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.
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 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