Abstract : This paper reviews the root canal preparation and the apical seat.
In my school, we have been teaching the standardized preparation technique using a reamer for these ten years. Although, various problems have been brought in clinical cases of the students ; such as overextension of the apical foramen, straightening of the canal, zipping, accidental perforation and others.
To avoid these accidents, the causes for them and the new method for the root canal preparation have been considered.
The results obtained were as follows :
1. Even in straight canals, the method such as the step-back technique which can minimize the transportation of the canal should be applied.
2. The minimum sized preparation should be performed in the vicinity of the apical foramen.
3. In vital teeth, the termination point of the canal preparation should be located 0.5 mm more coronally of the minor foramen, and the tip of the guttapercha point should be positioned within the apical constriction. On the other hand, in non-vital teeth, the apical foramen should be penetrated with #15-20 files. Then, the canal should be prepared so that the tip of the guttapercha point is seated at the same place as in vital teeth.
4. For the more accurate preparation near the apical formamen, the newly developed electronic apex locators (the Root ZX and the Apit) should be applied.
