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B. Niemiec1
1Veterinary Dental Specialties and Oral Surgery, Dentistry, San Diego, USA
Feline Tooth resorption (TR)
TRs are a very common malady. Reports vary as to their incidence, but approximately 60% of cats over 6 years of age have at least one, and those that have one typically have more. These lesions are caused by odontoclasts which are cells that are responsible for the normal remodelling of tooth structure. These cells are activated and do not down regulate, resulting in tooth destruction.
There are currently two recognized forms of resorptive lesions, type 1 and type 2. Clinically, they appear
very similar, as dental defects that are first noted at
the gingival margin. However, advanced cases will show significant tooth destruction and may appear
to be a fractured tooth. The best diagnostic tool for differentiating between types is dental radiology. With type 1 lesions, there is no replacement of the lost root structure by bone, whereas with type 2 there is generally marked replacement of the lost tooth structure.
Type 1 TRs are typically associated with inflammation such as caudal stomatitis or periodontal disease. In these cases, it is thought that the soft tissue inflammation has activated the odontoclasts. The inciting cause of class
1 lesions is a cemental defect. Odontoclasts move in
and destroy the dentin, leading to secondary enamel loss and a resorption lacuna. The weakened crown will eventually fracture, and in these cases the root canal system stays intact resulting in continued pain and infection for the patient.
Type 2 lesions are generally seen in otherwise healthy mouths; however the lesions will create local gingivitis. The etiology of type 2 TRs remains unproven. The two major current theories are abfraction injuries from eating hard food and excess vitamin D in the diet. Type 2 TRs show histological evidence of simultaneous repair of the defect by osteoblasts at the same time that tooth is being resorbed by odontoclasts.
Historically, restoration was a recommended therapy, however due to the progressive nature of the disease; extraction is now the treatment of choice. Extractions can be very difficult in these cases due to tooth weakening and ankylosis. Additionally, in some cases, there is little to no tooth structure remaining. In cases with significant weakening and or ankylosis, performing the extractions via a surgical approach is recommended to speed the procedure and decrease the incidence of fractured and retained roots.
Recently, crown amputation has been suggested as an acceptable treatment option for advanced type 2 lesions as it results in significantly less trauma and faster healing than complete extraction. This procedure, although widely accepted, is still controversial. Most veterinary dentists employ this technique, however in widely varying frequency. Veterinary dentists typically employ this treatment option only when there is significant or complete root replacement by bone. Unfortunately, the majority of general practitioners use this technique far too often. Crown amputation should only be performed on teeth with radiographically confirmed advanced type 2 TRs which show no peri-apical or periodontal bone loss. Crown amputation should not be performed on teeth with: type 1 TRs, radiographic or clinical evidence of endodontic or periodontal pathology, inflammation,
or infection; or in patients with L/P stomatitis. Those practitioners without dental radiology capability SHOULD NOT perform crown amputation. In these cases, the teeth should either be fully extracted or the patient referred to a facility with dental radiology.
Fractured teeth
This is very similar to canine endodontics. However, true fractures are rare in any teeth except the canines. Teeth with direct pulp exposure are painful and/or infected
and require root canal therapy or extraction. Root canal therapy is always recommended if possible as extraction of the maxillary canines is challenging and maxillary canine extraction carries a high risk of lip catching. (see below).
There are two main differences between dogs and cats with regard to endodontic disease. First, the pulp chamber of the canine teeth extends very close to the cussp tip. This means that any fracture (no matter how small) is suspect for endodontic disease. Anesthesia for careful probing and dental radiographs should be performed for any fracture. Secondly, cats will tend to resorb the root apex when a tooth has a chronic infection.
Lip trauma following maxillary canine extraction
In my experience, approximately 1/3 of cats that have maxillary cuspids extracted surgically will develop lip trauma from the mandibular canine. For this reason, we try to avoid extracting maxillary canines when possible preferring to perform root canal therapy or periodontal surgery if indicated.
Many of these cats will show no clinical signs, however if the lip is examined, ulcers will be present. These cats are painful and are in need of therapy. Other patients may show mild to severe evidence of discomfort.
The options for therapy include coronal amputation and vital pulp therapy or extraction of the offending mandibular canine.
Case report: “Sid” had both maxillary canines extracted elsewhere due to periodontal disease. He presented with
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