If a tooth recurs after a root canal treatment, it is usually considered that it can be treated with another root canal or apical surgery.
There are a number of reasons why a tooth may recur after a root canal treatment. This may be due to the depth of the filling, insufficient healing, and inflammation that still tends to develop; the affected tooth has a missed root canal, and the disease-causing microorganisms have not been completely removed during the previous root canal treatment; or, if there is periodontitis, and the tooth was only treated with a root canal, and there was no further periodontal treatment, the inflammation may recur as well.
In this case, you can remove the previous filling material, look for the missing root canal, and then redo the root canal treatment. If the inflammation recurs, apical surgery can be performed.
In general, you should pay attention to maintaining good oral hygiene and have regular oral health checkups. In daily life, you should avoid damaging your teeth with external forces, avoid biting hard objects with your teeth, and brush your teeth properly.