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PATHOLOGICAL TOOTH RESORPTION DEFINITION According to the American association of Endodontics in 1944, (Glossary – Contemporary Terminology for Endodontics) resorption is defined as “A condition associated with either a physiologic or a pathologic process resulting in the loss of dentin, cementum or bone.” Root-resorption is the resorption affecting the cementum or dentin of the root of tooth. CLASSIFICATION OF RESORPTION Pathologic tooth resorption is seen in both deciduous as well as permanent teeth due to underlying pathology. a. Internal Resorption

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PATHOLOGICAL TOOTH RESORPTION

DEFINITION

According to the American association of Endodontics in 1944,

(Glossary – Contemporary Terminology for Endodontics) resorption is

defined as “A condition associated with either a physiologic or a pathologic

process resulting in the loss of dentin, cementum or bone.”

Root-resorption is the resorption affecting the cementum or dentin of the

root of tooth.

CLASSIFICATION OF RESORPTION

Pathologic tooth resorption is seen in both deciduous as well as

permanent teeth due to underlying pathology.

a. Internal Resorption

Root canal replacement Resorption

Internal inflammatory Resorption

b. External Resorption

Surface Resorption

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Inflammatory Resorption

Replacement Resorption

Dentoalveolar ankylosis

MECHANISM OF TOOTH RESORPTION

Resorption of hard tissue takes place as two events. First, there is the

degradation of inorganic crystal structures – hydroxyapatite, after which, the

degradation of the organic matrix takes place.

Degradation of the Inorganic Crystal Structure

Degradation of the Inorganic Structure is initiated by the creation of

an acidic pH of 3 to 4.5 at the site of resorption. This is created by the

polarize de proton pump which is produced within the ruffled border of the

clastic cells. Below the pH of 5, the dissolution of hydroxyapatite is found to

occur.

Enzymes carbonic anhydrase II which catalyses the conversion of CO2

and H2CO3 intracellularly also maintains an acidic environment at the site of

resorption which is a readily available source of H+ ions. The enzyme acid

phosphatase also favors the resorption process.

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CO2 + H2O H2CO3

H2CO3 H+ + HCO3 –

Degradation of the Organic Matrix

Three main enzymes involved in this process are collagenase, matrix metallo

proteinases (MMP) and cysteine proteinases

Enzymes Involved in Degradation of Organic Matrix

1. collagenase

2. matrix metallo proteinases (MMP)

3. Cysteine proteinases

Collagenase and MMP act at a neutral or just below neutral pH – 7.4.

They are found more towards the resorbing bone surfaces where the pH is

near neutral, because of the presence of the buffering capacity of the resorbing

bone salts. MMP is more involved in odontoblastic action. Cysteine

proteinases are secreted directly into the osteoclasts into the clear zone via the

ruffled border. Cysteine proteinases work more in an acidic pH and near the

ruffled border, the pH is more acidic.

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Inhibitory Mechanisms of Resorption

Cementum

The innermost layer of cementum is lined by the cementoid tissue and

the cementoblasts. The cementoid is less mineralized and so it is more

resistant to resorption. Clastic cell are attracted or can attach themselves

only to mineralized tissues. The innermost layer of cementum is a highly

calcified layer, acts as a barrier between the dentinal tubules and the

sharpey’s fibers. They do not allow the passage of toxic products or

microorganisms under normal circumstances. Cementoblasts favor

cementum formation. Continuity of root cementum is an important factor to

be taken into consideration in various pathologies of resorption.

Dentin

Predentin layer of dentin, the just formed dentin, lined by odontoblasts

favor dentin deposition. Wedenberg et al has demonstrated it as an anti-

invasive factor in dentin.

According to silva et al, dentin contains numerous polypeptide

signaling molecules which may affect the healing and resorption of dental

and periodontal tissues.

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FACTORS REGULATING TOOTH RESORPTION

Systemic factors

Parathyroid hormones (PTH) favor resorption. They stimulate osteoclasts;

favor the formation of multinucleated giant cells.

1,2,5 Dihydroxy Vit D3 increases the resorption activity of the osteoblasts.

Calcitonin inhibits the resorption by suppressing the osteoclastic

cytoplasmic mobility of the ruffled border.

Local Factors

These are secreted from inflammatory cells and osteoblasts as a result

of stimulation by bacteria, tissue breakdown products and cytokines

themselves.

Factors Regulating Tooth Resorption

Local factors systemic factors

Macrophage colony Parathyroid hormone

Stimulating factor (M-CSF)

Interleukin 6 1,2,5 dihydroxy Vit D3

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Interleukin 1 calcitonin

TNF – alpha

Prostaglandin – PGE 2

Bacteria and toxins

Internal Resorption

According to shafer, “ internal resorption is an unusual form of tooth

resorption that begins centrally within the tooth, apparently initiated in most

cases by a peculiar inflammation of the pulp”. It is characterized by oval

shaped enlargement of root canal space. It is usually asymptomatic and

discovered on routine radiographs. Internal resorption may progress slowly,

rapidly or intermittently with period of activity and inactivity.

Etiology

Long standing chronic inflammation of the pulp

Caries related pulpits

Traumatic injuries

a. Luxation injuries

Iatrogenic injuries

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a. Preparation of tooth for crown

b. Deep restorative procedures

c. Application of heat over the pulp

d. Pulpotomy using Ca (OH)2

Idiopathic

Clinical Features of Internal Resorption

Usually asymptomatic until it perforates the root and communicates

with periodontium.

Common in maxillary central, but can affect any tooth

Spreads rapidly in primary teeth

Pathagnomonic feature is pink spot appearance of tooth which

represents the hyperplasic vascular pulp tissue showing off through

crown of tooth.

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Radiographic Features

The typical radiographic appearance is smooth widening of root canal

wall.

Types of Internal Resorption

Clinically, there are two types of internal resorptions:

a. Root canal replacement resorption.

b. Internal inflammatory resorption

Root canal replacement resorption

(Metaplastic Resorption)

Resorption of dentin and subsequent deposition of hard tissues are

found that resembles bone or cementum or osteodentin, but not dentin. They

represent areas of destruction and repair. This occurs mainly due to low

grade irritation of pulpal tissue.

Etiology

Trauma, extreme heat to the tooth, chemical burns during pulpotomy

procedures may initiate the root resorption.

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Radiographic features:

Radiographically the tooth shows enlargement of the canal space. This

space latter gets engorged with a material of radiopaque appearance giving

the expression of hard tissue.

Histopathology;

Osteodentin type of tissue is found in the place of pulp.

INTERNAL INFLAMMATROY RESORPTION

Radiographic features:

It presents round or ovoid radiolucent area in the central portion of the

tooth with smooth well defined margins. The defect does not change its

relation to the tooth, when the range is projected form an angulation.

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Management of internal root resorption

Treatment options in teeth with internal resorption

Without perforation –endodontic therapy

With perforation

a. Non-surgical: Ca (OH) 2 therapy –obturation

b. Surgical

i. Surgical flap

ii. Root Resection

iii. Intentional replantation

MANAGEMENT FOR PERFOARTING INTERNAL RESORPTION

a. Non-Surgical Repair

Indications

Non surgical repair is indicated in following cases:

i. When the defect is not extensive.

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ii. When defect is apical to epithelial attachment.

iii.When hemorrhage can be controlled.

The intracanal calcium hydroxide dressing is placed and over it

temporary filling is placed to prevent interappointment leakage. Patient

recalled after three months for replacement of calcium hydroxide dressing

and for radiographic confirmation of the barrier formation at the perforation

site. After the barrier is formed, the canal is obturated with gutta-percha as in

the non perforating internal resorption.

b. Surgical repair

Indication of surgical repair:

i. Surgical flap

ii. Root resections

iii.Intentional replantation

If the calcium hydroxide treatment is unsuccessful or not feasible,

surgical of the defect should be considered.

1. Surgical Flap:

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Here the defect is exposed to allow good access. The resorptive defect

is curetted, cleaned and restored. The restoration of the defect can be done

using an alloy, composite, glass ionomer cement, super EBA or more

recently MTA. Family the obturation is done using gutta –percha.

2. Root resection:

If the resorbed area is located in the radicular third, root may be

resected coronal to the defect and apical segment is removed afterwards.

Following root resection retrofilling is done.

If done root of a multirooted tooth is affected, root resection may be

considered based on anatomical, periodontal and restorative parameters.

4. Intentional replantation:

If the perforating resorption with minimal root damage occurs in an

inaccessible area, intentional replantation may be considered.

External root resorption:

External root resorption is initiated in the periodontium and in effects

the external or lateral surface of the root.

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Classification:

Surface resorption

External inflammatory root resorption

Replacement resorption

EXTERNAL INFLAMMATORY ROOT RESORPTION

Etiopathology

Injury of irritation to the periodontal tissues where the inflammation is

beyond repair

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Orthodontic tooth movement using excessive forces

Trauma from occlusion –leading to periodontal inflammation

Avulsion and luxation injuries

Pressure resorption occurring from pressure exerted by tumors, cysts

and impacted teeth.

Clinical Features

Patient gives history of trauma – recent or past

Necrotic pulp/irreversible pulpitis is frequently seen.

Tooth is usually mobile in most of the cases.

Inflammation of the periodontal tissues is commonly seen.

Percussion sensitivity is present.

Pocket formation may or may not be there. If the resorption area

communicates with the gingival sulcus, it can lead to pocket

formation.

Radiographic Features

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Bowl like radiolucency with ragged irregular areas on the root surface

is commonly seen in conjunction with loss of tooth structure and alveolar

bone.

Treatment

If the sustaining infection is pulpal, root canal therapy has been shown

to be a very successful means of treating inflammatory resorption.

Replacement Resorption

This is similar to ankylosis, but there is presence of an intervening

inflamed connective tissue, always progressive and highly destructive.

Etiopatho

genesis

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Replacement resorption usually occurs after a severe dental injuries

like intrusive luxation or avulsion injuries resulting in drying and death of

periodontal ligament cells.

Clinically

Replacement resorption is usually asymptomatic. Infra occlusion,

incomplete alveolar process development (if the patient is young), and

prevention of normal mesial drift are commonly seen. Pathagnomonic

feature is immobility of affected tooth and a distinctive metallic sound on

percussion.

Diagnosis

Diagnosis can be made from clinical evaluation and radiographic

observation.

Treatment

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Currently there is no treatment offered fro replacement resorption. It

may be possible to slow the resorptive process by treating the root surface

with fluoride solution prior to replantation.

Dentoalveolar Ankylosis

Dentoalveolar ankylosis is the union of tooth and bone with no

intervening connective tissue.

Etiopathology

Traumatic injuries to teeth.

Clinical features:

A tooth with dentoalveolar ankylosis shows:

Lack of mobility

Dull metallic sound on percussion (may be evident even before the

appearance of the radiograph)

Infraocculasion because of lack of the normal growth of the alveolar

process.

Lack of mesial drift.

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Radiogr

aphic Features

Radiographically one can observe the moth eaten appearance with

irregular border, absence of periodontal ligament and lamina dura.

Treatment of ankylosis.

No treatment is required for dentoalveolar ankylosis.

Prevention

Immediate replantation

Proper extraoral storage to prevent dehydration

Cervical root resorption (extra canal invasive resorption)

According to cohen, it is the type of inflammatory root resorption

occurring immediately below the epithelial attachment of tooth.

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Etiology

Orthodontic treatment

Trauma

Bleaching of non vital teeth

Periodontal treatment

Bruxism

Idiopathic

Clinical Features of Cervical Root Resorption

Initially asymptomatic

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Pulp vital in most cases

Normal to sensitivity tests

Long standing cases give pink spot appearance clinically,

misdiagnosed as internal resorption but confirmed radiographically

In due course, it spreads laterally along the root, i.e., apical and

coronal direction “enveloping” the root canal.

FRANK’S CLASSIFICATION OF CERVICAL ROOT RESORPTION

Supraosseous-coronal to the level of alveolar bone

Intraosseous-not accompanied by periodontal breakdown

Crestal-at the level of alveolar bone

RADIOGRAPHIC FEATURES

Radiographically there will be moth eaten appearance with intact

outline of the canal.

TREATMENT

A traditional approach is to treat the tooth endodontically first followed

by repair of the resorbed area either from an internal approach or an

external one.

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Another treatment is surgically exploring the resorbed lacuna and

curetting the soft tissue from the defect which can then be prepared for

restoration. This procedure is more conservative.If pulpal symptoms

develop later, root canal theraphy can be performed.

TRANSIENT APICAL BREAKDOWN

It is a temporary phenomenon in which the apex of the tooth displays

radiographic appearance of resorption followed by surface resorption. Repair

takes place within a year. It is commonly seen in mature teeth with completely closed apex.

ETIOLOGY

Moderate injuries such as

-Subluxation

-Extrusion

-Lateral luxation

-Infections

-Orthodontic treatment

-Trauma from occlusion.

TREATMENT

No treatment is recommended.

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CONCLUSION

Tooth resorption is a perplexing problem where the etiologic factors are

Vague and less clearly defined. Early diagnosis and prompt treatment are the

key factors which determine the success of the treatment.