DentAIstudy
Endodontics

RCT Failure: Diagnosis, Causes & Management

A clear exam structure to recognise failed root canal treatment and plan retreatment or extraction.

Quick Answers

How do you define RCT failure in exams?

Persistence or development of signs and symptoms of periapical disease after root canal treatment.

What are the three main causes of RCT failure?

Persistent infection, inadequate cleaning/obturation, and coronal leakage or poor restoration.

When is nonsurgical retreatment indicated?

When the root canal is accessible and the tooth is restorable, with no vertical root fracture.

When should you extract instead of retreat?

When the tooth is non-restorable, has advanced periodontal disease, or vertical root fracture.

1. What examiners want when they say “failed RCT”

RCT failure questions test whether you can recognise persistent disease, list common causes, and choose a logical management option. The topic crosses OSCE, viva, and written exams in ORE, ADC, NDEB and MFDS.

2. Clinical and radiographic signs of failure

Always structure your answer into symptoms, signs, and radiographic findings.

  • Persistent pain or tenderness to percussion / palpation.
  • Swelling, sinus tract, or recurrent abscess.
  • Radiographic periapical radiolucency that persists or increases in size.
  • Underfilled, overfilled, or poorly condensed root filling.

3. Main causes of RCT failure

Causes — exam list

1. Persistent intraradicular infection (missed canals, inadequate cleaning).
2. Extraradicular infection or biofilm at the apex.
3. Poor obturation (short, voids, overextension).
4. Coronal leakage due to faulty restoration.
5. Procedural errors: ledges, perforations, separated instruments.
6. Vertical root fracture.
7. Non-endodontic lesion misdiagnosed as endodontic.

4. Stepwise approach to a failed RCT case

Examiners like a calm, logical flow rather than random facts.

  • Take detailed history: timing of pain, swelling episodes, previous treatment.
  • Clinical examination: tenderness, sinus tract tracing, mobility, periodontal probing.
  • Radiographs: periapical view, angled views, CBCT if indicated.
  • Assess restorability: remaining tooth structure, caries, cracks.
  • Discuss options: observation, retreatment, surgery, extraction, replacement.

5. Nonsurgical retreatment — exam flow

Retreatment steps

1. Remove existing restoration and assess coronal seal.
2. Isolate with rubber dam and disinfect the field.
3. Remove old gutta-percha using solvents, files, or rotary retreatment files.
4. Re-locate missed canals, correct working length, and re-shape canals.
5. Irrigate aggressively with NaOCl, EDTA, and intracanal medicament (e.g. Ca(OH)2).
6. Re-obturate with dense, well-condensed filling and place definitive coronal restoration.

6. When to consider surgical endodontics

Surgical options are considered when nonsurgical retreatment is not possible or has failed.

  • Good root filling but persistent periapical lesion.
  • Blocked canal, fractured instrument, or ledge that cannot be bypassed.
  • Need for biopsy of suspicious periapical lesion.

The classic surgical procedure in exams is apicoectomy with retrograde filling and curettage of the lesion.

7. When extraction is the best answer

Sometimes the safest treatment is to remove the tooth and plan for replacement.

  • Tooth is non-restorable because of caries or structural loss.
  • Vertical root fracture confirmed clinically or radiographically.
  • Advanced periodontal disease with poor prognosis.
  • Multiple failed attempts at retreatment.

8. How DentAIstudy helps

DentAIstudy can turn any failed RCT case into structured exam material:

  • Problem lists separating symptoms, radiographic findings, and causes.
  • Decision trees: retreatment vs surgery vs extraction.
  • Short viva lines for each management option.
  • Flashcards for key causes and outcome criteria.

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References

  • Ingle JI, Bakland LK, Baumgartner JC, editors. Ingle's Endodontics. 6th ed. BC Decker; 2008.
  • European Society of Endodontology (ESE). Quality guidelines for endodontic treatment.
  • Ng YL, Mann V, Gulabivala K. Outcome of primary root canal treatment: systematic review. Int Endod J.