Is it harmful to accidentally swallow a piece of my top denture?

Vs. on purpose? If you could swallow it easily; yeah, otherwise it wouldn't be an ''accident''. As long as !) no difficulty in next, 6hrs., 12 hrs or 18.5 hrs & you can take pride in ''creative bowel movements'', you will be ok. If not, what do we do? Right, tell your physician. Umm, right away.
No but depends of th. No but depends of the size to avoid any problems with your dentures is better to have check up at least one a year to check for wear and tear of the acrylic appliance .
Can be. If the piece that you swallow does into the lungs, this can cause serious health issues including death. If you are experiencing any wheezing, chest pain or shortness of breath, go straight to the er or call 911. See an md for an evaluation.
Possibly. Probably not, but it could cause a laceration some where in the digestive tract with the possibility of an infection occurring.