Decision making when dealing with broken instruments 

Fig. 1

A 60 year old man was referred for the retreatment of teeth (16) and (17). The patient’s complaint was related to the crowns, mainly the accumulation of food in the interproximal spaces. So retreatments were scheduled before preparation for the new crowns. The teeth were asymptomatic. The initial radiograph shows inadequate previous endodontic treatments with a long broken instrument in the palatal canal of tooth (16). 

Fig. 2

After anesthesia and rubber dam placement, access cavities were corrected using ultrasonic tips. The filling material was removed with rotary NiTi instruments without solvent. The canals were copiously irrigated to remove debris. A 10 k file was used to negotiate the canals, except the palatal canal of tooth (16), till the foramen. 

Concerning the broken fragment, the decision made was to try removing it for the following reasons: 

• Access was relatively easy, the patient was cooperative and had a wide mouth opening. 
• The coronal part of the instrument was seen while operating under microscope and it extended into the coronal part of the canal.  
• The instrument was long, so bypassing it would be more difficult.  
• The palatal canal in that case is straight. 

Fig. 3

After preflaring, an ultrasonic tip ED6 was used from the inner wall side to vibrate the fragment until it “jumped” out of the canal. Before starting the vibrations, it was verified that the instrument had enough space next to the ultrasonic tip so that it could move coronally and not be pushed apically. It is important to note that the other orifices in the tooth were blocked with Teflon during this process to prevent the re-entry of the fragment in another canal. 

Fig. 4

After removal of the broken instrument, the treatment was continued as usual. Obturation was done using the warm vertical condensation technique. The access cavities were temporarily sealed and the patient sent back to the prosthodontist for completion of the treatment. 

Fig. 5

A 30 year old woman was referred for the retreatment of tooth (37). 

Clinically, the tooth was tender to percussion and mastication. 

The initial radiograph shows : 

• A short obturation in both roots and a slightly enlarged lamina dura around the apexes. 
• A broken instrument in the middle third of the mesial root: not too long but small in diameter. 
• A shaping mishap in the distal root, commonly seen with the inappropriate use of Gates Glidden resulting in an excessive removal of dentin and over-enlarging of the canal which leads ultimately to the weakening of the tooth. 

After anesthesia, the rubber dam was placed and access cavity was done using burrs followed by ultrasonic tips. 

Gutta-percha was removed using rotary NiTi files without solvent. A copious amount of sodium hypochlorite was used to flush away debris. 

The distal and MB canals were scouted till the foramen and shaped. 

Fig. 6

Concerning the instrument in the ML canal: 

• The patient had a limited mouth opening making the access difficult. 
• The instrument is not too long and is small in diameter. 

Therefore, the decision was to try to bypass the instrument. To do that, preflaring was done to remove coronal interferences. 

It is important to know that most instruments when they break, they lean on the outer wall of the canal because of their tendency to straighten themselves. Therefore, using  a 10 K file with a pre bent tip, it should directed towards the inner wall to try and find a path next to the broken fragment. After each try, the 10 k file is inspected and cleaned or replaced in case it shows any sign of distorsion. When it progresses 2 mm, an xray is taken to verify it is in the correct path. 

The canal is enlarged progressively until the 10 k file reaches the foramen. 

For shaping this canal, small tapered files (4%) were chosen. 

Fig. 7

Cones were fit, and the canals filled using the warm vertical condensation technique. The patient was referred again for the prosthodontic part of the treatment.

Fig. 8

Final X-rays