Tooth resorption is the most common dental problem in cats, with studies worldwide showing a prevalence rate (in cats presented for dental problems) of up to 75%. Many species of animals as well as people experience various types of tooth resorption, but no other species experiences the prevalence of this condition that cats do. Resorptions of permanent teeth in cats have commonly been referred to as feline odontoclastic resorptive lesions (FORLs). They have also been called neck lesions, cervical line erosions, and feline caries.
CLINICAL APPEARANCE AND DIAGNOSIS
On oral examination, FORLs are often associated with a localized, cherry-red, sometimes hyperplastic area of gingivitis (Figure 2). The teeth most commonly affected are the mandibular third premolars; however, all 30 of a cat's teeth are at risk. An FORL can be demonstrated on oral examination by gently brushing the suspected lesion with a thin wisp from a broken wooden cotton-tipped swab or a coarse paper point tip. Gently stimulating these lesions often invokes a strong jaw-chattering response. FORLs are best diagnosed on oral examination of an anesthetized patient by probing with a dental explorer. Record any tooth crown or root defects in a dental chart. Other clinical signs that may be associated with FORLs include a bony bulge over the root of an affected tooth that may occur because of an osteoproliferative response to the root resorption (Figures 3A & 3B). The maxillary canine teeth are most commonly affected with this bone proliferation.
The earliest lesions, confined to the root cementum, are not painful. If the resorption spreads apically, there can be marked destruction of root structure without pain. However, if the lesion progresses coronally and exposes the dentin to the oral cavity, pain is definitely present. Secondary bacterial contamination and inflammation can affect the surrounding periodontal tissues as well. In other words, lesions you can probe or visualize are painful. Lesions you cannot probe but can see on radiographs are probably not painful.
Clinical signs associated with FORLs include anorexia, drooling, refusal to eat the hard portions of the diet, and malaise. The most common clinical presentation in cats with resorptive lesions may be no (overt) sign of pain. If a cat has an FORL in one tooth, it is safe to assume that the cat is at a high risk for other teeth to eventually become affected.
Dividing a disease process into categories is helpful when it can guide treatment decisions. FORLs can be divided into three categories for this purpose: 1) normal-appearing teeth with radiographic evidence of an FORL, 2) teeth with clinical lesions and minimal radiographic root pathology, and (3) teeth with clinical lesions and radiographic evidence of root resorption and ankylosis (fusion between the root and alveolar bone).
Normal teeth with radiographic evidence of FORLs
Teeth that have been identified by radiography with evidence of FORLs but with no abnormal findings on oral examination (and, therefore, not painful) do not need to be immediately extracted. However, these teeth will probably progress to clinical disease at some time in the future. Conservative management (monitoring) is an option, but is incumbent upon a six-month recheck including anesthetizing and re-radiographing. And with monitoring, the prognosis is guarded. Alternatively, the affected teeth can be preemptively extracted.
Clinical lesions and minimal radiographic root pathology
Clinical lesions and radiographic evidence of root resorption and ankylosis
In multirooted teeth, if only one root is affected with resorption, the root exhibiting the resorption should be crown-amputated, and the healthy root should be elevated and routinely extracted.
If you perform dental extraction or crown amputation, manage the patient's pain with a combination of preoperative and postoperative analgesia, intraoral regional nerve blocks, and analgesics for a few days after the procedure. A common protocol would include premedication with hydromorphone, appropriate intraoral regional nerve blocks with bupivacaine hydrochloride, postoperative hydromorphone, and a fentanyl patch. Of course, many other options are available, and the individual pain management plan should be based on the expected degree of pain and the patient's general health status.
Postoperative antibiotics are often given prophylactically for five to seven days. Antibiotics effective against gram-negative anaerobic bacteria are good choices. Other postoperative oral hygiene measures such as oral rinsing with chlorhexidine can be used, but they are often poorly tolerated by cats.
Reevaluate patients two or three weeks after the procedure to verify that healing has occurred. At that time, a dental home care program can be reinstituted. This may include a combination of tooth brushing, dental diets, appropriate chew treats, and a scheduled six-month recheck. Keep in mind that although a home care program is an important tool in preventing periodontal disease and other oral problems, nothing can be done at home to prevent FORLs. This fact has assuaged many clients' guilt.
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"Dental Corner" was contributed by Daniel T. Carmichael, DVM, DAVDC, The Center For Specialized Veterinary Care, 609-5 Cantiague Rock Road, Westbury, NY 11590.