Previously, we’ve explained that root canal treatment “RCT” (endodontic treatment) is microsurgical debridement (a precisely-performed cleanout of infected and/or inflamed tissue) inside the root of an infected tooth, followed by careful insertion of stabilizing, protective material into the tooth’s interior structure, filling and protecting the several “canals” present in each tooth root. Often, pain in or around the affected tooth, or a foul odor from the tooth, or both, indicate a need for RCT, but occasionally an infected tooth will not produce any symptoms.

Quality endodontic treatment requires exacting procedures and techniques including proper visualization of the tooth’s interior, precise measurements of the root length, proper filling technique, and more. But what happens if the procedure is not done to a high standard? Inevitably, bacteria and inflamed tissue will remain in the tooth.

This may result in continuing pain, foul odor, etc., but even more problematic, inadequate root canal treatment allows bacteria and inflammation to progress beyond the confines of the tooth into the bone around the tooth root. New areas of inflammation and infection can form that, while related to the original problem, now involve the bone. This is called “periapical periodontitis”.

Once periapical periodontitis develops, it is difficult to eliminate. Why? Because bone can serve as a breeding area for more, different, and tougher” types of entrenched bacteria, which often form an entrenched biofilm or “mixed infection”—areas where bacteria show strength in numbers and diversity.

The xray below shows a dark area (circled) at the end of the root. This is evidence of infection that has spread down from inside the root of the tooth to the tissue below. A textbook-perfect root canal treatment is shown in the right. The infection inside the tooth’s roots has been cleaned out, and the canals filled properly to their end with sealing material. Bacteria can no longer travel down the canals of the tooth into the tissue below.


Now that the bacteria in the tooth has been has been removed, the infection at the base of the root (the dark area) will soon heal and will no longer appear dark on future xray.


To the left is an example of root canal treatment that was done poorly the first time. This xray shows thinly-filled, incompletely treated canals, which resulted in bacteria traveling through the root of the tooth to cause periapical periodontitis at the base of the tooth, now affecting the bone of the jaw.

Bacteria have likely established n entrenched “biofilm” in the bone area. Additionally, the end of the root has been somewhat ‘eaten away’. (This is know as (external resorption). These problems developed because the canals of the root were not properly cleaned and filled, and one tooth contained an “extra” canal which was overlooked during the procedure and left completely untreated.

Here, is the same tooth after the root canal treatment has been redone. Notice that the canals are now cleaned and properly filled to the end (the white lines) and how a small amount of additional sealer has “puffed” out of the resorbed root end and microscopic canal to fully seal off any opening at the root end.

While this re-treatment is very good, eliminating this advanced infection so long-established in the bone is NOT a sure thing.

In fact, while root canal treatment is successful 96% of the time when done to a high standard the first time, treatment that needs to be redone has a success rate as low as 48% to 69%.

To summarize:

Once tooth pulpal inflammation/infection has progressed from the tooth to the bone (a condition called periapical periodontitis), the infection less responsive to even good treatment.

Poor treatment only incompletely cleans out the root canal areas and allows infections to progress or become chronic. Success of saving the tooth after such infections have taken hold lessens considerably.

Quality endodontic therapy ( root canal treatment ) done correctly the "first" time by a skilled dentist, who only provides root canal care, will lead to very high success rates long term. It is more expensive and less successful to "re-treat" a pooly treated and "re- infected" past root canal.




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