Feline Tooth Resorption (TR) is a syndrome in

cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

s characterized by resorption of the

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

odontoclast An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated pro ...

s, cells similar to

osteoclast An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated pro ...

s. TR has also been called "feline odontoclastic resorption lesion" (FORL), neck lesion, cervical neck lesion, cervical line erosion, feline subgingival resorptive lesion, feline caries, or feline cavity. It is one of the most common diseases of domestic cats, affecting up to two-thirds. TRs have been seen more recently in the history of feline medicine due to the advancing ages of cats, but 800-year-old cat skeletons have shown evidence of this disease. Purebred cats, especially Siamese and

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s, may be more susceptible. Dental anatomy TRs clinically appear as erosions of the surface of the tooth at the

gingiva The gums or gingiva (plural: ''gingivae'') consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health. Structure The gums are part of the soft tissue lin ...

l border. They are often covered with

calculus Calculus, originally called infinitesimal calculus or "the calculus of infinitesimals", is the mathematical study of continuous change, in the same way that geometry is the study of shape, and algebra is the study of generalizations of arithm ...

or gingival tissue. It is a progressive disease, usually starting with loss of

cementum Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.Illustrated Dental Embryology, Histology, ...

and dentin and leading to penetration of the

pulp Pulp may refer to: * Pulp (fruit), the inner flesh of fruit Engineering * Dissolving pulp, highly purified cellulose used in fibre and film manufacture * Pulp (paper), the fibrous material used to make paper * Molded pulp, a packaging material ...

cavity. Resorption continues up the

dentinal tubules Bone canaliculi are microscopic canals between the lacunae of ossified bone. The radiating processes of the osteocytes (called filopodia) project into these canals. These cytoplasmic processes are joined together by gap junctions. Osteocytes do ...

into the tooth crown. The enamel is also resorbed or undermined to the point of tooth fracture. Resorbed cementum and dentin is replaced with bone-like tissue.

Clinical signs

Clinical signs of TRs are often minimal since the discomfort can be minor. However, there may be subtle signs of discomfort while chewing, as well as anorexia, dehydration, weight loss, and tooth fracture. The lower third premolar is the most commonly affected tooth.

Cause

There are two types of TR. "Type 1" lesions are focal defects often caused by local inflammation. "Type 2" lesions are characterized by a generalized loss of root radiopacity on a dental radiograph. The definitive cause of type 2 TRs is unknown, but

histologically Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

destruction of the cementum and other mineralized tissue of the tooth root by odontoclasts is seen. It occurs secondary to the loss of the protective covering of the root (the

periodontal ligament The periodontal ligament, commonly abbreviated as the PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which it sits. It inserts into root cementum one side and onto alveolar b ...

s) and possibly to a stimulus such as

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main caus ...

and the release of

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

s, leading to odontoclast migration. However, FORLs can develop in the absence of inflammation. The natural inhibition to root resorption provided by the lining of the root may be altered by increased amounts of

Vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...

, in cats supplied by their diet.

Treatment

Treatment for TRs is limited to

tooth extraction A dental extraction (also referred to as tooth extraction, exodontia, exodontics, or informally, tooth pulling) is the removal of teeth from the dental alveolus (socket) in the alveolar bone. Extractions are performed for a wide variety of reason ...

because the lesion is progressive. Amputation of the tooth crown without root removal has also been advocated in cases demonstrated on a radiograph to be type 2 resorption without associated periodontal or endodontic disease because the roots are being replaced by bone. However,

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

s are recommended prior to this treatment to document root resorption and lack of the periodontal ligament.

Tooth restoration Dental restoration, dental fillings, or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth structure resulting from caries or external trauma as well as to the replacement of such structure sup ...

is not recommended because resorption of the tooth will continue underneath the restoration. Use of

alendronate Alendronic acid, sold under the brand name Fosamax among others, is a bisphosphonate medication used to treat osteoporosis and Paget's disease of bone. It is taken by mouth. Use is often recommended together with vitamin D, calcium supplementati ...

has been studied to decrease progression of existing lesions.

Differential diagnosis: dental caries

True

dental caries Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complicat ...

are uncommon among companion animals. Although it has not been accurately documented in cats, the incidence of caries in dogs has been estimated at 5%. The term ''feline cavities'' is commonly used to refer to TRs; however, saccharolytic acid-producing bacteria are not involved in this condition.

References

{{Reflist

External links

Feline odontoclastic resorption lesions
- American Veterinary Dental College position statement.
''Feline Oral Resorptive Lesions'' (FORL) from Veterinary Partner
Cat diseases Veterinary dentistry