Feline Odontoclastic Resorptive Lesions

Also known as:

FORLs

Description

Feline odontoclastic resorptive lesions (FORLs) are the most commonly seen dental lesions in cats. On examination, there is a loss of dental tissue on the crown or at the neck of the teeth. The crown may be completely resorbed with the remaining root covered with gingiva.

The aetiology and pathogenesis of FORLs has not yet been demonstrated but is almost certainly multifactorial. Possible hypotheses that have been suggested include, the texture of the diet, abnormal calcium regulation, hypervitaminosis A, mechanical stress, anatomical abnormalities of the teeth, viral infections and plaque bacteria and periodontal disease.

Typical Signalment

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

Diagnosis

Clinical Signs

Anorexia, drooling, lethargy and pain on contact with the lesions.

Oral Examination

Visual Examination will identify the lesions or inflammed gingiva that overlies the remaining root.

Lesions that are subgingival may be identified using a dental probe.

Diagnostic Imaging

Radiographic signs of FORLs include erosion of alveolar bone at the cementoenamel junction, root resorption, root ankylosis and subsequent periodontal space loss and resorption of the dental crown.

Classifying the Lesions

Classifying the lesions allows a logical treatment regime to be implemented. It can be based on the severity of the resorptive lesions.

Disease type	Area affected
Stage 1	Enamel only
Stage 2	Enamel and dentine
Stage 3	Pulp exposure
Stage 4	Extensive structural damage
Stage 5a	Crown is resorbed but the roots are retained.
Stage 5b	Crown is intact but the root is resorbed

Pathology

Odontoclasts attack external and internal to the tooth. Initially they start at the neck/cervical region and extend into tooth root and also enter the root via the apical foramen (stage 3 lesions).

• • 20%+ of cats have them

FORLs are different from caries – demineralization by bacteria fermenting CHO on the enamel.

Odontoclasts normally only active in young animals to resorb the deciduous teeth to make way for the permanent teeth – so represents abnormal activation in adults. Additionally there may also be inflammatory infiltrates into the resportive lesions.

Treatment

There are various treatment options available for the different stages of disease.

• Stage 1-2
  • Scale and polish
  • Fluoride treatment
  • Pit and fissure sealant
• Stage 2
  • Scale and polish
  • Restoration of the tooth using glass ionomer, compomer or composite (High failure rate)
• Stage 2-4
  • Extraction
  • Crown amputation whilst retaining root
• Stage 5a
  • Extraction
  • Root retention
• Stage 5b
  • Crown amputation

References

• Tutt, C., Deeprose, J. and Crossley, D. (2007) BSAVA Manual of Canine and Feline Dentistry (3rd Edition) BSAVA

• Merck & Co (2008) The Merck Veterinary Manual