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

Area of Science:

• Endodontics
• Dental Materials Science
• Scanning Electron Microscopy

Background:

• Dentinal crack formation is a concern in root canal preparation.
• Evaluating new single-file systems for their impact on dentinal integrity is crucial.

Purpose of the Study:

• To compare dentinal crack formation in root canal walls after using three single-file systems with continuous rotation.
• To assess the incidence of cracks using scanning electron microscopy (SEM).

Main Methods:

• Seventy mandibular premolars were divided into five groups: Neolix NiTi, OneShape, OneCurve, Hand File (positive control), and unprepared (negative control).
• Roots were sectioned at 3, 6, and 9 mm from the apex after preparation with water irrigation.
• Sections were examined under SEM at ×100 magnification for crack detection. Statistical analysis was performed using the Chi-square test.

Main Results:

• Significant differences in crack formation were observed in the apical (P=0.012) and coronal (P=0.002) thirds across all groups.
• Maximum cracks occurred with One Shape in the apical third (55%) and Neolix NiTi in the coronal third (70%).
• OneCurve showed a statistically significant difference in crack formation across apical, middle, and coronal thirds (P=0.042).

Conclusions:

• A significant difference in dentinal crack formation exists between the apical and coronal thirds.
• The OneCurve file system demonstrated the lowest incidence of cracks compared to Neolix NiTi and OneShape.
• OneCurve may be a preferred choice for root canal preparation due to its lower crack induction potential.