The aim of this study was the comparative evaluation of the applicability of two manual and two rotary nickel-titanium root canal preparation systems to unex-perienced students. For that purpose the simulated curved root canals of 29 pattern resin training blocks were “endodontically” treated in a standardized scheme by students for each system. In addition the students had to answer a questionnaire to evaluate the subjective findings concerning the four different preparation systems. After digital superimposing the pictures of untreated and treated blocks zip, elbow and ledge aberrations were detected. The degree of canal transportation after treatment was evaluated at each 22 locations by indi-vidual adjustment of a standardized scale. A new method was developed to describe the extent of curvatures of inner and outer canal walls before and after treatment. Therefore the canal walls were described as an algebraical function to calculate the curvatures on the average, the curvatures maximum and its dislocation after root canal treatment. The statistical evaluation showed significantly less appearance (p<0,05) of ledges, elbows and transportations when rotary nickel-titanium systems were used. The detailed investigation of canal transportation showed statistically significant improved results for the FlexMaster and ProFile systems. Furthermore there could be found better values concerning the curvatures characteristic and the time of preparation for the use of rotary nickel-titanium systems.