Root resorptions

INTRODUCTION

The mechanisms of remodeling of mineralized tissues correspond to a physiological process which is based on a balance between resorption and apposition.

So bone tissue is constantly remodeling throughout life.

At the dental level, we have a physiological process of remodeling the cementum and alveolar bone that occurs depending on the forces exerted and dental migrations. “This is similar to a normally balanced scale.”

This phenomenon is limited; without these changes the bone would be brittle, as in osteoporosis.

1. Definition of resorption:

According to the American Association of Endodontists (AAE), resorption is a condition associated with a physiological or pathological process causing loss of dental, cementum, or bone tissue.

• There are two types of resorption:

Physiological resorptions or rhizalysis “only encountered on deciduous teeth” and pathological resorptions.

• Two types of pathological resorptions can be described depending on the starting point of the pathological process: internal and external resorptions .

2. Etiology :

• An initial cause (trauma, bacteria, pressure, chemical factor, necrotic debris) is necessary to trigger the process leading to resorption.
• Traumatic origin;

A common consequence of trauma is: ankylosis Definition:

Superficial external resorption may stop and be filled by tissue similar to the original tissue or as part of replacement resorption.

Following dental trauma, the progressive disappearance of the ligament and therefore of the periodontal space is often observed. The injured tooth becomes welded to the surrounding alveolar bone; this is called alveolo-cemental ankylosis (Piette and Goldberg, 2001).

• Orthodontic origin; “a wisdom tooth that is developing by putting pressure on the second molar or orthodontic treatment with poorly controlled forces.
• Malocclusion, Bruxism and other parafunctions; Dysfunctions.
• Endodontic origin: Apical resorption in the vicinity of a granuloma; Incomplete root canal filling;
• Periodontal origin: chronic inflammation of the periodontal ligament.

• Bleaching techniques can cause cervical resorptions.
• JEC Position:

In 60% of cases, the cementum slightly covers the enamel, where it forms asperities on the enamel surface.

In 30% of cases, the enamel and cementum are in contact without leaving any exposed dentin and there is a smooth cervical dental surface.

In 10% of cases, the cementum and enamel do not join and the dentin is exposed. The tooth thus becomes more vulnerable to caries and any inflammatory event because the dentin mineralization rate is lower than the enamel and cement mineralization rates. This will therefore promote root resorption in the cervical area.

• Ontogenetic origin: Epidermoid cyst or odontogenic keratocyst, Resorption near an included tooth.
• Surgical origin. “reimplantation of an expelled tooth”.
• General origin.
• Idiopathic resorption.

3. Evolution :

When we are faced with a case of resorption, it is necessary to establish the etiology in order to treat it; in fact, resorption tends to worsen and not stop as long as the cause is still present. It will therefore be necessary to implement a treatment adapted to each type of lesion and otherwise, resorption can go as far as leading to the complete disappearance of the root and causing the loss of the tooth if the discovery of the lesion is too late (Arathi et al. 2008).

4. Classification:

Trope Classification:

The most recent classification is that of Trope (1998), it takes into account all the results compiled and analyzed so far and conducts external and internal resorptions together.

If traumatic injuries occur, this will result in external root resorption. Resorptions of purely internal origin are very rare.

According to Trope, root resorption requires two factors: damage to the protective layer (cementum) and an inflammatory stimulus.

The mechanisms of traumatic lesions occur in two stages: a destructive phase causing root resorption, then a healing phase which can be favorable or unfavorable.

Trope explains that all resorptions of purely intracanal origin are inflammatory root resorptions and are reversible, bearing in mind that the first 24 hours are the most critical. Thus, all efforts must be focused on minimizing inflammation and reducing the products of acute inflammation.

Other classification possibilities

• Root resorption is often classified according to the location of the lesion;
• Which will be apical, lateral or cervical.

5. Internal root resorption:

They are called internal because they develop within the pulp cavity. They can be inflammatory or replacement.

1. The different types of internal resorption:
2.  Internal inflammatory resorptions:

• These lesions appear to be related to chronic pulp inflammation. The resorbed space is filled by granulation tissue within which giant inflammatory cells centrifugally destroy the canal walls, causing localized widening with a defined and clear outline of the canal.
• Elle peut être localisé au 1/3 Apical ou du 1/3 médian « localisation la plus fréquente ».
• Elle peut également concerner le 1/3 coronaire : le tissu de granulation donne une teinte Rose à la couronne « Pink Spot » c’est le signe pathognomonique de la résorption interne cervicale.
• Thérapeutique :

Elle dépend de la sévérité de la résorption « perforation ou pas de la paroi radiculaire.

• En cas de non perforation :
  • Réalisation du traitement endodontique.
  • Intérêt d’une médication intracanalaire : du fait du PH alcalin.
• En cas de perforation :
  • Le PC est fonction de la localisation et de l’étendue de la résorption « Si la résorption est supra crestale, un traitement endodontique est associé à un débridement chirurgical puis une restauration au CVI ou composite.

**Un suivi clinique et radiologique régulier est instauré.

2.  Les résorptions de remplacement :

• Probablement due à une irritation pulpaire continue « pulpite chronique ou traumatismes »

La dentine éliminée est remplacée par du tissu osseux. Ce phénomène est dû à une métaplasie pulpaire liée à la transformation de certaines cellules de la pulpe en ostéoblastes lesquels vont déposer de l’os dans les lacunes de résorption.

• Il en résulte une lésion à contours irréguliers ou le remaniement osseux constant est responsable de la perte progressive de dentine péricanalaire.

Le remodelage osseux provoque un accroissement continu de la perte de substance (Piette et Goldberg, 2001).

Elle est auto-limitante.

• Thérapeutiques :

• Traitement endodontique.
• Suivi clinique et radiologique.

2. Diagnostic :

• La dent devient symptomatique lorsque la résorption provoque une perforation radiculaire et que le tissu pulpaire entre en contact avec le tissu parodontal ; à ce stade il est parfois difficile de voir radiologiquement si la résorption initiale était d’origine interne ou externe
• Lorsque la résorption provoque une perforation radiculaire, celle-ci est visible radiographiquement par un volume pulpaire très important et une ostéolyse à l’endroit de la perforation.
• Dans le cas de résorption interne de remplacement on observe une cavité pulpaire asymétrique irrégulièrement élargie et dont l’intérieur révèle un réseau radio-opaque tacheté donnant l’apparence d’une oblitération partielle du canal.
• La réponse aux tests thermiques se situe dans les limites de la normalité même si la pulpe est atteinte d’une inflammation chronique.
• La percussion négative signe l’intégrité de la paroi radiculaire. Lorsqu’il y a perforation, elle devient positive et une douleur peut se déclencher.
• Dans ce cas, on peut noter aussi la présence d’une mobilité anormale où le parodonte est atteint avec présence éventuelle d’une tuméfaction gingivale ou d’une fistule (Piette et Goldberg,

2001).

6. Résorptions externes :

La résorption externe radiculaire pathologique correspond à la perte sous-gingivale de tissu radiculaire plus ou moins étendue dont le point de départ est externe et concerne les dents permanentes.

1- ) External resorptions caused by damage to the external surface of the root:

A-) Surface resorption:

• The damage causes the loss of the cementum layer “concussion, subluxation” A localized inflammatory reaction is thus triggered causing localized resorption of the surface.

Appear in 4% of concussion cases; 7% of subluxation cases; 15% of extrusion cases; 30% of intrusion cases

30% of cases of lateral dislocation. “Naulin Ifi 2005”.

• If no other inflammatory stimulus is present, a healing process occurs within 14 days in the form of cementum apposition.
• Diagnosis:

They very often go unnoticed on an X-ray.

When visible on images, they appear as small excavations surrounded by healthy periodontal ligament.

Asymptomatic lesion.

They are limited and transitory.

• Therapeutic:

No therapy is indicated because these lesions are not progressive. The pulp is not involved.

Simple clinical and radiographic monitoring.

B-) Replacement resorptions:

Etiology:

In the presence of diffuse root damage “greater than 20% of the root surface” With loss of the cementum layer; following violent trauma such as intrusion or avulsion with a long extra-oral time”

The cells will attempt to recolonize the large root areas devoid of cementum; competition between the fibroblastic cells of the ligament and the bone cells will take place. In most cases, the bone cells are the fastest.

The consequence is the formation of bone tissue at the level of these resorption zones: the bone tissue is in contact with the dentin: this is dentoalveolar ankylosis.

The root dentin will therefore be gradually transformed by bone.

The longevity of the tooth is compromised because it is an evolutionary process and will continue until the root of the tooth is completely replaced by bone.

• Diagnosis:

Generally asymptomatic.

It is scalable

In young patients, it can be very rapid.

Loss of physiological mobility of the tooth “due to disappearance of the LAD”. Metallic sound on percussion.

In young patients, the tooth is infraclusive relative to the antagonist. Radiologically, the tooth has a “moth-eaten” appearance with “irregular contours.”

• Therapeutic:

Therapeutics should stimulate the cementum repair pathway rather than the bone repair pathway. In cases of DC of alveolodental ankylosis:

The tooth must be extracted. One of the disadvantages is that bone loss is often significant and can cause aesthetic damage or even complicate prosthetic rehabilitation.

An interesting approach is decoronation.

2-) External inflammatory resorption:

Four types of inflammatory stimuli can cause external inflammatory resorptions: “Pressure; infection; certain tooth whitening products; dental trauma “dislocations +++”.

A-) external inflammatory resorptions linked to pressure:

• Etiology:

Significant or poorly conducted orthodontic forces. Impacted teeth

Tumors;

• Therapeutic:

It is recommended that as soon as the diagnosis is made, orthodontic forces be stopped for a period of two to three months; if the resorptions are severe, the treatment should be stopped permanently.

In general, resorptions continue to evolve 4 weeks after the application of forces has stopped.

 B-) resorptions linked to pulp infection:

At the apical or lateral level.

• At the apical level:

The presence of intracanal bacteria causes LIPOE. They are very often associated with root resorption.

• Therapeutic:

Carrying out endodontic treatment.

• External lateral inflammatory resorption:
  • Etiology and characteristics:

• It is progressive and follows an inflammatory process.
• Occurs on teeth that have suffered trauma. ; With localized loss of cementum and pulp necrosis.
  • Therapeutic:
• Good clinical monitoring after trauma allows us to anticipate necrosis and avoid complications.
• The use of caoh2 in intracanal medication is interesting for its anti-inflammatory qualities.
• A surgical approach can remove all of the granulation tissue and fill the cavity.

C-) Idiopathic inflammatory resorptions:

Probably linked to systemic diseases or endocrine pathologies “phosphocalcic metabolism”.

D-) External cervical or invasive cervical inflammatory resorption:

• Etiology:

• The use of internal bleaching products “hydrogen peroxide 30 to 35%”
• History of trauma to the tooth.
• Applying heat to the tooth.
• Diagnosis:

• May occur years after clearing “Importance of follow-up”
• The lesion appears below the marginal epithelial attachment.
• The resorption gaps are filled by fibrous tissue and blood vessels and then by clastic cells.
• Therapeutic:

• Surgical debridement of lesions + CVI or MTA.
• Prevention “prefer sodium Perboate for lightening”.

VII-) Radiographic diagnosis:

• It is necessary to distinguish between internal resorptions and external resorptions; because the therapeutic approach is different.
• It is necessary to take off-center radiographs:

• In the case of internal resorption, the lesion will remain centered on the endodontic system , regardless of the angulation
• In the case of external resorption, the lesion will move depending on the angulation of the radiograph.
• The use of CBCT (cone beam computed tomography) which, thanks to 3D reconstruction, allows the lesion to be visualized and its location and extent to be specified, thereby refining the diagnosis and the possibilities for preservation.

CONCLUSION :

• Depending on the starting point of the resorptions we will speak of: Internal or external resorptions .
• In most cases, resorptions are progressive lesions which lead to root perforation, if no treatment is implemented.
• The anamnesis, clinical examination, and additional tests are the keys to an accurate diagnosis which will be followed by appropriate treatment.

Root resorptions

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Interdental brushes remove food debris between teeth.
Adequate hydration helps maintain healthy saliva, which is essential for dental health.

Root resorptions