Efﬁcacy of the ProTaper retreatment system in
removing Thermaﬁl, GuttaCore or vertically
compacted gutta-percha from curved root canals
assessed by micro-CT
odig , J. Wagner, A. Wiegand & M. Rizk
Department for Preventive Dentistry, Periodontology and Cariology, University Medical Center G
odig T, Wagner J, Wiegand A, Rizk M.
the ProTaper retreatment system in removing Thermaﬁl,
GuttaCore or vertically compacted gutta-percha from curved
root canals assessed by micro-CT. International Endodontic
Journal, 51, 808–815, 2018.
Aim To evaluate ex vivo the efﬁcacy of ProTaper
Universal Retreatment ﬁles (Dentsply Sirona, Bal-
laigues, Switzerland) in removing Thermaﬁl, Gutta-
Core (both Dentsply Sirona) or vertically compacted
gutta-percha from curved root canals using micro-CT.
Methodology Sixty curved molar roots with the
same mean canal curvatures and radii in two direc-
tions were prepared using ProFile instruments (Dents-
ply Sirona) to size 30 with .04 taper and obturated
with either Thermaﬁl, GuttaCore or vertically com-
pacted gutta-percha and AH Plus (n = 20). Specimens
were retreated using the ProTaper Universal Retreat-
ment ﬁles D1, D2 and D3 to working length, and root
canal preparation was completed with ProTaper Next
(Dentsply Sirona) to size 94. Percentages of residual
ﬁlling material and dentine removal were assessed
using micro-CT imaging. Working time and
procedural errors were recorded. Statistical analysis
was performed using Kruskal–Wallis and Wilcoxon
Results No signiﬁcant differences between carrier-
based and warm vertical compaction regarding residual
ﬁlling material (14.2–19.3%) and dentine removal (2.7–
)weredetected(P > 0.05). Time to reach work-
ing length was signiﬁcantly faster for canals ﬁlled with
GuttaCore than that observed for Thermaﬁl and warm
vertical compaction (P < 0.05). Five lateral perforations
with the D3 ﬁle occurred during retreatment, one in the
Thermaﬁl and four in the vertical compaction group.
Conclusions Remaining ﬁlling material and den-
tine removal were similar for all canal ﬁlling tech-
niques. Regaining working length was signiﬁcantly
faster for GuttaCore compared with Thermaﬁl and
vertically compacted gutta-percha. Procedural errors
occurred during retreatment of severely curved root
canals with the ProTaper Universal Retreatment ﬁles
in 5 of 60 canals (8%).
Keywords: curved root canals, GuttaCore, micro-
CT, ProTaper retreatment ﬁles, retreatment, Thermaﬁl.
Received 23 October 2017; accepted 18 January 2018
Persistent intracanal infection is the main reason for
post-treatment disease associated with root ﬁlled teeth
(Siqueira 2001). During root canal retreatment, com-
plete removal of the existing ﬁlling material is the ini-
tial important step to allow thorough cleaning and
disinfection of the root canal system (Bergenholtz
et al. 1979). Carrier-based obturation systems have
been developed to simplify root ﬁlling procedures.
However, in retreatment cases, carrier-based systems
may be more time-consuming or more difﬁcult to
remove completely (Frajlich et al. 1998, Baratto et al.
2002). Recently, a new core-carrier system was
Correspondence: Dr. Tina R
odig, Department of Preventive
Dentistry, Periodontology and Cariology, University Medical
ottingen, Robert-Koch-Str. 40, 37075 G
Germany (Tel.: +49 551 39 22 877; fax: +49 551 39 22
037; e-mail: firstname.lastname@example.org).
© 2018 International Endodontic Journal. Published by John Wiley & Sons LtdInternational Endodontic Journal
, 51, 808–815, 2018