The final coronal restoration could influence the
outcome of endodontic treatment. The restoration
should provide adequate coverage to protect the
endodontically treated tooth against fracture, which
could ultimately lead to extraction.
Other potential problems associated with the final restoration playing a
role in the breakdown of root canal treatment include
a permanent restoration with marginal breakdown, or
bacterial penetration due to restorative procedures such
as post space preparation.
Both will result in micro-organisms invading the filled root canal space after
treatment.
The relationship between the quality of the coronal
restoration and the periapical status has been
investigated in several studies.
It has been suggested
that both root canal filling and the coronal restoration
serve as a barrier against fluid and bacterial penetration
into the periapical area.
A number of studies have
shown that inadequate root filling and coronal
restorations were associated with an increased incidence
of apical periodontitis,
but the technical quality of
the endodontic treatment (as assessed radiographically)
had a more substantial impact on the outcome of
treatment than the technical quality of the coronal
restoration.
In reality, there are no available materials
or obturation techniques that can confidently assure an
impervious seal of the complex root canal system.
Ricucci and Bergenholtz suggest that the problem of
coronal bacterial penetration may not be of such great
clinical importance, provided ideal instrumentation and
high technical quality root canal fillings are achieved,
and their findings challenged the significance of coronal
microleakage and numerous in vitro findings.
Fractures of endodontically treated teeth could lead
to infection of the root canal system or extraction of the
tooth. Vire et al.
observed that close to half of the
failures seen in the study were due to crown fractures.
Linn and Messer
in a laboratory study showed that
full coronal coverage of an endodontically treated
molar resulted in an increase in cuspal stiffness, and
this finding reinforces the importance of cusp coverage
to protect against fracture. Also, cusp coverage will
reduce cusp deflection and minimize mar ginal break-down.
Aquilino et al .in a retrospective cohort study
observed a strong association between crowns as a
coronal restoration and long-term survival of root
canal treated teeth.