The endodontic ledge: causes and management

Fig. 1

A 30 year old female patient was referred for the retreatment of tooth 36. The tooth was asymptomatic. The patient recalled having a root canal treatment almost 3 years ago.

The diagnosis was made: previously treated tooth with asymptomatic apical periodontitis.

After anesthesia and rubber dam placement, the composite filling was removed and the access cavity refined using ultrasonic tips.

Gutta-percha removal was done using rotary files while copiously irrigating with sodium hypochlorite to flush away debris.

Fig. 2

Looking at the initial radiograph, the presence of a ledge can be predicted because the filling material seems to be going in a straight line, not following the root’s curvature.

After removal of the old filling material, a 10 k file was used to scout the canals to the foramen. The DL, DB and MB were easy to negotiate. However, a blockage was felt in the ML canal as if the instruments were hitting a solid wall.

Fig. 3

The first step was to enlarge the coronal part 1mm shorter of the length reached by the 10 K file to remove all coronal interferences.

Then a pre-bent 08 K file was used to locate the canal lumen.

The search for the canal lumen was made by directing the tip of the file towards the inner wall, because ledges are usually located on the outer wall of the canal. It is advised to have rubber stoppers with directional signs to be able to direct the files toward the inner wall.

When the canal lumen was found, and without removing the K file from the canal, the 08 K file was used in a watch winding motion to reach the WL. At that level, pull push movements of small amplitude were applied in order to soften the ledge.

Then a 10 K file, with the same pre-bending as the previous file, was also inserted until it bypassed the ledge, and pull push motion was applied as previously described.

The pull-push motions were stopped when the file became loose in the canal.

Fig. 4

Then to shape the apical part, controlled memory NiTi files were used because they provide less canal transportation and more centering ability when compared to stainless steel manual files. In addition to that, it is less time consuming.

It is important to note that not all NiTi files can be used to bypass a ledge. The choice of instruments should be based on their ability to stay in a martensitic phase at body temperature. In this phase, the files do not return to their initial shape and can maintain the bending they are given.

To start, a rotary file of small diameter was prebent, and inserted manually past the ledge.

Inserting rotary files manually allows for better tactile sense. When the file bypasses the ledge, the endo motor is attached to it and activated.

The same process is repeated with the shaping files up to a size 25/.04

Fig. 5

After shaping, gutta percha cones were adapted and the warm vertical condensation technique was used to fill the canals.

The patient was referred back to her dentist for a final restoration.

Fig. 6

Angulated x-rays

Fig. 7

Follow up at 1 year post-op shows complete healing of the lesions. The patient had refused a crown for financial reasons and only agreed to a composite filling.