Clinical evaluation of nickel-titanium rotary instruments in preparation of narrow and curved root canal in posterior teeth

Objective To investigate the clinical application of nickel-titanium( Ni-Ti) rotary instruments( TF,ProTaper and combined use of Pathfile and TF,and combined application of Pathfile with ProTaper) in preparation of narrow and curved root canals of posterior teeth. Methods A total of 170 narrow and curved root canals in premolar or molar teeth were prepared by TF( group TF),ProTaper( group P),combined use of Pathfile and TF( group PathT) and combined use of Pathfile and ProTaper( group PathP) rotary instruments,obturated with continuous wave compaction technique. The root canal preparation time,fracture of instruments,change of root canal curvature and obturation were recorded and analyzed. Results Operative time of group TF,group PathT,group P,group PathP was( 3. 50 ± 0. 13) min,( 2.80 ±0.09) min,( 5.39 ±0.08) min,( 4.66 ±0. 12) min,there were significant difference in four groups( F =374. 081,P 0. 001). Operative time of group PathT( 2. 80 ± 0. 09) min was shortest than other groups( P 0. 001).Operative time of group PathP( 4. 66 ± 0. 12) min was shorter than group P( 5. 39 ± 0. 08) min( t = 28. 65,P 0. 001). Root canal curvature variation of group PathT( 0. 90° ± 0. 69°) was minimum in four groups( F = 12. 201,P 0. 001). There were satisfied obturation in four groups,less filling and gutta overfilled were not happened in four groups. Conclusion TF nickel-titanium file is effective for the treatment of narrow and curved root canal,combination of TF with Pathfile are more recommendable,for these instruments can improve the efficiency of root canal preparation and reduce transportation of root canal.