Page 13 - The Beauty and Sorrow in Endodontics (WL and C/S)

point on the root where the file touches the PDL is where the radiographic terminus is.

This point is always reproducible no matter the angulation of the radiograph (Figs A2,
A3, A4, A5).

The outer reference point is usually a flat surface on the dental crown that is closest to

the canal orifice. It is important to make sure the rubber stoppers can sit

perpendicularly on the files to avoid any discrepancy in measurements due to the
tilting of the rubber stoppers (Fig A6).

B. Patency: Keep the apical open (or portal of exit) with a tiny file

During cleaning and shaping, if a small file (eg. ISO #10) can enter the canal orifice,
follow the natural curvature of the canal apically until it peeks through the apex, and

a radiograph can verify that the RT has been reached, then patency of the canal is said

to be achieved. As long as patency can be maintained throughout the procedure, then
proper cleaning and shaping can be carried out for the entire root canal system. Dr.

Schilder often reminded his students to regularly allow small files to peek through the
apex to check for canal patency, ensuring that the apex is not blocked by dentinal

debris created during cleaning and shaping.

Apical patency: This refers to the absence of soft and hard tissue obstruction in the
canal in relation to cleaning and shaping. We want the canal open and unobstructed

during the process of cleaning and shaping.

To maintain apical patency:
1. Requires lots of irrigation (NaOCl);

2. Move the sharp and short pre-curved file passively through the apical constriction
to reach the RT;

3. Let the small files (#10f or #15f) touch the PDL frequently and gently (by slipping,

sliding, and gliding motion).

C. Peeking through

A mouse will always sneak a peek before exiting its hole in the wall to make sure it’s

11