[Experimental study of preparing curved root canals with different instrument]

Area of Science:

• Endodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Root canal preparation aims to clean and shape the canal system.
• Different file systems, including stainless steel K-files and nickel-titanium (NiTi) rotary files, are used for this purpose.
• Understanding their shaping ability and effect on the apical foramen is crucial for successful endodontic treatment.

Purpose of the Study:

• To compare the shaping ability of hand ProTaper, stainless steel K-files, and rotary ProTaper.
• To evaluate the influence of these instruments on the apical foramen during root canal preparation.
• To assess the impact of root canal curvature on instrumentation outcomes.

Main Methods:

• Forty simulated resin root canals with varying degrees of curvature (20°, 30°, and <5°) were prepared.
• Instruments used included hand ProTaper, stainless steel K-file, and rotary ProTaper.
• Digital imaging captured root canal morphology and apical foramen size before and after instrumentation.
• Image analysis software (Auto-CAD) quantified root canal transportation and apical foramen enlargement.

Main Results:

• Rotary ProTaper (group B) showed significantly higher root canal transportation compared to hand ProTaper (group A) and stainless steel K-files (group C).
• The apical foramen size was significantly larger in group B than in other groups.
• A 30-degree canal curvature resulted in significantly larger apical foramen size compared to a 20-degree curvature post-instrumentation.

Conclusions:

• Both stainless steel K-files and NiTi files cause root canal transportation, with curvature being a primary factor.
• NiTi files, particularly rotary ProTaper, demonstrate a superior ability to maintain the original root canal shape and apical foramen size compared to stainless steel K-files.
• Proper instrument selection is essential for minimizing procedural errors and preserving root canal anatomy.