title: Dentinal crack formation during root canal preparations by the twisted file adaptive, Reciproc and WaveOne instruments.
abstract: OBJECTIVE
  This study aimed to compare the frequency of dentinal microcracks after root canal shaping with 2 reciprocating (Reciproc and WaveOne) and 1 combined continuous reciprocating motion twisted files adaptive (TFA) rotary system.
  
  
  METHODS
  Ninety molars were chosen and divided into three groups of 30 each. Root canal preparation was achieved by using Reciproc R25, Primary WaveOne and TFA systems. All the roots were horizontally sectioned at 15, 9, and 3 mm from the apex. The slices were then viewed each under a microscope at × 25 magnification to determine the presence of cracks. The absence/presence of cracks was recorded, and the data were analyzed with a Chi-square test. The significance level was set at P < 0.05.
  
  
  RESULTS
  Instrumentation with Reciproc produced significantly more complete cracks than WaveOne and TFA (P = 0.032). The TFA system produced significantly less cracks then the Reciproc and WaveOne systems apically (P = 0.004).
  
  
  CONCLUSIONS
  Within the limits of this study, the TFA system caused less cracks then the full reciprocating system (Reciproc and WaveOne). Single-file reciprocating files produced significantly more incomplete dentinal cracks than full-sequence adaptive rotary motion.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Saint Joseph University, Beirut, Lebanon.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Gergi
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Saint Joseph University, Beirut, Lebanon.
authors.forename: Nada E
authors.initials: NE
authors.lastname: Osta
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Saint Joseph University, Beirut, Lebanon.
authors.forename: Alfred S
authors.initials: AS
authors.lastname: Naaman
keywords: Adaptive motion; dentinal defects; microcracks; reciprocation; single-file system