The ‘Hidden Canal’ Problem: Why MB2 Canals Matter in Upper Molars

🦷 What Is an MB2 Canal?

Upper molars often have more than one canal in the mesiobuccal root. The second canal in that root is commonly called MB2. Because it can be small or calcified, it may be difficult to locate without magnification and careful technique.

🔍 Why It Matters

If a canal is not treated, bacteria may remain in the tooth, which can contribute to persistent symptoms or non-healing in some cases. That said, symptoms are not always caused by a missed canal—cracks, leakage, or new decay can also be involved.

🔬 How Microendodontics Helps

• Operating microscope: Improves illumination and magnification to help identify tiny canal openings.
• Ultrasonics: Can help refine access conservatively.
• CBCT (when indicated): May help clarify complex anatomy if the scan is expected to change diagnosis or treatment planning.

🧭 What If an Old Root Canal Isn’t Healing?

When symptoms persist after a prior root canal, evaluation focuses on the full picture: the tooth’s restorability, the seal of the crown/filling, canal anatomy, and any cracks. If retreatment is appropriate, the goal is to disinfect and reseal the canal system and coordinate a well-sealed restoration.

ℹ️ Important Note

This page is for general education and does not diagnose your tooth. Whether an MB2 canal is present and treatable is determined after an exam and imaging review.

📚 References

• Buhrley LJ, et al. Effect of magnification on locating the MB2 canal in maxillary molars (J Endod, 2002).
• AAE & AAOMR. Use of CBCT in Endodontics—2015/2016 Update.