A tooth with necrobiosis has both inflamed and
necrotic (usually infected) pulp tissue.
Many dentists use the term “partial necrosis” for this stage of the
disease process; however, “necrobiosis” was suggested
by Grossman
because it more accurately indicates the
condition – the key factor to the spread of the disease
process is the presence of bacteria within the necrotic
part of the pulp rather than the necrosis itself of part of
the pulp. The necrotic tissue may be in the coronal
portion of the pulp (e.g., pulp chamber) with the
inflamed tissue apically, or the different tissue states
may exist in different canals of a multi-canal tooth.
Teeth with this condition can be quite difficult to
diagnose since they usually present with a mixture of
the signs and symptoms of both pulpitis and necrosis
with infection. The symptoms may be mild with
intermittent painful episodes over many weeks or
months. Pulp sensibility test results are mixed and
frequently inconclusive or inconsistent with the
patient’s description of symptoms. Teeth with
necrobiosis may also have apical periodontitis with
radiographic evidence of a widened periodontal
ligament space, which may be unexpected because the
patient has reported sensitivity to hot and/or cold stimuli.