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Understanding external cervical resorption patterns in endodontically treated teeth
Accepted manuscript online:
understand the pattern of external cervical resorption (ECR) in
endodontically treated teeth. To compare characteristics and mechanisms
of ECR in root filled teeth with those established in teeth with vital
cases of endodontically treated permanent teeth displaying ECR were
investigated. ECR diagnosis was based on clinical findings and
radiographic examination with cone-beam computed tomography (CBCT). The
extracted teeth were further analysed by a nano-focus computed
tomographic (nano-CT) system, hard tissue histology and scanning
electron microscopy (SEM). To make a comparison with teeth with vital
pulps representative cases with ECR were also included.
endodontically treated teeth had a similar ECR pattern. This pattern
reflected many similarities to that seen in teeth with vital pulps, that
is, three stages were observed namely initiation, resorption and
repair. In particular, during the initiation stage (1st stage) the resorption started below the gingival epithelial attachment, at the level of cementum. In the resorption stage (2nd
stage) ECR spread towards the treated pulp space and in a
coronal-apical direction, creating multiple resorption channels. The
pulp and the Pericanalar Resorption Resistant Sheet (PRRS) had been
removed during root canal treatment and thus offered no retarding or
defence mechanism towards ECR. In the reparative stage (3rd stage) reparative hard tissue formation occurred at a localized scale.
ECR patterns were observed in all examined teeth. These pattern
consisted of an initiation, a resorption and a reparative stage. Some
differences were noticed between endodontically treated and teeth with
vital pulps, mainly in the resorption and reparative stages. The
resorption stage in root canal filled teeth was more intense than the
repair stage, as many clastic cells and abundant granulation tissue were
observed in all samples. This is possibly due to the absence of the
pulp and protective PRRS layer and/or to the altered chemical
composition of the root dentine after root canal treatment. Furthermore,
at the repair stage, formation of reparative bonelike tissue took place
to a lesser extent in root filled teeth.