Challenges
Curved root canals present several significant difficulties, including
challenges in instrumentation, insufficient cleaning, and complications
during the filling process (16). According to Călin et al.’s systematic
review, continuous rotary systems appear to be preferable to
reciprocating systems in managing the extracted teeth root canal
instrumentation with moderate and severe curvatures (17). Ultrasonic
activation of irrigation has been proven to enhance the effectiveness of
disinfection in the apical third, which is usually unreachable due to
canal curvature (16, 17). The single-cone, warm vertical compaction, and
lateral condensation techniques, which are common obturation methods,
have significantly different efficacy and suitability for curved root
canals (18). The single-cone method, although simple and time-efficient,
often fails to achieve the desired level of canal adaptation and has a
high tendency to form voids, especially in irregularly shaped and curved
canals (19, 20). Lateral condensation enhances obturation quality
through mechanical compaction but has less ability to fill complex
anatomical spaces well due to its reliance on lateral pressure (21). on
the other hand, the warm vertical compaction technique demonstrates
superior adaptability and sealing ability in curved canals by using
thermoplasticized gutta-percha, which flows to conform to the canal’s
intricate morphology, including isthmuses and lateral canals. This not
only significantly reduces microleakage and voids but also enhances
long-term results (21). While much of the previous studies utilized
single-cone and lateral condensation techniques, the authors propose
warm vertical compaction as a more favorable option in complicated cases
and consider the application of other methods limited to simpler cases
(22, 23).
S-shaped root canals present even greater difficulties due to their
double curvatures in opposite directions, which makes it harder to
navigate the instruments (9, 24). In this case report, we demonstrated
precise instrumentation to treat three double-curved root canals with
severe curve angles based on the Schneider approach (25). Previous cases
have not highlighted severe S-shaped teeth as seen in our study.