Jan Bellows, DVM, DAVDC, DABVP, FAVD
I had no idea what “supernumerary” meant (much less how to spell it) when I first heard the term some 30 years ago. But time and experience have taught me the importance of paying attention to this dental condition that often needs immediate care.
Both extra and supernumerary teeth refer to the same medical condition — hyperdontia — which describes when teeth or odontogenic structures develop from tooth germs in excess of the usual number for any given region of the dental arch. It’s thought that these teeth develop from either a cleaved tooth bud caused by hyperactivity of dental lamina near the regular tooth bud or from splitting the regular tooth bud itself. Heredity may also play a role in this anomaly, as supernumeraries often occur in littermates of affected dogs and cats.
Supernumerary teeth may be single or multiple, unilateral or bilateral, and erupted or impacted. The condition is less common in deciduous (baby) teeth than in permanent teeth.
Why more isn’t always merrier
Not all dogs and cats with supernumerary teeth are in trouble. Some are able to accommodate extra teeth in the arch without adverse effects. In such cases, pay close attention to these teeth during follow-up clinical and intraoral radiograph examinations for the life of the patient (Figures 1A and 1B).
However, supernumerary teeth can cause several problems, as described below:
Eruption failure. The presence of a supernumerary tooth may cause a mechanical blockage of the eruption pathway that prevents a permanent tooth from erupting normally, leading to either partial or complete eruption failure (Figures 2A-2D). The resulting unerupted tooth is predisposed to dentigerous cyst formation, with an enlarged follicular sac often noted clinically and on radiographic examination (Figures 3A-3D).