Efficacy of Different Disinfection Technologies in Molar Non-Surgical Retreatment

Efficacy of a Multisonic System vs. Conventional Therapy in the Disinfection of Molar Retreatment Cases: A Randomized Clinical Trial

Post-treatment apical periodontitis is commonly associated with persistent intracanal infection following root canal treatment. Effective disinfection of the complex root canal system during nonsurgical retreatment remains challenging due to anatomical complexities that may harbor microbial biofilms. Conventional retreatment protocols typically involve nickel-titanium rotary instrumentation combined with irrigation using sodium hypochlorite and activation techniques such as Passive Ultrasonic Irrigation (PUI).

The GentleWave System (GWS) is a minimally invasive irrigation technology designed to enhance tissue dissolution and microbial removal through multisonic energy, advanced fluid dynamics, and negative pressure. Although preliminary studies suggest promising results in root canal disinfection and patient outcomes, high-level clinical evidence comparing GWS with conventional retreatment techniques remains limited, particularly in molar teeth with post-treatment apical periodontitis.

This randomized clinical study aims to compare the disinfection efficacy of GWS with a conventional nickel-titanium rotary instrumentation protocol combined with PUI in nonsurgical retreatment of molars with post-treatment apical periodontitis. Intracanal bacterial load will be quantified using quantitative polymerase chain reaction (qPCR), and microbial composition will be analyzed using next-generation sequencing (NGS). Residual organic debris will be evaluated using the chairside diagnostic device Endocator and facultative bacterial culturing. Postoperative pain levels will also be recorded to assess short-term clinical outcomes.

The results of this study will provide clinical evidence regarding the comparative effectiveness, safety, and potential advantages of advanced irrigation technology for root canal disinfection in complex retreatment cases.

Study Overview

• Status: Not yet recruiting
• Conditions: Apical Periodontitis
• Intervention / Treatment: Procedure: GentleWave System; Procedure: Conventional rotary instrumentation with passive ultrasonic irrigation

Detailed Description

Post-treatment apical periodontitis in root canal-treated teeth is caused by persistent, secondary, or recurrent intra-canal infection. The complex anatomy of the root canal system-including isthmuses, fins, and lateral canals-can limit the effectiveness of conventional instrumentation and irrigation, allowing microbial biofilms to persist. As a result, nonsurgical endodontic retreatment often presents a lower success rate compared with primary root canal treatment.

Conventional retreatment protocols typically involve mechanical debridement using nickel-titanium rotary instrumentation combined with irrigation using sodium hypochlorite. Irrigation activation techniques such as passive ultrasonic irrigation (PUI) are commonly used to improve irrigant penetration and enhance removal of debris and bacteria from complex canal anatomy. However, these techniques may still be limited in their ability to completely eliminate microbial biofilms and may carry a risk of irrigant extrusion.

The GentleWave System (GWS) is an advanced irrigation technology that uses multisonic energy, negative pressure, and optimized fluid dynamics to enhance tissue dissolution and microbial removal throughout the root canal system. This system allows effective disinfection while minimizing the need for extensive mechanical instrumentation, potentially supporting minimally invasive endodontic approaches. Although studies have demonstrated promising results, well-designed randomized clinical trials evaluating its effectiveness in retreatment cases remain limited.

This randomized clinical trial will compare the disinfection efficacy of GWS with a conventional retreatment protocol consisting of nickel-titanium rotary instrumentation combined with PUI in molars diagnosed with post-treatment apical periodontitis. Microbiological samples will be collected before treatment and prior to obturation. Intracanal bacterial load will be quantified using quantitative real-time polymerase chain reaction (qPCR), and microbial community composition will be analyzed using next-generation sequencing (NGS). In addition, residual organic debris will be evaluated using the chairside device Endocator, which provides a rapid quantitative Endoscore to determine the degree of disinfection of each group.

The primary outcomes of the study are reduction in intracanal bacterial load and changes in microbial composition following disinfection. Secondary outcomes include the efficacy of the chairside device Endocator in disinfection of the root canal, compared with PCR-based methods as well as facultative bacterial culturing, and short-term postoperative pain assessment. These findings from this study aim to provide high-quality clinical evidence regarding the comparative effectiveness of advanced irrigation technologies versus conventional disinfection protocols in endodontic retreatment.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Can Wang, PhD; Phone Number: 205-934-1141; Email: cw24@uab.edu
• Study Contact Backup: Name: Ashraf F Fouad, DDS, MS; Phone Number: 205-934-5373; Email: afouad@uab.edu

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35233
      • University of Alabama at Birmingham
      • Contact: Can Wang, PhD; Phone Number: 2059341141; Email: cw24@uab.edu
      • Contact: Ashraf F Fouad, DDS,MS; Phone Number: 205-934-5373; Email: afouad@uab.edu
      • Principal Investigator: Can Wang, PhD
      • Sub-Investigator: Ashraf F Fouad, DDS, MS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Molars showing radiographic evidence of post-treatment apical periodontitis: a lesion that exceeds 3 mm in diameter on one or more roots.
• Evidence from periapical and CBCT examination suggests that retreatment is a viable option, i.e., there are low risks of vertical root fracture, no major root canal obstruction, evidence of coronal leakage, and potential improvement on the previous treatment.
• The initial root canal therapy was performed at least 2 years previously, or more than 1 year if the patient has signs and symptoms or symptomatic disease (pain, swelling, or sinus tracts).
• Patients show no chronic systemic disease that may influence the outcome of care, such as uncontrolled diabetes, autoimmune disease, malignancy treated with chemotherapy or patients who are on immunosuppressive medications or require antibiotic prophylaxis before dental treatment.
• Patients who are able to read and consent in English.

Exclusion Criteria:

• Patients with a tooth requiring RCT retreatment that also presents with periodontal pocket(s) deeper than 5mm
• Patients with a tooth requiring RCT retreatment that also presents with severe crown destruction that would prevent proper rubber dam isolation or an adequate restoration
• Patients with a tooth requiring RCT retreatment that also presents with evidence of vertical root fracture, or cracks with probing defects > 5 mm
• Patients with a tooth requiring RCT retreatment that is deemed unrestorable
• Patients who received antibiotic therapy within the previous 3 months.
• Patients under the age of 16 or those incapable of providing informed consent
• Patients with a tooth requiring RCT retreatment that also presents with immature or open apices
• Patients with a tooth requiring RCT retreatment that also presents with apices in the maxillary sinus or those teeth where the apical lesion has eroded the bone of the maxillary sinus floor
• Patients with a tooth requiring RCT retreatment that also presents with apices that are less than 1 mm from the mandibular canal
• Patients with a tooth requiring RCT retreatment that also presents with internal or external root resorption

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: GentleWave Disinfection Group; Participants with molars requiring nonsurgical endodontic retreatment will undergo root canal disinfection using the GentleWave System following minimal mechanical instrumentation. Microbiological samples will be collected prior to retreatment and before obturation to evaluate intracanal bacterial load and microbiome composition. Residual organic debris will be assessed using the chairside device Endocator, and postoperative pain will be recorded.	Procedure: GentleWave System; Minimally invasive root canal disinfection using the GentleWave multisonic irrigation system following minimal instrumentation. The system delivers multisonically activated sodium hypochlorite and EDTA solutions under negative pressure to enhance irrigation dynamics and debris removal within the root canal system during nonsurgical endodontic retreatment.
Active Comparator: Conventional Rotary Instrumentation with Passive Ultrasonic Irrigation; Participants with molars requiring nonsurgical endodontic retreatment will undergo conventional chemomechanical preparation using nickel-titanium rotary instrumentation combined with irrigation using Sodium hypochlorite and activation with Passive Ultrasonic Irrigation. Microbiological samples will be collected prior to retreatment and before obturation to evaluate intracanal bacterial load and microbiome composition. Residual organic debris will be assessed using the chairside device Endocator, and postoperative pain will be recorded.	Procedure: Conventional rotary instrumentation with passive ultrasonic irrigation; Conventional nonsurgical endodontic retreatment using nickel-titanium rotary instrumentation followed by passive ultrasonic irrigation (PUI). Irrigation is performed using sodium hypochlorite delivered via a side-vented needle and ultrasonically activated irrigation to enhance canal disinfection after mechanical preparation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
change of the intracanal Bacterial Load	Change in total bacterial load in the root canal system following disinfection, measured by quantitative real-time polymerase chain reaction (qPCR) targeting the universal 16S rRNA gene. Bacterial load will be quantified from microbiological samples collected before instrumentation (S1) and after completion of the disinfection protocol (S2) to determine the reduction in bacterial load between the two time points.	During the treatment visit (baseline before instrumentation and immediately after completion of the disinfection protocol).
Root Canal Microbiome Composition	Differences in the prevalence and relative abundance of bacterial taxa in root canal samples before and after disinfection, assessed using next-generation sequencing (NGS) of bacterial 16S rRNA gene amplicons. Alpha diversity and beta diversity metrics will be analyzed to compare microbial community structure between treatment groups.	During the treatment visit (baseline before instrumentation and immediately after completion of the disinfection protocol).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
change of the Residual Intracanal Organic Debris Score	Residual organic debris within the root canal system will be measured using the chairside device Endocator. The device provides a quantitative Endoscore representing the level of intracanal bioburden. Scores will be recorded before instrumentation and after completion of the disinfection protocol to assess debris reduction. Endoscore values will be categorized as follows: (1) 1-25: Low Bioburden; (2) 26-50: Medium Bioburden; (3) 51-100: High Bioburden, as instructed by the device protocol.	During the treatment visit (before instrumentation and immediately after completion of disinfection).
Post-operative Pain	Patient-reported post-operative pain intensity measured using a numerical rating scale from 0 (no pain) to 10 (worst imaginable pain). Participants will record their pain levels following the treatment procedure using a post-treatment pain diary.	1 day, 2 days, 3 days, 5 days, and 7 days after the treatment visit

Collaborators and Investigators

• Sponsor: University of Alabama at Birmingham
• Investigators: Principal Investigator: Can Wang, PhD, University of Alabama at Birmingham

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2027
• Primary Completion (Estimated): June 1, 2030
• Study Completion (Estimated): December 1, 2030

Study Registration Dates

• First Submitted: March 9, 2026
• First Submitted That Met QC Criteria: March 9, 2026
• First Posted (Actual): March 13, 2026

Study Record Updates

• Last Update Posted (Actual): April 8, 2026
• Last Update Submitted That Met QC Criteria: April 2, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative pain; Next-generation sequencing; Quantitative PCR; Endodontic retreatment; Passive ultrasonic irrigation; Post-treatment apical periodontitis; Root canal disinfection; GentleWave System; Nickel-titanium rotary instrumentation; Sodium hypochlorite irrigation; Intracanal bacterial load; Root canal microbiome; Endocator
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Periodontal Diseases; Mouth Diseases; Stomatognathic Diseases; Postoperative Complications; Pathologic Processes; Periapical Diseases; Jaw Diseases; Periodontitis; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Periapical Periodontitis
• Other Study ID Numbers: IRB-300015590; Pending (Clinical Research Information Service)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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