[Evaluation of four methods of preparing curved canals]

The authors used the protocol provided by Bramante, Berbert and Borges, to evaluate the respect of the canal position during the curved canal preparation. They compared four preparation types, two hand preparation and two engine driven ones: the step back technique, the anticurvature filing technique, the contact shaping technique, the canal finder. A statistic analysis of the results shows that the preparation is done to the detriment of the furcation wall and that only the step back technique is not suitable for the curved canal preparation.