It has equally been found in infected teeth that had not been previously endodontically treated. Nevertheless, it is most frequently observed in teeth that have suffered recurrence, that is to say failure of previous endodontic treatment.
También se ha encontrado en dientes infectados sin historia de tratamiento de endodoncia previo, pero donde se observa con mayor frecuencia es en dientes que han presentado recidiva, es decir, fracaso del procedimiento endodóntico.