Page 11 - The Beauty and Sorrow in Endodontics (WL and C/S)

Haste Makes Waste

When getting ready for cleaning and shaping, dentist often aim to get the small hand

file to the apex as soon as possible to measure the working length of the canal.
Subconscious use of excess pressure to achieve that goal usually results in the creation of

a wrong pathway of the canal or perforations. Even if one is lucky and realizes the file is

heading in the wrong direction prior to perforating the canal, navigating back to the
original canal can still be difficult, and a ledge may be created. Negotiating the correct

pathway of canal is thus one of the most common difficulty in retreatment cases. Dr.
Schilder often reminded his students to “treat a canal, not make a canal” and “let the

canal take the instrument in” during shaping of the canals.

Terminology regarding working length determination on root apex (Fig A1):

1. Cemento-Dentinal Junction (CDJ)

The cemento-dentinal junction (CDJ) can only be seen under histological slides.

During development, cementum is not deposited at the same rate around the root, thus
the CDJ on the mesial surface of the root may not be at the same height as the CDJ on

the distal surface. There have even been reported cases of unilateral deposition of

cementum 5-7mm into the root canal. Clinically, it is impossible to determine the
location of the CDJ as it does not show up on radiographs, and therefore cannot be

used as a reference point for measuring the working length.

2. Apical Foramen

If the root apex is visualized in a three-dimensional manner, the apical foramen will
appear as a cone-shaped area, with the pointed area being the minor opening or apical

constriction, and the wider base as the major opening towards the external root surface.
It is difficult to reference an exact point as the “apical foramen” within this large area.
It should be noted that once the pulp has necrosed or has been removed mechanically,

even after healing of the apical lesion, there will no longer be blood flow into this
cone-shaped area. This means that our immune system will not be able to remove
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