Influence of Continuous Rotation Versus Reciprocation Motion of MG3 Blue Rotary File on Postoperative Pain and Intracanal Bacterial Reduction of Teeth With Necrotic Pulps.

Influence of Continuous Rotation Versus Reciprocation Motion of MG3 Blue Rotary File on Postoperative Pain and Intracanal Bacterial Reduction of Teeth With Necrotic Pulps: A Randomized Clinical Trial

he main objective of this study is to compare the impact of two different file motions-continuous rotation versus reciprocation-using the same endodontic file system (MG3 Blue rotary files) on postoperative pain and the amount of remaining bacteria inside the root canal in single-rooted teeth with necrotic pulps.

Extrusion of infected debris and persistent intracanal bacteria during root canal treatment can lead to postoperative pain and treatment complications. While various instrumentation systems have been evaluated, differences in file metallurgy, design, and number of files often obscure whether the observed outcomes are due to the movement (kinematics) or the file itself. This study aims to isolate the effect of motion kinematics by using identical rotary files in two distinct movement modes.

Participants will be randomly assigned to one of two groups:

Intervention Group (Reciprocation Motion): Canals will be prepared using MG3 Blue files operated in reciprocation motion.

Comparator Group (Continuous Rotation Motion): Canals will be prepared using MG3 Blue files operated in continuous rotation motion.

All procedures will be performed on single-rooted mandibular premolars diagnosed with pulp necrosis without apical periodontitis. Microbial samples will be collected before and after canal instrumentation to measure the reduction of cultivable bacteria (in colony-forming units, CFU/mL). Postoperative pain levels will be recorded by participants using a Visual Analogue Scale (VAS) at baseline, 24 hours, 48 hours, 72 hours, and 7 days after the first appointment.

The primary outcome of the study is post-instrumentation pain at 72 hours. Secondary outcomes include post-instrumentation pain at 7 days and the amount of remaining intracanal cultivable bacteria following canal preparation.

Study Overview

• Status: Not yet recruiting
• Conditions: Necrotic Pulps With no Apical Periodontitis
• Intervention / Treatment: Device: Engine driven files utilized in reciprocation motion; Device: engine driven rotary files utilized in continuous rotation motion

Detailed Description

Background and RationaleA fundamental aim of root canal therapy is controlling pain and resolving apical periodontitis by thoroughly disinfecting the root canal system. Residual bacteria-particularly virulent species like Enterococcus faecalis-and their byproducts inside dentinal tubules are the leading cause of post-treatment complications and endodontic failure. During instrumentation, extruded infected debris can injure periapical tissues, triggering an inflammatory immune response and leading to postoperative pain and flare-ups. While previous research has evaluated how reciprocating versus continuous rotary systems affect postoperative pain and remaining bacteria, most studies used different file designs, cross-sections, or numbers of files, making it difficult to determine whether outcomes were driven by kinematics or file characteristics. This randomized clinical trial isolates the effect of motion kinematics by using identical MG3 Blue rotary files under two different motion dynamics. Study ObjectivesTo compare the effect of different kinematics (continuous rotation versus reciprocation) using MG3 Blue rotary files on:The intensity of postoperative pain. The amount of remaining intracanal cultivable bacteria. Trial DesignType: Parallel, single-center, randomized controlled trial (superiority framework). Allocation Ratio: 1:1. Setting: Post-graduate outpatient clinic of the Endodontics Department, Faculty of Dentistry, Cairo University, Egypt. Participants and Eligibility CriteriaInclusion Criteria:Patients aged between 18 and 50 years (males and females). Systemically healthy (ASA I or II) with no history of anti-inflammatory or antibiotic medications in the past month. Mandibular premolars presenting with a single canal and non-vital pulps (negative response to ethyl chloride cold test, absence of spontaneous pain, and no apical periodontitis). Patients capable of understanding the pain scale and signing the informed consent. Exclusion Criteria:Medically compromised patients (ASA III or IV), pregnant females, or teeth with swelling, fistulous tracts, acute/chronic periapical abscesses, grade II/III mobility, previous root canal therapy, non-restorable structure, or open/immature apices. Intervention Procedures & Protocol StepsPreoperative Evaluation: Medical/dental history collection and baseline pain assessment using a Modified Visual Analogue Scale (VAS). Local Anesthesia & Disinfection: Local anesthesia administration followed by disinfection of the oral cavity using 0.2% chlorhexidine gluconate mouthwash and rubber dam isolation. Access Cavity & Working Length: Access cavity preparation, followed by patency confirmation using stainless steel K-files (#10 and #15). Working length is determined via an electronic apex locator and verified radiographically to be 1 mm shorter than the radiographic apex. Pre-instrumentation Sampling (S1): Initial intracanal microbiological samples are collected using sterile paper points retained for 60 seconds (placed in LAL water for endotoxin assay and VMGA III transport medium for microbial cultivation). Randomized Mechanical Preparation: Patients are allocated via computer-generated randomization to one of two groups: Intervention Group (Reciprocation Motion): Canals are prepared using MG3 Blue rotary files in reciprocation motion (#20/0.10, #15/0.03, #20/0.04, #25/0.04, #30/0.04, and #35/0.04 at 300 RPM and 2 Ncm torque). Comparator Group (Continuous Rotation Motion): Canals are prepared using the same MG3 Blue rotary files in continuous rotation motion following manufacturer instructions (same sizes, 300 RPM, and 2 Ncm torque). Irrigation Protocol: Canals are thoroughly irrigated between file sizes using 3 mL of 2.25% sodium hypochlorite via a 27-gauge side-vented needle, finalized with a saline wash. Post-instrumentation Sampling (S2): Second microbial sample collected identically to S1. Canals are dried, temporarily sealed, and patients are scheduled for a 7-day follow-up appointment for root canal obturation via warm vertical compaction. Outcomes and AssessmentPrimary Outcome: Post-instrumentation pain measured at 72 hours post-procedure using the Visual Analogue Scale (VAS ranging from 0 to 10). Secondary Outcomes:Post-instrumentation pain measured at 7 days post-procedure. Amount of remaining intracanal cultivable bacteria measured via microbiological culture techniques in colony-forming units (CFU/mL) pre- and post-instrumentation.

• Study Type: Interventional
• Enrollment (Estimated): 42
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Mohamed G Farahat, Assist. Lecturer of Endodontic; Phone Number: +20 1151444452; Email: mohamed-farahat@dentistry.cu.edu.eg

Study Locations

• Egypt
  • Cairo Governorate
    • Cairo, Cairo Governorate, Egypt, 11251
      • Cairo University
      • Contact: Mohamed G Farahat, Assist. Lecturer of Endodontic; Phone Number: +20 1151444452; Email: mohamed-farahat@dentistry.cu.edu.eg
      • Principal Investigator: Mohamed G Farahat, Assist Lecturer of Enndodontic

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Age between 18-50 years.
• Males/Females.
• Mandibular premolars:
• Single canal.
• Non-Vital pulps.
• Negative response to cold pulp tester (ethyl chloride spray1).
• Absence of spontaneous pain.
• Absence of apical periodontitis.
• Systemically healthy patients (ASA I or II)
• No anti-inflammatory or antibiotic medications taken in the past month
• Patients' acceptance to participate in the trial.
• Patients who can understand pain scale and can sign the informed consent

Exclusion Criteria:

• Medically compromised patients having significant systemic disorders. (ASA III or IV).
• Teeth with swelling or fistulous tract.
• Teeth with acute or chronic periapical abscess.
• Mobility Grade II or III.
• Previous root canal therapy.
• Non-restorable teeth.
• Immature teeth
• Pregnant females.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: MG3 Blue rotary file - Reciprocation; MG3 Blue rotary file utilized in reciprocation motion	Device: Engine driven files utilized in reciprocation motion; MG3 blue rotary files utilized in reciprocation motion
Active Comparator: MG3 Blue rotary file - Continuous rotation; MG3 blue rotary file utilized in continuous rotation motion	Device: engine driven rotary files utilized in continuous rotation motion; MG3 Blue rotary files utilized in continuous rotation motion

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
post operative pain	Visual Analogue Scale	72 hours post instrumentation, 7 days post instrumentation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intracanal bacterial reduction	Microbiological Culture Technique. Sample 1 will be collected from canals after access cavity preparation and Sample 2 will be collected right after mechanical preparation of the canals.	Sample 1 before instrumentation, Sample 2 immediately after instrumentation

Collaborators and Investigators

• Sponsor: Cairo University
• Investigators: Study Chair: Alaa Diab, Professor of Endodontics, Cairo University; Study Director: Sarah Samir, Associate professor, Cairo University

Study record dates

Study Major Dates

• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): February 1, 2027

Study Registration Dates

• First Submitted: October 18, 2026
• First Submitted That Met QC Criteria: October 28, 2026
• First Posted (Actual): November 4, 2026

Study Record Updates

• Last Update Posted (Actual): November 4, 2026
• Last Update Submitted That Met QC Criteria: October 28, 2026
• Last Verified: October 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: New Endo 3-3-3

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No