The complex morphology of the root canal system causes the canal
instrumentation to face challenges. Perforation, apical transportation,
and ledge formation are some of the errors that may be encountered
during the instrumentation of canals with a double curvature or S-shape.
Therefore, it is necessary to determine the curvature of the canal
before starting the RCT (21). To avoid these errors, the basic
principles of RCT should be followed. Proper radiography, obtaining SLA,
precurving the files, adequate irrigation, and most importantly using
Ni-Ti instrumentation systems (22).
The broken file in the third case of the present study led to more
challenging RE root canal therapy. One of the most important factors in
managing the retrieval of a broken file depends on the location of the
instrument separation (23). The current study used the loop technique
and bypass to manage two broken files. The success of the bypass method,
especially in the more apical spots, has been emphasized in previous
studies (24), and the use of removal kits with a loop system shows
promising results (25, 26).
In the present study, three cases of RE were discussed. Management of RE
treatment requires special care that should be considered within the
framework of the RCT basic principles. In addition to the management of
RE treatment, canals with double curvature or S-shapes add to the
treatment challenges, which may lead to errors such as broken files,
which were also noted in the present study. Therefore, prior knowledge
of the morphological characteristics of the possible anatomical
variations, the appropriate use of clinical or paraclinical tools, and
increasing technical sensitivity are essential for preoperative planning
and effective therapeutic intervention.