Clinical evaluation of ProTaper Ni Ti hand instruments in preparation of curved root canals

[Objective] To investigate the clinical effects of ProTaper Ni Ti hand instruments in preparation of curved root canals.[Methods] One hundred and twenty root canals of 120 patients were equally divided into two groups at random.The cases in experimental group were instrumented by ProTaper Ni Ti hand files using ProTaper technique(NT group);those in control group were instrumented by stainless steel hand K-files using Step-down technique(SS group).The shape of root canal and effects of obturation were evaluated with radiographs during and after operation.The incidence of post-operative pain and the rate of instrument fracture were recorded.[Results]The rate of root canal deformity after preparation was 53.33% in control group and 3.33% in Ni Ti group.86.67% of the canals in Ni Ti group were properly obturated as compared with 63.33% in control group.The incidence of post-operative pain were 11.67% in Ni Ti group while 75% in control group.The rate of instrument fracture in Ni Ti group was 2.78%.The rate of instrument deformity in control group was 41.67%.[Conclusions] Under clinical conditions,ProTaper Ni Ti hand instruments can prepare root canal effectively and safely,the ProTaper Ni Ti hand instrumentation technique is an efficient root canal preparation method for curved canals.But fracture of the instrument should be avoided.