DIFFERENTIAL-DIAGNOSIS OF RESORPTIVE DENT AL LESIONS (FORL) AND CARIES

Feline Odontoclastic Resorptive Lesions (FORL, previously known as ''n eck lesions'') on cat teeth are compared to caries and differentiated with the use of new methods. Radiological examination reveals typical odontoclastic resorptive processes, which take place at the dental roo t and at the paradontium. These lesions demonstrate the destruction on the desmodont and the following ancylosing reaction.The rhodamine B s tain which is selective for caries, stains regions which are softened by caries in a dark red way. Fuchsin/Acetic-Light Green stained histol ogical preparations demonstrate the resorptive lacunae, resorptive lag oons and resoptive canals. Giant cells with multiple nuclei and repara tive cementum can also be shown with the same stain. Hardness measurem ents using a Knoop diamond (KHN, Knoop hardness number) give informati on about the degree of hardness of the different tissues. Electron mic roscopic investigations are performed to show the dentinal tubules and allowing the differentiation between FORT and caries. Since FORT, als o has been found in wild cats we deduced that alimentation has no effe ct on the pathogenesis of the disease.