the Canal System Orifice After Endodontic Treatment
treatment is not complete until the tooth is permanently
restored. The major cause of post endodontic
failure is orthograde bacterial microleakage. Think of the
pulp tissue as the root’s first line of defense against
bacterial infiltration. It’s more than just “the
nerve”. After the connective tissue and circulatory
component have been removed or have become non-vital, the
body’s immune system is no longer poised to prevent
the invasion of bacteria into the alveolar bone via the root
In addition to well instrumented
and three dimensionally
obturated root canal spaces, bacteria
must be excluded from the internal aspects of the crown leading
to the the canal orifices. Although endodontic cases are
frequently referred for specialty care, it is actually the
restorative dentist who is responsible for completion of
the canal space obturation procedure.
the convenience of placing core build-ups, the endodontic case
is most often presented for completion with the gutta-percha
recessed approximately one millimeter into the orifice followed
by an intervening
layer of cotton fibers and an appropriate temporary restoration.
It is very disconcerting to observe, on endodontic recall examination,
a lucent space between the margin of a new porcelain crown
and the coronal extent of the obturation material. In those cases, either the cotton wasn’t removed or
the core material did not flow into the canal orifices and
Understanding root canal
orifice anatomy is important. A simple principle is the “one
root equals one root canal space” axiom. The mesial
root of a mandibular molar generally has two spaces that
can initially accept small endodontic files. In reality, there is only one root
canal space present. The microscopic isthmus that connects
the mesiobuccal and mesiolingual main canal spaces can retain
tissue if not properly soaked with tissue dissolving irrigants
such as sodium hypochlorite. Of similar importance, if the connecting isthmus is not
obturated, this area becomes very vulnerable to future microleakage
and endodontic failure. The
same holds true for the mesiobuccal root of maxillary molars
and the distal root of mandibular molars with “two” canals.
The most advanced techniques
for the hybridization of dentin through dentin bonding are
appropriate and necessary steps in core build-up procedures
to ensure that the root canal space is completely sealed
from the apex to the margin of the restoration.
Communicate your restorative intentions with regard to post-space and
core build-ups to your endodontic colleagues.
Completely restore endodontically treated teeth as soon as possible.
Remove all temporary filling material from the access cavity and complete
the endodontic obturation by sealing all canal orifices and connecting
isthmuses with dentin hybridization bonding procedures.
Southard DW. Immediate core buildup of endodontically
treated teeth: The rest of the seal.
Pract Periodont Aesthet Dent 1999;11:519-526.
Belli S, Zhang Y, Pereira P, Ozer F, Pashley D.
Regional bond strengths of adhesive resins to
pulp chamber dentin. J Endodon 2001;27: 527-532.
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