Objective: Isthmuses are narrow communications between root canals, and form as the
result of the merging of the two root canals widening in a buccolingual direction. This widening
causes the high ovality of isthmuses. The shaping and cleaning of all root canal systems are regarded
as one of the major difficulties in long-oval shaped root canals. This study aims to make
quantitative analysis of Vertucci type II root canal systems following preparation with Self-
Adjusting file (SAF), Reciproc or Revo-S.
Methods: Major diameter and roundness values were measured at the level 1.2 mm from apical foramen
before and after preparation. A ‘post-preparation node’ point was described when the minimum
minor diameter value was smaller than major diameter of apical 1.2 mm. Data were analysed
using one-way ANOVA, Tukey and Chi-square tests.
Results: Preparation resulted in a significant increase in the major diameter values regardless of the
instrumentation (p = 0.000). Preparation with Reciproc led to the significant increase in roundness
values (p = 0.000), whereas no significant difference was detected in specimens prepared with SAF
(p = 0.21) and Revo-S (p = 0.15).
Conclusion: Root canal preparation with SAF, Reciproc and Revo-S led to a significant increase in
the major diameter of apical 1.2 mm and resulted in high frequencies of the post-preparation node.