File Retrieval in Endodontics: A Narrative Review with Clinical Illustrations Emphasizing Technique Selection, Dentin Preservation, and Operator Variability

Instrument separation during root canal treatment and retreatment represents a significant procedural complication that may compromise canal disinfection, treatment efficiency, and longterm prognosis.¹,² Although the presence of a separated instrument does not invariably result in treatment failure, obstruction of infected apical regions may hinder adequate chemo-mechanical debridement and negatively influence periapical healing. Advances in magnification, ultrasonic technology, imaging modalities, and minimally invasive retrieval systems have substantially improved the predictability of file retrieval.³–⁶ This narrative review synthesizes contemporary evidence on the etiology, decision-making principles, and techniques for file retrieval in endodontics, with particular emphasis on ultrasonic and loop-based approaches. Recent experimental and clinical studies, including nano-computed tomography analyses and in vivo quantitative assessments, are discussed to elucidate the balance between retrieval success, time efficiency, operator variability, and dentin preservation.¹³–¹⁵ To enhance clinical translation, three representative clinical cases are integrated as narrative illustrations, demonstrating real-world application of the reviewed principles. The review highlights the importance of case-specific strategy selection, controlled dentin removal, and operator judgment in achieving predictable outcomes while preserving the biomechanical integrity of endodontically treated teeth.