Page 16 - The Beauty and Sorrow in Endodontics (WL and C/S)

file (Fig A20). Then holding them side-by-side, adjust the rubber stopper to mark the

working length (Fig A21).

Crown-Down Technique Reduces Risk of Post-Operative Pain

When patients experience post-operative pain after root canal treatment, we often
attribute it to over-instrumentation. It is true that improper use of the files can result in

post-operative discomfort. However, it is inappropriate to assume that a small flexible file
peeking through the apex gently to verify canal patency will cause such immense pain.

Clinically, often the teeth that require root canal treatment have either necrotic pulp or at
least some degree of pulpal inflammation. If the operator is too eager to get the file to

reach RT without cleaning out the coronal and middle segments first, they will

inadvertently push debris out the apex and into the surrounding structures. These debris
that contain bacteria, bacterial byproducts, or diseased tissue that are pushed out the apex

is actually what causes most post-operative pain clinically. Additionally, some lecturers
promote the idea of creating an artificial apical stop 1-2mm coronal to the true apex in

order to NOT over-instrument. However, if you think about it, the last apical 1-2mm has

the most complex system with many lateral canal branches that requires the most time
and effort to treat (and this is why apicoectomy requires the removal of the apical 2-

3mm), without properly cleaning, shaping, and disinfecting the area, how many
pathogens is left behind that can potentially cause problems in the future?

Clean and Shape the Apical Third Last

The crown-down technique has many benefits:
1. it increases the accuracy of working length determination;

2. it reduces the risk of extruding pathogens out when using a small file to check patency

by peeking through the apex;
3. it reduces the risk of ledging or perforating dentinal wall, transporting the canal, or

breaking the file; and

4. it ensures proper cleaning and disinfection of the apical third.

14