Page 38 - The Beauty and Sorrow in Endodontics-Chapter 1

previous root canal treatment and its quality, any posts or obstacles in the
canals, the presence of periodontal disease, the size of the lesions, etc.

This information allows the operator to assess the difficult of the
(re)treatment prior to initiation. This also acts of evidence of the
condition of the untreated tooth.

2. Fig 20E (Trial file) – This radiograph confirms placement of the small
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file to the radiographic terminus (RT). One should also keep an eye out
around the path of the file, for example: is there any curvature of the file
and is it consistent with the external root surface? If the file does not
reach RT, what’s the problem and how can one correct it during cleaning

and shaping to avoid future problems? Is the access cavity prep
appropriate? Are there any remaining carious tooth structures or failing
restoration that still need to be removed? Is the file centered in the canal

or is another canal suspected?

3. Fig 20F (Master Apical File) – This radiograph is used to confirm that
the largest file used to clean the apical ⅓ has reached the RT. Similar to

the second x-ray, this is the time to verify that the file is centered in the
canal and follows the natural curvature of the canal. This file should also
resemble the flow of the trial file to confirm no transportation of the apex

has occurred. In addition, since this is the last instrument used to clean
and shape the canal, it is necessary to carefully examine the image to
make sure nothing requires correction. Questions to consider include: is

the apical taper and the continuous taper throughout the canal adequate
and follow the natural curvature of the canal? Has the apical opening
been damaged? Has the apical opening been expanded and cleaned

adequately? … etc.

4. Fig 20G (Master Cone Fit) – This radiograph is used to check the master
GP cone fit. The master cone should be placed easily to 0.5~1.0mm short
of RT. The taper and flow of the GP should conform to the shape of the

root, leaving enough dentinal wall thickness; this is to ensure adequate
cleaning and shaping have been carried out. This is the most critical

radiograph in a root canal treatment and must be taken. Once the master
cone at a good position presents with adequate tugback and resistance to
apical push, the operator can proceed with obturation.

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