The aim of this clinical study is to evaluate the effect of root canal filling, which is the last stage of root canal treatment (RCT), on the post-operative pain level on single rooted permanent teeth with wide lesions with apical periodontitis, and the effect on the healing of the periapical tissue and lesion by comparing periapical radyography images, which was taken at the beginning and after one year.

This study aims to evaluate the impact of different root canal filling techniques on postoperative pain levels and the healing of periapical tissues in teeth with periapical lesions, using periapical radiographic imaging. Specifically, the effects of resin-based sealers, bioceramic-based sealers, and two obturation techniques-cold lateral compaction and warm vertical compaction-will be compared. Postoperative pain will be assessed using VAS (Visual Analog Scale) and VRS (Verbal Rating Scale) following the final stage of root canal treatment in incisor and premolar teeth with single roots. Additionally, the healing of periapical lesions will be evaluated by comparing periapical radiographs taken at baseline and at a one-year follow-up. To date, no study has been found in the literature that evaluates these specific combinations of materials and techniques using periapical radiographic imaging.

The study includes four experimental groups based on the combination of obturation technique and sealer type as follows:

Group 1: Cold lateral compaction with AH Plus (epoxy resin-based sealer)

Group 2: Cold lateral compaction with AH Plus Bioceramic (calcium silicate-based sealer)

Group 3: Warm vertical compaction with AH Plus

Group 4: Warm vertical compaction with AH Plus Bioceramic

All treatments will be performed under standardized clinical conditions by an experienced endodontist using a rubber dam in aseptic conditions. Chemomechanical preparation will be done using rotary NiTi instruments and an irrigant protocol consisting of Sodium Hypochlorite (NaOCl), Ethylenediaminetetraacetic Acid (EDTA), and distilled water using Ultrasonic irrigation device. Root canal filling will be performed in a single visit for all patients.

VAS and VRS scores will be recorded at multiple time points postoperatively: immediately after treatment, and at 6, 12, 18, 24, 48, and 72 hours, as well as at 1 week and 1 month. Pain diaries will be provided to all participants.

Radiographic evaluation will be performed using standardized periapical radiographs taken with a parallel technique. Periapical healing will be assessed by comparing lesion size at baseline and at 1 year by two blinded observers.

This study aims to provide clinical data that may guide endodontic decision-making regarding the choice of sealer and obturation technique, particularly in teeth with pre-existing periapical pathology.

Inclusion Criteria:

• Single rooted anterior and premolar teeth with radiographically confirmed periapical lesions classified as Periapical Index (PAI) scores of 4 or 5 will be included in the analysis
• Age between 18 and 60 years
• Systemically healthy individuals
• To be able to read and sign the informed consent form
• Physical and mental fitness to undergo treatment
• Willingness to attend all follow-up sessions

Exclusion Criteria:

• Patients with systemic diseases classified as ASA III or higher
• Presence of severe periodontal disease (probing depth >4 mm)
• Use of analgesics within the last 12 hours or antibiotics within the past month before the treatment

All collected individual participant data (IPD), including all IPD that underlie the results reported in the publication

Data will be shared starting 6 months after publication.

Qualified researchers may request access to all de-identified individual participant data (IPD) and study protocols. Access will be granted upon reasonable request by contacting the corresponding author via email and after signing a data sharing agreement