Endodontic morphology. III. Canal preparation

Three hundred nine root canals in 164 extracted human teeth were prepared with endodontic instruments for obturation by the lateral condensation technique. Variations in tooth lengths for each group of teeth were marked, pointing up the need for adequate control of instruments through careful assessment of tooth lengths in clinical practice. In most cases the canals were prepared to the desired depth and flared coronally with the assistance of chelates. Some instrument failures were noted, along with the tendency for files to force debris in an apical direction during instrumentation.