Effect of Apical Patency on Periapical Lesion Healing

This prospective, non-randomized controlled clinical trial evaluates the volumetric effect of maintaining apical patency on the healing of periapical lesions in maxillary anterior teeth with pulpal necrosis. The study is conducted at the Recep Tayyip Erdogan University Faculty of Dentistry, Department of Endodontics.

Study Design and Standardized Interventions Participants meeting the eligibility criteria (adults aged 18-60 with a minimum 2 mm periapical lesion on maxillary single-rooted teeth) are assigned to one of two treatment arms. In the Apical Patency group, a size #10 K-file is passively advanced 0.5-1.0 mm beyond the apical foramen after each rotary instrument use to maintain canal patency without enlarging the constriction. In the Non-Patency (Standard Care) group, instrumentation is strictly confined to the established working length, and the apical foramen is not intentionally penetrated after the initial glide path preparation. To ensure consistency, all endodontic procedures are performed by a single experienced endodontist using strictly standardized chemo-mechanical protocols (2.5% NaOCl, 17% EDTA, rotary instrumentation, and standard obturation techniques).

Radiological Assessment and ALARA Compliance The healing process is monitored using a combination of two-dimensional (2D) and three-dimensional (3D) imaging. Standard 2D periapical radiographs are obtained at the 6-month post-operative follow-up to evaluate intermediate healing. For the primary 3D volumetric assessment, Cone-Beam Computed Tomography (CBCT) scans are evaluated at baseline (T0) and at a 12-month follow-up (T1). To adhere to the ALARA (As Low As Reasonably Achievable) principle, no additional CBCT scans are taken solely for research purposes; the study exclusively utilizes CBCT images acquired for routine clinical indications where 2D radiography is insufficient.

Evaluation Methodology CBCT scans are exported in DICOM format and analyzed using 3D image segmentation software (e.g., ITK-SNAP). The 3D segmentation involves defining the Region of Interest (ROI) across axial, coronal, and sagittal planes to generate a volumetric model and calculate the total lesion volume in cubic millimeters (mm³). To eliminate bias, image analysis is conducted independently by two blinded, experienced observers (an endodontist and an oral radiologist). Inter-observer reliability is statistically evaluated using the intraclass correlation coefficient (ICC), with a third expert consulted in case of discrepancies.