Ankylosis of Teeth in Cats

Tooth ankylosis can affect all types of cats

Tooth ankylosis is a process where a tooth ends up fused to the bone underneath it. It occurs under several conditions, the most common being feline tooth resorption. Ankylsosis of the tooth can cause several problems to the cat from difficulty eating to a broken tooth. It can affect any type of cat, from domestic or feral, to large exotic cats.

Periodontal Tissues

The periodontal ligament attachs the tooth root to the alveolar bone.

Tooth ankylosis involves three of the periodontal tissues: the periodontal ligament, cementum and alveolar bone. The periodontal ligament is a structure of strong collagen fiber that contains blood vessels and nerves. Cementum is the substance that covers the root surface of the tooth; it is very similar to bone. The periodontal ligament fastens into the cementum to anchor the tooth to the alveolar bone.

What is Ankylosis?

The periodontal ligament attaches the tooth root to the alveolar bone. Infection or chronic inflammation can cause damage to the periodontal ligament. In tooth ankylosis, the periodontal ligament is partially or totally destroyed, and the cementum on the tooth root fuses to the alveolar bone.

Effects

Without the cushioning effect of the periodontal ligament, a cat's teeth are more susceptible to breakage

One of the functions of the periodontal ligament is to act as a shock absorber for the tooth as the cat chews its food. Without the ligament, there is no flexibility in the tooth, so it breaks more easily. In addition, because the tooth root is securely fused to the bone, if the ankylosed tooth needs to be removed, the extraction can be especially difficult. Attempting to remove an ankylosed tooth can cause tooth fractures, jaw fractures or both, as well as heavy bleeding. Special care must be taken and special tools used for these extractions.

Ankylosis and Feline Tooth Resorption

One disease process where ankylosis is commonly found is in feline tooth resorption (also called feline odontoclastic resorptive lesion or FORL). According to the Animal Emergency Center, 72 percent of cats over five years of age have at least one FORL. In this disease, the periodontal ligament starts to degenerate and the periodontal spaces get more narrow. The collagen fibers of the periodontal ligament are replaced by bone-cementum tissue. Cells called osteoclasts start to destroy the root surface in the cementum. The tooth roots become attached to the bone resulting in ankylosis. Finally the enamel gets resorbed, or breaks, because of the underlying tooth damage. A cat with FORL may lose its appetite, or refuse to eat hard food; it may drool excessively, and act generally like it doesn't feel well. If the tooth crown breaks, the FORL can be very painful for the cat.

Diagnosing Ankylosis

Tooth ankylosis is diagnosed by dental radiographs. If a cat undergoing a dentistry exam needs any extractions, radiographs should be taken first to evaluate tooth root structures and look for ankylosis. Extraction is the most common treatment when dealing with ankylosis, although some dentists are performing root canal therapy as an alternative treatment.

References

• All Pets Dental: Feline Dental Pathology and Care
• Animal Dentistry and Oral Surgery Specialists: Root Canal Therapy for Dogs and Cats
• Animal Emergency Center: Veterinary Dental Techniques and Secrets
• Veterinary Dental Services: Feline Tooth Resoprtion
• The Royal Veterinary College: Veterinary Periodontal Disease