title: [Comparison of penetration and obturation density using nickel-titanium and stainless-steel spreader in curved canals].
abstract: OBJECTIVE
  To compare the initial penetration depth of nickel-titanium (NiTi) and stainless-steel (SS) spreader during lateral compaction and the quality of the seal in curved canals.
  
  
  METHODS
  Forty extracted mandibular premolars with a single curved canal were divided into two groups: no more than 20 degrees and more than 20 degrees based on degree of curvature. All canals were instrumented using a rotary instrumentation technique. NiTi and SS spreaders were used to obturate the canals containing a master cone while the penetration depths were measured. Horizontal sections were cut in 2 and 4 mm from the apex and photographed under stereomicroscope. The percentage of gutta-percha-filled are (PGP) of cross-sections was measured using an image analysis program.
  
  
  RESULTS
  In canals of more than 20 degrees, the penetration depths and PGP of 2 mm from the apex of NiTi spreaders were higher than SS spreader. In canals of no more than 20 degrees, there were no significant difference between them (P > 0.05). At 4 mm from the apex, there was no significant difference between two groups.
  
  
  CONCLUSIONS
  NiTi spreaders has a higher penetrated depth and obturation density than SS spreaders in severed curved canals.
authors.affiliation: Dept. of Stomatology, Vocational School, Wuhan University, Wuhan 430060, China.
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Xia
authors.forename: Bin
authors.initials: B
authors.lastname: Peng
authors.forename: Zhuan
authors.initials: Z
authors.lastname: Bian
authors.forename: Ming-Wen
authors.initials: MW
authors.lastname: Fan
mesh_terms: D006171:Gutta-Percha; D006801:Humans; D009532:Nickel; D012389:Root Canal Obturation; D013193:Stainless Steel; D014025:Titanium
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium