Feline Oral Resorptive Lesions (FORL's)

FELINE ORAL RESORPTIVE LESIONS (FORLs)
Jan Bellows, D.V.M.
9111 Taft Street
Pembroke Pines, Florida
954-432-1111

A common feline oral malady is the feline oral resorptive lesion (FORL). A
majority of the affected cats are older than four years. These tooth
defects have been called cavities, neck lesions, external or internal root
resorptions, and cervical line erosions. FORLs are usually found on the
outside of the tooth where the gum meets the dental surface. The lower jaw
premolars are mostly affected, however FORLs can be found on any tooth. The
cause is unknown, but theories supporting an autoimmune response, calici
virus, and metabolic imbalances relating to calcium regulation have been
proposed.

The resorptive lesion often erodes into sensitive dentin, causing a cat to
show pain and jaw spasms whenever the lesion is touched (picture 15).
Patients effected with FORLs may show increased salivation, oral bleeding, or
difficulty eating. Most times it is up to the veterinarian or astute owner
to diagnose FORLs.

The FORL can present in many stages. Initially (stage 1) an enamel defect is
noted. The lesion is usually minimally sensitive because it has not entered
the dentin. Therapy of this defect usually involves a thorough cleaning,
polishing, and smoothing out the defect. In stage 2, the lesion penetrates
enamel and dentin. These teeth may be treated with restoratives which
release fluoride ions to desensitize the exposed dentin, strengthen the
enamel, and chemically bind to tooth surfaces. The long term (greater than
two years) effectiveness of restoration of stage 2 lesions have not been
proven. Restorative application to the FORL does not automatically stop the
progression or the disease. Intraoral x-rays are essential to determine if
the lesions have entered the pulp chamber (stage 3) requiring either root
canal therapy or extraction. Often x-rays will reveal resorption of the tooth
root necessitating extraction. In stage 4 FORLs, the crown has been eroded
or fractured. The gum tissue grows over the root fragments leaving a
sometimes painful and/or bleeding lesion upon probing. Treatment of choice is
flap surgery and extraction of the root fragments that appear to be inflamed
or painful to the patient.