DentaltownUK August 2017 - 18

Fig. 9a. The apical 10mm of the file transforms into a bulb more coronally and a tip in the last few
millimeters. When rotating at canal temperature, the Finisher exhibits a total expansion of 3mm.

Fig. 9b. Moved up and down in 7-to-8mm increments, the natural shape of the canal expands or
constricts the tip or the bulb and disrupts debris, tissue or biofilm, which is removed by the turbulence
of the irrigant.

within the root canal is to scrape the walls
that it contacts, rather than debride and
sculpt a shape into the wall of the canal.
When the file is cooled below 35 degrees
Celsius, it's in the martensite phase and
can be bent to any other shape. When
the file is heated to body temperature
(37 degrees Celsius), it will change to the
austenite phase. When the file is rotated
in the austenite phase, it creates a uniquely
shaped cleaning instrument; the apical
10mm of the file transforms into a bulb
shape coronally while retaining a tip in
the last few millimeters. Since the depth of
the spoon is 1.5mm, the total diameter of
the bulb and tip is 3mm. However, if the

AUGUST 2017 // dentaltownuk.com

bulb is 'squeezed,' the tip will expand to a
maximum of 6mm. Relatedly, if the tip is
'squeezed,' the bulb will likewise expand
to a #600 file (Fig. 9a).
However, because the instrument
can't cut, the only impact on the dentin
is optimised scraping. Therefore, if moved
up and down in the canal, the bulb and
tip will expand or contract in concert
with the natural 3-D diameter of the
canal. Maximum loss of length when
transforming from straight to full austenite
phase is 1mm.
The small core diameter of the file
maintains its flexibility and cyclic fatigue
resistance, causing it to scrape, not shape, the
dentinal walls. This, plus the turbulence that
is created in the irrigant, results in a large
surface area of the canal being touched by
the file and removal of biofilm that would
never be removed by round files.
Fig. 9b shows the action of the XP-3D
Finisher. In the 'M-phase' the finisher is
placed in the canal before it changes to full
austenite phase. The middle illustration
demonstrates full austenite phase at canal
temperature; the file will expand to the
extent that is determined by the canal
anatomy. By moving the finisher up and
down in a 7-8mm swath, it expands and
contracts per the anatomy of the canal. A
recent study demonstrated the efficacy of the
XP-3D Finisher, compared with traditional
modes of hard tissue debris.14 The results
are reflected in Fig. 10 (p. 20).
A more recent study showed that the
XP-3D Finisher had the greatest bacterial
reduction, when compared with standard
needle irrigation, sonic agitation with
the EndoActivator, and photon-initiated
photoactivated acoustic streaming.15
Another study demonstrated that the
inclusion of the XP-3D Finisher as an adjunct
to conventional needle irrigation and passive ultrasonic irrigation enhanced biofilm
eradication more than a continuous irrigation
protocol in an in vitro biofilm model.16
Fig. 11 (p. 20) is an example of the
unique action of the finisher. The irregularity
Continued on p. 20

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Table of Contents for the Digital Edition of DentaltownUK August 2017