LEDGE (causes and management )

CAUSES

1. Incorrect or insufficient access cavity preparation
2. Incorrect assessment of root canal direction and curvature
3. Incorrect length determination of the root canal
4.  Re-treatment ,Occasionally, after removal of pre-existing filling materials or fractured instruments from the root canal, dentists may encounter ledges that had already been formed by previous attempts to negotiate the canal.
5. An attempt to negotiate a calcified or a very narrow root canal .
6. During post-space preparation after the completion of root canal treatment.
7. Use of non-precurved stainless-steel instruments in curved root canals
8. An attempt to retrieve or by-pass a fractured instrument or a foreign object (pin, post, etc.) from the root canal .

MANAGEMENT

         Copious irrigation with sodium hypochiorite and frequently replenished chelating     agents is required throughout the procedure.

Pre-enlargement of the canal coronal to the ledge is obtained by removing any curvature or obstructions.

The ledge is first probed with a precurved K-ffle ISO size 08 or 10. Hand instruments provide a better tactile sensation and are thus preferred to rotary instruments. In order to by-pass the ledge and gain access to the apex, the shortest instrument that can reach the level of the ledge should be used in a ‘watch-winding’ and gentle ‘picking’ motion of a short amplitude to look for a catch. Shorter instruments provide more stiffness and allow the clinician’s fingers to be positioned closer to the tip, resulting in a greater tactile sensation and control over the instrument. Directional tear-shaped rubber stops can be used on the file in order to orient its curvature.

The use of endodontic pathfinders and C-files that have originally been introduced for the initial instrumentation of the root canal can be very helpful when attempting to by-pass a ledge.

                                                REF: Endodontic Topics 2009, 15, 56—74