ABSTRACT
Objective To study and assess clinical application of two Nickel-Titanium(NiTi)rotary instru- ments,namely ProTaper and Hero 642,in preparation of root canals.Methods 125 teeth were divided into three groups and respectively instrumented by stainless K-files,ProTaper or Hero 642 rotary instruments.All teeth were obturated with lateral condensation method.The efficiency of preparation and obturation was analyzed with radio- graphs.Results NiTi rotary instruments were better in keeping the curvature and flow of curved canals than stain- less K files.There was no transportation,apical blockage and ledge in NiTi groups.The operative time was shorter and endodontic flare-up seldom occurred in NiTi groups.Conclusion The NiTi rotary instrumentation technique could be used to prepare curved root canals effectively and quickly.The future use of NiTi engine-driven rotary in- strument appeared to be promising.