a massive mobilization
of the inflammatory defense will take place (43,
64) (Fig. 2.22). A most conspicuous feature is the aggregation
of neutrophils. Often a local abscess develops
(Fig. 2.23). Clinically, upon excavation of caries, a droplet
of pus may sometimes appear at the exposure site.
Although short-lived in an acute inflammatory lesion,
neutrophils release tissue-destructive elements, including
oxygen radicals, lysosomal enzymes and excessive
amounts of nitric oxide. These agents contribute to degradation
of the pulpal tissue (see Advanced concept 2.5).
There will also be renewed and intense immunological
activity, as expressed by an accumulation of immune
cells (35). Collectively, this means that the microbial load
on the pulp has increased dramatically and the vital
functions of the pulp at this stage are clearly threatened
(Fig. 2.24). Nevertheless, in spite of the massive bacterial
attack and the intense inflammatory response, the pulp
may retain vital functions for an extended period of time,
although the end result is likely to be pulpal necrosis.