Many teeth that are examined by dentists will have
had previous pulp therapy or endodontic treatment.
Such treatments include pulp capping, partial pulpotomy,
pulpotomy, partial pulpectomy and pulpectomy. These
teeth may or may not have signs or symptoms, and they
may or may not have apical periodontitis associated
with them. The technical standard of the previous
treatment may also vary considerably and this can only
be partly assessed by the radiographic appearance of
the material(s) placed in the pulp space or root canal(s).
Essentially, the radiographic appearance of a root
filling only indicates the radiodensity of the material
and where the material has been placed. Radiographs
do not provide any indication of whether or not the
root canal system was disinfected during the previous
treatment, how effectively the canal was sealed,
whether the seal has been maintained, whether any
bacteria survived the previous treatment and whether
any new bacteria have entered the root canal system
since the treatment was completed.
When assessing a tooth that has had previous
conservative pulp therapy that was designed to preserve
the pulp (such as pulp capping, partial pulpotomy,
pulpotomy and partial pulpectomy), the key decision to
make is whether or not the remaining pulp is healthy.
In contrast, when assessing a tooth that has had
previous endodontic treatment (i.e., pulpectomy), the
key decision is whether the root canal system is infected
or not (Fig 5). If the root canal system is infected, then
the decision is usually based on the presence of some
form of apical periodontitis, an apical abscess or facial
cellulitis. In such cases, the radiographic appearance
(i.e., the technical standard) of the root canal filling is
irrelevant as the root filling will need to be removed in
order to manage the infection and periapical condition.
The presence of a widened periodontal ligament
space or a periapical radiolucency is an important and
sometimes the only indicator of apical periodontitis.
However, the cause of a radiolucency is not necessarily
just an infection in the apical part of the root canal
system.
In some cases, the radiolucency may indicate
a periapical true cyst, an extra-radicular infection, a
foreign body reaction or a periapical scar.
The radio-lucency may also be an indication of periapical tissues
that are still healing when assessing teeth that have had
recent root canal treatment, because some periapical
lesions may take 2–5 years to heal.
Technical inadequacy of a root canal filling may be
seen on a radiograph but it may often be obscured due
to the two-dimensional nature of radiographic images.
Assessment of a previously treated tooth should also
include identification of any other “mechanical”
problems such as a fractured file, a root perforation,
etc.