Brush up your knowledge on feline resorptive lesions

Feline tooth resorption along with gingivitis in cats, is one of the most common dental disorders seen in general practice. Also known as feline odontoclastic resorptive lesions (FORLs), feline resorptive lesions are very painful and their prevalence has increased dramatically since the 1960s.¹

It is an area of feline dentistry where there is still much to learn, but what do we know so far? One study², which investigated the prevalence of feline resorptive lesions in a population of 228 cats, showed that:

• Prevalence in the general feline population was 29 percent
• Prevalence increased with age
• The mandibular third premolars (307 and 407) were the most commonly affected feline teeth
• In most cats, development of feline resorptive lesions is symmetrical

Aetiology of feline resorptive lesions

Understanding the underlying cause of feline resorptive lesions is a work in progress. From a clinical perspective, this means that with no one definitive cause, in the vast majority of cases, prevention is not possible.

However there is a significant knowledge base surrounding the pathophysiology of the condition. In the initial stages, odontoclasts destroy the tooth surface. The process begins in the cementum, progressing to the dentine of the root and crown, with the pulp not involved until a late stage of disease. Eventually tooth resorption progresses through the dentine to the enamel of the crown, which is then resorbed or breaks off. It is only at this very advanced stage that lesions become clinically apparent. At the root level, the resorbed tissue is replaced by a bone-like substance.

Resorptive lesions that are visible on clinical examination are already very advanced

As to what triggers this chain of events, further study is needed, but what do we know so far?

Currently there are two main theories

• Peripheral inflammatory root resorption – this is thought to be triggered by periodontal inflammation, which may lead to the movement of odontoclasts into the affected region. Controlling this periodontal inflammation with veterinary and home dental care may have a role in the management of feline resorptive lesions.
• Replacement resorption – which is idiopathic.³

In all cases, lesions are progressive and there is no known cure.

Clinical signs

Clinical signs commonly include:

• Pain (from exposed dentine and pulp irritation)
• Jaw chattering
• Dysphagia
• Hissing at food and running from the bowl
• Increased salivation
• Anorexia
• Dehydration

The disease may be asymptomatic before clinically visible lesions develop.

Diagnosis

Diagnosis is based on a combination of clinical examination and dental radiography.

• Clinical examination, including the use of a dental probe is the first step in diagnosis. Lesions are most commonly found at the cemento-enamel junction and their appearance varies from a pink spot on the tooth to an irregular crown with obvious loss of tooth structure. The surrounding gingiva is often hyperplastic, and lesions may be filled with granulation tissue.
• Dental radiography is imperative because clinical examination only reveals lesions above the margin of the gingiva. Resorptive lesions are visible as radiolucencies, usually at the cemento-enamel junction or tooth furcation.

A comprehensive oral examination may require as many as eight to ten radiographs but if finances are an issue, radiographs of the mandibular premolar regions can be used for screening. If there is evidence of resorption on these views, then full oral radiographs should be obtained.

Top tip: Dental radiographs of the left and right mandibular premolar regions will diagnose 90% of cats with resorptive lesions⁴

Treatment of feline resorptive lesions

There are relatively few options for the treatment of resorptive lesions.

• Conservative treatment may be suitable for lesions which are not apparent on clinical examination but are visible on dental radiography, as long as they are not causing pain. However as most lesions are not detected until they are advanced this is rarely an option.
• Extraction is often the treatment of choice. However it can be challenging, not least because resorbing roots can be very difficult to extract. Extractions should always be preceded by dental radiography. Any post-extraction bleeding can be controlled by gentle pressure, or the use of products such as Haemostem™ Dental Cubes.
• Coronal amputation may be indicated in some circumstances, where there is root resorption for example. After creating a gingival flap, the crown is amputated to below the level of the alveolus, and the flap is then sutured closed. Careful post-operative monitoring, both clinically and radiographically, is needed to ensure the surgical site is healing and to make sure that the roots are continuing to resorb. Coronal amputation is not suitable if there is periodontal disease, endodontic disease, or feline gingivostomatitis.

Is atomising roots with a high speed drill OK?

The answer to this is no. Removing the roots in this way….

• Does not remove root tips
• Damages alveolar bone
• Risks damaging neurovascular bundles
• May cause root fragments to enter the mandibular canal or nasal cavity

Extraction of teeth affected by feline resorptive lesions is the mainstay of management. However, improving oral health through client education, veterinary dental work and the use of suitable dental home care products such as MAXIGUARD® Oral Cleansing Gel, will have long term benefits for pets and their owners.

References

1. Harvey, C. E. and Alston, W. E. (1990) Dental diseases in cat skulls acquired before 1960. In Proceedings of the 4th Annual Veterinary Dental Forum. Las Vegas. pp 41-43
2. Ingham, K.E. et al. (2001) Prevalence of odontoclastic resorptive lesions in a population of clinically healthy cats. Journal of Small Animal Practice, 42: 439-443
3. Gorrel C. (2015) Feline Resorptive Lesions: Aetiology, Pathogenesis, Diagnosis and Management. World Small Animal Veterinary Association Congress Proceedings
4. Heaton M. et al. (2004) A rapid screening technique for feline odontoclastic resorptive lesions. J Small Anim Pract; 45: 598–601