Objective: This in vitro study aimed to assess the efficiency of retreatment files in root canals prepared using three different obturation techniques and quantify remaining debris in extracted mandibular premolars. Methods: Fifty-four single-rooted premolars were decoronated, prepared, and obturated using lateral condensation (CLC), single cone (MTSC), and downpack backfill (DBF) techniques. Each group was subdivided based on the retreatment file system (Protaper Universal, Coltene Micromega Hyflex Remover, Neoendo). Retreatment times were recorded, and debris was quantified at coronal, middle, and apical thirds post-sectioning using ImageJ software. Statistical analyses were conducted using SPSS.