The dental pulp may be exposed to a number of
irritants that are noxious to the health of the pulp and
jeopardize the functions of the pulp. They may be either
constant irritants or specific events that interfere with
the pulp blood supply (Table 1). Irritants can be
classified as being short-term, long-term or due to
trauma. Each type of irritant or injury will have a
different effect on the pulp – in general, the effects will
be acute inflammation, chronic inflammation or necrosis
(Table 2). Short-term irritants will usually cause acute
inflammation which will then be followed by resolution
of the inflammation and repair of the tissue since the
irritant does not persist or is no longer occurring.
Common examples of short-term irritants are the cut-ting or
drying of cavities during their preparation and
traumatic injuries that have not displaced the tooth so
the apical blood supply has not been disrupted. In
contrast, typical long-term irritants are dental caries,
restorations breaking down, cracks, erosion and
chemical substances which all lead to the loss of tooth
structure. Long-term irritation will cause chronic
inflammation of the pulp and, if left for long enough,
pulp necrosis which will then be followed by infection
of the pulp space since bacteria will have a pathway by
which they can enter the tooth. In these situations, the
pathway of entry for the bacteria will be where the
tooth structure has been lost. Trauma that causes
displacement (luxation or avulsion) of the teeth will
result in severing of the apical blood vessels. In teeth
with fully developed roots, these blood vessels will
often not be able to heal and revascularize the pulp.
Therefore, in these cases, the response of the pulp to the
injury is immediate necrosis. Subsequently, the necrotic
pulp may become infected but this requires that there
be a pathway for bacterial entry such as through a
crack or fracture. A crack or a fracture may have been
created during the same traumatic incident that
displaced the tooth so infection is not unusual in these
cases. No matter what the cause, once a pulp has
necrosed and become infected, in all such cases the
bacteria within the root canal system will digest and
remove the necrotic pulp so the tooth then becomes
pulpless.
irritants that are noxious to the health of the pulp and
jeopardize the functions of the pulp. They may be either
constant irritants or specific events that interfere with
the pulp blood supply (Table 1). Irritants can be
classified as being short-term, long-term or due to
trauma. Each type of irritant or injury will have a
different effect on the pulp – in general, the effects will
(Table 2). Short-term irritants will usually cause acute
inflammation which will then be followed by resolution
of the inflammation and repair of the tissue since the
irritant does not persist or is no longer occurring.
Common examples of short-term irritants are the cut-ting or
drying of cavities during their preparation and
traumatic injuries that have not displaced the tooth so
the apical blood supply has not been disrupted. In
contrast, typical long-term irritants are dental caries,
restorations breaking down, cracks, erosion and
chemical substances which all lead to the loss of tooth
structure. Long-term irritation will cause chronic
inflammation of the pulp and, if left for long enough,
pulp necrosis which will then be followed by infection
of the pulp space since bacteria will have a pathway by
which they can enter the tooth. In these situations, the
pathway of entry for the bacteria will be where the
tooth structure has been lost. Trauma that causes
displacement (luxation or avulsion) of the teeth will
result in severing of the apical blood vessels. In teeth
with fully developed roots, these blood vessels will
often not be able to heal and revascularize the pulp.
Therefore, in these cases, the response of the pulp to the
pulp may become infected but this requires that there
be a pathway for bacterial entry such as through a
crack or fracture. A crack or a fracture may have been
created during the same traumatic incident that
displaced the tooth so infection is not unusual in these
cases. No matter what the cause, once a pulp has
necrosed and become infected, in all such cases the
bacteria within the root canal system will digest and
remove the necrotic pulp so the tooth then becomes
pulpless.