Effect of various single file systems on microcrack formation in root canals: Scanning electron microscope study

The aim of this study was to compare dentinal crack formation in root canal walls following 3 single file systems with continuous rotation under a scanning electron microscope (SEM).

In this SEM study, seventy mandibular premolars were randomly divided into 5 groups. 3 experimental groups (n = 20) and 2 control groups (n = 5) as follows: Group I: Neolix NiTi file system, Group II: OneShape systems, Group III: OneCurve file system, positive control: conventional Hand File system, negative control: unprepared. After root canal preparations, the roots were sectioned at 3, 6, and 9 mm from the apex with water irrigation. The sections were inspected in all directions under SEM at × 100 magnification to determine the presence of cracks. The Chi‑square test was used to analyze the data. There is a statistically significant difference in the crack formation between the apical third (P = 0.012) and coronal third (P = 0.002) when comparing all the 5 groups. No significant difference is found in the middle third (P = 0.46). P < 0.05 is considered statistically significant.

Maximum cracks in the apical third were seen with One Shape file 11 (55%) and in the coronal third with Neolix NiTi 14 (70%). There is a statistically significant difference in the crack formation only in OneCurve when comparing the apical, middle, and coronal third for the individual group (P = 0.042).

There was a significant difference in crack formation in apical and coronal third. OneCurve caused the least incidence of cracks when compared to other file systems. OneCurve file system can be a choice for canal preparation over Neolix Niti and OneShape.