title: Fracture resistance exhibited by endodontically treated and retreated teeth shaped by ProTaper NEXT versus WaveOne: An in vitro study.
abstract: OBJECTIVE
  To compare the fracture resistance exhibited by teeth after primary endodontic treatment and retreatment.
  
  
  METHODS
  One hundred freshly extracted human teeth were selected. 20 samples served as control (untreated). Eighty experimental samples were divided into two groups (n = 40) for instrumentation using rotary Protaper NEXT (PTN) or reciprocating WaveOne (WO) files and obturated using warm lateral compaction. Half of the samples (n = 20) from each group were subjected to a load. The remaining half were subjected to retreatment using Protaper universal retreatment files (RFs) followed by a file larger than the master apical file used in groups 1 and 2 and reobturated. Group A: Control, Group B: PTN + obturation, Group C: WO + obturation, Group D: RF + PTN + obturation and Group E: RF + WO + obturation. The retreatment specimens were also subjected to load and the readings acquired were statistically analyzed.
  
  
  RESULTS
  When compared between the groups, control group exhibited the highest fracture resistance (P < 0.01). When multiple tests were performed, Group E exhibited significantly less fracture resistance (P < 0.01).
  
  
  CONCLUSIONS
  Endodontic treatment and retreatment both results in lowering the fracture resistance of a tooth.
authors.affiliation: Department of Conservative Dentistry and Endodontics, YMT Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra, India.
authors.forename: Neha Deepak
authors.initials: ND
authors.lastname: Khalap
authors.affiliation: Department of Conservative Dentistry and Endodontics, YMT Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra, India.
authors.forename: Vibha
authors.initials: V
authors.lastname: Hegde
authors.affiliation: Department of Conservative Dentistry and Endodontics, YMT Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra, India.
authors.forename: Sharad
authors.initials: S
authors.lastname: Kokate
keywords: Fracture resistance; Protaper NEXT; WaveOne; retreatment