Define a ledge in endodontics.

• A. An artificial irregularity on the canal wall that prevents proper working length.
• B. A natural canal curvature that requires adjustment.
• C. A hole in the canal wall due to perforation.
• D. An irregularity on the canal wall that prevents proper working length.

Answer: (A)

A ledge is an artificial irregularity created on the canal wall during instrumentation, where the file deviates from the original canal path and forms a shelf-like irregularity that prevents obtaining or establishing the true working length. This distinguishes a ledge from natural canal curvatures or perforations. The key idea is that the irregularity is produced by the clinician’s instrumentation rather than being an inherent feature of the canal.