Retreatment of a first mandibular molar with three independent mesial canals

Fig. 1

A 40-year-old patient comes to the office with severe pain after broken his composite filling while eating.

Exploring the preoperative X-ray we can see the presence of a threaded post in the mesial root and incomplete cleaning and shaping of both roots, especially the mesial one. 

Following the Recommendation 3 of the AAE and AAOMR Joint Position Statement we take a CBCT for suspecting complex anatomy with some extra canal.

The diagnosis was previously treated tooth with symptomatic apical periodontitis.

Fig. 2

Image of the sagittal plane of the CBCT where we can see the apical periodontitis because of an incomplete treatment of the two roots and additional canals in both.

Fig. 3

Image of the axial plane of the CBCT showing the distance between mesial canals and the extra canal in the distal root.

Fig. 4

Image of the coronal plane of the CBCT showing the complexity of the mesial root and all its canals.

Fig. 5

First of all we have to eliminate the old composite filling and then, we can see the threaded post and remains of cement in the pulp chamber.

In this case, we cleaned the cement and removed the threaded post with a ultrasonic tip.

Once the pulp chamber was cleaned, we activated the tip for removing the post, unscrewing it in an anticlockwise direction. 

It is important not to apply lateral forces with the ultrasonics in order to avoid a root fracture.

Fig. 6

After cleaning the pulp chamber and removing the threaded post, we can see there is some gutapercha inside the mesial isthmus. 

We use a Micro-Opener for looking for the middle mesial in this area.

The cleaning of the isthmus was carried out with EndoTracer 004 (Komet) for eliminate any coronal interference.

Once we found the middle mesial, we filled the chamber with 4,25% NaOCL and removed the coronal gutta-percha using a Gates Glidden number II. For the middle third we used a heat treated file.

As soon as the coronal and middle third was cleaned, we measured for the first time the canals and confirmed that the mesial canals were independent. Then, proceeded to clean the apical area using Hedstroem and K-Files.

We repeated the measuring of the canals after the apical third was completely cleaned and ended up increasing the apical preparation up to 35/03 in mesials and 40/03 in distals.

Fig. 7

During all the treatment, 4,25% NaOCl was used, filling the pulp chamber while shaping and cleaning all the canals after the entrance of each file.

Right after the mechanical disinfection was completed, we started the final irrigation protocol.

Ultrasonic activation of 4,25% NaOCl in all canals, followed by apical negative pressure, with both 4,25% NaOCl and 17% EDTA, using a tip that allow us to reach the apical third without any problem.

In this case we used Irriflex for the suction and delivery of the irrigants to the apical third.

Fig. 8

Final rinse with 4,25% NaOCl without any kind of activation and after that, physiological serum to clean the remains of the irrigants before obturation.

All the canals were dried with paper points, leaving them with moisture, since in this case, we used an hydraulic cement for the obturation.

Fig. 9

For the obturation, we gauged the 4% gutta-percha cones up to 40 in mesial canals and 45 in distals. 

We delivered a heat compatible BC sealer to the middle third and brought the gutta-percha cones to the working length using soft pressure, without pumping the cones.

After that, warm vertical compaction was performed for the final obturation of all the canals.

Fig. 10

Orthoradial projection, showing the untreated anatomy of both roots and the correct filling of all the canals.

Fig. 11

Mesioradial projection shows the three canals in the mesial root and gives us a better projection of the Vertucci Type II configuration of the distal root.

Fig. 12

Distalizing the X-Ray focus we can see the three independent mesial canals more clearly, showing a Vertucci type VIII configuration.