In doubt about amending

Dear Sirs:

  My name is Curtis L Poykko and I've finished my taxes and received my refund and very satisfied with your service.

  My question regards a $41,115.00 dental bill that I didn't think could be deducted by filling the short form that I did.  

  Can I deduct the dentist expense?  If I can, can it be done on next years taxes? Can we amend this years taxes after I have received the refund? Is it even worth the effort?

Thank you in advance for your help and courtesy.