title: Ex vivo study of the efficacy of H-files and rotary Ni-Ti instruments to remove gutta-percha and four types of sealer.
abstract: OBJECTIVE
  To compare the efficacy of ProFile rotary Nickel-Titanium (Ni-Ti) instruments and Hedstroem-files (H-files) combined with Gates-Glidden (GG) drills during removal of gutta-percha root fillings used in combination with one of the four representative sealers.
  
  
  METHODS
  Forty-eight single-rooted human teeth, with fully formed apices and straight root canals were used. The root canals were accessed and instrumented using a stepback technique with H-files. They were randomly assigned to four groups and subsequently filled with a combination of lateral and vertical condensation of gutta-percha and one of the following sealers: Roth 811, AH26, Endion and Roekoseal. The root fillings were removed 1 year later, using either H-files in combination with GG drills or the ProFile Ni-Ti system. Teeth were then grooved longitudinally and split. The amount of gutta-percha and sealer remaining on the root canal walls was traced and scored visually with the aid of a stereomicroscope. The scores were analysed and statistically compared with the Kruskal-Wallis test between the ProFile and H-file groups, as well as among the four sealer subgroups. Two samples from each group were studied under the scanning electron microscope to enhance inspection of canal walls and remaining material.
  
  
  RESULTS
  Sealer remnants were observed with both techniques mainly in the middle and apical third of the root canal. The ProFile system and the H-files were associated with similar amounts of remaining filling material (P > 0.05). In the cervical third of the root canal all sealer remnants were removed with both techniques. In the middle and apical third AH26 was associated with a statistically significant greater quantity of remnants on the root canal walls with both removal techniques (P < 0.05). Endion, Roth 811 and Roekoseal were associated with approximately the same amount of filling material in the middle third of the root canal (P > 0.05), whereas in the apical third Endion was associated with significantly more remnants of filling material than the other two sealers with either ProFile or H-files (P < 0.05).
  
  
  CONCLUSIONS
  None of the methods used for the removal of root fillings was totally effective, especially in the apical third of the root canal.
authors.affiliation: Department of Endodontology, Dental School, Aristotelion University of Thessaloniki, Thessaloniki, Greece. elkosti@dent.auth.gr
authors.forename: E
authors.initials: E
authors.lastname: Kosti
authors.forename: T
authors.initials: T
authors.lastname: Lambrianidis
authors.forename: N
authors.initials: N
authors.lastname: Economides
authors.forename: C
authors.initials: C
authors.lastname: Neofitou
mesh_terms: D003738:Dental Cements; D006171:Gutta-Percha; D006801:Humans; D019233:Retreatment / Q000295:instrumentation; D012390:Root Canal Therapy / Q000295:instrumentation*
chemical_list: D003738:Dental Cements; D006171:Gutta-Percha