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Feline Odontoclastic Resorptive Lesions (view source)
Revision as of 14:59, 30 August 2013
, 14:59, 30 August 2013no edit summary
Both forms are triggered by destruction of the cementoblasts. In PIRR, the osteoclast-activating factors, which perpetuate the resorptive process, are provided by an inflammatory lesion in the adjacent periodontal tissues. EIRR, on the other hand, receives its stimulus for continued resorption from an infected necrotic pulp. In other words, the common factor for these two types of resorption is inflammation in the adjacent tissues.
Both forms are triggered by destruction of the cementoblasts. In PIRR, the osteoclast-activating factors, which perpetuate the resorptive process, are provided by an inflammatory lesion in the adjacent periodontal tissues. EIRR, on the other hand, receives its stimulus for continued resorption from an infected necrotic pulp. In other words, the common factor for these two types of resorption is inflammation in the adjacent tissues.
Tooth resorption in cats accounts for a large proportion of the dental case load seen in general veterinary practice. Most studies have shown an increased incidence with increasing age. The lesions have also been shown to occur in both feral and wild cats, and in other species, e.g. man, dog and chinchilla.
It is likely that the lesions are either peripheral inflammatory root resorption (triggered by inflammation of periodontal tissues) or replacement resorption (idiopathic).
==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 increasing age.
==Clinical Signs==
Anorexia, drooling, lethargy and pain on contact with the lesions.
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.
==Diagnosis==
==Diagnosis==
===Oral Examination===
The lesions can be detected by means of a combination of visual inspection, tactile examination with a [[Dental Explorer|dental explorer]] and radiography.
Visual Examination will identify the lesions or inflammed gingiva that overlies the remaining root.
===[[Oral Examination]]===
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
* 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>
* Missing/fractured teeth; site may have inflamed covering gingiva and / or bony swelling. <font color="red">TR5</font color>
• Root fragments
===[[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.
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.
Radiography will identify lesions that are localized to the root surfaces within the 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>
Radiographic features of RLs:
a) loss of integrity of the periodontal ligament space
b) loss of the lamina dura
c) irregularities on the root surface
d) diffuse decrease in radiodensity of the entire root compared with adjacent roots
e) radiolucent areas within the root dentine often extending into the crown dentine
f) replacement of root substance by bone-like tissue.
g) resorbing roots present with clinically missing crown
Classification of tooth resorption : (American Veterinary Dental College classification) ask about using their pictures from the website – I think you can as long as they are acknowledged
Stage 1 (TR 1): Mild dental hard tissue loss (cementum or cementum and enamel).
Stage 2 (TR 2): Moderate dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not extend to the pulp cavity).
Stage 3 (TR 3): Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity.
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.
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.
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.
TR4c Root is more severely affected than the crown.
Stage 5 (TR 5): Remnants of dental hard tissue are visible only as irregular radiopacities, and gingival covering is complete.
===Diagnostic Imaging===
===Diagnostic Imaging===