Micro-Ultrasonic Technique In Managing Instrument Separation In Mandibular Molars

Instrument separation during root canal treatment compromises disinfection and prognosis. This report demonstrates successful retrieval of fractured instruments from a mandibular first molar (#46) and second molar (#47)the D600 ultrasonic system with an ET20 tip (Woodpecker) under dental microscope guidance. A 36-year-old male presented with right mandibular occlusal pain. Teeth #46 and #47 exhibited vertical percussion tenderness and apical mucosal fluctuance.CBCT reveals the mesiobuccal and mesiolingual root canals of tooth 46, and a separated instrument within the mesiobuccal root of tooth 47. Based on CBCT evaluation of the fractured instrument positions, root canal curvature, and root canal wall thickness, the treatment plan involves microscopic removal of separated instruments from teeth 46 and 47; followed by microscopic root canal retreatment and full crown restoration for both teeth. This case highlights the efficacy of micro-ultrasonic technology in minimally invasive retrieval of separated instruments while preserving dentinal structure. Preoperative CBCT evaluation is critical to assess retrieval difficulty and procedural risks. Studies indicate that when the residual dentinal wall thickness averages less than 1.3 mm, the risk of root fracture increases significantly. Additionally, greater root canal curvature necessitates more extensive dentin removal to establish straight-line access, elevating the likelihood of complications such as lateral perforation. Micro-ultrasonic techniques represent a reliable approach for managing intracanal instrument separation. Clinicians must balance the feasibility of retrieval against procedural risks to develop optimal, patient-specific treatment plans.