MB2 near palatal

Anatomy of the mesio-buccal 2 (MB2) canal that is close to palatal canal

The mb2 canal can be close to palatal canal. This is not where it typically exists but needs to be an area that dentists are looking. When performing root canal therapy on the maxillary molars, one of the most commonly overlooked anatomical variations is the mesio-buccal 2 (MB2) canal. This tiny but significant canal can greatly impact the success of endodontic treatment, making its identification and management crucial.

What is the MB2 Canal?

The mesio-buccal root of the maxillary first molar typically contains two canals:

  1. Mesio-buccal 1 (MB1) – The primary canal in the mesio-buccal root.
  2. Mesio-buccal 2 (MB2) – A second, smaller canal that may join MB1 or have a separate exit at the apex.

The MB2 canal is frequently missed in endodontic procedures, leading to persistent infection, post-treatment pain, or treatment failure.

PA of a maxillary molar with a mesial buccal (MB2) canal close to the palatal canal.

How Often is MB2 Present?

Studies show that the MB2 canal is present in more than 90% of maxillary first molars. This number drops to around 40% in the second maxillary molar. However, the MB2 detection ability varies depending on method and practitioner. Despite its high prevalence, MB2 is often challenging to locate due to its position and smaller diameter. It’s even more challenging to cleanse and shape. Thus some MB2 canals that can be seen can not be cleansed and shaped.

Does MB2 Join MB1? Does the MB2 canal being close to palatal canal impact whether or not they join?

One of the key considerations in treating the MB2 canal is whether it has a separate exit or merges with MB1. Research indicates:

  • In 50-80% of cases, MB2 joins MB1 before reaching the apex.
  • In the remaining 20-50%, MB2 maintains a separate exit, requiring thorough instrumentation and obturation.

The research does not show how the initial presentation of location of the MB2 impacts whether or not it joins the MB1. Our professional experience is that when the mb2 canal is close to palatal canal, it has a separate exit and does not join the MB1. Therefore it is even more important that we find and clean those canals.

Mesial buccal 2 canal close to the palatal canal.

How to Locate and Treat MB2

  1. Magnification & Illumination – A dental operating microscope (DOM) significantly improves MB2 detection. Magnification of 4.0x starts to increase the probability of finding the MB2.
  2. Troughing with Ultrasonics – Carefully removing dentin with ultrasonics can expose the MB2.
  3. CBCT Imaging – 3D imaging helps visualize the number and orientation of canals before treatment.

What about the MB2 canal that’s close to the palatal canal?

This means that the MB2 is closer to the palatal canal than the MB1 canal. It will still be mesial of a line dissecting the MB1 and palatal, as the MB2 canal always is. It may or may not appear to be in the developmental groove connecting the two canals. We consider this to be a potential anatomical variation.

Conclusion

Failing to locate and treat MB2 is a leading cause of endodontic failure in maxillary molars. Given that MB2 is present in 90%+ of cases and joins MB1 in 50-80% of them, recognizing its anatomy is essential. Using magnification, ultrasonics, and CBCT significantly increases the success of finding and treating MB2, ultimately improving long-term outcomes for patients.

Have you encountered challenges treating MB2 canals? Share your experiences below!