It is not unknown for faked bite marks to reach court. A fictional example in the recent Wallace and Gromit film, A Matter of Loaf and Death, occurs when the Bake O Lite girl bites herself on the forearm, and has Gromit imprisoned for it.

Gromit’s defence should have been able to show that the mark, although definitely caused by teeth, was not a dog bite and was in a position where it could have been self inflicted. It should not have been necessary to construct casts of Gromit’s own teeth (for comparison with a measured, distortion-free photograph of the mark), but it could be done to show that the mark could not have been made with Gromit’s teeth – except that Gromit doesn’t actually have a mouth!

It would be expected that the Bake O Lite girl would refuse consent for dental impressions of her teeth; and since Wallace was the only other person present, dental casts of his teeth should have been able to eliminate him.
Although the example is fiction, and comedy at that, such events certainly occur in real life!