Factors Affecting the Removal Time of Separated Instruments

Area of Science:

• Endodontics
• Dental Materials Science

Background:

• Separated endodontic instruments can negatively impact treatment success.
• Ultrasonic techniques combined with dental operating microscopes offer effective removal of separated instruments.

Purpose of the Study:

• To evaluate the influence of root canal curvature and separated instrument length on the time required for loosening and retrieving instrument fragments.
• To analyze the efficiency of different retrieval methods.

Main Methods:

• Retrospective evaluation of 128 separated instrument retrieval procedures.
• Cone-beam computed tomography (CBCT) for measuring instrument length and canal curvature.
• Utilized ultrasonic instruments, wire loops, and XP Shapers for fragment removal.
• Recorded procedure times and performed statistical analysis using log-normal regression, structural equation modeling, and linear regression.

Main Results:

• All separated instruments were successfully retrieved.
• 89.8% of instruments were removed using ultrasonic instruments alone (mean time: 221 seconds).
• Instrument removal time was significantly influenced by both instrument length and root canal curvature.
• Longer preparation times were observed with increasing separated instrument lengths, particularly when loop devices were necessary.

Conclusions:

• The preparation phase is crucial for successful separated instrument retrieval.
• Instrument length and root canal curvature are independent predictors of retrieval time.
• Increased file lengths and higher degrees of canal curvature generally extend procedure times.