Female 1 Follow-Up Studies 1 Humans 1 Male 1 Middle Aged 1 Periapical Periodontitis 1 Retrospective Studies 1 Root Canal Filling Materials 1 Root Canal Obturation 1 Root Canal Therapy 1 Thermafil Tooth, Nonvital 1 Treatment Outcome 1 clinical outcome 1 endodontic procedure 1 endodontics 1 female 1 follow up 1 human 1 male 1 middle aged 1 prognosis 1 retrospective study 1 root canal filling material 1 root canal obturation 1 root canal treatment 1 survival 1 tooth periapical disease 1 tooth pulp disease 1 treatment outcome 1