We don’t know for sure. The Soviets and the NKVD played a lot of games with pics of his corpse (totally intact when we know he was burned), claiming they never found him, etc. There is no way to know for sure they’re his teeth..
There were pictures of a Hitler look alike who was found dead on a street.
The Russian army took pictures and kept the body. The lookalike “Hitler” was quickly debunked as he was wearing darned socks and a patched shirt, something Hitler probably wouldn’t have done even to escape.
Several time the Russians have given permission for scientists to perform limited experiments on the skeletal remains only to pull the permission once the scientists got to Moscow.