Endodontic morphology. IV. A comparative study

One hundred sixty-four extracted human teeth of all denominations were subjected to radiographic study after their canal systems were prepared with endodontic instruments and perfused with a water-soluble, radiopaque contrast medium. The same specimens had been studied prior to endodontic instrumentation by means of the same technique, and a comparison of the two sets of radiographs was made. Results of this comparative study were combined with information gained during the instrumentation procedures, and an analysis of the success rate for each group of specimens has been given. The over-all rate of success was high (92 per cent), being highest in the case of maxillary incisors and canines (100 per cent) and lowest in mandibular incisors and canines (81.8 per cent). The belief that the canals of molars present more difficulties than those of other teeth was not substantiated in this experiment, with the success rate for maxillary and mandibular molars being 92.1 per cent. Discussed were the potential for the packing of debris into the apical ends of root canals during instrumentation, the presence of residual traces of alloy within canals after canal preparation, and the known and unknown fracturing of endodontic instruments.