The Oregonian has rather a lengthy story in today's regarding the impending attempt to remove an infected left tusk from an elephant at Oregon Zoo. 

He broke his left tusk about 14 years ago in California. A veterinarian sawed off the fractured portion flush with Tusko's lip, hoping it would scar over and heal.

And this is how the problem began.  Although The Oregonian inaccurately reports that Tusks are hollow, they actually are not.  Only the portion extending from the sulcus to approximately eighteen inches distally is hollow; the remainder of the tusk is very much solid, as any cursory examination will readily indicate.

The "hollow" portions of the tusk are indeed not hollow at all; they contain blood and nerve supplies that are responsible for effecting the continuous growth of the tusk.  When the veterinarian some years ago sawed the tusk off at what The Oregonian incorrectly refers to as the upper lip, the pulp cavity containing the blood supply and nerves was exposed.  The veterinarian at the time hoped that it would simply heal over, but this is generally not the case.  Exposing the pulp cavity simply provides a comfortable venue for infection to become established.

Once this occurs and no healthy pulp remains in the root canal, extraction is essentially the only reasonable treatment option that remains.  However, although tusks are modified incisors, it's not a simple matter of pulling a tooth.  The morphology of the tusk; in particular, the branching of the root tips, are designed to hold the tusk firmly in place - thus, a conventional extraction procedure (applying force and pulling it away) would simply fracture the upper jawbone of the animal. 

Thus, removal becomes a major operation.  First, the animal must be cued to lie down at a specific location, and in a specific location.  Once this is accomplished, it must be anesthetized.  This would be analagous to attempting to treat the entire Seattle Seahawks team, including the bench, the coach, and the cheerleaders.  We're talking nearly seven tons of animal.

Once the above has been accomplished, you chainsaw through the tusk to create a solid access point, then you drive chisels in to split the tusk into multiple segments.  As the tusk is relatively thin near the sulcus, this can be quickly accomplished.  From there, it becomes a matter of extracting splinters.