Carnassial Slab Fracture

April 2006
Dr Gerhard Steenkamp

A five year-old Spaniel is presented for routine professional scale and polish.  While assessing the mouth you see the right maxillary 4th premolar presenting with calculus spread in a peculiar way on its surface. (DSC 05326)

A Why would plaque/calculus be spread on the tooth surface as in this case?

B What is the reason for the defect on the 4th premolar tooth?

C What should be recommended to this owner?


A Plaque/calculus will attach to rougher surfaces much quicker than on smooth enamel covered crown. In this photo it is clear to see that there is a depression on the surface of this carnassial (4th premolar) tooth, where the plaque/calculus is accumulating. This depression is most probably caused by trauma (fracture) exposing the rougher dentine where plaque/calculus will attach much faster.

B Fractures of the 4th maxillary premolar tooth is often referred to as a slab fracture.  A fragment of enamel with underlying dentine will shear of the lateral tooth surface, usually as a result of increased pressure on the crown.  The most common reason for this is a dog biting hard on a hard object like bones, cow hooves or stones. Of particular importance is if the slab that shears of exposes the pulp and how deep does the slab shear of below the gingiva.

C Prevention – Change the toys or treats that the dog gets to something more friendly to the teeth.  The feeding of tooth friendly chews like rawhide chews should be encouraged and the feeding of bones and cow hooves are discouraged. Toys made of rubber or rope is also preferable to sticks, stones or other very hard objects substituting as toys.
Treatment – In this particular case the pulp is exposed (Fig DSC 05326) and this should be addressed by root canal treatment if it is important for this tooth to be saved.  It is impossible to view the depth of this slab fracture without the aid of an explorer, but if the fracture extends deeper than 3 mm the prognosis is deteriorating for this tooth to be saved.

Should this not be an essential tooth for this dog (ie show dog) extraction should be offered as treatment of choice.  Should no treatment be performed, the pulpitis/pulpnecrosis will eventually lead to a periapical abscess and possible draining under ventral to the eye.



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