Influence of the rotary and/or oscillatory reciprocating systems in the morphological changes of narrow and curved molar root canals anatomy

objective: this study evaluated four mechanized endodontic systems, protaper universal, k3 endo, twisted file (rotary) and the oscillatory reciprocating system endo - eze tilos, in order to verify and measure alterations in original anatomy with deviations at cervical, medium and apical root canal thirds. material and method: it was used mb root canals of 60 extract human lower molars, to produce a line of severe angles, according to the classification of schneider. samples were included in ester vinyl resin, mounted in the teflon furnace, transversally sectioned at the cervical, middle and apical thirds, which were subsequently photographed using a digital camera cyber shot dsc-tx10,attached to an operating microscope 3101xy dfvasconcelos with 40× magnification in order to measure the anatomical transversal area of the root canal, using the software autocad 2008, comparing pre and post-instrumentation. all samples assembled in the furnace also were submitted to x-ray in a standardized way to enable the comparison of the angle of schneider pre-and post-instrumentation. once collected the data, they were compared statistically using the program bioestat 5.0. result: the analysis of the results showed that in the cervical third, rotary systems were more effective than endo-eze tilos system with statistically significant differences (p ≤ 0,05). apical and middle third changes in anatomy were similar, but apically, the protaper system caused more deviations when comparing the angle of schneider,and areas before and after instrumentation(p ≤ 0,05). conclusion: it was concluded that all the systems caused alteration in the original anatomy of the root canal when parameters as angle of schneider and areas before and after preparation were used.