Nonsurgical Retreatment, Instrument Separation, and Management of Procedural Complications
When to retreat
Retreatment is indicated when a tooth remains symptomatic or shows a new or persisting periapical lesion, when the root filling is inadequate in length, density or taper, when coronal leakage is evident, or when the tooth requires a new restoration that will expose the canal. Initial treatment succeeds in roughly 85–95% of cases; retreatment outcomes are somewhat lower (about 75–85%), so the patient should be counselled realistically.
Technique
Remove the coronal restoration and any post, then remove gutta-percha with rotary retreatment files, heat, or solvents such as chloroform or eucalyptol, always with isolation and suction. Re-establish patency, re-determine working length, and assume that a previously treated canal still harbours biofilm - reinstrument and re-irrigate as vigorously as in a primary case.
Separated instruments
Prognosis depends on the level of separation, whether the canal can be bypassed, the presence of infection, and the ability to clean and fill beyond the fragment. A separated file in a clean apical third with a bypassed canal may heal; an infected canal blocked by a fragment usually needs removal or surgery. Attempt removal under magnification with ultrasonic tips, but know when to stop and refer.
Other complications
- Perforation: seal immediately with a calcium-silicate material; prognosis worsens with delay and with a more coronal location.
- Ledge, transport and zip: re-establish patency and use precurved files; severe transport may need surgery.
- Sodium hypochlorite accident: stop, irrigate with saline, allow drainage, prescribe analgesia, and review.
- Subcutaneous emphysema from air-driven handpieces: swelling, crepitus; usually self-limiting but must be recognised.
Rule of thumb: retreatment is a repeat of the whole cleaning process, not simply a replacement of the filling.