The Impact of Using Different Final Irrigation Modes on Postoperative Pain Following Root Canal Treatment of Non-vital Mandibular First Molar With Periapical Lesion.

Clinical Study Protocol

1. General Information Study Title: The impact of using different final irrigation modes on postoperative pain following root canal treatment of mandibular first molar with symptomatic periapical lesions: A Randomized Controlled Trial. Protocol Date: May 2026 Sponsor/Institution: Department of Endodontics, Faculty of Oral and Dental Medicine, Future University in Egypt. Principal Investigator: Osama Said Abdrabou Mohamed, BDS. Supervisory Committee: * Dr. Adel Abd El Wahed Mahmoud (Future University in Egypt) Dr. Ahmed Maged Negm (NewGiza University) Dr. Hesham Mohamed Salah (Future University in Egypt)
2. Abstract \& Rationale Statement of the Problem: Postoperative pain (PP) remains a significant complication in endodontics, occurring in 3% to 58% of cases. It often results from the extrusion of debris or chemical irritants into the periapical tissues during the cleaning and shaping process. Rationale: Conventional needle irrigation (CNI) relies on positive pressure, which increases the risk of apical extrusion. Advanced irrigation activation systems-including Apical Negative Pressure (ANP) and Continuous Apical Negative-Pressure Ultrasonic Irrigation (CANPUI)-aim to improve disinfection efficiency while minimizing the pressure directed toward the apex. This study seeks to determine which activation mode provides the most comfortable postoperative recovery for patients.
3. Study Objectives \& Hypotheses Primary Objective: To evaluate and compare the intensity of postoperative pain at 6, 12, 24, and 48 hours following root canal treatment (RCT) using four different final irrigation protocols. Secondary Objective: To assess the frequency and quantity of analgesic intake (Ibuprofen 400mg) among the study groups. Null Hypothesis (H 0

• There is no statistically significant difference in postoperative pain reduction between the tested irrigation activation modes.

1. Study Design Trial Design: A prospective, randomized, parallel-group, double-blinded clinical trial. Allocation Ratio: 1:1:1:1. Blinding: Double-blinded. The patient and the outcome assessor will be blinded to the group assignment.
2. Participant Selection \& Eligibility 5.1 Inclusion Criteria Age: 20-40 years. Health Status: Systemically healthy (ASA Class I or II). Tooth Type: Lower first permanent molar. Diagnosis: Symptomatic apical periodontitis with a non-vital pulp and a detectable periapical lesion (3-5 mm diameter via CBCT). Anatomy: Mandibular molars with Weine Type III canal configuration in both mesial and distal roots. Consent: Patients must be willing to participate and sign a written informed consent. 5.2 Exclusion Criteria Teeth with previous root canal treatment or calcified canals. Teeth with Grade 2 or 3 mobility or periodontal pockets >3 mm. Patients who have taken analgesics or anti-inflammatory drugs within 12 hours prior to the procedure. Pregnant or lactating females. Patients with chronic pain disorders (e.g., fibromyalgia) or psychological disturbances.
3. Interventions (Clinical Protocol) All treatments will be performed in a single visit by a single operator to ensure consistency. 6.1 Common Procedural Steps Diagnosis: Confirmed via clinical exam, thermal tests, periapical radiographs, and CBCT. Anesthesia: Inferior Alveolar Nerve Block (IANB). Isolation: Rubber dam isolation. Preparation: Access cavity using carbide and Endo-Z burs. Working length (WL) determined by electronic apex locator and confirmed by X-ray (0.5-1 mm from apex). Shaping: Crown-down technique using rotary files with 2.5% NaOCl irrigation between each file. 6.2 Experimental Groups (Final Irrigation) After shaping, the final irrigation protocol (2 ml of 17% EDTA for 1 min, followed by 2 ml of 2.5% NaOCl for 1 min) will be activated as follows: Group A (Control - Conventional Needle): 30-gauge side-vented needle placed 2 mm from WL with manual up-and-down movements. Group B (Ultra X - Positive Pressure): Ultrasonic activation using the Ultra X blue tip placed 2 mm from WL (3 cycles). Group C (EndoVac - Apical Negative Pressure): Irrigant delivered via Master Delivery Tip while the microcannula draws fluid via vacuum at the WL. Group D (iVac - CANPUI): Simultaneous ultrasonic activation and negative pressure suction at the working length. 6.3 Obturation \& Restoration Canals will be dried with paper points and obturated using Continuous Wave Condensation with resin-based sealer. Final restoration will be completed with resin composite.
4. Outcomes \& Measurement 7.1 Primary Outcome: Postoperative Pain Tool: Modified Visual Analog Scale (VAS) score (0-10). Intervals: Pre-treatment, 6h, 12h, 24h, and 48h. 7.2 Secondary Outcome: Analgesic Intake Data Points: Number of participants requiring medication and the total number of 400mg Ibuprofen tablets consumed.
5. Statistical Plan Sample Size: Based on a power of 95% (α=0.05), 52 total patients (13 per group) are required. Analysis: * Normality: Shapiro-Wilk test. Parametric Data: One-way ANOVA followed by Tukey's post hoc test. Non-parametric Data: Kruskal-Wallis followed by Dunn's post hoc test. Categorical Data: Chi-square test. Software: R statistical software version 4.3.2.
6. Ethics \& Dissemination Ethics: Approved by the Ethics Committee of Future University in Egypt.

Confidentiality: All data will be encrypted and stored securely for 1 year.

Publication: Results will be submitted to peer-reviewed dental journals and presented as part of a Master's Degree thesis.