[ in vitro evaluation of canal preparation by passive step back and rotary profile system on canal curvature of human first molar teeth]

ABSTRACT

Statement of Problem: One of the difficulties that a dentist encounter during root canal treatment is the cleaning and shaping of curved root canals. While doing this procedure the probability of zipping, perforation, apical transportation and canal curvature change increases that all of those are the result of not following the original root canal path by the file. This will fail the prognosis of root canal treatment