Effectiveness of different endodontic files for preparing curved root canals: a scanning electron microscopic study

Area of Science:

• Endodontics
• Dental Materials Science
• Microscopy

Background:

• Root canal preparation aims to clean and shape the canal system.
• Maintaining the natural root canal anatomy is crucial for successful endodontic treatment.
• Different endodontic files may influence the final preparation shape.

Purpose of the Study:

• To compare the shaping effectiveness of four different endodontic files.
• To evaluate the impact of these files on root canal anatomy, particularly the apical third.
• To assess the conservation of apical constriction and the incidence of ledging.

Main Methods:

• Scanning electron microscopy (SEM) was used to analyze 80 prepared curved root canals.
• Four types of endodontic files were tested: Tri-files, Flex-R files, Flexofiles, and conventional K-type files.
• Files were used with linear and circumferential motions, progressing to a size 30 file in the apical third.

Main Results:

• Tri-file and Flex-R files produced well-centered, tapered preparations.
• These instruments effectively conserved apical constriction and avoided ledging.
• Flexofile and conventional K-type files frequently resulted in ledging and alteration of apical constriction, creating an 'hour-glass' shape.

Conclusions:

• Tri-file and Flex-R files demonstrate superior shaping ability in curved root canals.
• These files better respect the natural root canal anatomy, minimizing procedural errors.
• Flexofile and conventional K-type files are associated with significant anatomical deviations during preparation.