[Chelation].

The use of chelation in endodontics demands a knowledge of the workings of its physico-chemical process. To explain this, we must define unsaturated salts and contrast them with the complexes to which the chelates belong. A few examples of application illustrate these different properties especially the action of E.D.T.A. on the calcified tissues of the endodontium. The mode of action of liquid E.D.T.A. or chelating gels in calcified root canals, poses several questions. The varied studies realized in this domaine allow us to affirm the usefulness of E.D.T.A. in root canal disinfection and in opening up lateral and accessory canals. Also, we must consider the possible influence of chelating agents on the apical seal when the permanent root filling is post poned, and their role in changing the permeability of dentine.