q-tips. Use one q-tip sideways to push her nose up and wedge between her jaws. Then use a second to fish the piece out. A second person holding her may help if she's not used to the q-tip treatment (mine are used to the q-tip oral checks, but they did a lot of squirming first time.)
Edit: You might want to use tweezers or a coffee stir stick to fish the bark out, actually, since q-tips can shred on python teeth. And then you've got cotton AND bark in there.