title: The effects of canal preparation and filling on the incidence of dentinal defects.
abstract: OBJECTIVE
  To evaluate ex vivo the incidence of defects in root dentine before and after root canal preparation and filling.
  
  
  METHODS
  Eighty extracted mandibular premolars were divided equally in four groups. Group 1 was left unprepared. All other root canals were prepared using Gates Glidden drills and System GT files up to size-40, 0.06 taper at the working length. Group 2 was not filled while the canals of the other groups were filled with gutta-percha and AH26, either with a master cone and passive insertion of secondary gutta percha points (group 3) or lateral compaction (group 4). Roots were then sectioned horizontally 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects (fractures, craze lines or incomplete cracks) was noted and the differences between the groups were analysed with the Fisher's exact test.
  
  
  RESULTS
  No defects were observed in the roots with unprepared canals. The overall difference between the groups was significant (P < 0.05). Canal preparation alone created significantly more defects than unprepared canals (P < 0.05). The total number of defects after lateral compaction was significantly larger than after noncompaction canal filling.
  
  
  CONCLUSIONS
  Root canal preparation and filling of extracted teeth created dentine defects such as fractures, craze lines and incomplete cracks.
authors.affiliation: Department of Cariology, Endodontology, Pedodontology, Academic Centre of Dentistry Amsterdam, Amsterdam, The Netherlands. hshemesh@acta.nl
authors.forename: H
authors.initials: H
authors.lastname: Shemesh
authors.forename: C A S
authors.initials: CA
authors.lastname: Bier
authors.forename: M-K
authors.initials: MK
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Tanomaru-Filho
authors.forename: P R
authors.initials: PR
authors.lastname: Wesselink
mesh_terms: D001641:Bicuspid; D001729:Bismuth / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000293:injuries*; D003804:Dentin / Q000293:injuries*; D004338:Drug Combinations; D004853:Epoxy Resins / Q000627:therapeutic use; D004867:Equipment Design; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D008422:Materials Testing; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012389:Root Canal Obturation / Q000009:adverse effects / Q000379:methods; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D012834:Silver / Q000627:therapeutic use; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014025:Titanium / Q000627:therapeutic use; D014082:Tooth Fractures / Q000209:etiology / Q000473:pathology
chemical_list: D004338:Drug Combinations; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D012834:Silver; C028044:epoxy resin AH-26; D006171:Gutta-Percha; D014025:Titanium; D012973:Sodium Hypochlorite; D001729:Bismuth