I wish to redirect all demands from ex-ample.com to example.com. The url structure should stay the same, I simply want to "replace" the "-" in domain...

http://www.ex-ample.com/asdf123
redirects to:
http://www.example.com/asdf123

thanks!

If it is only a single hyphen:

RewriteCond %{HTTP_HOST} ^([^-]+)-([^-]+)$
RewriteRule ^ http://%1%2%{REQUEST_URI} [L,R]