Shark's teeth
This website shows there are three types of shark's teeth, traditional triangular cutting teeth, short crushing teeth and pointed gripping teeth. Yours looks like the last type
Take a look at the photo showing three cutting, upper teeth from the Hemipristus species and the lower teeth. The middle lower one looks very much like yours. I makes sense because shark's don't all hunt and feed on the same things so not all will need teeth for the same function.
It seems I was half right in that the upper part does look like shark's teeth because it was. I just didn't know about the variations in the bits of the teeth sticking out of the shark's mouth.
Hope this helps.