Often we forget about the possibilities inside of teeth. It’s so easy to say that a tooth is cracked when it appears to be failing. Here is a tooth story that demonstrates another possibility of what is actually happening on the inside.  In this case, it’s all about the middle mesial canal!

For context, the tooth was previously treated with tenderness to percussion, so the diagnosis was: Previously Treated and Symptomatic Apical Periodontitis.

So, let’s look at the tooth now.  The obturations are a few millimeters short.  That’s a definite source of bacteria, right? I question the patency in this case, for sure.

Are you looking at that “J-shaped” radiolucency around the mesial root? Studies show that the mesial root of the mandibular first molar is one of the most common roots to fracture.

So, is it reinfected or is this tooth fractured?

To answer, we have to go inside!

Once I started working and removing the gutta percha, I did something I do in every mandibular molar: I troughed in between the MB and the ML canals.  

And once I did, I found this:

A middle mesial canal!

No wonder there was a lesion around the mesial root. There was still original bacteria in that canal, so of course there was a radiolucency around that root!

Did you know the percentage of middle mesial canal can be anywhere from 2 to 18%? That’s pretty high.

So my recommendation to you is to look for it in EVERY SINGLE mandibular molar.


Check out my other Tooth Story blogs to raise your awareness of the endless possibilities in teeth so that you give teeth a chance.  There is so much more that we can do for our teeth.

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