Feline Odontoclastic Resportive Lesions (FORLs)

What are Feline Odontoclastic resorptive Lesions (otherwise known as FORLs)?

FORLs are a common condition that affects somewhere between 25-75% of ALL adult cats. Often multiple teeth are involved and the lesions can be found anywhere on the tooth including below the gum line.

Odontoclasts are cells whose normal function in life is to remove the roots of the deciduous (baby) teeth as the permanent teeth erupt. Once the permanent teeth have erupted odontoclasts have no further function. However for some reason, in some cats, the stem cells in the periodontal ligament differentiate into odontoclasts (no one has yet ascertained what the stimulus is) and these begin to attack the dental structures.

This means that Odontoclasts are normal cells, which just happen to be in the wrong place at the wrong time! The odontoclasts basically eat their way into the tooth! Once the dentine is exposed the tooth becomes extremely painful and eventually the lesion will invade the pulp of the tooth where the nerve is (even more painful). The process continues until the root and crown become separated and finally there is loss of the crown.

 Clinical signs

1. Pain, pain, pain – FORLS are one of the most painful conditions a cat can have – probing the tooth when cats are under general anaesthetic even usually causes the cat to “jump”.
2. “Teeth Chattering” or repetitive jaw movement especially during or after eating or drinking = acute dental pain.
3. Salivation or drooling
4. Changes in preference for food (often avoiding hard foods)
5. Foul smelling breath with inflammed gums
6. Gingival hyperplasia (granulation tissue growing up over the lesions in an attempt to protect the sensitive tooth).
7. In advanced cases a pinkish discolouration to the tooth
8. Heavy calculus and tartar build up on the affected side of the mouth – as the cat is avoiding using this side of the mouth due to pain. Note this is usually only evident if only one side of the mouth is affected.

 Diagnosis

• If FORLs occur above the gum line they can be easily seen, however if they occur below the gum line they can only be found using dental radiographs. Therefore we recommend dental radiographs of all cats with suspected FORLs.

 Treatment

• First is to complete a through dental assessment of your cats teeth under general anaesthetic including dental probing and dental xrays (remember sometimes these lesions are below the gum line and the tooth can look normal above the gumline). This will allow us to establish is FORLs are present and what teeth are affected.

• Then there is only one effective treatment for FORLs – removal of the tooth. Extraction can be difficult due to the fact that teeth affected by FORLs tend to be very brittle and can fracture easily leaving part of the root behind.