title: Influence of Temperature on Cyclic Fatigue Resistance of ProTaper Gold and ProTaper Universal Rotary Files.
abstract: BACKGROUND
  The aim of this study was to evaluate the cyclic fatigue resistance of ProTaper Universal (PTU; Dentsply Maillefer, Baillagues, Switzerland) and ProTaper Gold (PTG, Dentsply Maillefer) nickel-titanium rotary files at room and intracanal temperatures.
  
  
  METHODS
  A total of 120 files were used to test the cyclic fatigue resistance of PTU (S1 and F2) and PTG (S1 and F2) in an artificial canal at room temperature (20°C) and at intracanal temperature (35°C). The number of cycles to failure and the fracture length of the fragment were recorded, and data were subjected to statistical analysis.
  
  
  RESULTS
  PTG registered no differences in fatigue life between the 2 temperatures tested (P > .05), whereas PTU showed a statistically significant reduction in fatigue life at intracanal temperature compared with room temperature (P < .05). PTG instruments exhibited a statistically higher resistance to cyclic fatigue than PTU instruments both at room and intracanal temperatures (P < .05). There were no statistically significant differences among the fracture length of separated instruments (P > .05).
  
  
  CONCLUSIONS
  Intracanal temperature influenced the cyclic fatigue resistance of instruments produced with traditional nickel-titanium, whereas it did not influence the fatigue life of instruments produced with gold heat treatment. Gold heating treatment enhances the resistance to cyclic fatigue of ProTaper instruments.
authors.affiliation: Endodontics Unit, Department of Oral and Maxillo-Facial Sciences, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.affiliation: Department of Endodontics, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Grande
authors.affiliation: Department of Restorative Dentistry and Endodontics, Universitat Internacional de Catalunya, Barcelona, Spain. Electronic address: mmercade@uic.es.
authors.forename: Montse
authors.initials: M
authors.lastname: Mercadé Bellido
authors.affiliation: Endodontics Unit, Department of Oral and Maxillo-Facial Sciences, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Testarelli
authors.affiliation: Endodontics Unit, Department of Oral and Maxillo-Facial Sciences, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Gambarini
mesh_terms: D000497:Alloys; D003762:Dental Instruments; D004868:Equipment Failure; D006801:Humans; D013696:Temperature
chemical_list: D000497:Alloys; C013616:nitinol
keywords: Heat treatment; ProTaper Gold; ProTaper Universal; nickel-titanium alloys