Yaylali IE, et al. - The authors conducted a prospective trial in order to gauge whether maintaining apical patency (AP) during endodontic treatment increased the postoperative pain in molar teeth with necrotic pulp and apical periodontitis. When compared with the nonapical patency (NAP), the maintenance of AP in molar teeth with necrotic pulp and apical periodontitis was related to less postoperative pain.