Oval-shaped canal retreatment with self-adjusting file: a micro-computed tomography study

Area of Science:

• Endodontics
• Dental Materials Science
• Micro-Computed Tomography Imaging

Background:

• Root canal retreatment is crucial for eliminating persistent infections.
• Oval-shaped canals present unique challenges for complete filling material removal.
• Incomplete obturation removal can harbor necrotic tissue and bacteria, risking reinfection.

Purpose of the Study:

• To evaluate the efficacy of rotary retreatment files in removing filling material from oval canals.
• To assess the added benefit of the self-adjusting file (SAF) in conjunction with rotary instruments.
• To compare retreatment outcomes based on initial obturation techniques: cold lateral condensation (CLC) and vertical condensation (VC).

Main Methods:

• Twenty maxillary premolars with oval canals were prepared and obturated using CLC or VC techniques.
• Retreatment was performed using rotary instruments, followed by the SAF in a split group.
• Micro-computed tomography (micro-CT) was used to quantify the residual filling material volume after each step.

Main Results:

• Rotary retreatment alone left 1.59% (median) filling material in CLC and 0.42% in VC groups (p<0.05).
• After SAF use, residual material decreased to 1.26% in CLC and 0.12% in VC groups (p<0.05).
• The SAF significantly enhanced filling material removal in both obturation groups (p<0.05).

Conclusions:

• Complete removal of filling material from oval canals was not achieved by rotary instruments alone.
• The addition of the SAF significantly improved the cleanliness of root canals after retreatment.
• Enhanced canal cleanliness with SAF may improve irrigant efficacy and reduce the risk of persistent infection.