Resorption is a common sequel to dental trauma and
may be caused directly by the traumatic incident or
indirectly through subsequent infection. Andreasen has
described three types of resorption following trauma:
surface resorption, replacement root resorption and
inflammatory root resorption.
Root resorption has also been described as being
as ankylosis-related and
infection related.
Heithersay has extensively reviewed
root resorption and proposed a new system of
classification of these defects, as well as describing a
range of treatment options for these lesions.
The three most common resorptive patterns seen in
traumatized teeth are surface, replacement and
inflammatory resorption. Surface and replacement
resorption are trauma induced, whereas inflammatory
root resorption is caused by the combination of
traumatic injury and infection of the necrotic root canal
system.
Surface resorption is believed to be a self-limiting
response to a localized injury to the periodontal
ligament or cementum. In traumatized teeth this type of
resorption occurs more commonly in the apical portion
of the root and may be seen as a shallow rounding of
the tooth shape.
Replacement root resorption results in the
replacement of tooth structure by bone and can be
recognized radiographically by the diffuse nature of the
resorptive defect, the disappearance of the periodontal
space adjacent to the area of the resorption and the lack
of a bony defect adjacent to the resorptive defect.
Replacement resorption is generally associated with
replanted or luxated teeth. It is a progressive type of
resorption and the prognosis is very poor. It is thought
to be initiated by damage to the periodontal ligament
leading to a fusion between dentine and bone with
progressive replacement of the dentine by bone.
In most instances the majority of the root becomes
involved over time and, in these cases, the clinician may
elect to allow the process to continue to its inevitable
end result – i.e., total destruction of the root. This
process usually takes about five years but may take
much longer, especially in older patients.
Inflammatory root resorption occurs entirely as a
result of a necrotic and infected pulp. It can be
recognized radiographically by the development of a
radiolucency in the bone adjacent to the resorptive
defect. Removal of the infected pulp tissue, dressing
with an anti-clastic medicament (such as Ledermix®
paste) and subsequent filling of the root canal with
gutta-percha will usually halt the resorptive process.
Inflammatory and replacement resorption may occur
together in the one traumatized tooth. Endodontic
treatment may halt the inflammatory resorption but the
replacement resorption, once initiated, is generally
progressive.
Less commonly, traumatic injury may cause other
hyperplastic forms of tooth resorption. Heithersay
describes these as internal replacement resorption and
invasive coronal, cervical or radicular root resorption.
Treatment options for these types of resorptive effects
have been extensively described.
Recently, the desirability of replanting avulsed teeth
with long dry times in young patients has been brought
into question due to the inevitable complication of
ankylosis, infra-occlusion of the tooth and disturbances
in alveolar growth.
Additionally, since removal of
mature ankylosed anterior teeth is sometimes difficult
and destructive to the supporting bone, early removal
of ankylosed and resorbing mature teeth may be
warranted if implant replacement is to be carried out at
a later date. Alternatively, root submergence
(decoronation) in the growing patient allows continued
alveolar development and maintains bone for
subsequent implant placement when growth is
complete.