes, haemostasis and a barrier must
be now be achieved. Even though MTA sets in presence
of moisture the site should be kept as dry as possible,
because MTA will be difficult to place and manipulate. A
physical barrier must now be achieved at the perforation
site to prevent MTA from being packed into the bone or
through pulpal floor into the furcation site. To achieve
haemostasis and a physical barrier collagen type material
or calcium sulphate can be used.

64. PREOPERATIVE RADIOGRAPH
PLACEMENT OF MTA

65. REDUCED PROBING DEPTH AT 1-MONTH
HEALED LESION AT 6-MONTH

66. These materials are resorbable and needed to help
create a dry field and a solid foundation against which
operator packs MTA. The procedure is best
performed under a surgical microscope that provides
magnification and illumination.
After placement of calcium
sulphate /collagen MTA is placed. WMTA should be
preferred in cervical area of anterior tooth as gray
MTA not aesthetically pleasing. MTA is packed with a
condenser. A moist cotton pellet should be placed on
top of MTA and cavity is restored temporarily. In
next appointment MTA sets and teeth can be
permanently restored.

67. REPAIR OF ROOT RESORPTION
MTA can be used and is promising in treatment of
external as well as internal root resorption .
TECHNIQUE
In case of internal root resorption isolate the tooth
do RCT in usual manner. Once the canal has been
cleaned and shaped place a putty mixture of MTA
and fill the canal with it using a plugger or Gutta
percha cone. Next place a safe sider 25/.08 down
the canal to spread the cement laterally and create
a new canal. Fill canal with sealer and obdurate with
single Gutta percha cone. The set MTA will provide
structure and strength to the teeth by replacing
resorbed tooth structure.

68. In case of external root resorption ,do
RCT first, next raise the flap to remove
the defect and granulation tissue. Mix
MTA and apply it to root surface.
Remove excess cement and condition
root surface with doxycycline. Graft the
defect with bone grafting material and
close the site.

69. PULP CAPPING/PULPOTOMY
Direct pulp capping is a well established
method of treatment in which exposed dental
pulp is covered with a suitable material that
protects pulp from additional injury and
permits healing and repair. Pulp capping is
mainly recommended for reversible pulp injury
after physical or mechanical trauma on
developing or mature tooth.

70. TECHNIQUE
After proper isolation and achieving
haemostasis MTA is placed over exposure
site and light pressure has to applied with a
damp cotton pellet. The cavity can be
restored with amalgam / composite/ GIC.
MTA has shown to induce reparative dentin
formation in three weeks, earlier than
calcium hydroxide. The quality of calcific
bridge formed is also better than that
formed with calcium hydroxide.

72. ADVANTAGES
•Biocompatible
•Non toxic
•Non resorbable
•Good marginal sealing
•No irritation to surrounding
tissues
•Stimulates hard tissue
formation
•moisture insensitivity
•Radio opaque

73. DISADVANTAGES
•Difficult to manipulate
•Longer setting time
•Need two appointments

74. THANK YOU