title: The structure of dentine in the apical region of human teeth.
abstract: OBJECTIVE
  To study the structure of the apical region of human teeth with emphasis on dentinal tubules and their branches.
  
  
  METHODS
  This descriptive histological study employed demineralized stained sections for light microscopy, demineralized unstained sections for scanning electron microscopy, and undemineralized, acid-etched specimens for confocal tandem scanning microscopy.
  
  
  RESULTS
  The apical portion of human teeth showed marked variations in structure, including accessory root canals, areas of resorption and repaired resorptions, occasional attached, embedded and free pulp stones, varied amounts of irregular secondary dentine, and even cementum-like tissue lining the apical root canal wall. The apex often deviated from the long axis of the root canal. Primary dentinal tubules were irregular in direction and density. Some areas were devoid of tubules.
  
  
  CONCLUSIONS
  The irregular and variable structure of the apical region of human teeth represent special challenges during endodontic therapy. Obturation techniques based on the penetration of adhesives into dentinal tubules are unlikely to be successful and adhesive techniques must depend on impregnation of a hybrid layer.
authors.affiliation: College of Dentistry, University of Florida, Gainesville 32610, USA. imjor@dental.ufl.edu
authors.forename: I A
authors.initials: IA
authors.lastname: Mjör
authors.forename: M R
authors.initials: MR
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
authors.forename: F
authors.initials: F
authors.lastname: Mannocci
mesh_terms: D000328:Adult; D000368:Aged; D003804:Dentin / Q000033:anatomy & histology* / Q000648:ultrastructure; D003806:Dentin Permeability; D003809:Dentin, Secondary / Q000033:anatomy & histology; D006801:Humans; D018613:Microscopy, Confocal; D008875:Middle Aged; D019227:Tooth Apex / Q000033:anatomy & histology*