Changes

Two mechanisms are involved in resorption of hard tissue:

Two mechanisms are involved in resorption of hard tissue:

# The trigger

# The trigger

# A reason for the resorption to continue.

# A reason for the resorption to continue

The trigger mechanism in root resorption is a root surface detached from its protective blast cell layer. For the resorption to continue, a stimulus is required, e.g. infection or a continuous mechanical force.

The trigger mechanism in root resorption is a root surface detached from its protective blast cell layer. For the resorption to continue, a stimulus is required, e.g. infection or a continuous mechanical force.

Root resorption always starts at a surface, and is termed internal if emanating from the root canal wall and as external if emanating from the root surface. Internal resorption is rare in permanent teeth. Histological examination reveals resorption of the internal aspect of the root by multinucleated [[Giant Cells|giant cells]] adjacent to granulation tissue in the pulp. There are different theories regarding the origin of the pulpal granulation tissue involved in internal resorption. The most logical explanation is that it is pulp tissue that is inflamed because of an infected coronal pulp space. In addition to the requirement of the presence of granulation tissue, root resorption takes place only if the [[odontoblast]] layer and predentine are lost or altered. Traditionally, a pink tooth has been thought pathognomonic of internal root resorption; the pink colour is caused by granulation tissue in the coronal dentine undermining the crown [[enamel]]. However, a pink tooth can also be a feature of a specific type of external root resorption, namely peripheral inflammatory external root resorption (detailed later), which must be ruled out before a diagnosis of internal root resorption is made. A pink tooth can also be due to pulpal haemorrhage. There are different forms of external root resorption described in man. The underlying mechanism is understood for some of these, whereas other forms are still unexplained and therefore termed idiopathic. A classification system for external root resorption that have a known mechanism has been proposed in man and is as follows:

Root resorption always starts at a surface, and is termed internal if emanating from the root canal wall and as external if emanating from the root surface. Internal resorption is rare in permanent teeth. Histological examination reveals resorption of the internal aspect of the root by multinucleated [[Giant Cells|giant cells]] adjacent to granulation tissue in the pulp. There are different theories regarding the origin of the pulpal granulation tissue involved in internal resorption. The most logical explanation is that it is pulp tissue that is inflamed because of an infected coronal pulp space. In addition to the requirement of the presence of granulation tissue, root resorption takes place only if the [[odontoblast]] layer and predentine are lost or altered. Traditionally, a pink tooth has been thought pathognomonic of internal root resorption; the pink colour is caused by granulation tissue in the coronal dentine undermining the crown [[enamel]]. However, a pink tooth can also be a feature of a specific type of external root resorption, namely peripheral inflammatory external root resorption (detailed later), which must be ruled out before a diagnosis of internal root resorption is made. A pink tooth can also be due to pulpal haemorrhage. There are different forms of external root resorption described in man. The underlying mechanism is understood for some of these, whereas other forms are still unexplained and therefore termed idiopathic. A classification system for external root resorptions that have a known mechanism has been proposed in man and is as follows:

# Surface resorption

# Surface resorption

# Replacement resorption associated with ankylosis

# Replacement resorption associated with ankylosis

# Inflammatory resorption.

# Inflammatory resorption

This classification system works for external root resorption in cats and dogs as well.

This classification system works for external root resorption in cats and dogs as well.

==Typical Signalment==

==Typical Signalment==

There are no sex or breed predispositions, however, it does become more prevalent with increasing age.

There are no sex or breed predispositions, however, it does become more prevalent with age.

==Clinical Signs==

==Clinical Signs==

Clinically, they commonly present as a cavity at the cemento-enamel junction of the tooth. However, studies which included radiography have demonstrated that the resorption can occur anywhere on the root surfaces, i.e. not necessarily at the cemento-enamel junction.

Clinically, they commonly present as a cavity at the cemento-enamel junction of the tooth. However, studies which included radiography have demonstrated that the resorption can occur anywhere on the root surfaces, i.e. not necessarily at the cemento-enamel junction.

   

   

All types of teeth in the feline dentition may be affected by tooth resorption but molar and premolar teeth are more frequently affected than canine and incisor teeth. Also, the buccal/labial surfaces tend to be more affected compared with the lingual/palatal aspect of the tooth. The lesions are often bilaterally symmetrical.  

All types of teeth in the feline dentition may be affected by tooth resorption but molar and premolar teeth are more frequently affected than canine and incisor teeth. Also, the buccal/labial surfaces tend to be more likely to be affected compared to the lingual/palatal aspect of the tooth. The lesions are often bilaterally symmetrical.  

==Diagnosis==

==Diagnosis==

Visual inspection and tactile examination with a dental explorer will only identify end-stage lesions, i.e. when the process involves the crown and has resulted in an obvious cavity.  

Visual inspection and tactile examination with a dental explorer will only identify end-stage lesions, i.e. when the process involves the crown and has resulted in an obvious cavity.  

Visual inspection show signs consistent with RLs

Signs on visual inspection which are consistent with RLs:

* Focal hyperplastic gingival tissue covering the tooth defect. This gingival covering is usually, but not always, inflamed.  <font color="red">(picTR2)</font color>

* Focal hyperplastic gingival tissue covering the tooth defect. This gingival covering is usually, but not always, inflamed.  <font color="red">(picTR2)</font color>

* Red spot on crown of the tooth as seen in the pictures <font color="red">TR3 and TR4</font color>

* Red spot on crown of the tooth as seen in the images <font color="red">TR3 and TR4</font color>

* Missing/fractured teeth; site may have inflamed covering gingiva and / or bony swelling. <font color="red">TR5</font color>

* Missing/fractured teeth; site may have inflamed covering gingiva and/or bony swelling. <font color="red">TR5</font color>

• Root fragments  

* Root fragments  

===[[Intra-Oral Radiography - Small Animal|Intra-Oral Radiography]]===

===[[Intra-Oral Radiography - Small Animal|Intra-Oral Radiography]]===

A definitive diagnosis can only be made after an examination and intra-oral radiography with the cat [[Oral Examination Under General Anaesthesia|under general anaesthesia]]. The lesion can be felt as a concavity using a sharp explorer probe. <font color="red">Pic TR6</font color>. Often the lesions are only detected once the calculus has been removed.

A definitive diagnosis can only be made after an examination and intra-oral radiography with the cat [[Oral Examination Under General Anaesthesia|under general anaesthesia]]. The lesion can be felt as a concavity using a sharp explorer probe. <font color="red">Pic TR6</font color>. Lesions are often only detected once the calculus has been removed.

Visualisation is aided by drying the teeth using the air stream from a dental air-water syringe. With normal teeth, the marginal gingival will lift away from the tooth when the air is directed at the base of the [[Enamel Organ#Crown|crown]], but with RLs, the soft tissue seems “stuck” to the underlying tooth. General anaesthesia is imperative as examination of these lesions in a conscious cat is painful.  

Visualisation is aided by drying the teeth using the air stream from a dental air-water syringe. With normal teeth, the marginal gingiva will lift away from the tooth when the air is directed at the base of the [[Enamel Organ#Crown|crown]], but with RLs, the soft tissue seems “stuck” to the underlying tooth. General anaesthesia is imperative as examination of these lesions in a conscious cat is painful.  

Radiography will identify lesions that are localized to the root surfaces within the [[Enamel Organ#Alveolar Bone|alveolar bone]], which would not be detected by clinical methods. Radiography is also required to confirm the diagnosis and to assess the extent and type of the lesion. Radiographs often reveal a lesion that is more advanced than originally suspected from the clinical examination. <font color="red">PicTR7</font color>

Radiography will identify lesions that are localized to the root surfaces within the [[Enamel Organ#Alveolar Bone|alveolar bone]], which cannot be detected by clinical methods. Radiography is also required to confirm the diagnosis and to assess the extent and type of the lesion. Radiographs often reveal a lesion that is more advanced than originally suspected from the clinical examination. <font color="red">PicTR7</font color>

[[Radiographic Interpretation of Tooth Resorption - Small Animal|Radiographic features of RLs]]: <br>

[[Radiographic Interpretation of Tooth Resorption - Small Animal|Radiographic Features of RLs]]: <br>

a) loss of integrity of the periodontal ligament space <br>

a) loss of integrity of the periodontal ligament space <br>

b) loss of the lamina dura<br>

b) loss of the lamina dura<br>

|'''Stage 4 (TR 4)'''

|'''Stage 4 (TR 4)'''

|Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity. <br>

|Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity. <br>

'''TR4a''' Crown and root are equally affected; Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity.<br>

'''TR4a''' - Crown and root are equally affected. Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity.<br>

'''TR4b''' Crown is more severely affected than the root; Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity.<br>

'''TR4b''' - Crown is more severely affected than the root. Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity.<br>

'''TR4c''' Root is more severely affected than the crown.

'''TR4c''' - Root is more severely affected than the crown.

|-

|-

|'''Stage 5 (TR 5)'''

|'''Stage 5 (TR 5)'''

==Treatment==

==Treatment==

Currently, the suggested methods of managing odontoclastic resorptive lesions are:  

Currently, the suggested methods for management of odontoclastic resorptive lesions are:  

# Conservative management'''

# Conservative management

# Tooth extraction

# Tooth extraction

# Coronal amputation.

# Coronal amputation

Historically, restoration of the tooth surface has been recommended for the treatment of accessible lesions that extend into the dentine and do not involve pulp tissue. However, several studies have shown that tooth resorption continues and the restorations are lost. Consequently, the use of restoration of odontoclastic lesions as a major treatment technique cannot be recommended.

Historically, restoration of the tooth surface has been recommended for the treatment of accessible lesions that extend into the dentine and do not involve pulp tissue. However, several studies have shown that tooth resorption continues and the restorations are lost. Consequently, the use of restoration of odontoclastic lesions as a major treatment technique cannot be recommended.

===Conservative management===

===Conservative Management===

This consists of monitoring the lesions clinically and radiographically. This approach is recommended for lesions that are not evident on clinical examination, i.e. only seen radiographically, and there is no evidence of discomfort or pain. In general practice, most lesions are only diagnosed when pathology is extensive and conservative management is rarely an option.

This consists of monitoring the lesions clinically and radiographically. This approach is recommended for lesions that are not evident on clinical examination, i.e. only seen radiographically, and there is no evidence of discomfort or pain. In general practice, most lesions are only diagnosed when pathology is extensive and conservative management is rarely an option.

Teeth affected by resorption can be extracted using a closed technique, but an open technique is usually less traumatic to the tissues and easier to perform. The teeth are often prone to fracture so an open technique allows good access to any root fragments remaining.  

Teeth affected by resorption can be extracted using a closed technique, but an open technique is usually less traumatic to the tissues and easier to perform. The teeth are often prone to fracture so an open technique allows good access to any root fragments remaining.  

===Coronal amputation===

===Coronal Amputation===

The indications for, and outcome of, coronal amputation have been well documented and the procedure is recommended for selected cases, but needs radiographic monitoring at regular intervals postoperatively to ensure that the root is resorbing and that healing is uneventful. In brief, the technique involves raising a gingival flap to expose the margin of the alveolar bone. The crown of the affected tooth is amputated using a small round bur. A small amount of root tissue is also removed with the bur, just enough to ensure that the intentionally retained root(s) is (are) apical to the alveolar margin. The gingival flap is replaced and sutured in place. This technique is only appropriate for teeth that do not have any radiographic evidence of [[Endodontic Conditions|endodontic disease]] (ie. periapical inflammation) or [[periodontitis]], and teeth in cats with gingivostomatitis should be removed entirely.

The indications for, and outcome of, coronal amputation have been well documented and the procedure is recommended for selected cases, but needs radiographic monitoring at regular intervals postoperatively to ensure that the root is resorbing and that healing is uneventful. In brief, the technique involves raising a gingival flap to expose the margin of the alveolar bone. The crown of the affected tooth is amputated using a small round bur. A small amount of root tissue is also removed with the bur, just enough to ensure that the intentionally retained root(s) is (are) apical to the alveolar margin. The gingival flap is replaced and sutured in place. This technique is only appropriate for teeth that do not have any radiographic evidence of [[Endodontic Conditions|endodontic disease]] (ie. periapical inflammation) or [[periodontitis]], and teeth in cats with gingivostomatitis should be removed entirely.

[[Category:Dental Conditions]]

[[Category:Dental Conditions]]

[[Category:To Do - Dentistry Images]]

[[Category:To Do - Dentistry Images]]

[[Category:To Do - Dentistry preMars]] <!---GEMMA, once finished with this page, please put into "Category:LisaM reviewing" rather than the usual. Thanks, B --->

[[Category:LisaM reviewing]]