Thanks for writing your query.
Itching on your tongue may be due to allergic reaction
of local anaesthetic
agent used prior to extraction or presence of any rough surface or any sharp edges of teeth in the affected area.
So i would suggest you visit back your dentist
and get thorough examination done,if there is any sharp edges or rough surface present in the affected area get it corrected,if it is a allergic reaction of local anaesthetic agent,it will subside with in few days itself.
So i would suggest you do not scrape your tongue,otherwise it will lead to inflammation and redness
You can use lukewarm saline rinses for soothing effect.
Hope this will be helpful.