This study aims to compare the effectiveness of three root canal irrigation techniques-Conventional Needle Irrigation (CNI), Side-Vented Needle (SVN), and Ultrasonic Irrigation (UI)-in achieving irrigant penetration into the apical third of the root canal. Since conventional irrigation often fails to adequately clean complex root canal anatomy, the study evaluates whether activation methods improve irrigant penetration. A randomized controlled trial will compare these three techniques using extracted single-rooted mandibular premolars. A radiopaque dye mixed with sodium hypochlorite will be used to measure irrigant penetration on digital radiographs, and the results will be statistically analyzed to determine the most effective irrigation method.