Apical Patency, Periapical Lesion Volume, and Postoperative Pain After Root Canal Treatment

Eligible participants received standardized single-visit root canal treatment under local anesthesia and rubber dam isolation. In the apical patency group, a #10 stainless-steel K-file was passively advanced approximately 0.5-1 mm beyond the working length after each rotary instrument without intentional apical enlargement or dentin removal. In the no-apical-patency group, canal preparation was confined to the working length and no instrument was intentionally extended beyond the apical foramen. Conventional randomization was not used. To maintain numerical balance during enrolment, a systematic consecutive allocation approach was used, whereby apical patency was performed in one case and not performed in the subsequent case. Participants were aware of the treatment approach. Postoperative pain was assessed with a 100-mm visual analog scale at 8 hours, 24 hours, 3 days, 5 days, and 7 days. Analgesic use was also recorded. Periapical lesion volume was measured in cubic millimeters using manual three-dimensional segmentation with ITK-SNAP on eligible CBCT images obtained for clinical purposes.

Inclusion criteria

• Adult patients.
• Systemically healthy and not using regular systemic medications.
• A single-rooted maxillary anterior tooth requiring primary root canal treatment.
• Diagnosis of chronic apical periodontitis in the study tooth.
• The tooth was restorable.
• Absence of root fracture or crack.
• Absence of internal or external resorption.
• Root canal negotiable to the apical region with a small hand file.
• Ability to establish a reliable working length.
• Availability of a CBCT scan of the relevant maxillary anterior region, previously obtained for clinical purposes or indicated during the treatment process.

Exclusion criteria

• Pregnancy or breastfeeding.
• Previous endodontic treatment of the study tooth.
• Severe canal calcification.
• Suspected root fracture or crack.
• Internal or external root resorption.
• Periodontal probing depth of 5 mm or greater.
• Previous surgical intervention in the relevant region.
• Inability to negotiate the root canal.
• Inability to establish a reliable working length.