Dentaltown February 2020 - 85

hand-file the apical one-third to the
apical size of the last shaping file,
usually between sizes 25 and 35. This
part is mostly glossed over by dentists,
and it's important to achieve the best
possible gutta-percha fit to the established working length before cone-fit
radiographs. Spending an extra two
or three minutes on achieving an
excellent cone fit to working length
will end up saving you time.
* If the cone is 2mm short, instead
of having to shape after cone-fit
radiographs, refit new cones and
then take new cone-fit radiographs,
spend a few minutes reshaping the
apical third, and then placing new
QMix. Now try in the corresponding
cone and usually it will slide right to
working length.
When you're happy with the cone fit, have
a dental assistant take two quality straight
and shift periapical radiographs. Look
carefully at these two PAs, because this is
your last chance to correct any gutta-percha
length problems before sealing the canal
system forever and ever (at least, that's the
hope). Are the cones sitting at or within
0.5mm of the established working length
and near the radiographic apex? If so, well
done-it's time to obturate and seal the
cleaned canal system.
If I use 17% EDTA, then I first take
my cone-fit radiographs with bleach in the
canals. I then irrigate the canals with 17%
EDTA for one minute and then rinse out
the EDTA with bleach or saline.

I like to use the corresponding paper
point that fits the last shaping file. For
example, if the shape was prepared with
WaveOne Gold Primary, then I use the
WaveOne Gold Primary paper points; if
it was completed with ProTaper Gold F2,
then I use the ProTaper Gold F2 paper
points. At times, I also use either coarse
or extra-coarse paper points from Benco
or Henry Schein. One or two coarse paper
points usually work on most shapes and dry
the canal down to the apex.
If the shape is smaller than normal, I
use the microcannula, followed by medium
paper points. Make sure the canals are dry
and a pool of fluid does not sit in the apical
one-third. This could affect the apical seal
and increase the chance of sealer washout
in the most important area-the apical
third. If the canal will not dry because of
purulent exudate, I place a premixed calcium
hydroxide (UltraCal XS from Ultradent)
into the canal, prescribe antibiotics and
complete obturation in two weeks.
On these cases, two weeks allows time for
some apical "healing." Early in my career, I
would try to obturate these purulent drainage
cases after only a week and would often
encounter serous fluid drainage back into
the canal system. I was unable to dry the
apex of many of these cases, and then would
place calcium hydroxide again and reschedule
for a third appointment. Two weeks, in my
opinion, allows for some tissue "healing." I'm
now able to dry the canal and apex on most
of these cases and then complete obturation
at the second appointment.

Drying the canals

Buttering the
gutta-percha cones

The best way to efficiently dry the canal
system is to use a small vacuum on the end of
a suction. I use the EndoVac Macrocannula
to suck out most of the QMix in the canals
(Fig. 3), then follow this up with one or two
paper points per canal (Fig. 4).

In my prac t ic e, I t y pic a l ly u se
ThermaSeal Plus Ribbon sealer from
Dentsply Sirona or Pulp Canal EWT from
Kerr. My assistant mixes the sealer on a
pad and places it on the patient's shoulder/

Fig. 3

Fig. 4

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Dentaltown February 2020

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