title: Assessment of dentinal damage during canal preparation using reciprocating and rotary files.
abstract: BACKGROUND
  The role of motion kinematics in creating dentinal damage during instrumentation is not very clear. The purpose of this study was to compare the formation of dentinal cracks with instruments working in continuous rotation and reciprocating motion.
  
  
  METHODS
  One hundred twenty extracted human mandibular premolars were selected for the study. Thirty teeth served as controls, and the remaining 90 teeth were divided into 3 groups depending on the root canal preparation technique. Group 1 samples were treated with WaveOne primary files (Dentsply Maillefer, Ballaigues, Switzerland), group 2 samples with single F2 ProTaper (Dentsply Maillefer) working in reciprocating motion, and group 3 samples were prepared with sequential ProTaper (Dentsply Maillefer) until F2 working in continuous rotation motion. Roots were then sectioned at 3, 6, and 9 mm from the apex, and the cut surface was observed under a stereomicroscope for the presence of dentinal microcracks.
  
  
  RESULTS
  The control group and WaveOne, single F2 ProTaper in reciprocating motion, and continuous ProTaper groups caused cracks in 0%, 15%, 26%, and 53% of samples, respectively. A statistically significant difference was found between 2 reciprocating file groups (WaveOne and single F2 ProTaper in reciprocating motion) and the continuous rotation group (ProTaper) (P < .05). However, no significant difference was found among the 2 reciprocating file groups (P > .05).
  
  
  CONCLUSIONS
  Dentinal cracks are produced irrespective of motion kinematics. Within the limits of this study and the current literature, such incidence is less with instruments working in reciprocating motion compared with those working in continuous rotation.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Kansal
authors.affiliation: Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India. Electronic address: akhilraj_24@yahoo.com.
authors.forename: Akhil
authors.initials: A
authors.lastname: Rajput
authors.affiliation: Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Talwar
authors.affiliation: Department of Conservative Dentistry and Endodontics, Maulana Azad Institute of Dental Sciences, New Delhi, India.
authors.forename: Ruchika
authors.initials: R
authors.lastname: Roongta
authors.affiliation: Maulana Azad Institute of Dental Sciences, New Delhi, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Verma
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000293:injuries*; D003804:Dentin / Q000293:injuries*; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D009038:Motion; D009532:Nickel / Q000737:chemistry; D018583:Pliability; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D019415:Torque
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Dentinal defects; microcracks; nickel-titanium instruments; reciprocation; root canal preparations; root fracture