Quality Resource Guide –

Tooth Root Resorption 3rd Edition

www.metdental.com

Page 2

Etiology and Pathogenesis

The tooth root is a combination of mineralized

tissues (dentin and cementum), surrounded

by another mineralized tissue (bone) that is in

a constant state of resorption and apposition.

Approximately 25% of trabecular bone is replaced

in the adult skeleton every year. Given this

relationship, one must ask:

• Why doesn’t tooth root resorption happen

more often?”

• How does the tooth root resist resorption by

adjacent alveolar osteoclasts?

• Is the thin connective tissue layer of the

periodontal ligament enough to protect the

tooth root from resorption?

know

that

even

with

mild

trauma,

multinucleated clastic cells can readily migrate

through the periodontal ligament to the root

surface, but they do not always cause progressive

external resorption. Likewise, such cells can also

be recruited to the dental pulp in response to

inflammation caused by trauma or caries, but we

don’t typically see subsequent internal resorption.

What are the resistant mechanisms? It turns

out that clastic cells recognize the substrate to

which they attach via cell surface receptors called

integrins. Integrins are ubiquitous transmembrane

proteins that regulate a myriad of cell--cell and

cell-extracellular matrix interactions throughout

the body. The specific integrins responsible for

the attachment of the cells that resorb tooth root

structure rely on a unique amino acid sequence

for proper function. If the substrate does not

have that sequence, the cells cannot attach. Both

precementum on the external root surface and

predentin on the internal root surface, lack the

necessary attachment sequences. Therefore, these

surfaces offer protection against root resorption.

Damage to, or malformation of, the precementum

or predentin, are a prerequisite for external or

internal resorption, respectively. In some cases the

damage to the precementum or predentin is mild,

and there is no persistent inflammatory stimulus.

In those instances the resulting resorption will be

self-limiting, and repair may occur. In other cases,

greater damage may occur and/or the presence of

bacteria may perpetuate the resorptive process,

and a significant amount of root dentin may be lost.

Types of Tooth Root

Resorption

Tooth root resorption can be broadly clas¬sified

as internal or external, depending upon its point

of inception. While the clinical and radiographic

presentations and treatment modalities differ

greatly between the two types of resorption (Table

1), their pathogenesis is thought to be similar, as

described above.

Table 1 - Types of Resorption

Internal Resorption (non-perforating)

External Resorption

Conventional

Radiographic

Findings

Radiolucency with the following features:

• Well-defined border

•

Pulp canal space merges into lesion

•

Lesion does not appear to move in angled radiographs

Radiolucency with the following features:

•

Irregular borders

•

Pulp canal space can be seen through lesion

•

Lesion shifts in angled radiographs

Clinical

Findings

Pulp

•

Pulp is vital at onset of process; may eventually become

necrotic

Periodontium

•

Periodontal attachment unaffected by process

Crown

•

May have ‘pink tooth’ appearance if resorption

undermines enamel

Pulp

•

Pulp is typically vital and normally responsive

(except in resorption due to apical periodontitis)

Periodontium

•

May be probable to the level of the defect

Crown

•

May have ‘pink tooth’ appearance if resorption undermines enamel

Treatment

Non-surgical root canal therapy

•

Chemical debridement of resorptive defect

Sodium hypochlorite irrigant

Calcium hydroxide intracanal medicament for

at least 1 week

•

Obturation with softened gutta percha

Inflammatory

•

Endodontic therapy with calcium hydroxide as intracanal

medicament until resorptive process is halted; followed by

obturation

Replacement

•

No treatment: advise patient that the tooth will eventually be lost;

plan on replacement

Extra canal invasive

•

Combined surgical/restorative approach to debride and restore

lesion

•

Endodontic therapy if pulp will likely be exposed during treatment