Fig. 1

Pre operative X ray before the primary treatment of tooth number 46 showing deep carious lesion reaching the pulp chamber

Fig. 2

Cone Fit and post operative X-rays during the primary treatment.

Fig. 3

After 4 months.

The patient is experiencing pain with very high tenderness to percussion on the fist lower right molar, clinical examination and X-rays shows an Acute Apical Periodontist.

A missed second distal canal was suspected since the treatment on the X-rays are satisfactory and reaching the entire working lenght and also that the lesion was observed in a very short period of time after the primary treatment.

A CBCT study was examined and confirms the diagnoses of a missed disco-buccal canal.

After mandibular block anesthesia and a buccal infiltration were performed, rubber dam was put in place along with liquid dam.

Once the access cavity was redefined DB canal was located under microscope. After scouting pus was found extruding from the orifice due to pressure build up inside the canal space.

Then preflaring was achieved with the orifice modifier from the TruNatomy system Dentsply Sirona.

The shaping was finalized with the Protaper Gold F1 to working length in all 4 canals.

Special care was taken while cleaning and shaping both distal canals specially isthmus cleaning with ultrasonic tips, irrigation with IrriFlex from Products Dentaires (Vevey, Switzerland ) and irrigant sonic activation using EDDY from VDW(Germany).

Fig. 4

Retreatment  stages with cone fit of 4 canals and post operative X-rays showing final result of the obturation

Fig. 5

6 months follow up X-ray  showing partial and undergoing healing.


It is not always easy to detect all canals on the PA, it is essential to take many angulation like mesial or distal shift x-rays.

In fact, periapical X-rays alone can never be enough to decipher the internal anatomy of some teeth nor give us a clear idea about the periapical status. This is why it is mandatory when indicated to prescribe a Cone Beam CT before performing the root canal treatment or when needed for any periapical diagnoses.

On another note, the use of magnification will help enormously the clinician to locate extra canal orifices during the access cavity preparation and interpretation.

Untreated space and remains of pulp tissue will lead in the majority of the cases to root canal failure. Once the entire root canal tissue is eliminated and cleaning is achieved, prognosis will be positive leading to a healing and a favorable outcome.

This case report shows that missed canals have a significant impact on treatment prognosis. This is why the clinician should be aware of all measures available and equipped with specific tools to maximize canal identification.


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