Young Bui
 |
 T
HAS BEEN almost two years since I first wrote about the many uses of MTA
(Endo-Mail, January-February 2002). Since then, there have been many
articles published in dental journals praising the success of the material.
For those of you who did not get a chance to read that article when it
was first published, here it is again, expanded, and in greater depth.
MTA was developed by Dr. Torabinejad at Loma
Linda University in 1993. It is a compound mixture of hydrophilic
tricalcium silicate, tricalcium oxide, and tricalcium aluminate with some
other oxides. An independent analysis reveals that MTA is identical
to Portland cement with the addition of bismuthoxide. Because MTA
has a pH of 12.5, some of its biological and histological properties can
be compared to those of Ca(OH)2. The material sets in a moist environment
and has low solubility. The compressive strength of MTA is equal
to that of IRM and Super EBA but less than that of amalgam (Nahmias and
Bery).
There are clinical situations in root canal
therapy that would require the use of a product that would provide a reliable
clinical outcome and long-term prognosis. Pulp capping, lateral root
or furcation perforation, apexification, apicoectomy, and internal and
external resorption are some of the cases that would rely on the use of
such a product. An ideal root repair material should be non-toxic,
bacteriostatic, and non-resorbable. It should also promote healing
and provide a good apical seal. Compared to other materials, MTA
shows less microleakage, less toxicity, and better bacteriostatic effect.
Histologic examination has revealed that it has actually induced cementogenesis,
and bone deposition with minimal or absent inflammatory response.
Below is the list of clinical situations that
benefit from the use of MTA and the proper treatment for each case.
Pulp Capping
If you happened to cause a mechanical perforation, immediately place a
rubber dam over the tooth for proper isolation. Rinse the cavity
with sodium hypochlorite to disinfect the area. You do not have to
dry the area since MTA sets in a moist environment. Mix the MTA powder
with enough sterile water to give it a putty consistency. Apply it
over the exposed pulp and remove the excess. Blot the area dry with
a cotton pellet and restore the cavity with an amalgam or composite filling
material. MTA provides a higher incidence and faster rate of reparative
dentin formation without the pulpal inflammation that is seen when Dycal
is used.
Internal and External Root Resorption
In the case of internal root resorption, isolate the tooth and perform
RCT in the usual manner. Once the canal has been cleaned and shaped,
prepare a putty mixture of MTA and fill the canal with it, using a plugger
or gutta-percha cone. Next insert a SafeSiders 25/.08 down the canal
to spread the cement laterally and create a new canal. Flood the
canal with EZ-Fill cement and obturate it with a single gutta-percha cone.
The MTA will provide structure and strength to the tooth by replacing the
resorbed tooth structure.
In the case of external resorption, complete the
root canal therapy for that tooth. Next raise a flap and remove the
defect on the root surface with a round bur. Mix the MTA in the same
manner as above and apply it to the root surface. Remove the excess
cement and condition the surface with tetracycline. Graft the defect
with decalcified freeze-dried bone allograft and a calcium sulfate barrier.
Lateral Perforation and Strip
Perforation
If you happened to cause a strip or lateral perforation during instrumentation,
first finish cleaning and shaping that canal. Irrigate the canal
really well with sodium hypochlorite and dry it with a paper point.
The paper point will allow you to see where the perforation is located.
If the perforation is down at the mid to apical third, then follow the
directions for treating an internal resorption, above. The MTA will
seal off the perforation as it is spread laterally by the SafeSiders 25/.08
file and the gutta-percha cone. If the perforation is closer to the
coronal third, then fill the canal up with EZ-Fill cement and gutta percha
as usual. Next, remove the gutta percha about 2?3 mm below the perforation
using the Peeso reamer. (Be careful not to perforate again!)
Now mix the MTA and fill the rest of the canal up with a plugger.
Furcation Perforation
If you create a furcal perforation while accessing the tooth, there are
two ways to repair it.
If you can finish the root canal in one visit, then do
that first. Next remove the excess gutta percha in the chamber and
soak it for 5 minutes with sodium hypochlorite. Now mix the MTA and
fill the chamber with it. Using a moist cotton pellet, plug the MTA
down into the perforation site and remove the excess cement from the chamber.
Place a moist cotton pellet in the chamber to help with the setting of
the MTA and close the tooth up with a temporary cement of your choice.
If you cannot do a one-visit root canal, then first seal
the perforation with the MTA mixture. Make sure that you can locate
the canal while the MTA has not set and remove the excess material from
the area. Close the tooth as above and do the root canal the next
visit.
Apexification
Vital pulp: Isolate the tooth with a rubber dam and perform a pulpotomy
procedure. Place the MTA over the pulp stump and close the tooth
with a strong temporary cement until the apex of the tooth closes up.
Non-vital pulp: Isolate the tooth with a rubber dam and perform root
canal treatment. Once the canal has been cleaned and shaped, irrigate
it and dry it with a paper point. Mix the MTA and plug it down to
the apex of the tooth, creating a 2 mm thickness of plug. Wait for
it to set; then fill in the canal with cement and gutta percha.
November-December 2003
|
Here
is a list of clinical situations that benefit from the use of MTA and the
proper treatment for each case.
|
