Display rendered node in view mode X in self node in View mode Y How can I render a node in itself in a different view mode?
If you  want to do this job the one way is achieve  in node.tpl.php (and sub tpls like yourcontenttype--node.tpl.php ), and according to  variables in node tpl
 you can use both  teaser or full mode of node .also you can add your desire variable in theme preprocess ... , there is another  ways to do this with more developing solution