The structure of dentine in the epical region of human teeth

Aim To study the structure of the apical region of human teeth with emphasi s on dentinal tubules and their branches. Methodology This descriptive histological study employed demineralized stai ned sections for light microscopy, demineralized unstained sections for sca nning electron microscopy, and undemineralized, acid-etched specimens for c onfocal tandem scanning microscopy. Results The apical portion of human teeth showed marked variations in struc ture, including accessory root canals, areas of resorption and repaired res orptions, occasional attached, embedded and free pulp stones, varied amount s 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 r oot 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 hu man teeth represent special challenges during endodontic therapy, Obturatio n techniques based on the penetration of adhesives into dentinal tubules ar e unlikely to be successful and adhesive techniques must depend on impregna tion of a hybrid layer.