Clear the cache and try again. If this doesn’t work try installing the alternative CKEditor plugin and activating it (if you have the TinyMCE Advanced plugin, deactivate it before activating the CKEditor).
You can then deactivate CKEditor (and activate TinyMCE Advanced if installed) and TinyMCE should work. You may also need to clear the cache again.
I had the same issues as you did and found the solution here:
http://wordpress.org/support/topic/wordpress-331-tinymce-advanced-345-still-shows-old-buttons (though that post is for a rather different issue)
Interestingly I only had the issue with one of the two sites I updated.
