December 2006
Dr Gerhard Steenkamp

A 6 year-old Cocker spaniel is presented for a routine scale and polish.  On oral examination you see the following lesion on the left carnassial tooth.

Picture DSC 04373

a) Describe the lesion present.
b) What are your differential diagnoses for this type of lesion?
c) What is the etiology for this type of lesion?
d) What treatment options are available for this type of lesion?

Answer:
Picture DSC 04376

a) There is a pink semicircular lesion at the rostral ginigval margin of the crown.  Furthermore the crown has a pink discoloration.

b) Enamel chip fracture, Gingival hyperplasia, Odontoclastic resorptive lesion.  This is a case of an odontoclastic resorptive lesion in a dog.  The pink semicircular lesion is gingival hyperplasia due to the rough surface of the tooth.  The pink discolouration of the crown is due to internal resorption of the pulp chamber.  Resorptive lesions are often associated with pulpal hyperplasia and hence as the dentinal wall is resorped and becomes thinner, the pulp/pulpal hyperplasia or pulpal trauma (bleeding) becomes visible through the crown.

c) At this point the aetiology is unclear.  One case in the literature presented with hypothyroidism, but this has never been the case with the cases I have seen.  Resorptive lesions in dogs are rare compared to cats.  These animal usually appear to be painful only once the pulp becomes exposed and often undergoes hyperplastic changes

d) As for cats, these teeth should be extracted.  Before any surgery is attempted radiography should confirm the presence or abscence of these lesions on the other teeth.  A mucogingival flap is raised when extraction is performed (see photo).  In this case it is evident that the 3rd premolar tooth is also affected but this was not visible on the original photo.  Crown amputation can be used only if any signs of infection, radiographically or on probing is absent and if ankylosis between the tooth and the alveolar bone is present.  The latter technique should never be used if the criteria can not be established