My new molar crown, infected, root canalled by hole, temporary filling fall out, so went different dr, is filling method same, if root canalled or not?

Is this the problem?: 1) you had a new crown placed on one of your molars (was this a replacement for a previous crown that failed?) 2) infection then occurred, they did a root canal treatment& placed a temp filling which fell out 3) you went to new dentist, this treatment is possible: remove current crown, build up tooth & place new crown. Or if the crown is intact with just a small hole, fill hole up with composite.

Next?: I am not sure of your question. It is common and usually not problematic to perform a rct through a crown. There may be some pain or discomfort for awhile but it should subside within a few days or week at most. Wether or not there is a temporary filling will not cause pain. The hole should be filled with a permanent filling as long as there is enough sound tooth structure present.