In the second appointment, after providing anesthesia with Novocain and application of rubber dam again, the temporary filling will be removed and the antibiotic will be removed using sterile water. The canal will be then dried. During this appointment, 20 ml of whole blood will be taken from your arm vein and will be used to prepare concentrated cells for injection into the prepared canal and sealed again with a temporary filling material. This part is different than what the investigators normally do for patients who need root canal treatment. For those patients the investigators fill the canals and seal the opening into the root canals with a permanent filling material.