Modification of the working length after rotary instrumentation: a comparative study of four systems

Objective: To determine variation in post-instrumentation working length and root area in the following rotary systems: ProTaper, RaCe, Mtwo and K3. Study design: A sample of 40 resin blocks with double curvature (at 14 and 16 mm) and a 33º angle was used. Working length was verified with a digital measure using a number 10 K file. The specific sequence for each rotary system was followed. The canal was measured between each file, and the variation noted to determine which file showed the greatest variation within a same system and the different systems were compared. 1.5 X pre and post-instrumentation microscopic photographs were taken and measurements of the area were taken with an image …