It is extremely
seldom that the root canal has totally disappeared, although it cannot be
seen in the radiograph. In cases in which the canal is seen on radiograph
only at the few apical millemeters, histologically, it is typically found
already several millimeters more coronally. The treatment strategy with obliterated
root canals is divided into two phases, 1) finding the canal, 2) preparation.
1) Obliterated root canals are more easily found with an operating microscope.
Secondary dentine can be more easily distinguished, thus rendering preparation
safer.