title: Deformation and fracture incidence of Reciproc instruments: a clinical evaluation.
abstract: OBJECTIVE
  To investigate the incidence of fracture and deformation observed on Reciproc instruments after clinical use.
  
  
  METHODS
  A total of 1696 Reciproc NiTi instruments that were discarded after normal clinical usage over 30 months were collected. Of these 1580 instruments were R25 (93%), 76 were R40 (5%), and 40 were R50 (2%). The treatments included 3780 root canal preparations, 3023 primary treatments and 757 retreatments. Root canal preparation was standardized and followed the manufacturer's directions for the use of Reciproc files without creating prior glide path with hand instruments. In retreatment cases, Reciproc R25 instrument was used to remove all filling material and to complete the preparation. Each instrument was used for shaping only one tooth. All the instruments used were inspected under a microscope to detect signs of fracture or deformation and, if any fracture existed, the length of the files was measured. Data were analysed using a chi-square test with a level of significance set at P < .05.
  
  
  RESULTS
  A total of 8 Reciproc R25 instruments fractured during treatment, which represents 0.47% of the number of instruments used and 0.21% of the root canals treated. Five instruments fractured in primary treatment cases and three instruments during retreatments. Six Reciproc R25 deformed during clinical use (0.35% of the number of instruments used and 0.15% of the root canals treated), four during retreatments and two during primary treatments. The deformation reported was unwinding of the blades, one at 1 mm from the tip and five between 2 and 3 mm from the tip. No deformations or fracture were registered for the Reciproc R40 and R50 instruments.
  
  
  CONCLUSIONS
  Root canal instrumentation following the manufacturer's instructions can be performed with Reciproc instruments with a very low incidence of instrument fracture and deformation.
authors.affiliation: Private Practice, Grande, Plotino & Torsello - Studio di Odontoiatria, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Plotino
authors.forename: N M
authors.initials: NM
authors.lastname: Grande
authors.forename: P F
authors.initials: PF
authors.lastname: Porciani
mesh_terms: D003762:Dental Instruments; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D015994:Incidence; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: deformation; fracture; nickel-titanium; reciprocation