From now facebook use link such:

https://www.facebook.com/dialog/pagetab?app_id=[app_id]&next=[page-url-on-success]

[app_id] – your application id.
[page-url-on-success] – must be page tab url, or page canvas url.

http://www.gmosx.com/blog/agVnbW9zeHIPCxIHQXJ0aWNsZRjZsAIM/

http://umairj.com/146/how-to-clear-facebook-shares-cache/