Update on the Etiology of Tooth Resorption in Domestic Cats

Feline odontoclastic resorptive lesions (FORL) were first recognized and histologically differentiated from caries in the 1920s [1,2]. Some anecdotal reports describing caries-like lesions at the cervical region of feline teeth followed in the 1950s and 1960s, until two microscopic studies in the 1970s again revealed that FORL were not caries but a type of tooth resorption [3,4]. A recent study showed that cats with FORL have a significantly lower urine specific gravity and significantly higher serum concentration of 25-hydroxyvitamin D (25OHD) compared with cats without FORL [5], indicating that multiple tooth resorption in domestic cats could be the manifestation of some systemic insult rather than a local cause. In this article, the histologic and radiographic appearance of FORL and certain other peculiarities of feline teeth are reviewed. An attempt is then made to compare these findings with changes of the periodontium induced by administration of excess vitamin D or vitamin D metabolites in experi-mental animals. Histologic and radiographic features of feline odontoclastic resorptive lesion