Refinement influence in the cleaning efficacy of rotary nickel-titanium Mtwo instruments in oval-shaped canals by means of optical microscopy.

Objective: This study evaluated the cleaning efficacy of the rotary nickel-titanium Mtwo by means of optical microscopy in oval-shaped root canals and compared refinement influence using ultrasonic files or Hedströem files.

Materials And Methods: Twenty mandibular incisors were accessed, included in epoxy resin blocks, and cut transversely at 3, 6, and 9 mm from the apex. Teeth were instrumented using rotary nickel-titanium Mtwo.