A five year old female walrus (Odobenus rosmarus) had a history of
wearing the ends of her tusks by rubbing them on the rockwork in her exhibit. To prevent further
wear, the end of each tusk was protected with a titanium alloy cap. The criteria for the cap was
for it to be strong enough to withstand the rigors of her activities, and to be as thin-walled
as possible to prevent it from being caught on an edge and dislodged.
The procedure involved creating a mold of each tusk out of dental impression
material. This was done as a trained behavior with the walrus allowing the specialized cup of
impression material to be held for the appropriate amount of time to obtain the mold. From the
mold of each tusk a plaster replica was made. Titanium-alloy caps were made to fit the replicas,
allowing space for the dental cement.
The walrus was trained to station long enough to allow the caps to be placed
on to each tusk. A glass ionomer dental cement-powder mix was used to bond the caps to the
tusks. The walrus was kept out of the water and supervised for 30 minutes to allow enough time
for the cement to fully set before she was allowed back into the exhibit.
The longevity of these tusk caps has been impressive. Both were originally
placed on the tusks in January 1999. One cap had to be replaced in January 2001. The other cap
is still in place, over three years after it was originally bonded to the tusk. The tusks
continue to grow normally and while the walrus continues to occasionally rub the ends, there is
little wear to the titanium caps.