title: Evaluation of surface characteristics of rotary nickel-titanium instruments produced by different manufacturing methods.
abstract: BACKGROUND
  Instrument fracture is a serious concern in endodontic practice.
  
  
  OBJECTIVE
  The aim of this study was to investigate the surface quality of new and used rotary nickel-titanium (NiTi) instruments manufactured by the traditional grinding process and twisting methods.
  
  
  METHODS
  Total 16 instruments of two rotary NiTi systems were used in this study. Eight Twisted Files (TF) (SybronEndo, Orange, CA, USA) and 8 Mtwo (VDW, Munich, Germany) instruments were evaluated. New and used of 4 experimental groups were evaluated using an atomic force microscopy (AFM). New and used instruments were analyzed on 3 points along a 3 mm. section at the tip of the instrument. Quantitative measurements according to the topographical deviations were recorded. The data were statistically analyzed with paired samples t-test and independent samples t-test.
  
  
  RESULTS
  Mean root mean square (RMS) values for new and used TF 25.06 files were 10.70 ± 2.80 nm and 21.58 ± 6.42 nm, respectively, and the difference between them was statistically significant (P < 0.05). Mean RMS values for new and used Mtwo 25.06 files were 24.16 ± 9.30 nm and 39.15 ± 16.20 nm respectively, the difference between them also was statistically significant (P < 0.05).
  
  
  CONCLUSIONS
  According to the AFM analysis, instruments produced by twisting method (TF 25.06) had better surface quality than the instruments produced by traditional grinding process (Mtwo 25.06 files).
authors.affiliation: Department of Endodontics, Faculty of Dentistry, 19 Mayis University, Samsun, Turkey.
authors.forename: U
authors.initials: U
authors.lastname: Inan
authors.affiliation: Department of Endodontics, Faculty of Dentistry, 19 Mayis University, Samsun, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Gurel
mesh_terms: D000497:Alloys; D003722:Dental Alloys / Q000737:chemistry*; D003762:Dental Instruments; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation; D012399:Rotation; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D003722:Dental Alloys; C040654:titanium nickelide; C013616:nitinol; D009532:Nickel; D014025:Titanium