I know it's scary but it will be sharp coming back up too.
The only option you really have is to let it pass, or do exploratory surgery, which would be even riskier than just letting it work it's way out. A small piece of plastic like that wouldnt show up in an xray, so a vet would have to get extremely lucky with their first incision into the GIT, or, there is going to be a lot more damage done at the hands of a scalpel.
This happens from time to time and so far I haven't heard of one case where any real harm came to the dragon. We probably get something like this happening once every other month here.
Just watch for potential blood in the poo and general sickly behavior. but really like I said, this isnt too uncommon, it's just scary when it happens
-Brandon