DentaltownUK August 2017 - 20

Continued from p. 18
in the canal is in a mesiodistal dimension
because of internal resorption. The Finisher
enabled removal of debris and tissue in the
irregularity while retaining the original
shape of the canal and preventing further
weakening of the root.

Fig. 10. The image reflects the distal views of 3-D reconstructions of the mesial root canal systems of
four mandibular molars before (green) and after (red) canal preparation with reciprocating instruments.
The figures demonstrate the effectiveness of the Finisher in the apical region.

Fig. 11. The preoperative periapical radiograph shows a mesiodistal resorptive defect. The CBCT images
show that this is internal resorption that also extends buccolingually. The postoperative radiograph
shows that at the second visit the canal is filled completely, which is an indication that the tissue and
debris has been removed. The original shape of the canal has been maintained, and the tooth has not
been further weakened by the cleaning procedure.

AUGUST 2017 // dentaltownuk.com

Retreatment considerations
There is a third file in the XP-3D instruments-the XP-3D Finisher R-designed
for retreatment. This file is a #30/.00, making it slightly stiffer and more efficient in
removing root fillings materials adhering to
the canal walls, especially in the curvature
or oval areas. The residual amount of filling material remnants, when a tooth is
retreated, is difficult to calculate; however,
studies using histologic evaluation of teeth
with post-treatment apical periodontitis
show evidence that bacterial colonisation is
associated with the canal remnants.
A new supplementary strategy using a
finishing instrument was evaluated for its
ability to improve filling material removal.
A study showed substantial reduction in
residual contents when the "Mtwo" system
and "Reciproc" system were used for retreatment. The results using the XP-3D
Finisher instrument were encouraging.
The remaining filling volume showed a
69 percent reduction in volume contents.
In canals with residual filling material,
an adjunctive approach with the XP-3D
Finisher instrument significantly enhanced
removal17 (Fig. 12).

Conclusion
Preliminary studies on XP-3D instruments have shown remarkable removal of
soft tissues, fewer dentinal chips residual
in the isthmus and canal walls after instrumentation, and low dentinal stress (fewer
microcracks). The minimally invasive
conservative instrumentation engenders a
low amount of dentin removed coronally,
and efficient debridement and disinfection
of the apical third area.
Have we achieved the ideal fusion of
technology and biology for long-term positive
treatment outcomes? Perhaps.
What has been achieved is a redress of
a design flaw that has persisted for much
too long.
(Editor's note: Part 2 of this series will
address how the use of bioactive materials for
cold hydraulic obturation takes us yet another
step closer to the goal of predictable endodontic
success.) n

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Table of Contents for the Digital Edition of DentaltownUK August 2017