Introduction: Root canal preparation may cause inadvertent apical extrusion of debris causing postoperative pain. This debris varies with the instrumentation technique and design characteristics. One of the major revolutions in the design of the instruments is the introduction of files with an offset center of mass or/and rotation. which causes asymmetric rotary motion in the canal. https://spencertifieders.shop/product-category/reel-to-reel-accessories/