OBJECTIVETo evaluate clinical effect of the new ProTaper Nickel-titanium rotary instruments in preparation of curved root canals.

METHODS68 teeth with curved root canals were instrumented by ProTaper rotary instruments using crown-down technique, and by K files using step-back technique for control. All teeth were obturated with lateral condensation method. The efficiency of preparation and obturation was analyzed with radiographs before, during and after operation.

RESULTSNo transportation, apical blockage and ledge were found in test. The technique could keep the curvature and flow of curved canals. There were two ledge and more apical transportation (P < 0.01) in control than in test. The operative time was shorter and post treatment pain seldom occurred in ProTaper group.

CONCLUSIONThe ProTaper NiTi rotary instruments can prepare curved root canals effectively and safely. It is an efficient instrumentation method for curved canals and can be used widely.