The goal of this clinical trial is to learn which rinsing of root canals method works best to lower pain after a root canal in adults. The study focuses on participants aged 20 to 40 with an infection in a lower back tooth (mandibular first molar) and a small area of bone loss at the root tip.

The main questions it aims to answer are:

Does the type of tool used to rinse the tooth root canal change how much pain a participant feels after treatment?

Does the cleaning method lower the number of painkillers a participant needs to take?

Researchers will compare four different rinsing tools-ranging from a standard needle to advanced vacuum and vibration devices-to see if using suction and sound waves can lower pain levels.

Participants will:

Receive a complete root canal treatment in a single visit

Be randomly assigned to one of four cleaning groups (standard rinse, vibration, vacuum, or a combination of both)

Rate their pain on a scale of 0 to 10 at five specific times: before the visit, and at 6, 12, 24, and 48 hours after treatment

Record how many painkiller tablets (Ibuprofen) they take during the two days following the procedure

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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

the first blinding will be to the participants, where they will not know the type of irrigation activation device used the second blinding will be to the investigator, where another individual will be assigned to follow up with the participants and record the outcome measures the third blinding will be to the outcome assessors, where they will be blinded to the groups