Root canal treatments are successful about 90 – 95 % of the time. However, there are also situations in which your endodontic treatment may fail. If that happens, then your general dentist needs to decide whether to retreat it or opt for an alternative treatment method. Here are three things that may help your dentist make the decision:

Why the Treatment Failed

The reason for the treatment failure is important because it may provide pointers as to whether the retreatment may work or not. If the retreatment may not work, then you may be better off with alternative treatments such as dental implant.

For example, if the treatment failed because one of the canals wasn't properly cleaned, then a retreatment may be feasible. However, if it was occasioned by a physical trauma that cracked your tooth, then retreatment may not work (depending on the extent of the crack).

Probing

The dentist is also likely to use a periodontal probe to measure the depths of the pockets around the affected tooth. This will give an indication of the health of the tissues surrounding and supporting the tooth (the periodontium).  The statuses of these tissues determine whether or not the tooth can be saved via retreatment.

For example, if the pockets are too deep and wide, then it may mean that the periodontium is too damaged and weak to support the tooth. Such a tooth may not be stable in the long run, and treating it is akin to prolonging the inevitable. In such a case, it makes more sense to replace the tooth with an artificial one.

Radiography

There are cases where physical examination may not be effective in determining why a root canal treatment failed, and if it can benefit from further treatment. In such cases, the dentist may need pictures of the internal structure of the tooth for further assessment.

Radiography (such as x-rays or computed tomography) is a good way of getting these pictures. For example, it may reveal that one of the tooth's roots is fractured or broken. The dentist then examines the reason for the failure and determines a suitable way forward.

As you can see, your dentist will not just throw a dice to determine whether to retreat your root canal or not. Such a decision will only be made after a careful examination of the extent of damage, reason for failure and chances of success with retreatment. Therefore, it is important to take your dentist's recommendation seriously.