Articles of Interest
Here are a selection of articles written by Dr M K
Vasant, which were published in professional dental journals.
ENDODONTICS:
MODIFIED CHLOROFORM DIP TECHNIQUE FOR CANAL
OBTURATION
The Grapevine, KaVo |
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by Dr M
K Vasant MBE
MGDS RCS (Eng), MGDS RCS (Edin), FFGDP (UK),
FDS RCS (Edin)
In the last issue of The Grapevine, Dr Lumley
(Recent developments in root canal preparation)
covered various methods to prepare the root
canal. His opening sentence was “the
aim of the root canal preparation is to debride
the pulp space to produce a shape amenable
to obturation.” He went on to say, “the
anatomy of the root canal systems is complex
which makes it impossible to clean them in
their entirety…” These statements
are very valid and it could be argued that
as one cannot see the complexity of the root
canal system, it makes it unpredictable to
decide whether one can or has filled the whole
system. Many obturation techniques have been
advocated and as in every other aspect of
dentistry, there is a learning curve to develop
a technique that one would feel comfortable
with. |
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The modified chloroform dip technique has indeed confirmed
my suspicion about this unpredictability and following
obturation using this technique, I have often “found”
canals that I did not know existed.
MODIFIED CHLOROFORM DIP TECHNIQUE
Background and Discussion
The old chlorpercha technique was based on softening
gutta-percha in chloroform and using the paste thus
produced as a sealant. The criticism leveled against
this method was the shrinkage caused by evaporation
of the chloroform and subsequent lack of seal. This
is quite understandable as a fairly large amount of
solvent (chloroform) would have been used to achieve
this.
The chloroform (and xylene – which could be used
as an alternative) is toxic and could be carcinogenic .
However, the author is happy to take shelter under the
current premise of “evidence based medicine and
practice” and happy to argue about the validity
of an in vitro study. Many other solvents have been
evaluated for the purpose and the only one that come
close to chloroform is rectified turpentine oil .
Sadly, I have not been able to source this is in the
UK and the suggestion by Martindale that is the same
as turpentine in DIY stores gave more ammunition to
continue with the devil I know – chloroform! However,
I have found that used very judiciously, orange solvent
liquid (designed to clean zinc oxide/eugenol-based cements
on glass slabs) works well to remove old root fillings
in re-treatment. This sounds logical as most root canal
sealants are zinc oxide/eugenol-based as is most of
the gutta-percha point (65-70% is zinc oxide, waxes
and resins). Whilst, I have not been able to confirm
this, I am led to believe that the orange solvent available
from the dental depots is after all turpine based!
With the techniques described herewith, I use minimal
amounts of chloroform and arguably neither the shrinkage
nor the carcinogenic risk is applicable.
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Materials and Methods
Figures 1, 2, 3 (note how 5 second dip dissolves GP
on glass slab)
| Figure
1 |
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| Figure
2 |
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- Standardised and Accessory (GP points Kerr
work particularly well and offers a good selection)
- Slow setting sealant such as Grossmans
or Extended Working Time Sealapex (Kerr)
- Plastic sheath of a dental needle secured
on glass slab with ribbon wax for chloroform.
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| Figure
3 |
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The canal is prepared using a preferred technique ensuring
that there is enough coronal flare so as not to bind GP
points or other instruments.
Essentially, the technique consists of selecting a standardized
master point that will fit albeit fairly loose in the
canal but to the correct length. The canal, having been
dried thoroughly, is coated with sealant using a small
file or spiral filler if preferred. Secure the master
point in the canal to the correct length (confirm radiographically
if necessary). This will ensure that the root canal orifice
is not too wide open to allow overfilling of the canal
during subsequent procedures. The author then prefers
to use Mailleffer A25 (thin and flexible spreader) to
laterally condense GP points, although a finger spreader
will probably do the same job. Note the distinction between
a spreader and plugger. The latter has a flat end and
is useful for vertical condensation but not particularly
good for lateral condensation.
Having done this, a suitable accessory point is dipped
in chloroform for 3-10 seconds depending on the surface
softening required, and placed in the space created by
the spreader. It is important to hold the spreader in
place for a while to ensure the space remains patent for
some few seconds. Most of the time, the author dips the
accessory points upside down so that the tip (about 3mm)
does not become soft, and gives a good lead to the rest
of point into the canal. The plastic sheath from a dental
needle happens to be the right size container (secured
to a glass slab with ribbon wax) for this. Alternatively,
you may wish to cut the very soft tip off so it does not
bend during insertion. The GP thus softened behaves like
Thermafill with a hard core of GP and a softer surface-only
you have to control how soft you want it to be by varying
the time of dip in the chloroform. You can apply vertical
pressure as the hard core will enable you to do that at
the same time allowing the GP to slide beautifully in
place where sometimes due to an inadequate coronal flare
you may have held back the GP. Having completed this,
the excess GP points are cut off using a hot excavator
and vertical pressure applied with a thin amalgam plugger
or a root canal plugger to get some vertical additional
condensation.
It is important to assure that there is a good coronal
seal following obturation of the canal. The author uses
Cavit in preference to IRM as it is ready mixed and has
been shown to be equally effective in preventing bacterial
leakage.
Needless to say an intermediate restoration such as amalgam
is carried out within the next week or so.
Clinical Cases
1. Young child with an open apex
| A young child with an open apex was
treated, by using a customized accessory GP point
to fit snugly into the apical foramen. This was
done by dipping the GP point and then inserting
into the canal to effectively take an impression
of the canal. The protruding tip was subsequently
cut off and used as a master point, around which
other softened accessory GP points were laterally
condensed and cut off with heat, then vertically
condensed as explained above. |
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| Figure
4 |
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| Figure
5 |
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2. Premolar obturation
Figures 6 and 7 show premolars filled using the
above technique where the author discovered canals
that he would have never expected to find. It was
suspected that the peculiar system in figure 6 may
have been an escape of sealant in the periodontal
membrane. This was not the case!
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| Figure
6 |
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| Figure
7 |
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Examples of Molar treatments
Figures 8 and 9 show how the technique enabled the
author to bypass a broken file in the canal with
the technique so that the root filling sealed around
the broken instrument.
As with any technique, there will be a learning
curve!
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| Figure
8 |
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| Figure
9 |
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References
- Brodin P et al; Neurotoxic effects of root filling
materials on rat phrenic nerve in vitro. J Dent Rest
1982; 61:1020-3
- Kapolowitz G; Evaluation of the ability of essential
oils to dissolve gutta-percha J End vol;17 no9, Sept
1991
- Beach et al; Clinical Evaluation of Bacterial leakage
of endodontic temporary filling materials J Endo 22(9);
459-462, 1996
- Chloroform and Grossmans cement are available from
Guys and St Thomas’s pharmacy, Guys Hospital
St Thomas St, London SE1 Tel: 0171 922 8316
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