SEO urls to Dynamic downgrade

I am using phpbb forum, with some seo plugin, which turned all my dynamic urls "viewtopic.php?=1234" to SEO urls such as "/super-jackpot-t821.html". I was happy with it.

but now problme is, i have moved host, moved phpbb to sub folder and upgraded to latest phpbb. Now that plugin stopped working and all the urls are already indexed by google, yahoo etc.

So i was thinking is it possible to 301 redirect SEO urls ba开发者_运维百科ck to normal urls? May be picking the last 821 number of seo url using HTACCESS and turning it back to viewtopic.php?t=821 ???

thankx.

Here's a htaccess guide i found.

http://www.garnetchaney.com/htaccess_tips_and_tricks.shtml

to match 0 to 9999 the regex should be ^[0-9]{1,4}$