title: The effects of different nickel-titanium instruments on dentinal microcrack formations during root canal preparation.
abstract: OBJECTIVE
  The aim of the present study was to investigate the incidence of dentinal microcracks caused by different preparation techniques.
  
  
  METHODS
  120 extracted human mandibular incisor teeth were divided into five experimental groups and one control group (n = 20): Group 1: Hand preparation with balanced force technique up to #25 K-file. Group 2: Preparation with only ProTaper F2 instrument in a reciprocating movement. Group 3: Preparation with Reciproc R25 instrument in a reciprocating movement. Group 4: Preparation with ProTaper instruments up to F2 instrument. Group 5: Preparation with ProTaper Next instruments up to X2 instrument. No procedure was applied to control group. The roots were sectioned horizontally at 3, 6 and 9 mm from the apex and examined. Absence or presence of dentinal microcracks was noted.
  
  
  RESULTS
  The Chi-square test was performed to compare the appearance of cracked roots between all groups. There were no significant differences among the groups (P > 0.05).
  
  
  CONCLUSIONS
  In conclusion, except the hand file and control group, all experimental groups showed microcrack formations.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye.
authors.forename: Yakup
authors.initials: Y
authors.lastname: Ustun
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye.
authors.forename: Tugrul
authors.initials: T
authors.lastname: Aslan
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye.
authors.forename: Burak
authors.initials: B
authors.lastname: Sagsen
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye.
authors.forename: Bertan
authors.initials: B
authors.lastname: Kesim
keywords: Dentinal microcrack; ProTaper; Reciproc