Two nickel-titanium retreatment tools, respectively, cleaning effects on root canal filling materials are compared

Abstract

objective： To compare the effectiveness of the ProTaper Universal， R-Endo retreat-ment files, and a Hedstrom manual technique in the removal of gutta—percha during retreatmen Methods: 60 single-rooted straight mandibular premolars were selected． The root canals of all suitcases were formed by Nickel-Titanium revolving apparatuses Hero 642， and obturated with the lateral strengthening technique． Then all cases were randomly divided into 3 groups(n=20) and prepared with a Hedstrom manual technique．ProTaper Universal and R—Endo retreatment files, respectively． Eucalyptol was used as a solvent in the treatment． For all roots， the subse-quent data were documented： practical mistakes and time of retreatment． Bucco-lingual and proximal radiographs of the roots were taken, and the percentage area was calculated. The remain-ing material was premeditated by separating the area of the outstanding filling substantial by the area of the canal partition． Information was statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests (P=0．05) ． Results： None of the techniques completely removed the root fill-ing materials． The remaining filling material was meaningfully less after physical instrumentation than R-Endo or ProTaper composition (P< 0．05) ． The ProTaper and R-Endo retreatment docu-mentations had a positive influence, in dropping the time for retreatment (P<0．05) ． Conclusion： All tested instruments cannot completely remove the filling material inside the root canal．ProTaper, and R-Endo rotary instruments work faster than manual instruments