Lesson transcript

Hi guys. Hi Calogero Bugea from Italy. I'm a Gold member of the Style Italiano Endodontics. During this lesson I will talk about how to identify confluences, because their comprehension of the anatomy of the root canal system is an important factor when using the rotary nickel titanium instruments. 

Wayne classified merging canals in four types depending on the configuration of the main root. Canal along its course from the floor of the pulp chamber to the apex. This classification may be very practical to use in our daily practice when we have to treat two canals in one root. In type 1, 1 horifice, 1 root canal, 1 apical foramen. In type 2: 2 horifices, 2 root canals, 1 apical foramen. In type 3, we have 2 horifices, 2 root canals, 2 apical foramina. In type 4: 1 horifice, 2 root canals, 2 apical foramina. In type 1 and 3 the existing canal can be clean and shaped and obturated separately as if they were in different roots. In no situation in which we treat canals with possible confluences, we have to treat each canal root separately and not together. For example in 50 percent of cases, they mesio vestibular lower molar canal shares an apex with the mesio lingual canal. This canal, if it is confluent, it can be prepared in a conservative manner with less risk of weakening and stripping the root. 

Early diagnosis is fundamental to prevent over instrumentation and transportation of the apical foramen. If we shape the apex twice from two different directions we increase the possibility to transport the apex and create at drop foramen, difficult to manage during obturation. Fortunately, in a high percentage of cases an early diagnosis can be made. Great care must be taken during the cleaning, shaping and packing procedures. Another advantage of an early diagnosis is to prevent and reduce the risk of instrument fracture. In fact, in this area the abroupt change of direction in the common area can cause a lot of stress to the endodontic instrument. How to evaluate the presence of a confluence? 

There are different methods that we can use in different steps of the endodontic treatment to identify and confirm the confluence. Gutta percha cones and key files, apex locator, gutta percha cones and plastic carrier. The best method in my opinion to evaluate the presence of a confluence is with the use of gutta percha cones and k-files. I can visualize directly the confluence on a gutta percha cone. In a upper molar due to the presence of a MB2, that in a high percentage of cases is confluent, the first canal to prepare is the mesio-buccal canal. When we finish the preparation and the canal is ready to receive a gutta percha cone, we can introduce in the MB2 canal a small file. Sometimes it's possible to feel that contact with the cone, sometimes it is impossible, but in both cases when we extract the cone always after the k-file, if the conference exists we can see more some grooves scratches or folds, left by the non-invasive instrumentation of the MB2. This method is very efficient as it only requires few minutes to investigate the presence of a conference. This methods can fail in rare situations in which the k-file on the confluent canal is somehow unable to scratch their master cone. Another method requires the use of an electronic apex locator. After that the canal has been prepared, the operator checks the working length on the second canal with the use of an electronic apex locator. Then the operation is repeated leaving the last apical file inserted in the prepared canal at the foramen. If the working length of the second canal this time appears to be shorter by several millimeters, this would indicate that the second canal is sharing the foramen with their first canal. These method can be affected by the presence of irrigants or closed canals. Another method that we can use to confirm the presence of a confluence, is the use of a plastic carrier or gutta percha cones.

In case of confluence, for example, in a lower molar if we put the carrier into the mesio-lingual or in the mesio-vestibular canal, each carrier reach the working length. When are placed simultaneously, they can only advance alternatevely, if thevestibular goes to the working length, the lingual stay shorter and vice versa. The same operation may be done with gutta percha cones obtaining the same results. If only at this time we note the presence of a confluence, we have shaped the canal more than necessary, with the risk of over instrumentation and drop-foramen formation.

This method is very useful to confirm the presence of a confluence and to prepare in a perfect manner the gutta percha cone and the carrier for the obturation. During the irrigation in order to change frequently the solution, aspiration of the irrigant solution is recommended. In this manner, when the tip of the needle goes beyond the confluence, the solution will be drained from two canals at the same time. Aspiration and can be done with a dedicated endodontic irrigation tip. It's advisable to do these not only to confirm the confluence, but also to clean the confluence area. Even in the presence of multiple canals in one root, the procedures regarding the identification are the same.

With traditional X-ray, it's impossible to analyze a confluence of prior the treatment. It's very important for an endodontist to know very well all the possible variation. Canals might share part of the root canal system and have different ports of exit. I hope that you find these tips and tricks about how to identify and manage confluent canals very useful in your practice. 

Thank you for your attention.

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