title: The effect of endodontic procedures on apical crack initiation and propagation ex vivo.
abstract: OBJECTIVE
  To evaluate the potential effects of endodontic procedures (instrumentation and filling) on crack initiation and propagation in apical dentine.
  
  
  METHODS
  Forty extracted single-rooted premolars with two canals were selected, 1.5 mm of the apex was ground perpendicular to the long axis of the tooth and the surface polished. The specimens were divided into 4 groups. The buccal canals of groups A, B and C were enlarged to size 40 with manual K-files. Group A was filled with gutta-percha using lateral condensation and vertical compaction without sealer. Group B was filled with the same method as group A except only lateral condensation was used. Group C was left unfilled, while group D was left unprepared and unfilled. Images of the resected surface were taken after resection (baseline), after canal preparation, after filling and after 4-week storage. The images were then inspected for cracks originating from the canal.
  
  
  RESULTS
  A significant effect of preparation on crack initiation (P < 0.05) and no significant effect of filling (P > 0.05) or 4-week storage on crack initiation (P > 0.05) was found (logistic regression). Fisher's exact test revealed a significant effect of filling on crack propagation (P < 0.05) and no effect of 4-week storage on crack propagation (P > 0.05).
  
  
  CONCLUSIONS
  Root canal procedures can potentially initiate and propagate cracks from within the root canal in the apical region.
authors: Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors: C G
authors: CG
authors: Adorno
authors: T
authors: T
authors: Yoshioka
authors: P
authors: P
authors: Jindan
authors: C
authors: C
authors: Kobayashi
authors: H
authors: H
authors: Suda
mesh_terms: D004396:Coloring Agents; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D008751:Methylene Blue; D055100:Optical Fibers; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012389:Root Canal Obturation / Q000295:instrumentation / Q000379:methods*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013997:Time Factors; D019227:Tooth Apex / Q000648:ultrastructure*; D014172:Transillumination / Q000295:instrumentation
chemical_list: D004396:Coloring Agents; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C113130:obtura II; D006171:Gutta-Percha; D012973:Sodium Hypochlorite; D008751:Methylene Blue
keywords: apical root cracks; crack initiation; crack propagation; dentinal cracks; vertical root fracture