The goals of root canal instrumentation are complete debridement of pulp tissue, removal of microbes and affected dentin, and proper cleaning and shaping of the root canal space before obturation. Instrumentation with stainless steel files has been shown to produce undesirable results in canals, regardless of the improved techniques or modified file types used. Nickel-Titanium(Ni-Ti) alloy has been shown to be exceptionally elastic, having a lower bending moment and lower permanent set after torsion, compared with similar gauge stainless steel.
The purpose of this study was to evaluate the change of root canal morphology prepared by Ni-Ti rotary and stainless steel instruments. Thirty-four single rooted teeth of similar shape and canal size were divided into three exprermental and one unprepared groups. The teeth were scanned by computerized tomography before instrumentation. In K-file group, canals were instr unented using a step-back technique with K-file. In K-flex file group, canals were prepared with K-flex file using the same technique as group 1. Quantec group was prepared with Ni-Ti Quantec rotary instrument using the manufacture´s instructions. Instrumented teeth were again scanned using computed tomography, and reformatted
images of the uninstrumented canals were compared with images of the instrumented canals.
K-flex file and Quantec file caused significantly less canal transportation than K-file in the root canal section 8 mm from the apex (p<0.05). K-flex file and Quantec file produced more centered canal preparation than K-file in the 2 mm section (p<0.05). Quantec file maintained the center of the canal more precisely than K-flex file in the 10 mm section (p<0.05). There was no statistically significant difference in the removed volume of canals among each groups (p> 0.05).
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