Applied research of hand ProTaper Niti instruments in root canal therapy of molars

Objective: To evaluate clinical effects of hand ProTaper nickel-titanium(Niti) instruments in root canal preparation of molars.Methods:Eighty molars with pulpitis or perioapical periodontitis were randomly classified into two groups with 40 teeth in each group.Root canal preparation was carried out with hand ProTaper and Crown-down technique in Group A,while preparation with ss-k-file and step-back technique in Group B.Preparation time,the number of broken instruments and the change of WL were recorded.The efficiency of preparation and obturation was analyzed with radiograph before,during and after operation.Results:The preparation time of Group A was shorter than that of group B(P0.05)O.ne S1 was broken in Group A,while 8 pieces of ss-K-file were distorted in Group B.The WL of Group B reduced by(1.41±0.93)mm whereas there was almost no change in Group A(P0.01).Hand ProTaper could achieve more continuosly tapered root canal shape and less painafter operation than that of ss-K-file(P0.05).Conclusion:Hand ProTaper instruments can be advocatedas a new hand instrumen-tation technique,especially for those curve root canal of molars.