I just checked the original thread and Bart posted an autopsy version of Oswald and Jim posted the best copy of the Life Magazine article that he could photograph and what do you know, from this angle Oswald's teeth at the front had the same symmetry with an apparent space in the same place and then this space when compounded with what appears to be Oswald's swollen lip or he could be just stretching his top lip which blocks out those front teeth and gives the appearance of missing teeth.
So unlike Josephs added tooth above which doesn't fit the following gif shows that all the teeth fit into place!
The following composited teeth are
perfect unlike Oswald's asymmetrical crooked teeth but seeing the above gif you should get the general idea.
Conclusion.There was no alteration.
There was no missing teeth.
The teeth we see are either the very edge or underneath.
So there!
JohnM