Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
Issue link: http://todaysveterinarypractice.epubxp.com/i/619503
Today's VeTerinary PracTice | January/February 2016 | tvpjournal.com exTernal TooTh resorPTion in caTs Peer reviewed 20 Tooth resorption in cats is prevalent, affecting 28% to 68% of mature cats, depending on the population researched. 1 One study found histologic evidence of resorption in all teeth among cats with at least one clinically apparent resorption site; this led to the hypothesis that given enough time, all teeth of affected cats will develop tooth resorption. 2 A related study found that, in cats with at least one tooth resorption, more than half of the nonclinical teeth had histologic evidence of root resorption; only 8% of the teeth examined from cats without tooth resorption had similar lesions. 2 Tooth resorption also affects dogs to a lesser extent. Unfortunately, because an exact cause of tooth resorption in dogs or cats is still undetermined, it is unknown why cats are affected more clinically. This article defnes tooth resorption and theories about its cause and pathogenesis, and explains which teeth in cats are predisposed and how tooth resorption is classifed and diagnosed. In a follow-up article, we will review therapy for this prevalent and often painful condition (Figure 1). TERMINOLOGY Tooth resorption is a process by which the dentin in a single tooth—or several teeth simultaneously— erodes and eventually becomes irreparably destroyed. Over time, all areas of an affected tooth, from root to crown, may become involved. This disease differs from: • Periodontal disease, in which the support structures of the tooth—cementum, periodontal tissue, ligament, and alveolar bone—are affected • Feline stomatitis, an immune-mediated inflammatory reaction to plaque. At one time, these lesions were called cat cavities because of their clinical and radiographic similarity to human caries; however, cavity or caries is an incorrect term. Tooth resorption differs clinically and histologically from human caries (cavity). Caries is caused by cariogenic bacteria (mainly Streptococcus mutans) that ferment highly refned carbohydrates on the tooth's surface. Acids are released during this fermentation process, resulting in demineralization of enamel and dentin and bacterial infection of the pulp. 3 In cats, tooth resorption has also been referred to as neck lesions, external odontoclastic resorptions, feline odontoclastic resorptive lesions, feline oral resorptions, and cervical line erosions. The current accepted terminology by the American Veterinary Dental College is tooth resorption. 4 TYPES OF TOOTH RESORPTION External Versus Internal Resorption External resorption, or root resorption, is the breakdown or destruction and subsequent loss of the root structure of a tooth; it affects only the root. In humans, external root resorption is classifed as surface, infammatory, or replacement (noninfammatory) resorption. Internal root resorption occurs when the integrity of the outermost layer of pulp tissue is broached. It starts on the pulpal surface and extends toward the external aspect of the tooth. External root resorption is far more common than internal root resorption. 5 ExtErnal tooth rEsorption in Cats Part 1: Pathogenesis, Classifcation, & Diagnosis Jan Bellows, DVM, Diplomate AVDC & ABVP (Canine & Feline) All Pets Dental, Weston, Florida FIGURE 1. Clinical appearance of tooth resorption of right mandibular fourth premolar and frst molar.