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

• 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)

• 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.

• 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.
• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

Inclusion criteria

• Lower first molar Classification of root canal configuration according to weine classification: -
• Distal root: any type of root canal configuration given that the portal of exit is through only one apical foramen
• Mesial root: any type of root canal configuration given that the portal of exit is through only one apical foramen(18).

• Patient with mild pre-operative pain with pain score from 0-3
• Medically free patients with no systemic disease: (American Society of Anesthesiologists / (ASA Class I or II).
• The age range is between 20 to 40 years.
• Patients have restorable lower permanent molars that were diagnosed with symptomatic apical periodontitis with small to moderate periapical lesion.
• Positive patient's acceptance for participating in the study.
• Patients able to sign informed consent.

Exclusion criteria

• Patients with systemic conditions that may affect pain perception (e.g., fibromyalgia, chronic pain disorders)
• Patients currently taking or taken analgesics or anti-inflammatory medications before the trial in the last 12 hours.
• Pregnant or lactating females.
• Psychologically disturbed patients.
• Patients with a history of allergy to any medication used in the study are excluded.

Teeth that have:

• Periodontally affected with grade 2 or 3 mobility.
• Not restorable teeth.
• Abnormal anatomy and calcified canals.
• Previous root canal treatment.
• Any patient that matched the inclusion criteria, however had an unintentional errors during procedure, eg: over-instrumentation/over-obturation.