Friday, February 28, 2014

Dental extractions in cats: tips

Hero helps me revise a paper by keeping my notes warm.

Animal Referral Hospital and Sydney Pet Dentistry veterinarian Christine Hawke gave a superb talk last night on the topic of extractions in cats – when to do them, when not to do them.

Depending on which study you read, around 50 per cent of cats (28-67%) suffer from tooth resorption during their lifespan. It is painful.

Dr Hawke discussed different ways of classifying tooth resorption in cats, one of which classifies lesions by type.

Type 1 is inflammatory in nature, often beginning in the root and working its way up to the crown, but on radiographs the root looks like a root. There is a distinct tooth, distinct bone and a periodontal ligament holding the two apart. Crown or not, these babies need to be extracted.

Type 2 occurs when the periodontal ligament is lost and replacement resorption of the root occurs. (Odontoclasts are basically osteoclasts – normally, unlikely bone, the teeth do NOT undergo constant remodelling thanks to a tooth-bone-barrier. But when that barrier is breached, the root surface is exposed due to damage of cementum or the periodontal membrane, the odontoclasts access it. The remodelling process can then continue as part of normal skeletal bone turnover).

On radiographs, these are those “ghost teeth”. You can sometimes see there was a tooth there, but there is NO periodontal ligament. The teeth are being progressively replaced by bone. Attempting extraction, even where a crown is present, can be very frustrating.

But the only way to tell is dental radiographs.

Dr Hawke’s theory that the difference between Type 1 and 2 is essentially one of the degree of inflammation.(Type 3 is a combo of type 1 and 2 in the same tooth).

Diagnosis of tooth resorption in cats requires examination under general anaesthetic with a dental explorer, and intraoral radiographs. (Remember that cats often have additional roots – or as Dr Hawke says, “cats like to throw dental curveballs”).

Many clients ask if these lesions can be somehow filled? The short answer is no. Extraction is the gold standard. Leaving the inflammatory lesions in situ isn’t good.

So what do you do with type 2 lesions? If you are sure its Type 2, coronial amputation is appropriate. First you need to rule out the presence of a periodontal ligament (a thin black line hugging the tooth on radiographs), periodontitis and gingivitis, endodontic disease and retroviral infection.

When done properly this has a very high success rate.

An envelope flap is made and the crown is removed slightly below the crest using a round bur. This ensures that a clot formed over which granulation tissue can form.

So what were the take-home messages?

  • Tooth resorption in cats is common and painful
  • The aetiology is not completely understood
  • Radiographs are essential for diagnosis and treatment planning: “Doing dentistry without x-rays is like doing orthopaedics without x-rays”.
  • Treatment options are limited to extraction of affected teeth and coronal amputation of selected teeth.
Dr Hawke is presenting a seminar on dental disease in pets for the Centre for Veterinary Education on May 4. More info here.